Manual Single-ear Knife Gate Valve | DN50–1200 | PN0.6–2.5MPa | Class VI/IV Seal

Manual Single-ear Knife Gate (single-lug) - parallel gate with sharp blade + lug for stable install. Unlike wedge gates, sharp blade cuts thick media - free flow, shutoff, anti-clog. Manual handwheel simple, no auto needed - saves cost. Compact, low drop ≤0.5, harsh adaptability. Lug stable, flange (FF/RF/RJ), horizontal/vertical. Ductile iron handwheel + rising stem; bevel opt. large DN. Soft (EPDM/NBR/PTFE) Class VI zero or metal Class IV. Body cast/ductile iron/WCB/SS304/316; gate SS/hard alloy. Seats replaceable. DN50–1200, PN0.6–2.5MPa, -20~120°C/-40~425°C. Uni/bidirectional opt. For wastewater, mining, paper, chemical. MSS SP-81/ASME B16.34/API598. 3× life vs ordinary gates. OEM/ODM.

1. Sharp Knife Gate + Low Pressure Drop: The gate is made of high-quality stainless steel (304/316) with a precision-ground sharp edge - easily cuts through fibrous materials, solid particles, and viscous slurries (sludge, ore pulp, paper pulp), effectively solving blockage and jamming that occurs in ordinary gate valves. When fully open, the knife gate retracts completely above the flow path, providing a nearly unobstructed straight-through flow with minimal pressure drop (flow resistance coefficient ≤ 0.5) - reducing pipeline system energy consumption and improving operational efficiency. The thin blade design ensures smooth opening/closing even in harsh media conditions. Optional hard alloy overlay on the gate edge for highly abrasive service.

2. Single-ear (Lug) Structure: The unique single-ear (lug) design allows for easy and stable installation on pipelines - compatible with flange connections (FF flat face, RF raised face, RJ ring joint) and suitable for both horizontal and vertical installation. The lug-style body with bolt holes around the perimeter provides a secure, stable mount that reduces valve movement and vibration during operation. It reduces the overall weight of the valve compared to full-flanged bodies, saves installation space, and improves the stability of the valve during operation. The single-ear design also allows the valve to be installed between two flanges with through-bolts (wafer-style) or with threaded studs (lug-style) for dead-end service.

3. Manual Operation with High Convenience: Equipped with a heavy-duty ductile iron handwheel and a rising stem - the manual operation is labor-saving and precise. The rising stem extends upward as the valve opens, providing visual position indication (operator can see valve open/closed status at a glance). The stem is treated with anti-corrosion and anti-wear processes (e.g., nitriding, chrome plating), ensuring smooth rotation and long service life. For large-diameter models (typically DN300+), a bevel gear operator can be optionally equipped to further reduce operation effort - making large valves manageable by a single operator.

4. Reliable Sealing Performance: Optional soft seals (EPDM, NBR, PTFE) or metal seals are available to meet different working conditions. Soft seals achieve Class VI zero leakage (bubble-tight per ANSI/FCI 70-2), suitable for low-temperature and low-pressure scenarios with clean to slightly dirty media. Metal seals (stainless steel) are wear-resistant and high-temperature resistant, suitable for harsh environments with high pressure and abrasive media - achieving Class IV leakage (controlled rate). The seal surface is precision machined/ground to ensure no leakage during long-term use. The choice between soft and metal seal depends on your medium abrasiveness, temperature, and required leakage class.

5. Durable Material & Long Service Life: The valve body is available in cast iron, ductile iron, carbon steel (WCB), or stainless steel (304/316/316L) - all go through strict material testing and anti-corrosion treatment (such as galvanizing, painting, epoxy coating) to resist corrosion, wear, and impact. Cast iron for cost-effective general water service; ductile iron for higher strength; WCB for oil/gas/industrial; SS304/316/316L for corrosive chemical and food/pharma. The service life is 3 times longer than that of ordinary gate valves - reducing maintenance and replacement costs over the valve lifecycle.

6. Easy Maintenance: The valve structure is simple with fewer components, making disassembly and maintenance convenient. The seat and seal are replaceable without removing the valve from the pipeline (in many configurations) - reducing downtime. Daily maintenance only requires regular cleaning of the gate (removing accumulated debris) and adding lubricating oil to key components (stem threads, stem packing) - no professional technical personnel are needed. The rising stem design also makes stem packing inspection and replacement straightforward. This low-maintenance characteristic reduces total cost of ownership (TCO) over the valve's service life.

The Manual Single-ear Knife Gate Valve: handwheel → rising screw stem → sharp knife gate → seat → lug body. Turn ductile iron handwheel, rising stem lifts/lowers sharp SS gate. Closing: blade descends, cuts fibers/slurry, presses seat - soft Class VI zero or metal Class IV. Opening: gate rises, straight-through flow, drop ≤0.5, no dead corners. Lug body stable flange (FF/RF/RJ), horizontal/vertical. Rising stem extends upward - visual position. Bevel opt. large DN. Manual only. Uni/bidirectional opt. DN50–1200, PN0.6–2.5MPa, -20~120°C/-40~425°C. Flange/wafer/lug.

Municipal Environmental Protection: Ideal for wastewater treatment plants, sewage pipelines, sludge transportation, garbage leachate treatment, and river dredging slurry transport. The sharp knife gate cuts through sludge flocs, hair, and debris in sewage - preventing clogging in wastewater pipelines. Soft seal (EPDM/NBR) Class VI zero leakage prevents sewage leakage and environmental contamination. The single-ear/lug structure is easy to install in sewage plant piping and underground networks. The low pressure drop (≤0.5) reduces pumping energy in large municipal wastewater systems. Cast iron or SS304 body for general sewage; SS316 for corrosive industrial wastewater.

Mining & Metallurgy + Building Materials: Controls ore pulp, coal pulp, tailings transportation, and dust material control in mines and steel plants (Mining & Metallurgy) - and cement slurry, lime slurry, and construction waste treatment pipelines (Building Materials). The sharp blade cuts through mineral particles and cement/lime solids; the metal seal (Class IV) option handles abrasive mining and cement slurry. The low pressure drop ensures efficient transport of high-solids slurries. The durable construction (WCB/ductile iron with hard alloy overlay gate) withstands abrasive wear. Manual operation is reliable in remote mining and quarry sites without power. The 3× service life reduces replacement frequency in these high-wear applications.

Pulp & Paper + Food Processing: Transports various concentrations of pulp, paper pulp mixtures, and papermaking wastewater treatment systems (Pulp & Paper) - the sharp knife gate cuts wood pulp fibers and waste paper, preventing fiber wrapping and clogging. And transports jam, syrup, and food waste (Food Processing) - stainless steel (304/316) body and PTFE seal meet food-grade standards. The straight-through flow path allows easy cleaning (CIP) in food and paper processes. Soft seal (PTFE/EPDM) Class VI zero leakage prevents product contamination and waste. The compact single-ear structure fits food processing plant layouts with limited space.

Chemical Industry: Conveys corrosive fluids with solid particles, viscous chemical raw materials, and chemical wastewater discharge. SS316/316L body with PTFE/Viton seal handles corrosive acids, alkalis, and solvents; the sharp gate cuts through crystalline and particulate chemicals that would jam a conventional valve. Class VI zero leakage (soft seal) prevents hazardous chemical leaks. The bidirectional option handles chemical pipelines with potential reverse flow. The metal seal option handles high-temperature chemical processes (up to 425°C with custom materials). Flange connection (RF/RJ) for chemical plant piping standards. Manual operation provides reliable isolation in chemical batch processes.

Power Industry: Used for fly ash transportation in power plants, slurry pipelines in desulfurization and denitrification (FGD/SCR) systems, and slag water conveying. The sharp gate handles fly ash and FGD limestone/gypsum slurry; the metal seal (Class IV) option handles abrasive ash and slag. SS316L with PTFE for chloride-rich FGD scrubber liquor. The low pressure drop reduces pumping energy in ash handling systems. The single-ear/lug structure is stable under thermal cycling in power plant piping. Manual operation serves as reliable backup or primary isolation for power plant auxiliary systems. The durable construction provides long service life in power plant environments.

