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Flow orifice calculations
How to calculate orifice details (dp, beta ratio, etc.)
By Sunil Kumar on 18 October, 2006 - 12:11 am


Suppose I have to install Orifice plate in a line for which I know the Line Size, Flow range, Pressure Range, Operating pressure & temperature range. As well as Viscosity. How can I calculate the Orifice detail? How can I calculate dp, beta ratio? Do you know some software where u feed the detail you know and it will calculate the beta ratio & dp? and orifice thickness? I mean free software. Please help me. I need it urgently.

Hello Sunil,

You might find your answer at
Start by looking at the Bernouilli equation. You must take into account whether your fluid is compressible or not!


It is better to go through BS-1042. In case if you encouner any problem, please do not hesitate to contact me.

Arun Kumar

By Hilton Lawson on 28 October, 2006 - 1:56 am

Daniel flow has a downloadable flow orifice calculator that is menu driven and very to use. Daniel is a division of emerson electric.

A couple of sources for rigorous calculation procedures are:

R.W. Miller / Flow Measurement Engineering Handbook / McGraw-Hill
ASME standard MFC-3M-1985 or the latest version

There are many other less precise procedures also available

John Catch

How much does this book cost?


A more precise assembly of calculations can be found in " L. K. Spink's "Principals and practice of flow meter engineering".

These are user friendly and directed at the plant floor.