Self-operated Electric Temperature Regulating Valve DN15-300 0-350°C Factory

A Self-operated Electric Temperature Regulating Valve (also called Self-actuated Temperature Control Valve, Self-operated Thermostatic Regulating Valve, Temperature Regulator, or Self-powered Temperature Control Valve) is an energy-saving, self-powered automatic temperature control valve that requires NO external power supply (electricity) and NO compressed air - it operates by using a temperature sensor (immersion bulb + capillary tube filled with a thermally-sensitive medium) to detect the temperature of the controlled medium, and the thermal expansion or contraction of the sensing medium (which changes volume/pressure with temperature) drives a diaphragm, bellows, or piston actuator, which in turn moves the valve core to automatically adjust the valve opening and maintain the medium temperature at a pre-set, stable value - forming a standalone, closed-loop mechanical temperature regulator without any external energy, electronics, or control signal. Unlike conventional temperature control valves (which require an external electric or pneumatic actuator, a temperature transmitter (PT100/thermocouple), a temperature controller, and a 4-20mA control signal from a DCS/PLC), the self-operated temperature valve integrates sensing + actuation + regulation in one unit: the bulb is immersed in the controlled medium (e.g., heat exchanger outlet, tank, pipeline), the capillary transmits the thermal expansion force to the actuator, and the actuator positions the valve core - when the medium temperature rises above the set value, the sensing medium expands, increasing pressure/volume in the bulb/capillary/actuator, which drives the valve to close (cooling type) or open (heating type), changing the flow of heating/cooling medium until the temperature returns to the set value; when temperature drops, the sensing medium contracts, and the spring (or opposing force) moves the valve in the opposite direction - this mechanical thermal feedback loop provides automatic, continuous temperature regulation without any external energy, making it inherently reliable, energy-saving, and ideal for remote sites, hazardous areas, and applications where installing power/air/control lines is impractical or costly. It is specially designed for temperature control of heating/cooling media (steam, hot water, thermal oil, chilled water, cooling water) in heat exchangers, HVAC systems, industrial processes, oil coolers, chemical reactors, food/pharma processing, dyeing, and boiler feedwater - with two action modes: (a) Cooling Type - controls downstream temperature by reducing the flow of heating medium (when temp rises, valve closes → less heating medium → temp drops; the most common type, used for steam/hot water heating control); (b) Heating Type - controls downstream temperature by increasing the flow of heating medium (when temp rises, valve opens → more heating medium? - actually heating type is used when the valve controls cooling medium: when temp rises, valve opens → more cooling → temp drops; or for heating medium where more flow = more heat - terminology varies; core is "direct-acting" vs "reverse-acting"); regulation accuracy ±1~3°C (higher than self-operated pressure valves ±5-10%, because thermal expansion is more linear and predictable), on-line set temperature adjustment (top adjusting screw, no shutdown), capillary length 1-10m (bulb can be located remotely from valve), bulb immersion/insertion installation (bulb must be fully immersed in controlled medium for accurate sensing), temperature ranges segmented (0-120°C, 20-180°C, 50-250°C, 100-350°C - change bulb/sensing medium for different ranges), DN15–DN300 (1/2"–12"), PN1.6–4.0MPa (Class 150–300), body materials WCB, CF8 (304), CF8M (316), internal parts 304, 316L, PTFE, graphite, flange connection (GB/T 9113, HG/T 20592, ANSI B16.5) or threaded, leakage ANSI Class IV (hard seal) or Class VI (soft seal), actuator type diaphragm (standard), bellows, or piston, sensing medium water/glycol/oil/mercury/steam (selected per temperature range), and wide applications in heat exchanger temperature control, HVAC heating/cooling, industrial process temperature, oil cooler, chemical reactor, food/pharma, dyeing, boiler feedwater. The core highlights are: (a) No external energy (core): (i) no electricity, no compressed air, no temperature transmitter/controller; (ii) bulb + capillary + actuator = integrated sensing+actuation; (iii) standalone closed-loop mechanical temperature regulator; (iv) energy-saving, reliable, works in remote/hazardous areas; (b) Temperature control (not pressure/flow): (i) bulb senses medium temperature; (ii) thermal expansion drives actuator; (iii) regulates flow of heating/cooling medium to control temperature; (c) Cooling/Heating type: (i) cooling = reduce heating flow on temp rise; (ii) heating = increase heating/cooling flow on temp rise (direct/reverse acting); (d) Accuracy ±1~3°C: (i) higher than self-operated pressure (±5-10%); (ii) thermal expansion linear/predictable; (e) On-line set temp adjustment: top screw, no shutdown; (f) Capillary 1-10m: bulb remote from valve (flexible installation); (g) Bulb immersion: must be fully in controlled medium; (h) Temp ranges segmented: 0-120/20-180/50-250/100-350°C (change bulb/medium); (i) Wide range: DN15-300, PN1.6-4.0; (j) Materials: WCB/CF8/CF8M; trim 304/316L+PTFE/graphite; (k) Connections: flange/threaded; (l) Leakage: Class IV/VI; (m) Actuator: diaphragm/bellows/piston; (n) Sensing medium: water/glycol/oil/mercury/steam; (o) vs electric/pneumatic temp control valve: those need external actuator + temp transmitter + controller + 4-20mA, higher accuracy (±0.5°C), but more complex/costly; this = self-powered, ±1-3°C, simple; (p) vs self-operated micro-pressure valve: that controls pressure (0.5-100KPa), this controls temperature; (q) key difference: this valve = self-operated (no external energy), temperature control, bulb+capillary sensing, diaphragm/bellows/piston, heating/cooling medium flow regulation. This is the reliable self-powered temperature regulator.

The no-external-energy self-powered operation (temperature bulb + capillary filled with thermally-sensitive medium, thermal expansion/contraction drives diaphragm/bellows/piston actuator against calibrated spring, mechanical closed-loop, no electricity/air/electronics/temperature transmitter/controller), temperature-control specialization (bulb immersion sensing, thermal expansion force, regulates heating/cooling medium flow to maintain medium temperature), cooling/heating action modes (cooling type reduces heating medium flow on temperature rise, heating type increases heating/cooling medium flow on temperature rise - direct/reverse acting), on-line set temperature adjustment (top adjusting screw, no shutdown), high accuracy ±1~3°C (thermal expansion is linear and predictable, higher than self-operated pressure valves), remote capillary (1-10m, bulb can be located away from valve in tank/heat exchanger/pipeline), segmented temperature ranges (0-120/20-180/50-250/100-350°C, change bulb/sensing medium), and diaphragm/bellows/piston actuator options make this valve a specialized self-operated temperature regulator - distinct from electric/pneumatic temperature control valves (which require external actuator + PT100/thermocouple temperature transmitter + temperature controller + 4-20mA signal, offer ±0.5°C accuracy, DCS integration, but are more complex and costly) and from self-operated pressure regulating valves (which control pressure, not temperature, using pressure sensing instead of temperature bulb) and from thermostatic radiator valves (small, low-pressure, for HVAC radiators only) - designed for automatic, continuous, energy-free temperature control of heating/cooling media (steam, hot water, thermal oil, chilled water, cooling water) in heat exchangers, HVAC heating/cooling systems, industrial process temperature control, oil coolers, chemical reactors, food/pharma processing, textile dyeing, and boiler feedwater, where no external power/air is available, simple reliable temperature control is needed, or energy savings and low maintenance are priorities. Compared to other regulator/control valve types: (a) Single-seat control valve (pneumatic/electric): needs external energy, 4-20mA, <±1%, flow/pressure/temp control (with external sensor) - not standalone temp; (b) Sleeve control valve (electric): needs external energy, high ΔP, low noise, flow control - not temp; (c) Pneumatic three-way control valve: needs air, mix/split, temp/ratio (with external sensor) - not standalone; (d) Electric three-way control valve: needs power, mix/split, temp/ratio - not standalone; (e) Self-operated micro-pressure valve: NO external energy, pressure-only, 0.5-100KPa, diaphragm - not temp; (f) Self-operated temperature (this valve): NO external energy, temperature-only, bulb+capillary, ±1-3°C, heating/cooling medium flow; (g) Electric/pneumatic temp control valve: external energy + temp transmitter + controller, ±0.5°C, DCS - complex/costly; (h) Thermostatic radiator valve: small DN15-25, low pressure, HVAC only - not industrial; (i) This valve: direct-operated, self-powered, temperature, bulb+capillary, industrial DN15-300 PN1.6-4.0; (j) key difference: this valve is self-operated (no external energy) for TEMPERATURE control - not externally-actuated, not pressure control. Working principle (detailed): (a) temperature sensing: bulb immersed in controlled medium (e.g., heat exchanger outlet); (b) thermal expansion: sensing medium (water/glycol/oil/mercury/steam) in bulb expands when temp rises → pressure/volume increases in closed bulb+capillary+actuator system; (c) actuator drive: increased pressure acts on diaphragm/bellows/piston → moves stem/valve core; (d) cooling type (direct-acting for heating medium): temp rises → sensing medium expands → valve closes → less heating medium (steam/hot water) → downstream temp drops; (e) temp drops: sensing medium contracts → spring pushes valve opens → more heating medium → temp rises; (f) heating type (reverse-acting, or for cooling medium): temp rises → valve opens → more cooling medium → temp drops; (g) equilibrium: at set temp, expansion force = spring force → valve stable at corresponding opening; (h) continuous mechanical loop - no external energy; (i) set adjustment: turn top screw → compresses/releases spring → changes set temp (on-line). Temperature sensor (bulb + capillary, detailed): (a) bulb: stainless steel (304/316) cylindrical probe, filled with sensing medium, immersed in controlled medium; (b) capillary: small-bore stainless tube (2-6mm OD), connects bulb to actuator, transmits pressure/volume change; (c) length: 1-10m (standard 3m, custom); (d) insulation: capillary may be insulated (for high ambient or long runs); (e) sensing medium: (i) water (0-120°C); (ii) glycol/water (0-150°C); (iii) oil (20-250°C); (iv) mercury (0-350°C, toxic - restricted); (v) steam/saturated vapor (100-350°C, high sensitivity); (f) bulb installation: (i) immersion length: ≥100mm or 2/3 of bulb in medium; (ii) orientation: bulb vertical (tip down) for liquid, any for gas; (iii) thermowell optional (for high pressure/corrosive - bulb in well, well in medium); (iv) location: at point where temp is to be controlled (e.g., heat exchanger outlet), representative of controlled medium, avoid dead zones. Actuator types (detailed): (a) diaphragm (standard): large area, high sensitivity, for low force (temp range 0-200°C), NBR/FKM diaphragm; (b) bellows: metal bellows (316L), for higher force/temp, longer stroke, zero external leak; (c) piston: for high force (large DN, high temp, high ΔP), O-ring sealed, robust; (d) selection: (i) small DN/low temp → diaphragm; (ii) medium → bellows; (iii) large DN/high temp/high ΔP → piston. Cooling vs Heating type (detailed): (a) Cooling type (most common): (i) valve installed on heating medium supply (steam, hot water, thermal oil) to heat exchanger/process; (ii) bulb on heated medium outlet (downstream of heat exchanger); (iii) when outlet temp rises → valve closes → less heating medium → outlet temp drops; (iv) when outlet temp drops → valve opens → more heating medium → outlet temp rises; (v) use: steam heating control, hot water heating, thermal oil heating; (b) Heating type (reverse-acting): (i) valve installed on cooling medium supply (chilled water, cooling water) to cooler/condenser; (ii) bulb on cooled medium outlet; (iii) when outlet temp rises → valve opens → more cooling medium → outlet temp drops; (iv) when outlet temp drops → valve closes → less cooling → outlet temp rises; (v) use: chilled water cooling, oil cooler, condenser; (c) also called: direct-acting (cooling, closes on temp rise) / reverse-acting (heating, opens on temp rise); (d) select per what medium valve controls (heating = cooling type, cooling = heating type). Accuracy (±1-3°C, detailed): (a) regulation accuracy = temp fluctuation = ±1~3°C (better than self-operated pressure ±5-10%); (b) factors: (i) bulb immersion (fully immersed = better); (ii) capillary length (shorter = faster, longer = slower); (iii) sensing medium (steam/vapor = most sensitive, oil = linear); (iv) flow rate variation; (v) heating/cooling medium pressure variation; (vi) ambient temp (capillary exposed); (c) higher accuracy options: electric/pneumatic temp control (±0.5°C, with transmitter+controller); (d) ±1-3°C sufficient for most industrial temp control (heat exchanger, HVAC, process). Response time: (a) typical: 10-60 seconds (thermal lag - bulb must heat/cool, sensing medium expand/contract, capillary transmit); (b) faster: short capillary, large bulb, vapor sensing medium; (c) slower: long capillary, oil sensing, large heat exchanger (thermal mass); (d) not for fast temp transients (use electric/pneumatic for fast response). Temp ranges (segmented): (a) 0-120°C: water/glycol sensing, HVAC, low-temp process; (b) 20-180°C: oil/glycol, hot water, low-pressure steam; (c) 50-250°C: oil, medium-pressure steam, thermal oil; (d) 100-350°C: mercury/steam, high-pressure steam, high-temp thermal oil; (e) change bulb+sensing medium for different range (not just spring); (f) overlap ranges for flexibility. Installation (detailed): (a) valve orientation: actuator upright (stem vertical), flow direction per arrow; (b) valve location: on heating/cooling medium supply line (not on controlled medium line); (c) bulb location: (i) immersed in controlled medium at point of interest (e.g., heat exchanger outlet, tank, process line); (ii) ≥2/3 bulb length immersed; (iii) vertical (tip down) for liquid; (iv) thermowell if high pressure/corrosive; (d) capillary: (i) route from bulb to actuator, avoid sharp bends (min bend radius 50mm), avoid high heat sources, avoid damage; (ii) insulate if ambient varies or long run; (iii) support capillary (don't hang by capillary); (e) straight pipe: ≥5D upstream, ≥3D downstream of valve (for stable flow); (f) strainer upstream (protect seat/trim); (g) isolation valves + bypass (for maintenance); (h) no vibration (mount rigidly); (i) set temp adjustment: top screw (CW/CCW per type), on-line. Maintenance: (a) annual: set temp verification (compare to calibrated thermometer), leakage test, bulb inspect (corrosion, dents), capillary inspect (kinks, leaks, insulation), trim inspect, strainer clean; (b) 3-5yr: replace diaphragm/bellows (if rubber), replace spring, replace trim, gaskets, sensing medium recharge (if leak), full test; (c) bulb/capillary is key (if damaged → sensing medium leak → valve fails - replace bulb+capillary assembly); (d) spares: diaphragm, spring, trim, gaskets, bulb+capillary assembly (per temp range/sensing medium). Troubleshooting: (a) temp not stable/hunting: (i) bulb not fully immersed (install deeper); (ii) capillary kinked/too long (repair/shorten); (iii) flow demand changing rapidly; (iv) heating/cooling medium pressure fluctuating; (v) wrong action type (cooling vs heating reversed); (vi) oversized valve (operates <10%); (b) cannot reach set temp (too low): (i) heating medium pressure too low (B type - can't heat if supply low); (ii) valve undersized (can't pass enough heating medium); (iii) temp range wrong (set below range - change bulb); (iv) bulb/capillary leak (loss of sensing medium - replace); (v) strainer clogged; (c) cannot reach set temp (too high): (i) temp range wrong (set above range); (ii) valve stuck open (trim); (iii) seat leaking (cooling type: seat leak → too much heating → temp high); (iv) wrong action type; (d) external leak: (i) diaphragm/bellows rupture (replace); (ii) gasket (replace); (iii) capillary leak (replace bulb+capillary); (e) slow response: (i) bulb not immersed (install); (ii) capillary too long/kinked; (iii) sensing medium type (oil slower than vapor); (iv) large thermal mass (heat exchanger); (f) bulb/capillary damage: (i) dent/corrosion (replace); (ii) leak (sensing medium escapes - valve fails open/closed, replace assembly). Important: (a) self-operated = NO external energy (bulb+capillary thermal expansion drives actuator); (b) temperature control (not pressure/flow); (c) cooling type (heating medium, closes on temp rise) / heating type (cooling medium, opens on temp rise); (d) bulb must be immersed in controlled medium; (e) capillary 1-10m, avoid kinks/heat; (f) ±1-3°C accuracy; (g) temp ranges segmented (0-120/20-180/50-250/100-350, change bulb/medium); (h) on-line set adjustment; (i) DN15-300, PN1.6-4.0; (j) actuator diaphragm/bellows/piston; (k) sensing medium water/glycol/oil/mercury/steam; (l) bulb/capillary = key wear/sensitive part; (m) warranty: 18 months. With proper type (cooling/heating), temp range, bulb location, capillary routing, installation, calibration, and maintenance, this self-operated electric temperature regulating valve provides reliable energy-free temperature control.

