According to the working principle of the sealing element, it can be divided into four categories:
① Self sealing: The code Z achieves sealing by interference and pressure difference between the outer diameter of the sealing element and the inner diameter of the casing.
② Compression type: code Y compresses the sealing element by axial force, making the diameter of the sealing element larger to achieve sealing.
③ Wedge in type: code X relies on the wedge in piece to wedge into the sealing piece, making the diameter of the sealing piece larger to achieve sealing.
④ Expansion type: A liquid with a certain pressure code K, which acts on the inner cavity of the sealing element to enlarge the diameter of the sealing element and achieve sealing.