Every Manual Single-ear Knife Gate Valve is manufactured and tested per MSS SP-81, ASME B16.34, API 598, GB/T 12224, ISO 5208 - 100% tested. Raw materials: body MTR + tests, PMI SS; gate blade PT, overlay bond; castings RT/UT; dimensions checked. Assembly: gate-stem, smooth handwheel, alignment, seal, no binding, knife, lug fit. Pressure: shell 1.5×PN, seat 1.1×PN (soft Class VI, metal Class IV). Cycle test 5 cycles. Flow verified. Batch traceable. Ship with certs, reports, manual. 18mo warranty. Third-party on request.

Q1: What is a manual single-ear knife gate valve, and what does "single-ear/lug" mean?

A: A manual single-ear knife gate valve (also called manual single-lug knife gate valve) is a manually operated knife gate valve with a single-ear (lug) style body - the body has a ring of bolt holes (lugs/ears) around the perimeter that allow it to be mounted between pipeline flanges. "Single-ear" refers to the lug-style body design (as opposed to a full flanged body with two separate flanges, or a wafer body with no bolt holes). The lug design provides several advantages: (a) stable installation - the bolt holes secure the valve firmly between flanges, reducing movement and vibration; (b) dead-end service capability - unlike a wafer valve (which requires through-bolts and cannot be used at a pipeline dead end), a lug valve can use threaded studs on one side, allowing one flange to be removed without the valve falling (useful for dead-end/isolation service); (c) lighter weight than a full flanged valve, saving material and installation space; (d) compatible with FF (flat face), RF (raised face), RJ (ring joint) flange connections. The valve uses a thin, sharp knife-shaped gate (not a wedge) that cuts through thick media (slurry, pulp, sludge, fibers) - unlike a conventional wedge gate valve. It is operated by a manual handwheel (ductile iron) with a rising stem - no automatic actuator, making it cost-effective for infrequently operated isolation valves. For large diameters (DN300+), a bevel gear operator is optional to reduce effort. It is primarily for on-off/isolation service (not continuous throttling).

Q2: How does the sharp knife gate prevent clogging in slurry and fiber service?

A: Clogging is the #1 failure in slurry/fiber valves - solved by the sharp knife gate design: (1) Sharp cutting edge: the bottom of the gate is a precision-ground sharp blade (stainless steel 304/316, optional hard alloy overlay). As the gate descends to close, the sharp edge slices/shears through fibrous media (wood pulp, waste paper, hair in sludge, textile fibers), particulate media (coal, ore, cement, fly ash), and viscous slurries - cutting through material that would wedge and jam a conventional flat or wedge gate. (2) Thin blade profile: the gate is thin (much thinner than a wedge gate), so it displaces less media on closing and passes through solids more easily - less chance of "pushing" solids into the seat area. (3) Full retraction on opening: when fully open, the gate retracts completely above the flow path - there is no gate portion remaining in the flow stream to collect debris or create a dead zone. The straight-through flow path has no dead corners where solids can settle and pack. (4) Low pressure drop (≤0.5): the unobstructed flow means media moves through at velocity, self-cleaning the bore. (5) For highly abrasive service, a hard alloy overlay on the gate edge extends cutting life. Together these features ensure anti-clog operation in the harshest slurry, pulp, sludge, and powder applications - the valve's service life is 3× that of ordinary gate valves in these services. Regular gate cleaning (as noted in maintenance) further prevents buildup.

Q3: What is the difference between Class VI soft seal and Class IV metal seal, and which should I choose?

A: Two sealing options: (1) Soft seal (EPDM, NBR, PTFE): an elastomer/polymer seat ring. Achieves Class VI zero leakage (bubble-tight, per ANSI/FCI 70-2 - the highest soft-seat leakage class, essentially no visible bubbles). Temperature: -20℃~120℃ (EPDM/NBR; PTFE up to ~180-200℃). Choose soft seal/Class VI when: medium is non-abrasive or moderately abrasive (water, sewage, pulp, food, chemicals, light slurry), temperature is within the seal range, and zero leakage is required (environmental compliance, hazardous chemicals, food/pharma, vacuum service). Soft seals wear faster in highly abrasive service but are easily replaceable. (2) Metal seal (stainless steel, metal-to-metal): achieves Class IV leakage (a controlled rate - per ANSI/FCI 70-2, Class IV allows 0.01% of rated Cv for liquids, a small controlled drip; for this valve specified as Class IV). Temperature: -40℃~425℃ (with custom body materials). Choose metal seal/Class IV when: medium is highly abrasive or high-temperature (fly ash, slag, cement, mining tailings, high-temp process), and a small controlled leakage is acceptable (non-hazardous media). Metal seals last much longer in abrasive/high-temp service but do not achieve zero leakage. Selection guide: clean water/sewage/pulp/food/chemical → soft seal (EPDM for water, NBR for oil, PTFE for chemical/corrosive); abrasive mining/cement/ash/high-temp → metal seal. Always match seal material to your medium, temperature, abrasiveness, and required leakage class. Provide your conditions for the correct recommendation.

