The spring-loaded seats on the upstream and downstream […]
The spring-loaded seats on the upstream and downstream sides allow the valve to seal in two directions. Therefore, installation of the valve is possible in any flow direction during.
Trunnion pvc ball valve suites bidirectional sealing with both upstream and downstream flow applications best.
If pressure comes from upstream flow direction, it could be possibly cause valve seat damage. Unsupported Teflon seats can cold flow and be destroyed under high velocity fluid effects. They are primarily vulnerable to erosion or solids in the flow stream. It is always a good idea to provide all pressure and flow information for high pressure (2000+ psi) reverse flow directions when floating ball valves are required.
A ball valve design where the body is held in-line with the stem supporting the ball is a trunnion ball valve. In this configuration, the centerline of the ball spherical surface and centerline of the stem diameter are identical. Under operating conditions, the ball does not move from this position or “float” up or downstream.
Typically, a surface in the body which carries the pressure end loads supports the ball. There are seats on each side of the ball that are spring loaded into the ball making it a true bidirectional sealing valve.
Testing the trunnion design at full rated pressure in either flow direction is possible without any soft seat damage
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