Pressure drop in ventury flow model

[thought2007]

Hi

I have question on Pressure drop in ventury flow model

Is pressure loss at convergence & Orifice going to regain at divergence.The flow path is horizontal,length of convergence and divergence is same

Operating pressure:60psi
Fluid temp : -56degF to 230degF
Flow rate : 18gpm
Fluid : MIL-PRF-5606

would appreciate your suggestions

John

 

[thought2007]

This ventury flow model is built in ball valve

 

[JLSeagull]

Some permanent loss occurs even with the valve fully open. The control valve sizing formulas preduct the permanent loss based upon factors associated with the valve at various positions. Such data may not be available with ball valves not intended for throttling.

 

[JimCasey]

Thought2007
You did not specify the valve/pipeline size nor schedule (needed for i.d.) . Also: Venturi is spelled thusly.

JLSeagull: Ball valves are commonly listed with a Cv, which takes into account all losses between the pipe fittings. I'd use the sizing programs vs pencil & paper, since in this calse the Mil-spec lading probably has some viscosity that needs to be evaluated.
Reducer correction coefficient Fp would adjust losses to correct for a valve between reducers.

 

[thought2007]

Jimcasey,

Pipe dia: .875in
orifice dia:.6inch

John

 

[JimCasey]

Thought2007

1/2" sch40 pipe is 0.840 od, and 0.622 i.d.
I ran this application thru the Flowserve sizing program and used a full-port Worcester ball valve. 2 psi drop through the valve ( assumed SG-0.9 for Mil-Prf-6206)
The scary thing is that the velocity will be 105 ft/sec in the pipe. Is this one of those aerospace things that just has to last for 90 seconds, or will you be seeing repetitive or continuous duty. If durability is a concern, suggest you open up your pipe size to get the velocity down.