suitable type of rubber for butterfly valve seat handling steam

[diabeticoholic]

can anyone tell me what is the most suitable rubber for butterfly valve seat handling steam at 1.5 bar?

thank you in advance.

 

[btrueblood]

Classic choice would be an ethylene propylene rubber, and probably preferably a peroxide-cured EPDM. There are also some fluorocarbons than can hold up ok, which is useful if the steam carries lubrication oil mist along with it; google the Dupont website for the various versions of Viton rubber, one of the grades is said to be ok for steam.

 

[diabeticoholic]

thanks a lot sir. followup question. is there a way of knowing if the rubber on my butterfly valve is epdm? does it have physical characteristic that i can distinguish and say its epdm and not neoprene or ptfe.
thanks in advance.

 

[btrueblood]

Best method: ask the manufacturer.

PTFE will be a fairly stiff plastic, not a rubber. But it will be difficult to distinguish neoprene, nitrile, and EPDM rubbers, especially without removing the seal from the valve and/or doing destructive tests. At which point, you might as well just install a new, known material.

 

[diabeticoholic]

my concern is in confirming whether the replacement rubber seat is indeed epdm because we've had seat replacement almost every year due to wear on the same butterfly valves. could it be due to inferior material used (not epdm) or could it be something else causing this problem? thank you in advance.