Orifice Plate Flow 1

[LisaKnapman]

How do you calculate the flow through an orifice plate? They want to replace an existing orifice plate with one that has a smaller bore size. How can I calculate what the flow through the new plate is going to be?

 

[hacksaw]

Flow is proportional to the square of the bore for a given meter d/p, so

Q1/Q2 = d1^2/d2^3

you can rerange the d/p measurement though it is sqrt(h1)/sqrt(h2) ...

lots of parameters are ignored, so this is a just a plant calculation for what its worth...

 

[LisaKnapman]

Maybe I am having a blonde day...

I have the following information for the existing plate:

Fluid: Air
Specific Gravity: 1.0
Viscosity: 0.0192 cPS
K (CP/CV): 1.41
Barometer: 14.7 PSIA

Base Conditions:
Temperature: 60.0 Deg. F
Pressure: 14.73 PSIA
Compressibility: 0.9991

Flowing Conditions:
Temperature: 110.0 Deg. F
Pressure: 26.7 PSIA
Compressibility: 0.9993

Line Size: 6.0"
Differential Range: 0-20"H2O

My new orifice plate is 316SST, 150# flange rating, 6.0", Bore Size: 1.3543

What is the expected flow through this plate?

 

[Eltron]

Check out this website:

http://www.okcc.com/

They have a lot of useful info there.

Dan

http://www.eltronresearch.com

Dan's Blog

 

[schlebda]

Try any orifice flow sizing utility, there's lots of them.

http://www70.de.abb.com/fpd500/gui/index.html

 

[vpl]

You might also search for "orifice" on this site. This question comes up a lot.

Although I have a question about the data you posted. Suppose somebody here took it and came back with an answer "you need an orifice with an orifice of 1.15 inches." (This is a totally bogus number. Do NOT use it!!)

How would you justify using that value to your management? Do you really think saying "Someone on a free Internet site told me the answer" would work?

You'd be a lot better off asking "where can I find out how to calculate this myself. (and,by the way, do you have a copy of Crane's Technical Paper 410, "Flow of Fluids Through Valves, Fittings, and Pipes?")

Sorry, rant over.

Patricia Lougheed

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.

 

[LisaKnapman]

Thanks for all of your help! I will use your info to come up with a flow.

About the "info"... I posted it because I thought that someone who saw it might have the sizing program and be able to quickly pop out the flow I can expect to get. I already have an orifice plate, I just don't know what kind of flow I will get through it.

Unfortunately, I am not very familiar with orifice plates and do not have the software to help me.

 

[rikiraph2]

there is a program

http://www.controlengineering.se/flowcalc/flowcalceng.htm

it is freeware

 

[hacksaw]

Lisa,

Appologies for the delay, I come up with 135.5 scfm at the conditions you've provided for flange or close-up taps and a square-edged orifice plate.

 

[LisaKnapman]

Thanks hacksaw!! You're a life saver.

I just downloaded the program that rikiraph2 suggested. I'm going to try to duplicate your answer on my own so that I will know how to do if myself next time.

Thanks again!!!