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Orifice plate (diaphragm) flow and pressure drop calculation
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1. Introduction
2. Pressure drop through an orifice
3. Orifice flow and pressure drop
calculation tool
1. Introduction
Orifices
are often used in fluid mechanics to limit mechanically the flow. It
is important to be able to size them.
The
restriction orifice mentioned here is a thin perforated plate, also
called orifice plate or diaphragm.
2. Pressure drop through an orifice
How to calculate the pressure
drop through an orifice plate ?
The following correlation is given
by Gibson, it is reproduced in many books.It relates the flow through
the orifice and the pressure drop.
With :
K = Pressure drop coefficient
D = Pipe diameter (m)
d = orifice diameter (m)
um = fluid velocity, before diaphragm, (m/s)
ΔHs = Pressure drop in m
Equation 1 : singularity pressure
drop coefficient for an orifice
K = Pressure drop coefficient
D = Pipe diameter (m)
d = orifice diameter (m)
um = fluid velocity, before diaphragm, (m/s)
ΔHs = Pressure drop in m
The coefficient K can also be calculated thanks to the following graph :
Graph 1 : K coefficient as a
function of d/D
3. Orifice flow and pressure drop calculation tool
How to calculate the flow through an orifice plate ?
You can access to an Excel calculation tool in order to assess the flow and pressure drop through an orifice plate : Excel calculation tool
Warning : this calculator is provided to illustrate the concepts mentioned in this webpage, it is not intended for detail design. It is not a commercial product, no guarantee is given on the results. Please consult a reputable designer for all detail design you may need.
Source
Gibson et al., Hydraulics and its
applications, 5th edition, Constable London, 1952