Swing Check Valve

[JB23]

We are investigating the use of a swing check valve to control reverse flow at an air compressor inlet. A swing check valve was chosen to minimize flow restriction. I am under the impression that swing check valves offer the least resistance due to the straight flow path. I am concerned that the appropriate valve size for the flow and pressure requirements will contain a heavy valve disc requiring high energy to maintain an open position. Does anyone have formulations relating disc weight, position and flow energy (velocity, pressure) for swing checks in order to estimate the head loss?

 

[poetix99]

Contact the vendor. Gimpel Corp., for example, will give you loss data for your particular application.

 

[athomas236]

poetix99 is right about contacting a vendor but if you just wanted some ideas for preliminary investigations try Crane410.

Typical values of minimum velocity to keep valve fully open in metres per second are given by formula Vel= 45 to 60 times the square root of the specific volume in cubic meters per kilogram.

ahtomas236

 

[poetix99]

FYI - If you don't own, or are unfamiliar with Crane Technical Paper #410, it is a useful reference for calculating flow through piping and fittings. It's available for purchase at

http://www.cranevalve.com

 

[vanstoja]

The loss factor (LF) in velocity heads (ie, (rho*v^2)/2 for a zero seat angle, single-pivot swing check valve as function of inlet pipe inside diameter(in millileters) is given by Idelchik (pg.455)as follows:

D(mm) 40 70 100 200 300 500 750
LF 1.3 1.4 1.5 1.9 2.1 2.5 2.9
Idelchik,I.E.(1986), Handbook of Hydraulic Resistance, 2nd Ed. Hemisphere Publishing Corp. ISBN 0-89116-284-4
The cited reference, a 1931 Russian paper by Kuznetsov suggests aerodynamic rather than hydrodynamic data which fits your compressor. I've seen data from a 500+ millimeter diameter swing check valve for water flow with design objective loss factors of 1.0 (actually tested at 0.7 to 0.9 loss factors) which seems to make Idelchik's numbers rather conservative. For air or gas swing check valves, I wouldn't expect the disk assembly to be to be heavy compared to water service. For the latter it is imperative to get the disk seated before full backflow develops to limit the rho*v*c prssure surge which can be very high in water. If you've got a reciprocating compressor, pressure pulsations in the flow may cause instability problems for any inlet or discharge swing check valve and it's unclear to me whether a lighter or heavier disk would be the better choice for disk stability.