1.No External Energy - Self-powered Temperature Control

Requires NO electricity, NO compressed air, NO temperature transmitter (PT100/thermocouple), NO temperature controller, and NO 4-20mA control signal - the immersion bulb + capillary filled with thermally-sensitive medium detects temperature and its thermal expansion/contraction directly drives the diaphragm/bellows/piston actuator to regulate valve opening. Standalone mechanical closed-loop temperature regulator. Energy-saving, inherently reliable, works in remote sites, hazardous areas, and locations where power/air/control lines are impractical. Zero operating energy cost.

2.Temperature Sensor (Bulb + Capillary) + High Accuracy

Stainless steel immersion bulb (304/316) + capillary tube (1-10m, standard 3m) filled with thermally-sensitive medium (water/glycol/oil/mercury/steam) detects controlled medium temperature. Thermal expansion drives actuator with predictable, linear force. Regulation accuracy ±1~3°C (higher than self-operated pressure valves). Bulb must be fully immersed (≥2/3 length) in controlled medium; thermowell optional for high pressure/corrosive. Capillary insulated optional for long runs/variable ambient.

3.Cooling Type / Heating Type (Direct/Reverse Acting)

Cooling Type (direct-acting, most common) - installed on heating medium supply (steam/hot water/thermal oil), closes on temperature rise to reduce heating flow and lower downstream temperature. Heating Type (reverse-acting) - installed on cooling medium supply (chilled/cooling water), opens on temperature rise to increase cooling flow and lower temperature. Select based on whether valve controls heating or cooling medium. Both on-line set temperature adjustable via top screw.

4.Segmented Temperature Ranges + On-line Adjustment

Temperature ranges segmented by bulb/sensing medium: 0-120°C (water/glycol), 20-180°C (oil/glycol), 50-250°C (oil), 100-350°C (mercury/steam). Change bulb+sensing medium for different range (not just spring). Set temperature within range adjusted on-line by top adjusting screw (compresses/releases calibration spring), no shutdown required. Locking nut secures set value. Overlapping ranges available for flexibility.

5.Diaphragm/Bellows/Piston Actuator + Balanced Trim

Actuator options: diaphragm (standard, large area, high sensitivity, NBR/FKM, low-temp), bellows (316L metal, higher temp/force, zero external leak), piston (high force for large DN/high ΔP, O-ring sealed, robust). Valve core: balanced single-seat/double-seat to reduce unbalanced force for stable regulation. No packing (diaphragm/bellows seals stem) - zero friction, zero external leakage. Quick-opening or modified-linear characteristic.

6.Wide Materials + Connections + Standards

DN15–300 (1/2"–12"), PN1.6–4.0MPa (Class 150–300), temp range 0-350°C (segmented). Body/bonnet: WCB, CF8(304), CF8M(316). Trim: 304, 316L, PTFE, graphite. Connections: flange (GB/T 9113/HG 20592/ANSI B16.5), threaded (NPT/BSP, DN≤50). Leakage Class IV (hard) / Class VI (soft). Designed per GB/T 4213, ANSI/ISA-75, ASME B16.34; tested per GB/T 4213 (temperature regulation, 100%), API 598. ISO 9001, CE. 18-month warranty, OEM/ODM.

A Self-operated Electric Temperature Regulating Valve operates as a standalone, self-powered, mechanical closed-loop temperature regulator - it requires no external electricity, compressed air, temperature transmitter, or controller; instead, an immersion bulb (filled with a thermally-sensitive medium) is placed in the controlled medium (e.g., heat exchanger outlet, tank, pipeline), connected via a capillary tube to the actuator (diaphragm/bellows/piston), forming a closed, fluid-filled system - when the medium temperature changes, the sensing medium in the bulb expands or contracts (changing pressure or volume in the closed system), which acts on the actuator to move the valve core, changing the flow of heating or cooling medium, until the controlled medium temperature returns to the set value - this thermal-mechanical feedback loop continuously and automatically regulates temperature without any external energy input. The valve consists of a globular valve body (with inlet/outlet for heating/cooling medium, valve seat, balanced core), a stem, an actuator (diaphragm/bellows/piston + calibrated spring + top adjusting screw), and a temperature sensor (bulb + capillary + sensing medium). Thermal expansion principle (detailed): (a) closed system: bulb + capillary + actuator chamber are sealed and filled with sensing medium (liquid or vapor); (b) temperature rises: sensing medium in bulb expands (liquid) or vapor pressure increases (vapor) → pressure in closed system rises; (c) pressure acts on actuator: diaphragm/bellows/piston sees increased pressure → moves stem/valve core (against spring); (d) temperature drops: sensing medium contracts → pressure drops → spring pushes actuator back; (e) equilibrium: at set temperature, expansion pressure = spring force → valve stable at fixed opening; (f) no external energy - energy comes from heat (temperature difference) driving thermal expansion. Cooling Type operation (direct-acting, most common, detailed): (a) installation: valve on heating medium supply (steam, hot water, thermal oil) to heat exchanger/process; bulb on heated medium outlet (downstream of heat exchanger); (b) outlet temp rises above set: (i) bulb temp rises → sensing medium expands → system pressure increases; (ii) actuator moves → valve closes (reduces heating medium flow); (iii) less heating medium to heat exchanger → outlet temp drops back to set; (c) outlet temp drops below set: (i) bulb cools → sensing medium contracts → pressure drops; (ii) spring pushes → valve opens (more heating medium); (iii) more heating → outlet temp rises; (d) equilibrium: valve modulates to maintain outlet temp = set; (e) use: steam heating, hot water heating, thermal oil heating. Heating Type operation (reverse-acting, detailed): (a) installation: valve on cooling medium supply (chilled water, cooling water) to cooler/condenser; bulb on cooled medium outlet; (b) outlet temp rises above set: (i) bulb temp rises → expansion → actuator moves → valve opens (more cooling medium); (ii) more cooling → outlet temp drops; (c) outlet temp drops below set: (i) contraction → spring → valve closes (less cooling); (ii) outlet temp rises; (d) use: chilled water cooling, oil cooler, condenser, air conditioning. Note on terminology: some manufacturers define "cooling type" = valve on cooling medium (opens on temp rise), "heating type" = valve on heating medium (closes on temp rise) - the key is direct-acting (closes on temp rise, for heating medium) vs reverse-acting (opens on temp rise, for cooling medium). Confirm at order with application description. Temperature sensor (bulb + capillary, detailed): (a) bulb: (i) material: 304/316 stainless steel (corrosion resistant); (ii) shape: cylindrical probe, 8-15mm OD, 50-200mm length; (iii) filled with sensing medium (evacuated, then filled); (iv) immersion: ≥2/3 of bulb length in controlled medium (for accurate sensing); (v) orientation: vertical tip-down for liquid (ensures sensing medium in bulb, not capillary); any for gas; (vi) thermowell: optional (bulb inserted in well, well in medium - for high pressure/corrosive/abrasive, allows bulb removal without draining); (b) capillary: (i) material: 304/316 stainless, 2-6mm OD, 0.5-1mm wall; (ii) length: 1-10m (standard 3m, custom); (iii) function: transmits pressure/volume change from bulb to actuator; (iv) routing: avoid sharp bends (min radius 50mm), avoid high heat sources, avoid mechanical damage, support at intervals; (v) insulation: optional (foam/fiberglass) for long runs or variable ambient (prevents ambient temp affecting sensing medium in capillary); (c) sensing medium: (i) water: 0-120°C, low cost, safe, high expansion; (ii) glycol/water (ethylene/propylene): 0-150°C, lower freeze point, safe; (iii) oil (mineral/silicone): 20-250°C, linear expansion, stable; (iv) mercury: 0-350°C, high sensitivity, but toxic (restricted in many countries - use oil/steam alternative); (v) saturated vapor (e.g., water/ethanol/acetone vapor): 50-350°C, very high sensitivity (vapor pressure changes exponentially with temp), fast response; (d) selection: per temp range, medium compatibility, safety (mercury restriction), response need. Actuator types (detailed): (a) diaphragm actuator (standard): (i) large-area rubber diaphragm (NBR/FKM) + spring; (ii) high sensitivity (large area × pressure = force); (iii) for small-medium DN (≤100), low-medium temp (≤200°C), low ΔP; (iv) diaphragm also seals stem (no packing, zero external leak); (v) stroke 10-40mm; (b) bellows actuator: (i) metal bellows (316L/Hastelloy) + spring; (ii) higher force, higher temp (≤350°C), corrosion resistant; (iii) zero external leak (bellows seal); (iv) for medium DN, medium-high temp; (v) stroke 15-50mm; (c) piston actuator: (i) piston (metal) + O-ring + cylinder + spring; (ii) high force (pressure × piston area), for large DN (>100), high ΔP, high temp; (iii) O-ring seal (some friction, but robust); (iv) stroke 20-60mm; (d) selection: (i) small DN/low temp/low ΔP → diaphragm; (ii) medium → bellows; (iii) large DN/high temp/high ΔP → piston. Calibrated spring + set adjustment (detailed): (a) spring: 50CrVA, calibrated, provides opposing force to thermal expansion; (b) set temp adjustment: (i) top adjusting screw/handwheel → compresses/releases spring; (ii) more compression → higher set temp (spring pushes harder, needs more expansion to move); (iii) on-line (adjust during operation); (c) locking nut: secures set temp; (d) spring range: matched to temp range (one spring per bulb/medium range); (e) set temp pre-adjusted at factory per order, field-adjustable. Balanced trim (detailed): (a) heating/cooling medium (steam, water, oil) can have high ΔP → unbalanced force on valve core; (b) balanced single-seat: core with balance hole → pressure acts both sides → cancel; (c) double-seat: two seats, forces oppose; (d) purpose: reduce unbalanced force → actuator can position valve accurately → stable temp regulation; (e) leakage: single-seat Class IV/VI, double-seat higher (Class III/IV). Temperature regulation accuracy (±1-3°C, detailed): (a) accuracy = temp fluctuation around set = ±1~3°C; (b) why higher than self-operated pressure (±5-10%): (i) thermal expansion of liquid/vapor is more linear/predictable than gas pressure; (ii) bulb provides stable sensing; (iii) closed fluid system transmits force directly; (c) factors affecting accuracy: (i) bulb immersion (partial = lower accuracy); (ii) capillary length (long = slower, ambient effect); (iii) sensing medium (vapor = most sensitive/accurate); (iv) heating/cooling medium pressure variation (affects heat transfer); (v) flow rate variation; (vi) ambient temp on capillary (insulate); (vii) thermal lag of controlled system (heat exchanger mass); (d) improving accuracy: (i) fully immerse bulb; (ii) short/insulated capillary; (iii) vapor sensing medium; (iv) stable heating/cooling medium pressure; (v) correct sizing (valve operates 30-70%); (e) higher accuracy (±0.5°C): use electric/pneumatic temp control (PT100 + controller + actuator). Response time (detailed): (a) typical: 10-60 seconds (from temp change to valve response); (b) components of lag: (i) bulb thermal lag (bulb must heat/cool - mass of bulb + medium); (ii) sensing medium expansion (fast); (iii) capillary transmission (pressure wave - fast, but volume change slower); (iv) actuator movement (fast); (v) controlled system thermal lag (heat exchanger - large mass = slow); (c) faster: short capillary, large bulb, vapor medium, small system; (d) slower: long capillary, oil medium, large heat exchanger; (e) not for fast transients (use electric/pneumatic for <10s response). Temp ranges (segmented, detailed): (a) 0-120°C: (i) sensing: water/glycol; (ii) actuator: diaphragm (NBR); (iii) use: HVAC, low-temp process, food; (b) 20-180°C: (i) sensing: oil/glycol; (ii) actuator: diaphragm (FKM) or bellows; (iii) use: hot water, low-pressure steam, HVAC; (c) 50-250°C: (i) sensing: oil; (ii) actuator: bellows; (iii) use: medium-pressure steam, thermal oil; (d) 100-350°C: (i) sensing: mercury/steam; (ii) actuator: bellows/piston; (iii) use: high-pressure steam, high-temp thermal oil; (e) change range = replace bulb+capillary+sensing medium (and possibly actuator/spring); (f) overlap ranges for flexibility (e.g., 50-200, 100-250). Installation (detailed): (a) valve: (i) actuator upright (stem vertical); (ii) flow direction per arrow (heating/cooling medium through valve); (iii) on heating/cooling medium supply line (NOT on controlled medium line); (iv) ≥5D straight pipe upstream, ≥3D downstream; (v) strainer upstream; (vi) isolation valves + bypass; (b) bulb: (i) at point where temp is to be controlled (e.g., heat exchanger outlet, tank, process line); (ii) ≥2/3 immersed in controlled medium; (iii) vertical tip-down (liquid), any (gas); (iv) thermowell if high pressure/corrosive; (v) avoid dead zones, stratification; (c) capillary: (i) route from bulb to actuator; (ii) min bend radius 50mm (no kinks); (iii) avoid hot surfaces (above sensing medium temp); (iv) avoid mechanical damage (shield); (v) support at 1m intervals (don't hang valve by capillary); (vi) insulate if ambient varies or >3m; (d) startup: (i) fill heating/cooling medium line; (ii) ensure bulb immersed; (iii) adjust set temp (top screw); (iv) wait for stabilization (10-60s); (v) verify temp with calibrated thermometer; (d) set calibration: compare bulb reading to calibrated thermometer at controlled point, adjust top screw. Maintenance (detailed): (a) annual: (i) set temp verification (compare to calibrated thermometer at bulb location); (ii) leakage test (seat, external); (iii) bulb inspect (corrosion, dents, immersion depth); (iv) capillary inspect (kinks, corrosion, leaks, insulation); (v) trim inspect (if accessible); (vi) strainer clean; (vii) valve exercise (vary set temp up/down 10%); (b) 3-5yr: (i) replace diaphragm/bellows (if rubber/metal fatigue); (ii) replace spring; (iii) replace trim (core/seat); (iv) replace gaskets; (v) bulb+capillary assembly (if suspect leak/corrosion - replace with correct sensing medium/range); (vi) full temp regulation test (accuracy, response); (vii) seat leakage test; (c) bulb/capillary is critical: (i) if damaged (dent, corrosion, leak) → sensing medium escapes → valve fails (stuck open/closed); (ii) replace assembly (not repairable in field); (iii) keep spare (correct temp range/sensing medium/length); (d) spares: diaphragm, spring, trim, gaskets, bulb+capillary assembly. Troubleshooting (detailed): (a) temp hunting/oscillating: (i) bulb not fully immersed (install deeper/thermowell); (ii) capillary kinked/too long (repair/shorten/insulate); (iii) heating/cooling medium pressure fluctuating (stabilize); (iv) flow demand changing rapidly; (v) wrong action type (cooling/heating reversed - check); (vi) oversized valve (operates <10% - size down); (vii) controlled system has large thermal lag (normal - accept slower); (b) cannot reach set temp (too low): (i) heating medium pressure/flow too low (cooling type - can't heat); (ii) valve undersized (can't pass enough heating medium); (iii) temp range wrong (set below range min - change bulb/medium); (iv) bulb/capillary leak (loss of sensing medium - replace); (v) strainer clogged (clean); (vi) bulb not in hottest/correct location; (c) cannot reach set temp (too high): (i) temp range wrong (set above range max); (ii) valve stuck open (trim/debris - clean); (iii) seat leaking (cooling type: seat leak → too much heating → temp high - replace/lap seat); (iv) wrong action type (heating type installed as cooling); (v) bypass valve open (close); (d) external leak: (i) diaphragm/bellows rupture (replace); (ii) gasket (replace); (iii) capillary leak (replace bulb+capillary - sensing medium escapes); (e) slow response: (i) bulb not immersed (install); (ii) capillary too long/kinked (shorten/repair); (iii) sensing medium (oil slower than vapor); (iv) large thermal mass (heat exchanger - normal); (f) bulb/capillary damage: (i) dent/corrosion (replace - affects sensing); (ii) leak (sensing medium escapes - valve fails, replace assembly); (g) valve not moving: (i) no temp change (system stable - normal); (ii) bulb/capillary failed (replace); (iii) trim seized (clean/repair); (iv) spring broken (replace). Safety notes: (a) mercury sensing medium: toxic, restricted in EU/US - use oil/steam alternative if possible; handle/dispose per hazardous waste; (b) high temp bulb/capillary: burn hazard (insulate/guard); (c) steam/hot oil: high pressure/temp - proper PPE, isolation before maintenance; (d) bulb in pressurized system: use thermowell (allows bulb removal without depressurizing); (e) capillary: don't use as support/step (damage). Important: (a) self-operated = no external energy (bulb+capillary thermal expansion drives actuator vs spring); (b) temperature control (not pressure/flow); (c) cooling type (heating medium, closes on temp rise) / heating type (cooling medium, opens on temp rise); (d) bulb must be immersed (≥2/3) in controlled medium; (e) capillary 1-10m, avoid kinks/heat, insulate if long; (f) ±1-3°C accuracy; (g) temp ranges segmented (0-120/20-180/50-250/100-350, change bulb/medium); (h) on-line set adjustment; (i) DN15-300, PN1.6-4.0; (j) actuator diaphragm/bellows/piston; (k) sensing medium water/glycol/oil/mercury/steam; (l) bulb/capillary = key part (replace if damaged); (m) warranty: 18 months. With proper type (cooling/heating), temp range, bulb location, capillary routing, installation, calibration, and maintenance, this self-operated electric temperature regulating valve provides reliable energy-free temperature control.

