Estimate vapor pressure loss across full bore ball valve

[Ana Silva]

Hello,

I need to estimate the pressure loss of a vapor across full bore ball valve. I know the characteristics of the fluid, Temperature and Pressure before the valve. I though about using the excess head or equivalent length methods to do this but according to the literature these methods seem only to apply to incompressible flow in pipes. What would you recommend in this situation?

Thanks.

 

[RVAmeche]

Crane Technical Paper #410 has equations for compressible flow. If your vapor is flowing at less than 0.1-0.2M, you can reasonably calculate the dP assuming incompressible flow.

 

[georgeverghese]

Also see the chapter on instrumentation - control valves for estimating dP in gas service in the GPSA.

 

[Latexman]

I use K = 0.1 (incompressible) and N = 0.1 (compressible) for full port ball valves. If pressure loss across the valve <= 10% of the upstream pressure, incompressible methods are fine.

Good luck,
Latexman

To a ChE, the glass is always full - 1/2 air and 1/2 water