Butterfly valve seat is a removable part inside the valve, the main role is to support the valve plate fully open or fully closed, and constitute the sealing vice. Usually, the diameter of the seat is the size of the valve caliber. Butterfly valve seat material is very wide, commonly used materials are soft sealing EPDM, NBR, PTFE, and metal hard sealing carbide material. Next we will introduce one by one.
1.EPDM-Compared with other general-purpose rubber, EPDM rubber has great advantages, mainly reflected in:
A. Very cost-effective, in the commonly used bananas, EPDM's raw rubber seal is the lightest, you can do a lot of filling, reducing the cost of rubber.
B. EPDM material aging resistance, withstand sun exposure, heat resistance, water vapor resistance, radiation resistance, suitable for weak acid and alkali media, good insulation properties.
C. Temperature range, the lowest can be -40 ° C - 60 ° C, can be 130 ° C temperature conditions for long-term use.
2.NBR-oil resistant, heat resistant, wear resistant and at the same time has good water resistance, air sealing and excellent bonding properties. More applications in the oil pipeline, the disadvantage is that it is not resistant to low temperatures, ozone resistance, poor insulation properties, elasticity is also general.
3. PTFE: a fluorine plastic, this material has a strong resistance to acid and alkali, kang various organic solvents performance, while the material is high temperature resistance, can be used continuously at 260 ℃, the highest temperature can reach 290-320 ℃, PTFE appeared, successfully solved the chemical industry, petroleum, pharmaceutical and other industries in the field of many problems.
4. Metal hard seal (carbide): metal hard seal valve seat material has very good resistance to high temperature and high pressure, corrosion resistance, wear resistance characteristics, very good to make up for the defects of the soft sealing material is not resistant to high temperature and high pressure, but the hard seal material on the processing requirements of the process is very high, the only disadvantage of the metal hard seal valve seat sealing performance is poor, will be in a long time after the operation of the work of the leakage.