Coeff of Discharge for Leak 3

[rkinga2]

I'm doing some estimates of choked flow of methane thru a leak in a pipe. Any recommendations for what coefficient of discharge to use? I have used 0.6, but I've seen some examples on the web of 0.72.

My current problem is a 1" hole in a 1-1/4" elbow (1.38" ID),
but I'm also concerned with smaller leaks (.060&quot.

Pressure is low - 30-60 psig.

Thanks

 

[davefitz]

for a pressure of 30-60 psig, the flow is choked flow, and the discharge coefficient for choked compressible flow thru a thick walled , square edged hole is about Cd=0.83 .

 

[JoeTank]

Wow, a 1" leak in a 1 1/4" elbow... sounds like a blowout not a leak.

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com

 

[TD2K]

If you have a 1" hole in a 1 1/2" elbow, you'll have to likely take a look at the hydraulics through the entire system from 'where ever' you have a constant pressure source to your 1" hole. If the piping up to the 1" leak is 1 1/2", it's going to have a significant factor in setting the flow through your leak.

For the small holes, the effect of the pressure loss through the 1 1/2" piping will become less until it's not significant.