I have asked this in the Material forum but, I am not sure whether it is better to ask the Q here. Can anyone tell me what the Maximum recommended pressures & temperatures are for continuous use for the following valve (ball or butterfly) seat materials? Nylon, PTFE, RPTFE, Devlon & PEEK Are there any pressure / temperature tables available? I know there are chemical compatability issues as well but, I have found charts for them whereas nothing on the press. temp issue. at first instance, I usually consider the recommended service temperature range only (from the soft materials catalogues and/or data-sheets); but for more delicate applications and accurate information I'd suggest to refer to the Supplier directly. Some of that information can be found on the web... Du Pont - Dow (elastomers division) - for example - provides a "Chemical Resistance Guide" that may be downloaded after a free registration. The valve manufacturer will generally determine the limits on these by experiment using their designs. Generally ANSI pressure ratings where I have seen these materials used: PTFE 150 to 600 Nylon 150 to 600 RPTFE 150 to 900 Devlon 300 to 1500 PEEK 600 to 2500 It also depends on the valve size - a 4" 600# valve may be OK with a Nylon seat, but at 20", it needs PEEK. Again, it goes back to what the manufacturer has qualified in their R&D department.

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