Seats are classified by whether they are cut directly into the body, or if they are made of a different material: Hard seats are integral to the valve body. Nearly all hard seated metal valves have a small amount of leakage. Soft seats are fitted to the valve body and made of softer materials such as PTFE or various elastomers such as NBR, EPDM, or FKM depending on the maximum operating temperature.
Seats are classified by whether they are cut directly into the body, or if they are made of a different material: Hard seats are integral to the valve body. Nearly all hard seated metal valves have a small amount of leakage. Soft seats are fitted to the valve body and made of softer materials such as PTFE or various elastomers such as NBR, EPDM, or FKM depending on the maximum operating temperature.