• Heat Exchanger Temperature Control

Automatically maintain stable outlet temperature of shell-and-tube, plate, or finned heat exchangers by regulating steam, hot water, thermal oil (cooling type) or chilled/cooling water (heating type) flow. Bulb installed at heat exchanger outlet, capillary to valve on heating/cooling medium supply. No external power needed, ideal for remote heat exchanger stations, industrial heating/cooling loops, and energy-recovery systems. WCB/SS body, PTFE/graphite seal, accuracy ±1-3°C. Reliable for heat exchanger temperature regulation.

• HVAC Heating & Cooling

Maintain stable supply/return water temperature in HVAC heating (hot water/steam) and cooling (chilled water) systems, air handling units, fan coils, boilers, and chillers. Cooling type on heating boiler feed, heating type on chiller water supply. Bulb in supply water header, capillary 3-5m to mechanical room valve. Energy-saving (no power), simple, reliable, no controls needed. DN25-150, PN1.6, 0-120°C water/glycol sensing. Reliable for HVAC temperature control.

• Industrial Process Temperature

Regulate process fluid temperature in chemical, petrochemical, and manufacturing processes - reactor jackets, distillation column reboilers, evaporators, dryers, and process heating/cooling loops. Controls steam/thermal oil flow to maintain reactor/process temperature at set value. Bulb in process line/vessel, capillary to valve on utility supply. CF8/CF8M body for corrosive, 50-250°C oil sensing. Reliable for industrial process temperature.

• Oil Cooler & Lubrication Systems

Maintain stable oil temperature in turbine/generator/compressor/engine lubrication oil coolers, hydraulic oil coolers, and transformer oil cooling. Heating type valve on cooling water supply to oil cooler, bulb in oil outlet - when oil temp rises, valve opens more cooling water. Prevents oil overheating (viscosity loss, oxidation), critical for equipment protection. WCB/SS body, 20-180°C range. Reliable for oil cooler temperature control.

• Food/Pharma & Textile Dyeing

Precise temperature control for food processing (pasteurization, CIP, cooking, sterilization), pharmaceutical (reactor, fermentation, purification), and textile dyeing (dye bath temperature, drying, finishing) - where stable temperature ensures product quality and consistency. SS304/316L body for sanitary/corrosive, PTFE seal (FDA optional), 0-200°C range, bulb in product stream. No external power (safe for wash-down/hazardous). Reliable for food/pharma/dyeing temperature. 18-month warranty, OEM/ODM.

Our Self-operated Electric Temperature Regulating Valves are manufactured under an ISO 9001:2015 certified quality management system, with every valve undergoing rigorous inspection and testing at each production stage - because these valves are self-powered, standalone temperature regulators used in heat exchangers, HVAC, industrial process, oil coolers, food/pharma, dyeing where temperature regulation accuracy (±1-3°C), bulb/capillary integrity (sensing medium leak-free), actuator function, seat leakage, response time, and material compatibility directly determine temperature stability, product quality, equipment protection, and energy savings (the bulb+capillary assembly and temperature regulation test are critical additional quality points unique to self-operated temperature valves).

Raw material control: every body/trim/stem/bulb/capillary/actuator material batch comes with material certificate; WCB verified (ASTM A216); CF8/CF8M verified (ASTM A351 stainless); trim 304/316L verified; bulb/capillary 304/316 verified (wall thickness, pressure rating); diaphragm (NBR/FKM - material cert, hardness, burst test); bellows (316L - helium leak test); spring 50CrVA verified (calibrated); sensing medium (water/glycol/oil - purity, fill quantity verified; mercury - certified, handled per regulation).

Body manufacturing: (a) casting/forging; (b) heat treatment; (c) 100% visual; (d) NDT - UT/MT/PT of body (PN1.6+ 100%); (e) wall thickness; (f) machining (flanges, seat bore, stem guide); (g) chemical/mechanical/hardness per heat; (h) surface treatment - painted (WCB), pickled/passivated (SS); (i) nameplate (stainless, engraved - model, DN, PN, type cooling/heating, temp range, sensing medium, capillary length, material, serial).

Bulb + capillary manufacturing (critical, unique): (a) bulb: (i) 304/316 seamless tube, wall thickness verified (≥0.5mm); (ii) closed one end (welded, 100% leak test); (iii) fill port; (iv) length/OD per spec; (b) capillary: (i) 304/316 seamless tube, 2-6mm OD; (ii) straight/coiled, no kinks; (iii) pressure test (1.5× max working); (c) assembly: (i) bulb welded to capillary; (ii) capillary welded to actuator connection; (iii) evacuation: system evacuated (remove air/moisture - prevents inaccurate sensing); (iv) fill: inject sensing medium (water/glycol/oil/mercury/steam) - quantity verified by weight/volume; (v) seal: seal fill port (weld/crimp); (vi) 100% leak test: (1) pressure hold test (pressurize, hold 24h, no pressure drop); (2) bubble test (immerse in water, no bubbles); (3) helium leak test (high-sensitivity, if required); (d) calibration: (i) immerse bulb in temp-controlled bath; (ii) verify expansion pressure vs temp curve (matches sensing medium spec); (iii) label temp range + sensing medium; (e) bulb immersion length marked.

Actuator manufacturing (critical): (a) diaphragm: (i) NBR/FKM, reinforced, 100% inspect (thickness, visual, burst test); (ii) installed in housing (clamp evenly, no wrinkle); (b) bellows: (i) 316L, 100% helium/air leak test, stroke test; (c) piston: (i) metal, O-ring groove, sliding fit (no bind); (ii) O-ring verified; (d) spring: (i) 50CrVA, calibrated rate, set test; (ii) matched to temp range; (e) assembly: diaphragm/bellows/piston + spring + stem + adjusting screw, full stroke test (smooth, no bind).

Temperature regulation test (critical, 100% every valve): (a) test rig: (i) valve installed on heating/cooling medium supply (e.g., hot water/steam); (ii) controlled medium loop with heater/cooler + bulb location; (iii) calibrated temperature reference (PT100, ±0.1°C) at bulb; (b) procedure: (i) set temp (per order) via adjusting screw; (ii) vary heating/cooling medium or controlled load; (iii) measure controlled medium temp over time; (iv) accuracy: temp fluctuation = ±1~3°C (record); (v) response time: 10-60s (record); (vi) action type: verify cooling (closes on temp rise) or heating (opens on temp rise); (vii) set adjustment: verify on-line adjust works; (viii) no hunting: stable after settling; (c) 100% of valves undergo this test (not just type).

Testing - 100% every valve: (1) hydrostatic shell - 1.5× PN, body/bonnet/gasket no leak (actuator isolated or blinded); (2) seat leakage - Class IV (hard) / Class VI (soft), per ANSI B16.104 / GB/T 4213; (3) temperature regulation test - set temp, accuracy ±1-3°C, response, action type, no hunting (critical); (4) bulb+capillary leak test - pressure hold + bubble (no sensing medium leak); (5) bulb calibration - expansion vs temp curve; (6) actuator function - full stroke, smooth; (7) spring calibration - set range; (8) external leak - no leak at gaskets, stem (diaphragm/bellows seal), capillary; (9) material cert + NDT; (10) nameplate (type cooling/heating, temp range, sensing medium, capillary length).

Material traceability: unique serial; database: material cert (body, trim, bulb, capillary, diaphragm, spring, sensing medium), heat, NDT, hydro, seat leakage, temperature regulation test (accuracy, response, set temp, action type), bulb+capillary leak test, bulb calibration, actuator, production, inspector, DN, PN, type (cooling/heating), temp range, sensing medium, capillary length, body material, actuator type, order.

Coating & marking: exterior painted (WCB - epoxy), stainless pickled/passivated; valve marked: model, self-operated electric temperature regulating valve, DN, PN, type (cooling/heating, direct/reverse acting), temp range (e.g., 20-180°C), sensing medium, capillary length, body material, actuator type, flow direction arrow, pressure/temp rating, standard, serial, year, manufacturer; nameplate stainless engraved; bulb tagged (temp range, sensing medium, length).

Documentation: test report (hydro, seat leakage, temperature regulation [accuracy/response/set/action type], bulb+capillary leak, bulb calibration), material cert, temp range chart, dimensional drawing, manual (installation, bulb immersion, capillary routing, operation, set adjustment, maintenance, troubleshooting, cooling/heating selection, bulb replacement, spares), CE/ISO cert.

Warranty: 18 months from shipment or 12 months from installation (valve body + trim + actuator housing); wear parts (diaphragm, spring, seat, gaskets, bulb+capillary assembly) not covered under normal wear (bulb+capillary 5-8yr life under normal conditions - schedule inspection); consumables (sensing medium, strainer screen) not covered; extended warranty, spare parts kit (diaphragm, spring, trim, gaskets, bulb+capillary assembly), on-site calibration/service, bulb replacement available.

Safety/performance commitment: (a) no valve ships without 100% hydro + seat leakage + temperature regulation test (accuracy ±1-3°C) + bulb+capillary leak test + bulb calibration; (b) bulb+capillary 100% pressure-hold + bubble tested; (c) sensing medium fill verified (evacuated, correct quantity); (d) action type (cooling/heating) verified by test; (e) set temp pre-adjusted to order (if specified); (f) material traceable; (g) sizing guidance provided (Cv, temp range, cooling/heating type, bulb length, capillary length, sensing medium); (h) mercury handled per regulation (offered where allowed, oil/steam alternative recommended).

Q: What is a self-operated electric temperature regulating valve, and how is it different from electric/pneumatic temperature control valves?

