Hard seat and soft seat

dx · 10-22-2010, 10:15 PM

What exactly is a hard/soft seat valve, what purpose does each serve, and where is one used vs. the other?

http://store.webstonevalves.com/defa...itemcode=10542

**jimbo** · 10-23-2010, 06:40 AM

Hard seat means metal to metal contact. A soft seat would have a seating surface with a rubber gasket, or maybe a teflon ring, or such.

hj · 10-23-2010, 09:06 AM

When it comes to check valves, a soft seat will not make as much noise when it closes. The hard metal to metal contact of the hard seat can cause be quite loud, especially if there is a lot of back pressure "slamming " it shut. The hard contact can also cause it to "rebound" creating a chattering noise.

dx · 10-23-2010, 01:03 PM

Thanks guys. Related question: some swing checks are labeled "for horizontal installation only". I do understand why. But why aren't all of them labeled that way? Can some of them be installed vertical or is it just that some manufacturers fail to label them properly?

hj · 10-23-2010, 01:52 PM

I cannot imagine why they would be labled that way, since gravity and the weight of the liquid would close them in a vertical orientation. When they are installed horizontally, some have a label to show which side should be on top, because the hinge location is not obvious.