The sealing materials for plastic valves commonly used are PTFE, EPDM, FPM. Different material has different properties, select a right material of sealing for plastic valves is very important.

PTFE, also known as Teflon, has excellent chemical stability, corrosion resistance and non-toxic. It is one of the best materials with corrosion resistance in the world. Besides molten alkali metal, chlorine trifluoride, chlorine pentafluoride and liquid fluorine, it can withstand all other chemicals and boil in aqua regia without any change. It is widely used in various occasions requiring acid-base resistance and organic solvents. It has good sealing, high lubrication, no sticky, electrical insulation, good aging resistance and excellent temperature resistance. It can work long term at temperatures from -180 to 250 ℃

PTFE is usually used as seat material and packing material of BALL VALVE and BUTTERFLY VALVE, with good sealing, wear resistance and self-lubricating performance. PTFE is one of the best valve sealing materials under high temperature, high pressure, high corrosive working conditions, long-term use is not easy to deformation and damage. At present, the processing of PTFE parts is mainly machining and vulcanization. For the parts with complex structure, the processing cost is high. The hardness of PTFE is high, and the Plastic Valve body is easy to deform after a period of use at a higher temperature , Therefore, the assembly surface of the plastic valve and the PTFE seal may deform and leading to the risk of leakage.

EPDM rubber is a terpolymer of ethylene, propylene and non conjugated diene. EPDM has excellent aging resistance, corrosion resistance, water vapor resistance, elasticity and electrical insulation. Therefore, it is widely used as the sealing material of plastic valve. It has good resistance to general acid medium and alkaline medium. EPDM has good oil filling performance, so oil medium should be used carefully. EPDM has good vulcanization processing performance,so the cost is low, and can be made into complex structure parts. Moreover, the production cost of EPDM is not high, so it is often used as the sealing ring of plastic Ball Valve, plastic Butterfly Valve, plastic Check Valve, plastic Diaphragm Valve and other plastic valves, and can be used for industry application.

Fluororubber, also known as FPM, Viton, FKM, is a kind of synthetic rubber containing fluorine atoms. It has excellent heat resistance, oxidation resistance, oil resistance, corrosion resistance and aging resistance, and can be used for a long time at 200 ℃. FPM has a high degree of chemical stability, which is the best one of all elastomers at present. FPM is resistant to oil-based oil, diester oil, silicone ether oil, silicic acid oil, inorganic acid, most organic and inorganic solvents, drugs, etc., only ketone, ether, ester, amine, ammonia, hydrofluoric acid, chlorosulfonic acid, phosphoric acid hydraulic oil. Its corrosion resistance is better than EPDM rubber, and has good vulcanization processing performance, so it can be replaced by fluororubber when some PTFE materials can not be used. There are different types of fluororubber according to the content of fluorine, and they have different effects on the properties. Therefore, it is necessary to know the corresponding brand and performance from the supplier.