A: A Self-operated Electric Temperature Regulating Valve is a self-powered, standalone automatic temperature control valve that requires NO external electricity, NO compressed air, NO temperature transmitter (PT100/thermocouple), NO temperature controller, and NO 4-20mA control signal - it uses an immersion bulb + capillary filled with a thermally-sensitive medium (water/glycol/oil/mercury/steam) to detect the controlled medium temperature, and the thermal expansion/contraction of the sensing medium directly drives a diaphragm/bellows/piston actuator to adjust the valve opening and maintain temperature at a set value (±1~3°C accuracy), forming a mechanical closed-loop regulator with integrated sensing+actuation+regulation. The key difference from electric/pneumatic temperature control valves is the power source, components, and complexity. Here's the detailed explanation. What is a self-operated electric temperature regulating valve: (a) self-operated/self-actuated: powered by thermal expansion (heat energy from medium), no external energy; (b) electric in name = "thermal-electric" effect (thermal expansion drives mechanical actuator - not electrical; some markets call it "self-operated temperature" or "thermostatic" valve); (c) temperature regulating: controls temperature (not pressure/flow) by regulating heating/cooling medium flow; (d) structure: valve body + balanced trim + stem + actuator (diaphragm/bellows/piston + spring) + bulb+capillary (filled with sensing medium); (e) no packing (diaphragm/bellows seals stem); (f) two types: cooling (direct-acting, on heating medium) / heating (reverse-acting, on cooling medium); (g) standalone: install bulb in medium, set temp, and it regulates automatically. Self-operated temp vs Electric/Pneumatic temp control valve - detailed comparison: | Feature | Self-operated Temp (This Valve) | Electric Temp Control Valve | Pneumatic Temp Control Valve | |---|---|---|---| | Power source | Thermal expansion (heat, self) | Electricity (AC220/380/DC24) | Compressed air (0.14-0.5MPa) | | External energy? | NO | Yes (power) | Yes (air) | | Temperature sensor | Integrated bulb+capillary (no transmitter) | External PT100/thermocouple (transmitter) | External PT100/thermocouple | | Controller | None (mechanical set point) | Temperature controller (PID) | Temperature controller (PID) | | Control signal | None (mechanical) | 4-20mA / 0-10V | 4-20mA (to positioner) | | Accuracy | ±1~3°C | ±0.5°C (with PID) | ±0.5°C (with PID+positioner) | | Response time | 10-60s | 5-30s | 2-15s | | External components | None (valve + bulb only) | Actuator + transmitter + controller + cables | Actuator + positioner + transmitter + controller + air lines | | Failure mode | Spring to default (mechanical) | Hold / manual override | Spring fail-safe (FC/FO) | | Energy cost | Zero | Electricity | Air compressor | | Best for | Simple temp control, no energy, remote/hazardous, cost-sensitive | High accuracy, DCS, fast, complex | High accuracy, fast, hazardous (pneumatic) | | Cost (total) | Low (no auxiliaries) | Medium-high (valve + controls) | Medium-high (valve + air infra + controls) | Core differences explained: (a) Power source: (i) self-operated: heat → sensing medium expansion → mechanical force (energy from temperature difference); (ii) electric: motor drives stem (external power); (iii) pneumatic: compressed air drives diaphragm (external air); (b) Sensing: (i) self-operated: bulb+capillary integrated (no electronics, no calibration drift); (ii) electric/pneumatic: external PT100/thermocouple → transmitter → controller (electronic, needs calibration); (c) Control loop: (i) self-operated: mechanical closed-loop (bulb → expansion → actuator → valve → temp → bulb); (ii) electric/pneumatic: electronic closed-loop (sensor → transmitter → controller → signal → actuator → valve → temp → sensor); (d) Accuracy: (i) self-operated: ±1-3°C (mechanical, no PID); (ii) electric/pneumatic: ±0.5°C (PID tuning, high resolution); (e) Components: (i) self-operated: valve + bulb (2 pieces); (ii) electric/pneumatic: valve + actuator + transmitter + controller + cables/air (5+ pieces); (f) Installation: (i) self-operated: simple (mount valve, immerse bulb, set); (ii) electric/pneumatic: complex (wire actuator, install sensor, wire controller, configure PID, tune); (g) Reliability: (i) self-operated: high (no electronics, no power failure risk); (ii) electric/pneumatic: lower (electronics can fail, power/air loss); (h) Cost: (i) self-operated: low total (no auxiliaries); (ii) electric/pneumatic: higher (valve + controls + installation). When to choose self-operated temp (this valve): (a) need simple temperature control (heat exchanger, HVAC, oil cooler); (b) no external power/air available (remote site, hazardous area); (c) energy savings priority (zero operating energy); (d) high reliability, low maintenance (no electronics); (e) accuracy ±1-3°C acceptable (most industrial temp control); (f) cost-sensitive (low total cost); (g) typical: steam heating control, hot water HVAC, oil cooler, food processing. When to choose electric/pneumatic temp control: (a) need high accuracy ±0.5°C (precision process, pharma, lab); (b) need DCS/PLC integration (remote monitoring, data logging, alarm); (c) need fast response (<10s, rapid temp changes); (d) need complex control (cascade, ratio, PID tuning, multiple sensors); (d) need valve position feedback; (e) typical: reactor precision temp, semiconductor, aerospace, high-end pharma. Self-operated temp vs self-operated pressure valve: (a) self-operated pressure (previous product): (i) senses pressure (downstream/upstream); (ii) diaphragm sees medium pressure; (iii) regulates pressure; (iv) range 0.5-100KPa; (b) self-operated temp (this valve): (i) senses temperature (bulb in medium); (ii) bulb+capillary sensing medium expansion; (iii) regulates temperature; (iv) range 0-350°C; (c) both self-operated (no external energy) but different controlled variable (pressure vs temperature); (d) different actuator/sensor (pressure diaphragm vs temp bulb+capillary). Self-operated temp vs thermostatic radiator valve (TRV): (a) TRV: (i) small DN15-25, PN10; (ii) wax element sensor (integrated on valve body, not remote bulb); (iii) HVAC radiator only; (iv) low pressure/temp; (b) this valve: (i) industrial DN15-300, PN1.6-4.0; (ii) remote bulb+capillary (1-10m); (iii) industrial process (heat exchanger, oil cooler, reactor); (iv) high pressure/temp (to 350°C); (c) this valve = industrial-grade, TRV = residential HVAC. Direct-acting vs reverse-acting (cooling vs heating): (a) direct-acting (cooling type): temp rises → valve closes (for heating medium - less heat → temp drops); (b) reverse-acting (heating type): temp rises → valve opens (for cooling medium - more cooling → temp drops); (c) both maintain temp - difference is what medium valve controls; (d) select: valve on heating medium → direct/cooling type; valve on cooling medium → reverse/heating type. Common mistakes: (a) using for high-accuracy ±0.5°C (it's ±1-3°C - use electric/pneumatic); (b) no bulb immersion (must be ≥2/3 in medium); (c) wrong action type (cooling vs heating - valve works against temp); (d) capillary kinked (blocks expansion transmission); (e) using mercury in restricted countries (use oil/steam); (f) expecting fast response (<10s - it's 10-60s); (g) installing valve on controlled medium line (should be on heating/cooling medium supply). Important: (a) self-operated temp = no external energy, bulb+capillary, temperature control, ±1-3°C; (b) electric/pneumatic temp = external energy + PT100 + controller, ±0.5°C, DCS; (c) choose self-operated for simple/reliable/energy-free temp control; (d) choose electric/pneumatic for high-accuracy/fast/complex temp control; (e) this valve = industrial self-operated temp (not residential TRV); (f) cooling (heating medium) / heating (cooling medium) type; (g) tell us your medium (heating/cooling), temp range, controlled medium, bulb location, accuracy need - we recommend self-operated vs electric/pneumatic and cooling/heating type. This valve = a self-operated electric temperature regulating valve is a self-powered standalone temperature regulator that uses an immersion bulb + capillary filled with thermally-sensitive medium to detect medium temperature, and the thermal expansion/contraction of that medium directly drives a diaphragm/bellows/piston actuator to adjust the valve opening and maintain temperature at a set value - requiring no electricity, no compressed air, no temperature transmitter (PT100/thermocouple), no temperature controller, and no 4-20mA signal (it integrates sensing+actuation+regulation in one mechanical unit); compared to electric/pneumatic temperature control valves: (1) power - self-operated uses thermal expansion energy (zero operating cost, works anywhere) vs electric needs electricity and pneumatic needs compressed air; (2) sensing - self-operated has an integrated bulb+capillary (no electronics, no calibration drift) vs electric/pneumatic need an external PT100/thermocouple transmitter + PID controller + wiring/air lines; (3) accuracy - self-operated ±1~3°C (mechanical, no PID) vs electric/pneumatic ±0.5°C (with PID tuning); (4) response - self-operated 10-60s (thermal lag) vs electric 5-30s / pneumatic 2-15s; (5) components - self-operated is valve+bulb only (simple install, high reliability, no power-failure risk) vs electric/pneumatic need actuator+transmitter+controller+cables/air (complex, higher total cost); (6) best use - self-operated for simple, reliable, energy-free temperature control in heat exchangers, HVAC, oil coolers, food/pharma, dyeing where ±1-3°C is acceptable and no power/air is available, vs electric/pneumatic for high-accuracy (±0.5°C), fast, DCS-integrated, complex temperature control; it also differs from self-operated pressure regulating valves (which control pressure, not temperature, using pressure sensing instead of a temperature bulb) and from residential thermostatic radiator valves (small DN15-25, wax element, HVAC only - this is industrial DN15-300, PN1.6-4.0, remote bulb); choose this valve when you need simple, reliable, energy-free industrial temperature control with ±1-3°C accuracy, and choose an electric/pneumatic temperature control valve when you need ±0.5°C accuracy, DCS integration, or fast response - provide your heating/cooling medium, desired temperature range, controlled medium, and bulb location and we confirm cooling (direct-acting, for heating medium) or heating (reverse-acting, for cooling medium) type and correct bulb/sensing medium.

Q: What's the difference between cooling type and heating type?

A: The Cooling Type (direct-acting) and Heating Type (reverse-acting) are the two action modes of this valve, differing in what medium the valve controls and how the valve responds to temperature rise: Cooling Type is installed on the heating medium supply (steam, hot water, thermal oil) and closes when temperature rises (reducing heating flow to lower downstream temperature - the most common type), while Heating Type is installed on the cooling medium supply (chilled water, cooling water) and opens when temperature rises (increasing cooling flow to lower downstream temperature). Here's the detailed comparison. Cooling Type - direct-acting (detailed, most common ~70%): (a) what it controls: heating medium (steam, hot water, thermal oil) supply to heat exchanger/process; (b) bulb location: in heated medium outlet (downstream of heat exchanger - the medium whose temp is being controlled); (c) operation: (i) heated medium outlet temp rises above set: bulb heats → sensing medium expands → actuator moves → valve closes (reduces heating medium flow); (ii) less heating medium to heat exchanger → less heat transfer → outlet temp drops back to set; (iii) outlet temp drops below set: bulb cools → contraction → spring pushes → valve opens (more heating medium) → outlet temp rises; (d) net effect: maintains heated medium outlet temp = set by modulating heating medium supply; (e) also called: direct-acting, heating control, steam control valve; (f) typical: steam to heat exchanger, hot water to HVAC coil, thermal oil to reactor jacket. Heating Type - reverse-acting (detailed, ~30%): (a) what it controls: cooling medium (chilled water, cooling water, coolant) supply to cooler/condenser/oil cooler; (b) bulb location: in cooled medium outlet (downstream of cooler); (c) operation: (i) cooled medium outlet temp rises above set: bulb heats → expansion → actuator moves → valve opens (increases cooling medium flow); (ii) more cooling → more heat removal → outlet temp drops; (iii) outlet temp drops below set: contraction → spring → valve closes (less cooling) → outlet temp rises; (d) net effect: maintains cooled medium outlet temp = set by modulating cooling medium supply; (e) also called: reverse-acting, cooling control, chilled water control; (f) typical: chilled water to AHU coil, cooling water to oil cooler, coolant to condenser. Why the names can be confusing: (a) "cooling type" = valve controls heating medium to cool down (reduce) the temperature (i.e., it prevents overheating); (b) "heating type" = valve controls cooling medium to heat up (maintain) the temperature (i.e., it prevents overcooling); (c) alternative naming: (i) direct-acting = closes on temp rise (cooling type, for heating medium); (ii) reverse-acting = opens on temp rise (heating type, for cooling medium); (d) some manufacturers use "normally open" / "normally closed" (but this refers to failure mode, not action type - don't confuse); (e) always confirm with application description (what medium valve controls, what happens on temp rise). Cooling vs Heating - detailed comparison: | Feature | Cooling Type (Direct-acting) | Heating Type (Reverse-acting) | |---|---|---| | Valve controls | Heating medium (steam/hot water/thermal oil) | Cooling medium (chilled/cooling water) | | Bulb in | Heated medium outlet | Cooled medium outlet | | Temp rises → valve | Closes (less heating) | Opens (more cooling) | | Temp drops → valve | Opens (more heating) | Closes (less cooling) | | Purpose | Prevent overheating (maintain heating temp) | Prevent overcooling (maintain cooling temp) | | Commonness | Most common (~70%) | Less common (~30%) | | Also called | Direct-acting, heating control | Reverse-acting, cooling control | | Typical use | Steam heat exchanger, hot water HVAC | Chilled water AHU, oil cooler | How to select: (a) ask: what medium flows through the valve? (i) heating medium (steam, hot water, thermal oil) → Cooling Type (direct-acting); (ii) cooling medium (chilled water, cooling water, coolant) → Heating Type (reverse-acting); (b) ask: what do you want to happen when temp rises? (i) close valve (less heating) → Cooling; (ii) open valve (more cooling) → Heating; (c) ask: is the valve before a heater or a cooler? (i) before heater (heating medium) → Cooling; (ii) before cooler (cooling medium) → Heating; (d) if unsure: draw system (source → valve → heat exchanger → outlet with bulb) → we identify. Can one valve do both? (a) generally no - actuator spring orientation and internal linkage differ (direct vs reverse); (b) some designs can be converted in factory (reverse actuator), but not field-convertible; (c) order correct type (specify cooling/heating or direct/reverse); (d) body may look identical but actuator internal differs - check nameplate (marked cooling/heating or direct/reverse). Failure mode (related but different): (a) failure mode = what happens on bulb/capillary failure (sensing medium leak); (b) cooling type (direct-acting): (i) if bulb leaks → no expansion force → spring pushes valve open (fail-open → full heating → temp rises - safety risk for overheating); (ii) some designs fail-closed (optional, for critical heating); (c) heating type (reverse-acting): (i) if bulb leaks → spring pushes valve closed (fail-closed → no cooling → temp rises - safety risk); (ii) some designs fail-open (optional); (d) specify failure mode for critical applications (fail-safe open/closed per safety requirement); (e) note: action type (cooling/heating) ≠ failure mode (fail-open/closed) - both can be configured. Special: three-way temperature mixing/diverting: (a) some self-operated temp valves are three-way (one inlet, two outlets or two inlets, one outlet) - mixing hot/cold or diverting; (b) this product is two-way (single inlet/outlet) - for heating OR cooling medium, not both; (c) for mixing hot+cold in one valve → use three-way self-operated temp valve (different product). Installation difference (cooling vs heating): (a) cooling type: (i) valve on heating medium supply (e.g., steam line before heat exchanger); (ii) bulb on heated medium outlet (after heat exchanger); (iii) ensure steam trap after heat exchanger (for steam); (b) heating type: (i) valve on cooling medium supply (e.g., chilled water before AHU coil); (ii) bulb on cooled medium outlet (after AHU); (iii) ensure cooling water flow/return; (c) both: actuator upright, bulb immersed, capillary routed properly. Common mistakes: (a) ordering cooling type when valve controls cooling medium (should be heating type - valve will work against temp, causing oscillation or no control); (b) ordering heating type for steam (should be cooling type); (c) confusing action type with failure mode; (d) not specifying failure mode for critical service; (e) field-converting (not possible - order correct). Important: (a) Cooling Type = direct-acting, on heating medium, closes on temp rise (most common); (b) Heating Type = reverse-acting, on cooling medium, opens on temp rise; (c) select by what medium valve controls (heating = cooling type, cooling = heating type); (d) action type ≠ failure mode (specify both if critical); (e) not field-convertible (order correct); (f) this product = two-way (not three-way mixing); (g) tell us your system (heating/cooling medium, heat exchanger/cooler, bulb location) → we confirm type. This valve = the Cooling Type (direct-acting) is installed on the heating medium supply (steam, hot water, thermal oil) with the bulb in the heated medium outlet - when the outlet temperature rises above set, the sensing medium expands and the valve closes (reducing heating medium flow) to bring the temperature back down, and when temperature drops the valve opens - it is the most common type (~70%) and is used for steam/hot water/thermal oil heating control (heat exchangers, HVAC coils, reactor jackets); the Heating Type (reverse-acting) is installed on the cooling medium supply (chilled water, cooling water) with the bulb in the cooled medium outlet - when temperature rises the valve opens (increasing cooling flow) to bring temperature down, and when temperature drops the valve closes - it is used for chilled water/cooling water control (AHU coils, oil coolers, condensers); select Cooling Type when the valve controls a heating medium (steam/hot water/thermal oil) and you want to prevent overheating, select Heating Type when the valve controls a cooling medium (chilled/cooling water) and you want to prevent overcooling - note that "cooling/heating type" refers to the action direction (direct-acting closes on temp rise vs reverse-acting opens on temp rise), not the failure mode (fail-open/fail-closed on bulb failure, which can be specified separately for critical applications); the two types are generally not field-convertible (actuator internal linkage differs), so order the correct type by describing your system (what medium flows through the valve, whether it heats or cools, and where the bulb is located) - if you need both hot and cold mixing in one valve, use a three-way self-operated temperature valve (a different product).

Q: What temperature range can it control, and how do I select the bulb/sensing medium?