Q4: What sizes, pressures, temperatures, materials, and connections are available?

A: Sizes: DN50–DN1200 (2"–48"), custom sizes available (DN15–DN1000 on request). Pressures: PN0.6–PN2.5MPa (1.0–2.5MPa), ANSI Class 150, 10–16 Bar. Temperatures: -20℃~120℃ (rubber/soft seal); -40℃~425℃ (metal seal/custom material). Body materials: Cast Iron, Ductile Iron, Carbon Steel (WCB), Stainless Steel (304/316/316L) - customizable. Cast iron for cost-effective water; ductile iron for higher strength; WCB for oil/gas/industrial; SS304 for general corrosion/food; SS316/316L for chlorides/chemicals/pharma. Gate material: Stainless Steel (304/316), Hard Alloy Overlay (for abrasive service). Seal material: Soft Seal - EPDM (water/steam), NBR (oil/fuel), PTFE (chemical/corrosive/food); Metal Seal - Stainless Steel. Operation: Manual (ductile iron handwheel + rising stem, standard); Optional Bevel Gear for large diameter (DN300+). Connections: Flange Connection (ASME B16.5, ASME B16.47 - FF/RF/RJ faces), Wafer Connection, Lug Connection (the single-ear/lug body supports all three). Flow direction: Unidirectional or Bidirectional (optional - specify at order). Seal class: Soft Class VI (zero leakage), Metal Class IV. Design standards: MSS SP-81, MSS SP-135, ASME B16.34, API 598, GB/T 12224-2019. Test standards: ISO 5208, MSS SP-61, API 598 (100% quantity tested before delivery). The wide size range from DN50 (small plant isolation) to DN1200 (large municipal/industrial pipeline) makes this valve versatile. Provide your actual working conditions for the correct configuration.

Q5: What standards apply, and is 100% testing performed before delivery?

A: Design & manufacturing standards: MSS SP-81 (stainless steel knife gate valves - primary design standard for this valve type), MSS SP-135 (knife gate valve design), ASME B16.34 (valves pressure-temperature rating), API 598 (valve inspection and testing), GB/T 12224-2019 (Chinese national standard for steel gate valves). Testing standards: ISO 5208 (industrial valves pressure testing), MSS SP-61 (pressure testing of steel valves), API 598 (valve inspection/testing). 100% testing: Yes - every valve is 100% quantity tested before delivery (not sampling). Tests include: (a) Shell pressure test at 1.5× nominal pressure (hydrostatic) - verifies body integrity, no through-wall leaks; (b) Seat pressure test at 1.1× nominal pressure - verifies seat sealing (soft seal must achieve Class VI zero leakage; metal seal Class IV); (c) Cycle test - minimum 5 full open/close cycles to verify smooth handwheel operation, no binding, proper gate movement; (d) Flow direction verification for uni/bidirectional configurations; (e) Dimensional inspection - bore, flange face, lug hole pattern, face-to-face per MSS SP-81. Quality system: ISO 9001 certified. Raw material control: MTR (Mill Test Report) for all pressure-containing parts, PMI (Positive Material Identification) for stainless steel, NDT (RT/UT for castings, PT for gate blade). Traceability: material batch traceable from raw material to finished valve. Shipping documents: MTR, pressure test certificate, dimensional/cycle test reports, O&M manual, product certificate. Warranty: 18 months from shipment. Optional: third-party inspection (BV, SGS, DNV) on request, and CE marking for European export.

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