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Chapter 1. Installation
10 Sentinel™ User’s Manual
1.6.2 Pressure Drop
The flow conditioning plate causes a pressure drop through the line. This pressure drop is directly related to the gas
composition and properties, and to the flow velocity through the pipe.
Using a representative natural gas composition at 70° F, an estimate of the associated pressure drop can be
computed for reference. Figure 7 below shows pressure drop as a function of velocity for a uni-directional flow
installation with a single flow conditioning plate at various line pressures. The pressure drop through the meter
section would be doubled for a bi-directional installation with two flow conditioning plates.The example shown is for
natural gas, flowing at
40 ft/sec through a pipe with a pressure of 1000 psi. The pressure drop across the flow conditioning plate is about
1 psid.
When the actual gas properties are known, a more accurate calculation can be performed using the following basic
equation for the pressure drop:
where

P
is the pressure drop across the flow conditioning plate,
k
is the loss coefficient for the plate (1.6),  is the gas
density (based on pressure, temperature, and gas composition), and
V
is the flow velocity through the pipe.
Figure 7: Flow Conditioning Plate Pressure Drop

P
1
2--k

V
2
=
Flow Velocity (ft/sec)
Associated Flow Conditioning Plate Pressure Drop
Pr
es
su
re
D
ro
p
(p
si
d)