A: This valve controls temperature from 0°C to 350°C, segmented into multiple ranges by bulb and sensing medium (typically 0-120°C, 20-180°C, 50-250°C, 100-350°C - exact segments per manufacturer), and you select the range such that your desired set temperature falls in the middle 50-70% of the range (for best accuracy and sensitivity); the sensing medium (water, glycol, oil, mercury, or saturated vapor) is matched to the temperature range, and the bulb+capillary assembly is factory-filled and calibrated - changing to a different range requires replacing the bulb+capillary assembly (not just the spring). Here's the detailed guide. Controllable temperature range (detailed): (a) total range: 0°C – 350°C (some models to 400°C with special); (b) segmented (one bulb+medium per range): | Range | Sensing Medium | Typical Actuator | Applications | |---|---|---|---| | 0-120°C | Water / glycol-water | Diaphragm (NBR) | HVAC, food, low-temp process | | 20-180°C | Glycol / mineral oil | Diaphragm (FKM) / bellows | Hot water, low-pressure steam, HVAC | | 50-250°C | Mineral / silicone oil | Bellows | Medium-pressure steam, thermal oil | | 100-350°C | Mercury / saturated vapor | Bellows / piston | High-pressure steam, high-temp thermal oil | (c) overlap ranges (e.g., 50-200, 100-250) for flexibility; (d) below 0°C (refrigeration, cryogenic): special (butane/propane sensing, -40~0°C) - specify; (e) above 350°C: special (molten salt, special alloy bulb) - specify. How to select temperature range (detailed): (a) determine desired set temperature (T_set) - the temperature you want to maintain; (b) determine expected temp variation (min/max controlled temp in operation); (c) find range where T_set is in middle 40-60% of range: (i) good: T_set = 80°C → range 20-180°C (80 is 37.5% - acceptable; or 50-250 = 14% - too low; better 0-120 = 67% - ideal); (ii) better: T_set = 60°C → range 0-120°C (50% - ideal); (iii) bad: T_set = 115°C → range 0-120 (at top edge - poor); → use 20-180; (iv) bad: T_set = 5°C → range 0-120 (at bottom - poor); → use -20~80 special; (d) rule: T_set should be 25-75% of range (ideally 40-60%); (e) consider: (i) ambient temp (capillary exposed); (ii) heating/cooling medium temp (affects bulb if near); (iii) process temp variation; (f) if T_set near range edge: choose adjacent overlapping range. Sensing medium (detailed): (a) Water (H₂O): (i) range: 0-120°C (liquid, above 100°C needs pressurized); (ii) advantages: high expansion coefficient, low cost, safe, non-toxic; (iii) disadvantages: freezes below 0°C (burst risk), boils at 100°C (needs pressurized system for >100); (iv) use: HVAC, food, low-temp process; (b) Glycol-water (ethylene/propylene glycol, 30-50%): (i) range: -20~150°C (lower freeze, higher boil); (ii) advantages: freeze-resistant, safe, moderate cost; (iii) disadvantages: lower expansion than pure water; (iv) use: outdoor HVAC, cold climates, 0-150°C; (c) Mineral oil / silicone oil: (i) range: 20-250°C (mineral), -50~250°C (silicone); (ii) advantages: wide liquid range, linear expansion, stable, no freeze/boil issues; (iii) disadvantages: lower expansion than water/vapor, slower response; (iv) use: medium-temp process, steam, thermal oil; (d) Mercury (Hg): (i) range: 0-350°C (liquid metal, high expansion); (ii) advantages: very high sensitivity, wide range, linear, fast; (iii) disadvantages: TOXIC (restricted in EU (RoHS), US (some states), many countries - hazardous waste, spill risk); (iv) use: high-temp industrial (where allowed), legacy; (v) recommended alternative: oil or saturated vapor; (e) Saturated vapor (water/ethanol/acetone/other): (i) range: 50-350°C (vapor pressure of liquid in bulb); (ii) advantages: very high sensitivity (vapor pressure changes exponentially with temp - e.g., water vapor: 100°C=1atm, 120°C=2atm, 150°C=5atm), fast response; (iii) disadvantages: non-linear (exponential), limited to above boiling point of medium; (iv) use: high-temp, high-sensitivity, fast response; (f) selection: (i) <120°C, safe → water/glycol; (ii) 20-250°C → oil; (iii) 100-350°C, high sensitivity → saturated vapor; (iv) mercury → only if required and allowed (we recommend oil/vapor alternative). Bulb (detailed): (a) material: 304/316 stainless steel (standard); Hastelloy/Monel (corrosive, optional); (b) size: 8-15mm OD, 50-200mm length (per DN/range); (c) wall: 0.5-1mm (pressure rated); (d) immersion length: ≥2/3 of bulb in medium (e.g., 100mm bulb → ≥70mm immersed); (e) thermowell: (i) optional - bulb inserted in well, well in medium; (ii) use: high pressure (>PN4.0), corrosive/abrasive medium, need bulb removal without draining; (iii) well material: 304/316, Hastelloy; (iv) note: thermowell adds thermal lag (slower response); (f) bulb orientation: vertical tip-down for liquid (sensing medium stays in bulb, not capillary); any for gas/vapor. Capillary (detailed): (a) material: 304/316 stainless, 2-6mm OD; (b) length: 1-10m (standard 3m, custom); (c) routing: (i) min bend radius 50mm (no kinks - kink blocks pressure transmission); (ii) avoid hot surfaces above sensing medium temp (causes premature expansion in capillary); (iii) avoid cold surfaces (condensation, contraction); (iv) avoid mechanical damage (shield, support); (v) slope (for liquid sensing medium - ensure liquid returns to bulb, not trapped in capillary); (d) insulation: (i) optional foam/fiberglass jacket; (ii) use: capillary >3m, ambient temp varies, capillary passes through hot/cold zones; (iii) improves accuracy (ambient doesn't affect sensing medium in capillary). Set temperature adjustment (within range, detailed): (a) top adjusting screw/handwheel: (i) CW → compresses spring → increases set temp (needs more expansion to move); (ii) CCW → releases spring → decreases set temp; (b) on-line: adjust during operation (no shutdown); (c) procedure: (i) monitor temp at bulb (calibrated thermometer); (ii) turn screw 1/4 turn increments; (iii) wait 10-60s for stabilization (thermal lag); (iv) repeat until desired; (v) tighten locking nut; (d) adjustment range: full screw travel = full temp range; (e) do not force beyond stops (damages spring/screw). Changing temperature range (different bulb/medium, detailed): (a) when needed: desired set temp outside current range (e.g., currently 0-120, need 200°C); (b) what to replace: (i) bulb+capillary assembly (with new sensing medium for new range); (ii) possibly actuator spring (matched to new range); (iii) possibly actuator type (diaphragm → bellows for high temp); (c) procedure: (i) isolate/depressurize/cool valve; (ii) disconnect capillary from actuator (union/compression fitting); (iii) remove old bulb+capillary; (iv) install new bulb+capillary (correct range/medium), connect to actuator; (v) replace spring (if needed); (vi) pressurize, check for capillary/actuator leak; (vii) calibrate set temp (compare to calibrated thermometer); (viii) test regulation (accuracy/response); (d) time: 30-60min (experienced); (e) spare bulb+capillary: order with valve (one or more ranges) - labeled (range, medium, length); (f) not just spring (sensing medium+bulb is the range-defining component, spring is matched). Accuracy vs range position (detailed): (a) mid-range (40-60%): best accuracy ±1°C, stable; (b) near bottom (<25%): (i) sensing medium expansion small (low temp) → lower sensitivity; (ii) accuracy ±2-3°C; (c) near top (>75%): (i) sensing medium near critical/boiling → non-linear; (ii) spring near solid; (iii) accuracy ±2-3°C; (d) always select mid-range for best performance. Response time vs sensing medium: (a) saturated vapor: fastest (vapor pressure changes rapidly - 10-30s); (b) water/glycol: medium (liquid expansion - 20-40s); (c) oil: slower (higher viscosity, lower expansion - 30-60s); (d) mercury: fast (high expansion - 15-40s); (e) also affected by: bulb size (large = slower), capillary length (long = slower), controlled system thermal mass. Special ranges: (a) sub-zero (-40~0°C): (i) sensing: butane/propane/chlorinated hydrocarbon (vapor); (ii) use: refrigeration, cold storage, cryogenic (not extreme cryo); (iii) specify; (b) high-temp (>350°C): (i) sensing: special salt/metal vapor, molten metal; (ii) bulb: Inconel/ceramic; (iii) actuator: piston/bellows (high temp); (iv) use: molten salt, high-temp thermal oil, furnace; (v) specify; (c) corrosive medium bulb: (i) bulb: Hastelloy C, Monel, titanium, PTFE-coated; (ii) use: seawater, acid, chemical; (iii) specify. Common mistakes: (a) selecting range with set temp at edge (poor accuracy - use mid-range); (b) one bulb for all temps (not possible - segmented, change assembly); (c) using mercury in restricted countries (use oil/vapor); (d) capillary kinked (blocks transmission - repair); (e) bulb not immersed (partial = inaccurate); (f) expecting to change range by spring only (need bulb+capillary+medium); (g) ignoring ambient temp on capillary (insulate if long/variable); (h) using water above 100°C without pressurized (boils - use oil/vapor). Important: (a) range 0-350°C, segmented (0-120/20-180/50-250/100-350 typical); (b) select range with set temp in 40-60% (mid-range); (c) sensing medium: water/glycol (<120°C), oil (20-250°C), mercury/vapor (100-350°C); (d) mercury toxic (restricted - use oil/vapor alternative); (e) change range = replace bulb+capillary assembly (+ spring/actuator possibly); (f) adjust set temp on-line via top screw (CW=up, CCW=down); (g) mid-range = best accuracy ±1°C; (h) capillary 1-10m, insulate if long/variable; (i) bulb ≥2/3 immersed, vertical for liquid; (j) tell us T_set, temp variation, medium, ambient, capillary length, response need → we select range + sensing medium + bulb. This valve = it controls temperature from 0°C to 350°C, segmented into ranges by bulb and sensing medium (typically 0-120°C with water/glycol, 20-180°C with glycol/oil, 50-250°C with mineral/silicone oil, 100-350°C with mercury or saturated vapor - exact segments confirmed at order, with possible overlaps and special sub-zero/high-temp ranges on request); select the range so your desired set temperature falls in the middle 40-60% of the range (e.g., for an 80°C set point choose the 0-120°C range, not the 50-250°C range where 80°C is only 14% from the bottom) because mid-range gives the best accuracy (±1°C) and sensitivity, while operating near range edges (<25% or >75%) degrades accuracy to ±2-3°C due to low expansion or non-linearity; the sensing medium is matched to the range: water/glycol for 0-120°C (safe, high expansion, but freezes/boils - use glycol for outdoor), mineral/silicone oil for 20-250°C (wide liquid range, linear, but slower response), mercury for 0-350°C (high sensitivity but toxic and restricted in EU/US - we recommend oil or saturated vapor as alternatives), and saturated vapor (water/ethanol/acetone vapor) for 50-350°C (very high sensitivity and fast response because vapor pressure changes exponentially with temperature); the bulb is 304/316 stainless (8-15mm OD, 50-200mm length, with optional Hastelloy for corrosive media and optional thermowell for high pressure/corrosive or easy removal), must be ≥2/3 immersed in the controlled medium (vertical tip-down for liquids), and connects via capillary (1-10m, standard 3m, 304/316 stainless, min bend radius 50mm, optionally insulated for long runs or variable ambient) to the actuator; the set temperature within a range is adjusted on-line by the top adjusting screw (clockwise = increase set temp by compressing the spring, counterclockwise = decrease, with a locking nut), no shutdown needed; to change to a different temperature range you must replace the bulb+capillary assembly (with the correct sensing medium for the new range) and possibly the matched spring or actuator (diaphragm→bellows for high temp) - it is not just a spring change, because the sensing medium+bulb defines the range; spare bulb+capillary assemblies are available labeled by range/medium/length; provide your desired set temperature, expected temperature variation, controlled medium, ambient conditions, required capillary length, and response/accuracy needs and we select the correct range, sensing medium, bulb material/length, and actuator type - note that mercury is restricted in many regions, so specify if it is required or accept oil/vapor alternatives.

Q: The valve has a bulb and capillary - how do I install them, and what's their service life?

