FCO432 Users Guide Issue 1
Page 31
Using a Pitot Static Tube
The 400 Series Pressure transmitters can be configured for use with measuring devices that provide a
pressure signal that follows a square law such as the Furness Controls Pitot Static Tube.
Example:
A ventilation duct has an area of 1.4 m
2
and has a nominal airflow of 8 m
3
/s. A single point Pitot is
used to monitor the flow rate. The duct pressure is 1035mb absolute and the temperature is 23°C.
Using the Pitot Tube Volumetric flow calculation, the velocity for maximum flow is determined.
std
std
std
T
T
P
P
A
Q
V
14
.
293
14
.
296
103500
101325
4
.
1
8
V
V
= 5.651 m/s
Using the Pitot Tube velocity calculation, the
P for maximum velocity is determined.
rel
T
P
K
V
P
2
96
.
23
1
14
.
296
103500
1
2
96
.
23
651
.
5
P
P
= 19.44 Pa
Therefore, a Model 1 FCO432 is selected which has a maximum differential pressure range of 50Pa.
The desired scaling is
0 to 19.44Pa (4 to 20mA) with a display of 0 to 8 m
3
/s
Referring to the
Menu Details
section:
Set the
Display
mode to
square root
Set the
Units
to
Pa
Set the
Custom Units
to
m
3
/s
(CMS)
Set
DP Low
to
0.0
Set
DP High
to
19.44
Set the
Decimal Point
to
00.00
Set
Display Low
to
0000
Set
Display High
to
0800
