Check Valves

PROBLEM:

Chatter from check valves close coupled to an upstream elbow
Disc pin wear and breakage
Poor sealing due to disc pin and valve seat wear

SOLUTION:

BENEFITS:

Eliminates elbow induced flow turbulence in check valves
Extends disc pin and valve seat life
Improves sealing reliability

Check valves, by the very nature of their design, respond to flow and pressure disturbances such as turbulence in the upstream piping system. This can result in the disc oscillating back and forth on the pin support. When a check valve is close-coupled to an upstream elbow, the turbulence becomes severe and if the oscillations are of a large enough amplitude, the disc may bang against the stop. Eventually, the pin fails, leakage though the pin starts, and the valve seat will not seal.

Results of time history measurements of the complex fluid pressure waves resulting from the interaction of the elbow generated turbulence and the oscillating check valve generated turbulence are presented in the figures below. Without the CRV® as shown in Figure a, it may be seen that the interaction of these two turbulant flows, results in periodically large amplitude pressure bursts. These bursts are damaging to the check valve because they result in a more severe check valve oscillation.

In check valve systems with upstream close-coupled elbows, harmful high amplitude pressure bursts can be eliminated by installing a CRV® upstream of the elbow.

With a CRV® mounted in front of the elbow-check valve combination, turbulence generated by the elbow is eliminated. Figure b shows an absence of high amplitude pressure bursts. This results in minimized wear on the check valve pins; extended life; reduced vibration and noise; and better sealing reliability.