A: The bulb must be fully immersed (≥2/3 of its length) in the controlled medium at the point where temperature is to be regulated (e.g., heat exchanger outlet, tank, process pipeline), installed vertically tip-down for liquids (to keep sensing medium in the bulb), with an optional thermowell for high pressure/corrosive media or easy removal; the capillary (1-10m, stainless) must be routed from the bulb to the actuator with no sharp bends (min radius 50mm), away from hot/cold sources, supported at intervals, and optionally insulated for long runs or variable ambient; the bulb+capillary assembly has a service life of 5-8 years under normal conditions (replace if corroded, dented, or leaking - it is a sealed assembly not field-repairable). Here's the detailed guide. Bulb installation (detailed): (a) location: (i) at the point where temperature is to be controlled/monitored (e.g., heat exchanger outlet, tank mid-height, process pipeline, reactor outlet); (ii) representative of controlled medium (avoid dead zones, stratification, near heating/cooling inlet); (iii) accessible for maintenance/inspection; (b) immersion depth: (i) ≥2/3 of bulb length immersed in medium (e.g., 100mm bulb → ≥70mm in medium); (ii) full immersion ideal (if possible); (iii) partial immersion = inaccurate (sensing medium not fully at medium temp); (c) orientation: (i) liquid medium: bulb vertical, tip down (sensing medium (liquid) stays in bulb by gravity, not rising into capillary); (ii) gas/vapor medium: any orientation (vapor fills bulb+capillary); (iii) never bulb tip-up for liquid (sensing medium drains into capillary → inaccurate/slow); (d) installation method: (i) direct insertion: bulb through wall/pipe via compression fitting or threaded boss (welded boss on pipe/tank); (ii) thermowell: bulb inserted in thermowell (well installed in medium, bulb in well) - for high pressure, corrosive, abrasive, or need bulb removal without draining; (e) thermowell details: (i) material: 304/316, Hastelloy (per medium); (ii) installation: threaded/welded/flanged into pipe/tank; (iii) bulb fit: slip-in with spring-loaded contact (ensures thermal contact); (iv) note: thermowell adds thermal lag (slower response by 10-30%); (v) use when: pressure >PN4.0, corrosive, abrasive, frequent bulb removal; (f) pipe installation: (i) install in straight pipe (≥5D after elbow); (ii) bulb at center of pipe (max flow, representative temp); (iii) avoid near pump/valve outlet (turbulence, temp stratification); (g) tank/vessel installation: (i) at mid-height (representative bulk temp, not surface or bottom); (ii) away from inlet/outlet (stratification); (iii) agitator zone (well-mixed) if available; (h) sealing: compression fitting (ferrule) or threaded boss with gasket (PTFE/graphite) - no leak. Capillary installation (detailed): (a) routing: (i) from bulb to actuator, follow shortest practical path; (ii) min bend radius: 50mm (no sharp kinks - kink restricts pressure/volume transmission, can crack); (iii) avoid moving parts (doors, hinges), hot surfaces (above sensing medium temp - causes false expansion), cold surfaces (condensation, contraction), chemicals (corrosion); (iv) avoid direct sunlight (ambient heating of capillary); (b) support: (i) support capillary at 1m intervals (clips/clamps with rubber cushion - don't crush); (ii) do NOT hang valve by capillary (capillary is not structural - support valve separately); (iii) leave small service loop at actuator (for removal/maintenance); (c) slope (for liquid sensing medium): (i) capillary should slope upward from bulb to actuator (or continuously) so liquid sensing medium drains back to bulb (not trapped in low points); (ii) avoid traps (U-shapes) where liquid can collect; (iii) for vapor sensing medium, slope doesn't matter; (d) insulation (optional but recommended): (i) when: capillary >3m, ambient temp varies significantly, capillary passes through hot/cold zones, high accuracy needed; (ii) material: foam rubber, fiberglass, silicone foam; (iii) thickness: 10-20mm; (iv) benefit: prevents ambient temp from affecting sensing medium in capillary (improves accuracy); (e) protection: (i) shield capillary in conduit/trunking where exposed to mechanical damage; (ii) avoid foot traffic, equipment movement; (f) connection to actuator: (i) compression fitting (union) at actuator - allows disconnection for maintenance; (ii) ensure no leak (pressure-tight - sensing medium leak = valve failure); (g) length: 1-10m (standard 3m); longer = slower response, more ambient effect (insulate); shorter = faster, but limits bulb location. Actuator/valve installation (related): (a) actuator upright (stem vertical, diaphragm horizontal) - critical (alignment, diaphragm life); (b) valve on heating/cooling medium supply (not on controlled medium line); (c) flow direction per body arrow; (d) straight pipe: ≥5D upstream, ≥3D downstream; (e) strainer upstream (protect seat/trim); (f) isolation valves + bypass (for maintenance); (g) support valve/piping (don't load actuator). Startup & calibration (detailed): (a) pre-startup: (i) verify bulb immersed (≥2/3), orientation correct; (ii) verify capillary (no kinks, supported, connected, no leak); (iii) verify valve installation (actuator upright, flow direction, strainer); (b) fill/pressurize: (i) slowly fill heating/cooling medium line (avoid water hammer); (ii) pressurize to working pressure; (iii) check for leaks (valve, capillary, bulb fitting); (c) start controlled system: (i) start heat exchanger/cooler/process; (ii) allow medium to reach bulb; (d) set temp adjustment: (i) monitor temp at bulb with calibrated thermometer (independent reference); (ii) turn top adjusting screw (CW=up, CCW=down) 1/4 turn increments; (iii) wait 10-60s for stabilization (thermal lag); (iv) repeat until temp = desired; (v) tighten locking nut; (e) verify: (i) vary load (change flow/heating) and verify temp stays ±1-3°C; (ii) check valve stroke (responds to temp changes); (iii) no hunting/oscillation; (f) record: set temp, date, calibration reference. Bulb+capillary service life (detailed): (a) typical life: 5-8 years (normal conditions); (b) factors affecting life: (i) corrosion: bulb in corrosive medium (acid, seawater, chloride) → shorter (1-3yr) - use 316/Hastelloy; (ii) temperature: high temp (>250°C) → bulb material creep, sensing medium degradation → shorter (3-5yr); (iii) pressure: high pressure → bulb wall stress → shorter; (iv) mechanical damage: dents, vibration, capillary kinks → shorter (fail); (v) sensing medium degradation: oil oxidation, water contamination, mercury → slower/inaccurate; (vi) cycling: frequent temp cycles → bulb fatigue (thermal expansion/contraction) → shorter; (vii) quality: material, fabrication, leak-tightness; (c) end-of-life signs: (i) leak: sensing medium escapes (capillary/bulb pinhole, corrosion) → valve fails (stuck open/closed) - visible oil/water/mercury at bulb/capillary, or pressure loss; (ii) inaccurate: temp drifts, slow response, hunting (sensing medium degraded, partial loss); (iii) bulb damage: dents, corrosion, cracks (visual); (iv) capillary damage: kinks, corrosion, cracks; (d) preventive replacement: every 5-8yr (or per inspection) - don't wait for failure (failure = temp runaway, safety risk for critical heating/cooling); (e) spare: keep bulb+capillary assembly (correct range/medium/length) for critical valves. Bulb+capillary replacement (detailed): (a) when: leak, damage, inaccurate, or 5-8yr preventive; (b) procedure: (i) isolate/depressurize/cool valve and controlled system (LOTO); (ii) disconnect capillary from actuator (union fitting - catch any sensing medium, especially mercury); (iii) remove bulb from thermowell/pipe (unscrew compression fitting); (iv) remove old assembly (capillary + bulb); (v) install new bulb (in thermowell/pipe, ≥2/3 immersed, correct orientation); (vi) route new capillary (no kinks, support, connect to actuator); (vii) pressurize, check for leaks (bulb fitting, capillary, actuator connection); (viii) calibrate set temp (compare to calibrated thermometer); (ix) test regulation (accuracy, response, no hunting); (c) time: 30-60min; (d) disposal: (i) if mercury sensing: handle as hazardous waste (per local regulation - don't break bulb, contain); (ii) oil/water: standard industrial waste; (e) spare assembly: order by model, temp range, sensing medium, capillary length, bulb material/length. Inspection & maintenance (bulb+capillary): (a) monthly: (i) visual: bulb (corrosion, dents, immersion), capillary (kinks, corrosion, insulation, support), leaks; (ii) temp reading (compare to reference - drift indicates issue); (b) annual: (i) bulb inspect (remove from well if possible - corrosion, pitting, wall thickness); (ii) capillary pressure test (if suspect - pressurize, hold, no leak); (iii) calibration check (compare to calibrated thermometer, adjust if drifted >±3°C); (iv) strainer clean; (v) valve exercise (vary set temp); (c) 5-8yr: replace bulb+capillary (preventive), diaphragm/bellows, spring, trim, gaskets. Troubleshooting bulb+capillary: (a) temp not responding / valve stuck: (i) bulb/capillary leak (sensing medium lost) → replace assembly; (ii) capillary kinked/blocked → repair/replace; (iii) bulb not immersed → install deeper; (b) inaccurate / drifting: (i) bulb partial immersion → deeper; (ii) capillary exposed to ambient → insulate; (iii) sensing medium degraded (oil oxidation/water) → replace assembly; (iv) bulb corroded (slow response) → replace; (c) slow response: (i) thermowell (thermal lag - normal, or use direct insertion); (ii) long capillary → shorten/insulate; (iii) oil sensing (slower than vapor) → accept or change range/medium; (iv) bulb calcified/fouled (scale on bulb → slow) → clean bulb; (d) hunting/oscillation: (i) capillary too long (lag) → shorten; (ii) bulb location (dead zone/stratification) → relocate; (iii) oversized valve → size down; (e) external leak at capillary: (i) fitting loose → tighten; (ii) capillary crack → replace assembly; (f) bulb corrosion: (i) medium corrosive → use 316/Hastelloy bulb; (ii) replace damaged bulb. Safety notes: (a) mercury sensing: if bulb breaks, mercury spills - hazardous (use PPE, contain per regulation, don't use vacuum cleaner); consider oil/vapor alternative; (b) high temp bulb/capillary: burn hazard (insulate/guard, PPE); (c) high pressure bulb: use thermowell (bulb failure can eject - well contains); (d) capillary under pressure: don't cut/puncture (sensing medium under pressure - hot oil/steam can spray); (e) bulb in hazardous medium: use thermowell (prevents medium release if bulb fails). Common mistakes: (a) bulb not immersed (partial → inaccurate); (b) bulb tip-up for liquid (sensing medium in capillary → slow/inaccurate); (c) capillary kinked (blocks transmission); (d) hanging valve by capillary (damages capillary/connection); (e) no thermowell for high pressure/corrosive (bulb failure risk); (f) capillary near hot/cold source (false sensing); (g) not insulating long capillary (ambient effect); (h) ignoring 5-8yr replacement (failure = temp runaway). Important: (a) bulb ≥2/3 immersed, vertical tip-down (liquid), at representative point; (b) thermowell for high pressure/corrosive/easy removal; (c) capillary 1-10m, min bend 50mm, support 1m, no hot/cold, insulate if long; (d) bulb+capillary life 5-8yr (replace preventively, not field-repairable); (e) calibrate on startup with calibrated thermometer; (f) inspect monthly (visual), annual (calibration/corrosion), 5-8yr replace; (g) mercury = hazardous (use oil/vapor alternative); (h) spare assembly for critical valves; (i) we provide bulb+capillary replacement (specify range/medium/length/bulb material). This valve = bulb installation: the stainless steel bulb (304/316, 8-15mm OD, 50-200mm length, optional Hastelloy for corrosive media) must be installed at the point where temperature is to be controlled (heat exchanger outlet, tank mid-height, process pipeline center), ≥2/3 of its length fully immersed in the controlled medium (partial immersion causes inaccurate sensing), vertically with tip pointing down for liquid media (to keep the liquid sensing medium in the bulb by gravity, not rising into the capillary - any orientation is acceptable for gas/vapor), via a direct compression/threaded boss or an optional thermowell (use a thermowell for pressure >PN4.0, corrosive/abrasive media, or when bulb removal without draining is needed - note that a thermowell adds 10-30% thermal lag); avoid dead zones, stratification, and locations near heating/cooling inlets. Capillary installation: the stainless capillary (2-6mm OD, 1-10m length, standard 3m) is routed from the bulb to the actuator along the shortest practical path with a minimum bend radius of 50mm (no sharp kinks - kinks block pressure transmission and can crack), kept away from hot surfaces (above the sensing medium temperature, which causes false expansion), cold surfaces, direct sunlight, chemicals, and moving parts; supported at 1m intervals with cushioned clips (do NOT hang the valve by the capillary - it is not structural), sloped upward from bulb to actuator for liquid sensing media (to prevent liquid trapping), and optionally insulated with 10-20mm foam/fiberglass for runs >3m or variable ambient (to prevent ambient temperature from affecting the sensing medium in the capillary and degrading accuracy); leave a small service loop at the actuator connection. Startup and calibration: after filling/pressurizing the heating/cooling line and starting the controlled system, monitor the temperature at the bulb with an independent calibrated thermometer, adjust the top screw (CW=increase set temp, CCW=decrease) in 1/4-turn increments waiting 10-60s between adjustments for thermal stabilization, then tighten the locking nut and verify stability under varying load. Service life: the bulb+capillary assembly typically lasts 5-8 years under normal conditions (shorter at 1-3 years in corrosive media or high temperature >250°C, longer up to 10 years in benign conditions) - it is a sealed, factory-filled assembly that is not field-repairable; replace it preventively every 5-8 years or immediately if you detect leakage (sensing medium escaping), bulb corrosion/dents, capillary kinks/cracks, or temperature drift/inaccuracy >±3°C; replacement takes 30-60 minutes (isolate, disconnect capillary union, remove bulb, install new assembly, calibrate) and spare assemblies are available labeled by temperature range, sensing medium, capillary length, and bulb material. Inspection: monthly visual check (bulb immersion/corrosion, capillary kinks/leaks, temperature reading vs reference), annual calibration check against a calibrated thermometer and bulb/corrosion inspection, and 5-8 year major replacement (bulb+capillary, diaphragm/bellows, spring, trim, gaskets). Safety: if the sensing medium is mercury, handle bulb breakage as hazardous waste per local regulation (we recommend oil or saturated vapor alternatives where mercury is restricted); high-temperature bulb/capillary is a burn hazard (insulate/guard); for high-pressure or hazardous media use a thermowell to contain potential bulb failure. Provide your bulb location (pipe/tank, medium, pressure/temp), desired capillary length, and ambient conditions and we supply the correct bulb material, thermowell (if needed), and capillary length with installation guidance.

Q: How do I size this valve, and what's the difference between diaphragm, bellows, and piston actuators?

