flow calculation of air through orifice

[woutertje]

Goodevening fellow engineers,

A short question. I have a piece of pipe of known diameter, and orifice of known diameter, and air at known properties. If the range of the orifice DP transmitter is known (for example x mm H2O), how can this be converted into volumetric flow range? I have been browsing around for a while but always get lost in the big heap of information on the net. Thank you for your help!

 

[mbeychok]

Woutertje:

I strongly suggest that you read the "Orifice plate" article at:

http://en.wikipedia.org/wiki/Orifice_plate

Especially, study the section entitled "Flow of gases through an orifice. It contains the equations you need, for non-choked flow.

I also strongly suggest that you read the "Choked flow" article at

http://en.wikipedia.org/wiki/Choked_flow

which has the equations for choked flow as well as explaining how to differentiate between choked and non-choked flow.

Milton Beychok
(Visit me at www.air-dispersion.com)
.

 

[Ashereng]

Woutertje (Chemical):

Is this a homework question?

The reason I ask is that the orifice lab is a first or second year course for chemmies.

Homework questions are not allowed on Eng-Tips.

"Do not worry about your problems with mathematics, I assure you mine are far greater."
Albert Einstein
Have you read FAQ731-376 to make the best use of Eng-Tips Forums?

 

[Cockroach]

Your pressure drop is directly related to velocity of flow through the pipe via Bernoulli Equation. In the absence of compressive flow, typically the case for neglegable pressure drops across the orfice, then the volumetric flow is simply cross sectional area of the pipeline times velocity of the stream.

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada