The soft valve seat material of the ball valve mainly relies on high-performance polymers, which can be divided into two categories: core materials and auxiliary materials according to performance requirements:
1. Mainstream core materials
Polytetrafluoroethylene (PTFE)
Features: extremely strong chemical inertness (acid and alkali corrosion resistance), low friction coefficient (small operating torque), applicable temperature -50℃ to +180℃.
Limitations: easy to creep at high temperatures, and the sealing performance decreases when it exceeds 180℃.
Modified applications: adding glass fiber or carbon fiber to enhance wear resistance, used for particle-containing media.
Fluororubber (FKM)
Applicable scenarios: excellent oil resistance, tolerance to petroleum media and weakly corrosive chemicals (such as hydraulic oil, fuel), temperature range -20℃ to +200℃.
Contraindications: not resistant to amine media (such as liquid ammonia) and ketone solvents.
2. Auxiliary sealing materials
EPDM rubber (EPDM)
Advantages: Outstanding ozone resistance and weather resistance, suitable for water, steam and refrigeration systems (such as HVAC), temperature range -50℃ to +150℃.
Disadvantages: Poor oil resistance, easy to swell when in contact with mineral oil.
Nitrile rubber (NBR)
Positioning: Economical choice, resistant to petroleum-based oils, reliable sealing at room temperature (0℃ to +80℃).
Limitations: Hardens at low temperatures, ages quickly at high temperatures, not suitable for extreme working conditions.