A: Sizing a self-operated temperature regulating valve requires calculating the required Cv (flow coefficient) of the heating/cooling medium (steam, hot water, thermal oil, chilled water) based on flow rate, inlet pressure, outlet pressure (or ΔP), and medium properties, then selecting a valve whose rated Cv is 1.5-2× the required Cv (so normal flow operates at 30-70% opening); the actuator type is selected by force requirement: diaphragm (standard, large area, high sensitivity, for small DN ≤100 and low-medium temp ≤200°C), bellows (metal, higher temp/force, zero leak, for medium DN and medium-high temp ≤350°C), and piston (high force, for large DN >100, high ΔP, high temp) - all are self-powered by the bulb's thermal expansion. Here's the detailed guide. Sizing steps (detailed): (a) define parameters: (i) medium through valve: heating (steam, hot water, thermal oil) or cooling (chilled water, cooling water); (ii) flow rate Q (max/normal/min - kg/h for steam, m³/h for liquid); (iii) inlet pressure P1 (heating/cooling medium supply pressure, bar/psig); (iv) outlet pressure P2 (after valve, bar/psig) - or ΔP = P1-P2; (v) medium temp (inlet, °C); (vi) medium properties: density, specific heat, latent heat (steam), viscosity; (b) calculate heat duty (if not given flow): (i) Q_heat = m × Cp × ΔT (liquid heating/cooling) or m × h_fg (steam condensing); (ii) then derive medium flow rate from heat duty; (c) calculate ΔP across valve: (i) ΔP = P1 - P2 (available pressure drop); (ii) typical: 0.2-1.0 bar for water, 0.5-2.0 bar for steam (but depends on system); (iii) minimum ΔP: ≥0.1 bar for controllability (below = poor); (d) calculate Cv: (i) liquid (water/oil): Cv = Q_gpm / √(ΔP_psi / G) or Kv = Q_m³/h / √(ΔP_bar / G), Cv = 1.167×Kv; (ii) steam (saturated, lb/h): Cv = W_lb/h / (63.3 × √(ΔP_psi × P1_inlet_psi)) for subcritical (ΔP < 0.5×P1); or Cv = W / (32 × P1) for critical/choked; (iii) use steam tables for exact; (e) select valve: rated Cv = 1.5-2× required Cv (normal flow = 30-70% open); (f) check: (i) min flow: >10% of rated (below = hunting); (ii) max flow: <90% of rated (above = can't maintain); (g) select actuator: per DN, ΔP, temp (see below); (h) select temp range/bulb: per controlled medium temp (see Q3). Cv vs DN (typical, reference for water/steam): | DN | Cv (typical) | Water m³/h (ΔP=0.5bar) | Steam kg/h (ΔP=1bar, P1=3bar) | |---|---|---|---| | DN15 | 3-6 | 1-2 | 10-30 | | DN25 | 10-20 | 3-8 | 50-150 | | DN40 | 25-40 | 8-15 | 150-300 | | DN50 | 40-80 | 15-30 | 300-600 | | DN80 | 80-150 | 30-60 | 600-1200 | | DN100 | 150-250 | 60-100 | 1200-2000 | | DN150 | 300-500 | 120-200 | 3000-5000 | | DN200 | 500-800 | 200-320 | 5000-8000 | | DN250 | 800-1200 | 320-480 | 8000-12000 | | DN300 | 1200-1800 | 480-720 | 12000-18000 | (exact Cv per model - confirm at order) Actuator force requirement: (a) actuator force must overcome: (i) medium unbalanced force on valve core (ΔP × core area - reduced by balanced trim); (ii) spring force (set point); (iii) friction (stem guide, O-ring if piston); (iv) seating force (for tight shutoff); (b) available force = (sensing medium pressure) × actuator effective area (diaphragm area / bellows area / piston area); (c) sensing medium pressure: (i) liquid expansion: 1-10 bar (per temp range); (ii) vapor: up to 10-30 bar (high temp); (d) selection: (i) small force (small DN, low ΔP, balanced trim) → diaphragm; (ii) medium force → bellows; (iii) large force (large DN, high ΔP, high temp) → piston. Diaphragm actuator (detailed, standard): (a) structure: large-area flexible diaphragm (NBR/FKM, fabric-reinforced) clamped in housing, spring on top, stem connected to center; (b) effective area: 200-2000 cm² (per size - large for high force/sensitivity); (c) force: pressure × area (e.g., 5bar × 500cm² = 2500N = 250kgf - sufficient for DN≤100); (d) advantages: (i) high sensitivity (large area, low friction - responds to small pressure changes); (ii) zero external leak (diaphragm seals stem, no packing); (iii) low cost; (iv) fast response (flexible, low inertia); (e) disadvantages: (i) temp limited by diaphragm material (NBR ≤100°C, FKM ≤200°C - sensing medium/actuator temp, not medium temp; actuator is away from hot medium, but capillary/actuator can warm); (ii) pressure limited (diaphragm burst - typically ≤10bar sensing pressure); (iii) diaphragm wear (3-5yr, rubber aging/fatigue); (iv) stroke limited (10-40mm, diaphragm flex); (f) best for: DN15-100, low-medium temp (sensing ≤200°C), low-medium ΔP, high sensitivity needed, general HVAC/process. Bellows actuator (detailed): (a) structure: metal bellows (316L stainless, Hastelloy, multi-ply) welded to stem and housing, spring outside/inside, pressure inside/outside bellows; (b) effective area: bellows cross-section (50-500 cm² - smaller than diaphragm); (c) force: pressure × bellows area (e.g., 10bar × 200cm² = 2000N); (d) advantages: (i) high temp (metal bellows ≤350°C+, no rubber); (ii) high pressure (bellows rated to 20-40bar); (iii) zero external leak (bellows hermetic seal, no packing); (iv) long life (metal, no rubber aging - 5-10yr); (v) corrosion resistant (316L/Hastelloy); (e) disadvantages: (i) lower sensitivity (smaller area, metal stiffness - higher hysteresis); (ii) higher cost; (iii) bellows fatigue (cycling life 10k-100k cycles - less than diaphragm flex cycles); (iv) shorter stroke (15-50mm); (f) best for: DN25-200, medium-high temp (sensing >200°C, oil/mercury/vapor), medium ΔP, corrosive, longer life needed. Piston actuator (detailed): (a) structure: metal piston in cylinder, O-ring seal, pressure on one side, spring on other, stem connected; (b) effective area: piston area (π/4 × D² - 50-1000 cm², large for big bore); (c) force: pressure × piston area (e.g., 15bar × 500cm² = 7500N = 750kgf - high, for large DN); (d) advantages: (i) very high force (large piston area × high pressure); (ii) high pressure (cylinder rated 20-40bar); (iii) high temp (metal, no rubber - O-ring limit ≤200°C FKM, or metal seal for higher); (iv) long stroke (20-60mm); (v) robust (for large/heavy valves); (e) disadvantages: (i) friction (O-ring on cylinder wall - lower sensitivity, higher hysteresis); (ii) external leak possible (O-ring wear - needs replacement); (iii) larger/heavier actuator; (iv) higher cost; (f) best for: DN100-300, high ΔP (>2bar), high temp, large valves, high force needed, industrial heavy-duty. Actuator comparison summary: | Feature | Diaphragm | Bellows | Piston | |---|---|---|---| | Material | NBR/FKM rubber + fabric | 316L/Hastelloy metal | Metal + O-ring | | Effective area | 200-2000 cm² (large) | 50-500 cm² (medium) | 50-1000 cm² (large) | | Force | Medium (high area × low pressure) | Medium (medium area × medium pressure) | High (large area × high pressure) | | Sensitivity | High (low friction, large area) | Medium (metal stiffness) | Lower (O-ring friction) | | Temp limit | ≤100°C (NBR) / ≤200°C (FKM) | ≤350°C+ | ≤200°C (O-ring) / higher (metal seal) | | Pressure limit | ≤10 bar | ≤20-40 bar | ≤20-40 bar | | External leak | Zero (diaphragm seal) | Zero (bellows seal) | Possible (O-ring wear) | | Life | 3-5yr (rubber) | 5-10yr (metal) | 5-8yr (O-ring replace) | | Stroke | 10-40mm | 15-50mm | 20-60mm | | Cost | Low | Medium-high | High | | Best DN | 15-100 | 25-200 | 100-300 | | Best for | Low-med temp, high sensitivity, general | Med-high temp, corrosive, long life | Large DN, high ΔP, heavy-duty | How to select actuator: (a) by DN: (i) DN≤100 → diaphragm (standard); (ii) DN25-200 → bellows (if high temp/corrosive); (iii) DN≥100 → piston (if high ΔP/large); (b) by temp (sensing/actuator): (i) ≤200°C → diaphragm (FKM) or bellows; (ii) >200°C → bellows or piston (metal seal); (c) by ΔP: (i) ≤1bar → diaphragm; (ii) 1-3bar → bellows or diaphragm (large area); (iii) >3bar → piston (or bellows with high pressure); (d) by sensitivity: (i) high accuracy/fast → diaphragm; (ii) standard → bellows; (iii) robust → piston; (e) by medium: (i) corrosive → bellows (316L/Hastelloy) or piston (special O-ring); (ii) general → diaphragm; (f) we recommend based on your DN, ΔP, temp, medium, accuracy. Balanced trim (related to actuator force): (a) heating/cooling medium ΔP creates unbalanced force on valve core; (b) balanced single-seat/double-seat reduces unbalanced force → smaller actuator can be used; (c) without balance: large ΔP × large core = huge force → needs piston (or can't regulate); (d) all our valves have balanced trim (single or double) - specify if need tight shutoff (single-seat Class VI) vs high capacity (double-seat). Sizing example (to illustrate): (a) application: heat exchanger, heating medium = saturated steam, inlet P1=3bar(g), outlet after valve (steam chest) ~1bar, ΔP=2bar, steam flow needed = 500kg/h, controlled medium outlet temp = 80°C (set); (b) Cv steam (subcritical, ΔP=2bar=29psi, P1=4bar abs=58psi, ΔP/P1=0.5 → critical): Cv = W/(32×P1_psi) = 500×2.2 lb/h / (32×58) = 1100/1856 = 0.59 (too small - check formula; actually use Cv = W/(63.3×√(ΔP×P1)) for subcritical: 1100/(63.3×√(29×58)) = 1100/(63.3×41) = 0.42 - seems low; steam sizing is complex - use software); (c) select: DN25 (Cv 10-20) is oversized for this flow - but steam valves often oversized for startup; use DN25 with reduced trim or DN20; (d) actuator: DN25, ΔP=2bar, temp sensing 80°C (range 0-120, water) → diaphragm; (e) bulb: in heated medium outlet, 0-120°C water sensing, capillary 3m; (f) type: cooling (steam heating medium, direct-acting); (g) we provide exact sizing (give parameters). Common sizing mistakes: (a) oversizing (very common - "bigger is better" → valve operates <10% → hunting/poor control; select 1.5-2× required Cv, not 5×); (b) undersizing (can't pass max flow → temp can't reach set); (c) ignoring ΔP (too low ΔP = low controllability, too high = high force/cavitation); (d) wrong actuator (diaphragm for high ΔP large DN → insufficient force; piston for small low-temp → overkill/cost); (e) steam sizing errors (use correct formula/software, consider critical flow); (f) ignoring startup conditions (startup needs more flow than steady state - size for startup but not excessive). Important: (a) size: Cv from flow/P1/P2/medium, select rated Cv = 1.5-2× required; (b) avoid oversizing (hunting) and undersizing (can't reach set); (c) actuator: diaphragm (DN≤100, ≤200°C, high sensitivity, low cost), bellows (DN25-200, ≤350°C, corrosive, long life), piston (DN≥100, high ΔP, heavy-duty); (d) balanced trim reduces actuator force; (e) we provide sizing (give flow, P1, P2, medium, temp, DN, ΔP); (f) select actuator per DN/ΔP/temp. This valve = sizing: calculate the required Cv of the heating/cooling medium (steam, hot water, thermal oil, chilled/cooling water) from the flow rate, inlet pressure P1, outlet pressure P2 (or ΔP=P1-P2), and medium properties (for liquids: Cv = Q_gpm/√(ΔP_psi/G); for steam: use saturated-steam formulas accounting for subcritical vs critical/choked flow - we can size for you if you provide flow, P1, P2, medium, and temperature), then select a valve with rated Cv = 1.5–2× the required Cv so normal flow operates at 30-70% opening (below 10% = hunting/poor control, above 90% = can't maintain temperature) - oversizing is the most common mistake (valve hunts at tiny openings), so do not over-size "for safety"; also ensure minimum ΔP across the valve is ≥0.1 bar for controllability. Actuator types: (1) Diaphragm actuator (standard) - large-area fabric-reinforced NBR/FKM rubber diaphragm (effective area 200-2000cm²), high sensitivity (low friction, large area), zero external leak (diaphragm seals stem, no packing), low cost, but temperature-limited (NBR ≤100°C, FKM ≤200°C at the actuator) and pressure-limited (≤10bar sensing), stroke 10-40mm, diaphragm life 3-5 years - best for DN15-100, low-medium temperature, low-medium ΔP, high-sensitivity general HVAC/process; (2) Bellows actuator - metal bellows (316L/Hastelloy, effective area 50-500cm²), higher temperature (≤350°C+), higher pressure (20-40bar), zero external leak, longer life (5-10 years, no rubber aging), corrosion-resistant, but lower sensitivity (metal stiffness/hysteresis) and higher cost, stroke 15-50mm - best for DN25-200, medium-high temperature (oil/mercury/vapor sensing), corrosive media, longer-life requirements; (3) Piston actuator - metal piston with O-ring in a cylinder (effective area 50-1000cm²), very high force (large area × high pressure), high pressure/temp capability, long stroke 20-60mm, robust for large valves, but has O-ring friction (lower sensitivity, possible external leak with O-ring wear), larger/heavier, higher cost - best for DN100-300, high ΔP (>2bar), high temperature, large heavy-duty industrial valves; all three are self-powered by the bulb's thermal expansion (no external energy), and the selection depends on DN, pressure drop ΔP, temperature, required sensitivity, and medium - diaphragm for small/low-temp/high-sensitivity, bellows for medium/high-temp/corrosive, piston for large/high-ΔP/heavy-duty; all valves include balanced trim (single-seat or double-seat) to reduce medium unbalanced force so a smaller actuator can position the valve accurately. Provide your heating/cooling medium, flow rate (max/normal/min), inlet/outlet pressures, medium temperature, controlled medium set temperature, and required accuracy and we supply a complete sizing with recommended DN, Cv, actuator type, cooling/heating action, temperature range/bulb, and capillary length.

Q: What maintenance and troubleshooting does this valve need?

