Hi, I'm looking for some help ma

[hhughes2589]

Hi,

I'm looking for some help making a convincing argument regarding a butterfly valve that utilizes EPDM to achieve an enhanced seal (improves with pressure) operating in HVAC duty (water, glycol @ <250F) versus PTFE(teflon). Which seems to have a mysterious "buzz" with specifying engineers for some unknown reason.

My knowledge of materials is limited, and my general understanding is that the properties PTFE are not superior performance wise given the low temp (below 250) and benign nature of the media (CHW, HW, CW glycol). PLEASE HELP

Am willing to send gift of appreciation at the conclusion of my many unanswered questions on this topic.

 

[btrueblood]

Dunno what to say. EPDM is the preferred choice for that service, and it's a true elastomer, and so won't suffer from cold flow (creep) and wear issues that PTFE will. The elastomeric nature of the EPDM may result in a higher breakaway torque, but that's a pretty small trade for the tighter shutoff capability.

 

[Metten]

EPDM valve with ptfe coating?

 

[GrahamBennett]

Such low service temperatures and relatively benign liquids are indicative of a perfect EPDM-based butterfly valve compound. I wouldn't fill the compound with whiting though because of the water. Using a PTFE-based compound here would be a complete waste of money in my opinion.