A: A self-operated electric temperature regulating valve needs annual inspection/calibration and periodic bulb+capillary/diaphragm replacement (every 5-8 years for bulb+capillary, 3-5 years for diaphragm) - the bulb+capillary assembly (sensing medium leak/corrosion) and diaphragm/bellows (aging/fatigue) are the key wear parts, along with seat/core wear, spring fatigue, strainer cleaning, and set temperature calibration; common issues are temperature hunting/oscillation, inability to reach set temperature, external leakage (diaphragm/bellows/capillary), slow response, and seat leakage, each with specific causes and fixes. Here's the detailed maintenance and troubleshooting guide. Maintenance philosophy: (a) simple, few moving parts (bulb+capillary, actuator, spring, stem, trim) - low maintenance; (b) key wear parts: (i) bulb+capillary (5-8yr, sensing medium leak/corrosion); (ii) diaphragm (3-5yr, rubber aging - if diaphragm actuator); (iii) bellows (5-10yr, metal fatigue - if bellows actuator); (iv) spring (fatigue, corrosion); (v) seat/core (wear, erosion); (c) frequency: light duty (stable, low cycle) = annual; heavy duty (high cycle, corrosive, high temp) = quarterly; (d) preventive avoids bulb/capillary failure (temp runaway, safety hazard) and regulation drift. Daily/weekly inspection (operator): (a) temperature gauge (at bulb/process): stable at set? (if drifting >±3°C → issue); (b) visual: (i) external leak at valve/gaskets/actuator/capillary/bulb fitting (medium or sensing medium escaping); (ii) bulb (corrosion, dents, immersion depth - if visible); (iii) capillary (kinks, corrosion, insulation damage, support); (iv) actuator housing (corrosion, damage); (v) piping/vibration; (c) noise: (i) hunting (clicking/vibrating from actuator/trim); (ii) cavitation/whistling (high ΔP liquid); (iii) steam leak hiss; (d) strainer: differential pressure (if equipped) or scheduled clean; (e) record temp readings (log). Monthly maintenance: (a) set temp verification: (i) compare process temp to calibrated reference thermometer at bulb; (ii) if drifted >±3°C → readjust top screw; (b) strainer clean/blowdown: (i) close isolation, open strainer blowdown, clean screen; (c) external leak check: (i) soapy water at flanges, actuator, capillary fittings, bulb fitting; (d) valve exercise (if normally static): (i) manually vary set temp (up/down 10-20°C) to exercise actuator/trim, then return to set (prevents sticking); (e) check capillary: (i) kinks, corrosion, support, insulation; (f) check bulb immersion (if accessible - verify still ≥2/3 in medium, no fouling/calcification). Annual maintenance (recommended minimum): (a) set temp calibration: (i) use calibrated thermometer (±0.1°C) at bulb location; (ii) verify accuracy ±1-3°C at set; (iii) adjust if needed; (iv) check response (vary load/heating, verify temp recovers); (b) seat leakage test: (i) isolate, close valve (cooling type: shut off heating, verify no flow; or remove and test); (ii) measure leak (Class IV/VI); (iii) if high → seat worn (replace/lap); (c) bulb+capillary inspect: (i) bulb: remove from thermowell (if possible), inspect corrosion/pitting/dents, wall thickness (UT if suspect); (ii) capillary: inspect kinks/corrosion/cracks; (iii) pressure test (if suspect): pressurize bulb+capillary with air/nitrogen (1.5× working), hold 1h, no pressure drop (or bubble test); (iv) calibration check: immerse bulb in temp-controlled bath, verify expansion/actuator movement matches spec; (v) if >5-8yr or suspect → replace assembly; (d) actuator inspect: (i) diaphragm (if equipped): remove top cover, inspect (cracks, blisters, stickiness, permanent set), air test (apply pressure, no leak to atmosphere); (ii) bellows: inspect (cracks, corrosion), helium/air leak test; (iii) piston: inspect O-ring (wear, hardening), cylinder (scoring); (iv) spring: inspect (corrosion, set, broken); (e) trim inspect (if valve removed): (i) valve core/seat (wear, scoring, balance passage clear); (ii) stem guide (wear); (iii) clean (debris, scale); (f) strainer: deep clean, inspect screen (replace if damaged); (g) gaskets: inspect (replace if hard/cracked); (h) capillary insulation: inspect/replace if damaged; (i) update records (calibration date, leakage, bulb condition, diaphragm/bellows condition, parts replaced). 3-5 year major overhaul (diaphragm actuator) / 5-8 year (bellows/piston + bulb): (a) replace diaphragm (if diaphragm type - rubber aging, even if looks OK); (b) replace bulb+capillary assembly (key wear part - sensing medium degradation, corrosion, fatigue; preventive); (c) replace spring (fatigue, corrosion - matched to temp range); (d) replace trim (core/seat if worn/scored - balanced type); (e) replace gaskets (body, actuator, capillary fitting); (f) replace O-rings (piston type, sensing port); (g) replace strainer screen; (h) hydro test body (1.5×PN, actuator isolated); (i) full temperature regulation test (accuracy ±1-3°C, response, action type cooling/heating, no hunting); (j) seat leakage test (Class IV/VI); (k) bulb+capillary pressure-hold + bubble test; (l) re-calibrate set temp; (m) paint (if needed). Bulb+capillary replacement (detailed procedure): (a) isolate/depressurize/cool valve AND controlled system (LOTO - bulb may be in hot/corrosive medium); (b) if thermowell: remove bulb from well (well stays in system); if direct: drain/remove from boss; (c) disconnect capillary from actuator (union/compression fitting - catch sensing medium, especially mercury = hazardous); (d) remove old bulb+capillary (route out); (e) install new bulb (in thermowell/boss, ≥2/3 immersed, correct orientation - tip-down for liquid); (f) route new capillary (no kinks, min bend 50mm, support, connect to actuator); (g) pressurize system, check for leaks at bulb fitting, capillary, actuator connection; (h) calibrate set temp (compare to calibrated thermometer); (i) test regulation (accuracy, response, no hunting); (j) time: 30-60min; (k) disposal: mercury sensing = hazardous waste (per local reg); oil/water = industrial waste. Diaphragm replacement (if diaphragm actuator): (a) isolate/depressurize/cool; (b) remove actuator top cover/cap; (c) remove adjusting screw, spring seat, spring; (d) unclamp diaphragm housing bolts; (e) remove old diaphragm (center from stem, edge from housing); (f) clean housing; (g) install new diaphragm (correct material NBR/FKM, center to stem, edge aligned, no wrinkle); (h) clamp evenly (torque sequence); (i) reinstall spring, seat, screw; (j) pressurize, check external leak (soapy water at actuator vent); (k) calibrate set temp; (l) test regulation. Spare parts kit (recommended for critical valves): (a) bulb+capillary assembly (1, correct temp range/sensing medium/length/bulb material - KEY); (b) diaphragm (1, if diaphragm actuator, NBR/FKM); (c) spring (1, matched to temp range); (d) trim set (valve core + seat ring, balanced type); (e) gaskets (body + bonnet + actuator housing + capillary fitting, 2 sets); (f) O-rings (piston type, sensing port); (g) strainer screen (1); (h) label with valve tag/serial, type (cooling/heating), temp range, sensing medium, capillary length, actuator type, body material; (i) store cool/dry, rubber diaphragm away from ozone/UV/solvents, bulb+capillary protected (no kinks/dents). Safety during maintenance: (a) isolate valve (heating/cooling medium) both ports (close isolation, lockout/tagout); (b) depressurize (verify 0 pressure); (c) cool (high-temp steam/oil → burn hazard); (d) bulb in controlled system: if bulb directly in pressurized/hot/corrosive medium - drain/depressurize that system too, or use thermowell (bulb removable without draining); (e) mercury sensing: if bulb/capillary breaks - mercury spill (hazardous - PPE, contain, don't use vacuum, per hazardous waste protocol); recommend oil/vapor alternative; (f) sensing medium under pressure: don't cut/puncture capillary (hot oil/steam spray); (g) spring compression: when removing adjusting screw, spring may be under load - release slowly, follow procedure; (h) re-test (seat leakage + temp regulation + bulb/capillary leak) before service. Troubleshooting - detailed: Problem 1: Temperature hunting / oscillating / unstable (a) causes: (i) heating/cooling medium pressure fluctuating (boiler/compressor pulsation, upstream regulator issues); (ii) flow demand changing rapidly (frequent load changes); (iii) wrong temp range (operating near edge - low sensitivity/hysteresis); (iv) valve oversized (operates <10% open - poor control, on-off behavior); (v) vibration (piping/valve not rigidly mounted); (vi) bulb not fully immersed (partial → inaccurate sensing); (vii) capillary kinked/too long (slow/lagging feedback → oscillation); (viii) diaphragm stiff (aging - slow response, overshoot); (ix) controlled system large thermal mass (heat exchanger - inherent lag, normal); (x) wrong action type (cooling vs heating reversed - valve works against temp); (b) fixes: (i) add upstream pressure regulator or accumulator for heating medium; (ii) check temp range (move set to mid-range, change bulb if needed); (iii) size valve correctly (if oversized, install smaller or restricted trim); (iv) mount rigidly, eliminate vibration; (v) immerse bulb ≥2/3, install deeper or thermowell; (vi) repair/shorten/insulate capillary; (vii) replace diaphragm (if stiff/aging); (viii) accept thermal lag for large systems (or use electric/pneumatic for fast); (ix) verify action type (cooling/heating) matches medium. Problem 2: Cannot reach set temperature (temperature too low) (a) causes: (i) heating medium pressure/flow too low (cooling type - can't heat if supply insufficient; check boiler, supply valve, strainer); (ii) valve undersized (can't pass enough heating medium at set - pressure drops); (iii) temp range wrong (set below range minimum - change bulb/medium to lower range); (iv) bulb/capillary leak (loss of sensing medium - valve fails open/closed, replace); (v) strainer clogged (restricts heating medium flow - clean); (vi) seat stuck closed (trim/debris - clean/repair); (vii) bulb location wrong (not at hottest point, or in dead zone - relocate); (viii) bypass valve open (heating medium bypassing heat exchanger - close); (b) fixes: (i) verify heating medium supply pressure/flow; (ii) size up valve (if undersized); (iii) change to lower temp range (bulb+capillary); (iv) replace bulb+capillary (if leak); (v) clean strainer; (vi) clean/repair trim; (vii) relocate bulb to representative point; (viii) close bypass. Problem 3: Cannot reach set temperature (temperature too high) (a) causes: (i) temp range wrong (set above range max - change to higher range); (ii) valve stuck open (trim binding, debris - clean/repair); (iii) seat leaking (cooling type: seat leak → too much heating medium → temp high - replace/lap seat); (iv) wrong action type (heating type installed as cooling - opens on temp rise for heating medium → more heat); (v) bypass valve open (close); (vi) bulb not in controlled medium (sensing wrong temp - install/immerse); (vii) adjusting screw at max (already at top - need higher range); (b) fixes: (i) change to higher temp range (bulb+capillary); (ii) clean/repair trim; (iii) replace/lap seat (Class VI soft seat for tight shutoff); (iv) verify/reorder action type (cooling/heating); (v) close bypass; (vi) install/immerse bulb correctly. Problem 4: External leakage (at actuator / capillary / body) (a) causes: (i) diaphragm rupture (diaphragm actuator - medium or sensing medium escapes through actuator vent; replace); (ii) bellows crack (bellows actuator - replace bellows/actuator); (iii) capillary leak (crack/corrosion/fitting - replace bulb+capillary assembly); (iv) bulb fitting leak (loose/cracked - tighten/replace); (v) gasket leak (body/bonnet/actuator housing - replace gasket, retorque); (vi) body casting defect (NDT/replace); (vii) flange gasket (replace, retorque evenly); (b) fixes: (i) diaphragm/bellows rupture → replace immediately (isolate, use bypass), install leak detector for hazardous; (ii) capillary/bulb leak → replace assembly; (iii) replace gaskets; (iv) repair/replace body. Problem 5: Slow response / sluggish (a) causes: (i) bulb not fully immersed (slow heat transfer - install deeper); (ii) thermowell (thermal lag - normal 10-30% slower; use direct insertion if faster needed); (iii) capillary too long/kinked (slow transmission - shorten/repair); (iv) sensing medium type (oil slower than vapor/water - accept or change range/medium); (v) large thermal mass system (heat exchanger - inherent, normal); (vi) diaphragm stiff (aging - replace); (vii) trim sticking (debris, corrosion - clean); (viii) bulb fouled/calcified (scale insulates - clean bulb); (b) fixes: (i) immerse bulb fully; (ii) accept thermowell lag or use direct insertion; (iii) shorten/repair capillary; (iv) select faster sensing medium (vapor) if needed; (v) accept system lag; (vi) replace diaphragm; (vii) clean trim; (viii) clean bulb (descale). Problem 6: High seat leakage (internal) (a) causes: (i) seat worn/eroded (replace/lap); (ii) foreign material on seat (clean); (iii) double-seat design (inherent higher leakage - switch to single-seat balanced or soft seat Class VI); (iv) trim misalignment (reassemble); (v) valve not fully closed (set temp, trim travel, actuator force); (b) fixes: (i) replace/lap seat; (ii) clean; (iii) use single-seat or soft seat (PTFE/NBR/FKM Class VI); (iv) reassemble trim. Problem 7: Bulb+capillary frequent failure (a) causes: (i) wrong bulb material (medium corrosive - use 316/Hastelloy); (ii) temperature too high (exceeds bulb/medium rating - use high-temp version); (iii) mechanical damage (vibration, kinks, impact - protect/support); (iv) capillary kinked (stress concentration - route properly); (v) sensing medium incompatible (degradation - select correct); (vi) overpressure (bulb wall rated - don't exceed, use thermowell); (b) fixes: (i) select correct bulb material per medium; (ii) use high-temp version (bellows/piston, special medium); (iii) protect/support capillary, no kinks; (iv) use thermowell for high pressure/corrosive. Problem 8: No response / valve not moving (a) causes: (i) no temperature change (system stable - normal); (ii) bulb/capillary failed (leak, no sensing medium - replace); (iii) trim seized (corrosion, debris - clean/repair); (iv) spring broken (replace); (v) adjusting screw at limit (no more adjustment); (vi) capillary disconnected (reconnect); (b) fixes: (i) verify system temp changing; (ii) replace bulb+capillary; (iii) clean/repair trim; (iv) replace spring; (v) reconnect capillary. Problem 9: Temperature drift over time (slowly changes from set) (a) causes: (i) sensing medium partial loss (slow leak - bulb/capillary micro-leak, replace); (ii) spring fatigue (set drifts - replace spring, recalibrate); (iii) diaphragm permanent set (aging - replace); (iv) bulb fouling (scale, insulation effect - clean); (v) ambient changes on capillary (insulate); (vi) heating medium pressure trend (boiler output change); (b) fixes: (i) replace bulb+capillary (if micro-leak); (ii) replace spring; (iii) replace diaphragm; (iv) clean bulb; (v) insulate capillary; (vi) stabilize heating medium pressure. Common mistakes: (a) ignoring bulb+capillary replacement (failure = temp runaway, safety hazard); (b) wrong action type (cooling/heating - valve oscillates or no control); (c) bulb not immersed (inaccurate); (d) capillary kinked (slow/blocked); (e) no strainer (debris damages seat/trim); (f) oversizing valve (hunting); (g) using mercury without hazardous handling (spill risk); (h) not calibrating annually (drift); (i) field-repairing bulb+capillary (sealed, not repairable - replace assembly); (j) ignoring thermowell lag (expecting fast response with well). Important: (a) daily/weekly: temp gauge stable, external leak, noise, vibration, bulb/capillary visual, strainer; (b) monthly: set temp verify (±3°C), strainer clean, valve exercise, leak check, capillary/bulb inspect; (c) annual: calibration (±1-3°C), seat leakage, bulb+capillary pressure test + calibration, diaphragm/bellows inspect, spring inspect, trim inspect, gaskets; (d) 3-5yr (diaphragm) / 5-8yr (bulb+capillary/bellows): replace bulb+capillary (key), diaphragm, spring, trim, gaskets, full test; (e) bulb+capillary = 5-8yr life (replace preventively, sealed not field-repairable); (f) diaphragm = 3-5yr (rubber aging); (g) hunting: medium pressure fluctuation, wrong range, oversized, vibration, bulb partial, capillary kink, diaphragm stiff, wrong action type; (h) can't reach low temp: heating supply low, undersized, range too high, bulb leak, strainer clogged, stuck closed; (i) can't reach high temp: range too low, stuck open, seat leak, wrong type, bypass open; (j) external leak: diaphragm/bellows rupture, capillary/bulb leak, gasket; (k) slow: bulb partial, thermowell, capillary long, oil medium, system mass, diaphragm stiff, bulb fouled; (l) keep spares (bulb+capillary, diaphragm, spring, trim, gaskets); (m) isolate/depressurize/cool/purge before work; (n) mercury = hazardous; (o) we provide spares + service + bulb+capillary replacement kits. This valve = maintenance: daily/weekly check the temperature gauge (at bulb/process) for stable set temperature (drift >±3°C indicates an issue), inspect for external leakage at valve/gaskets/actuator/capillary/bulb fitting (sensing medium or process medium escaping = diaphragm/bellows rupture or capillary/bulb leak, replace immediately), listen for hunting/clicking/cavitation noise, check bulb condition (corrosion, dents, immersion) and capillary (kinks, corrosion, insulation, support), and clean the strainer; monthly verify set temperature against a calibrated reference thermometer and readjust the top screw if drifted >±3°C, clean/blowdown the strainer, perform a manual set-temperature exercise (vary up/down 10-20°C then return) if the valve is normally static (to prevent trim sticking), and check capillary/bulb for damage; annually calibrate set temperature (verify ±1-3°C accuracy and response under varying load), test seat leakage (Class IV/VI), inspect and pressure-test the bulb+capillary (1.5× working pressure hold, no leak; calibration check in temp bath), inspect diaphragm/bellows (air leak test, visual for cracks/blisters/stiffness), inspect spring (corrosion/fatigue), inspect trim (core/seat/balance passage), deep-clean strainer, and replace gaskets if hardened; every 3-5 years (diaphragm actuator) or 5-8 years (bellows/piston + bulb+capillary) perform a major overhaul: replace the bulb+capillary assembly (key wear part - sensing medium degrades, bulb corrodes, capillary fatigues; it is a sealed factory-filled unit that is NOT field-repairable, replace the whole assembly), replace diaphragm (if rubber type, aging), replace spring (fatigue), replace trim (core/seat), replace gaskets/O-rings, hydro-test the body, then run full temperature-regulation, seat-leakage, and bulb+capillary leak tests and recalibrate; bulb+capillary replacement takes 30-60 min (isolate both the valve and the controlled system if bulb is direct-inserted, or just remove from thermowell if used, disconnect capillary union, install new assembly, calibrate) and mercury-sensing units must be disposed as hazardous waste (we recommend oil/vapor alternatives). Troubleshooting: temperature hunting/oscillation = heating/cooling medium pressure fluctuation (add regulator/accumulator), wrong temp range (set near edge - move to mid-range), oversized valve (operates <10% - size down), vibration (mount rigidly), bulb not fully immersed (install deeper), capillary kinked/too long (repair/shorten/insulate), stiff diaphragm (replace), or wrong cooling/heating action type (verify); cannot reach low temperature = heating medium supply too low (cooling type), valve undersized, temp range too high (change bulb), bulb/capillary leak (replace), strainer clogged (clean), or trim stuck closed; cannot reach high temperature = temp range too low (change bulb), trim stuck open, seat leaking (cooling type, replace/lap seat), wrong action type, or bypass open; external leakage = diaphragm/bellows rupture (replace immediately, use bypass), capillary/bulb leak (replace assembly), or gasket failure (replace); slow response = bulb not immersed, thermowell lag (normal, or use direct insertion), capillary too long, oil sensing medium (slower than vapor), large system thermal mass (normal), stiff diaphragm (replace), or bulb fouling/calcification (clean); high seat leakage = worn seat (replace/lap), debris (clean), or double-seat inherent (switch to single-seat or soft PTFE Class VI); frequent bulb+capillary failure = wrong bulb material for corrosive medium (use 316/Hastelloy), over-temperature, mechanical damage/kinks, or overpressure (use thermowell); keep a spare parts kit (bulb+capillary assembly, diaphragm, matched spring, trim set, gaskets, strainer screen) and always isolate both ports, depressurize, and cool (and drain the controlled system if bulb is direct-inserted) before maintenance - we supply matched bulb+capillary/diaphragm/spring/trim/gasket spare parts by valve serial/model and provide on-site calibration/service and bulb replacement.

Hot Tags: Self-operated Electric Temperature Regulating Valve DN15-300 0-350°C Factory, China Self-operated Electric Temperature Regulating Valve DN15-300 0-350°C Factory manufacturers, suppliers, factory, argon gas pressure regulator, flow control valves, tank blanketing, air flow regulator valve, vacuum pressure regulator, pressure regulator pneumatic