13
Procedure for Measuring Static Pressure
1. Select the location for the static pressure reading and drill a
1/4" hole. You may wish to paint a circle around the hole and
number it for future convenience.
2. Assemble the Velometer for positive (or negative) readings
as described above.
3. Place the rubber cup of the probe firmly over the hole, and
read the static pressure on the black or red “Inches of Water
Gauge” scale.
4. Record the reading on an appropriate air balancing worksheet.
Fan Inlet
Fan
Discharge
Procedure for Air Flow Measurement in Ducts
To calculate the air volume passing through a duct, measure the average
velocity inside the duct, determine the cross-sectional area of the duct, and
apply the following equation:
Q = A
x
V
Where
English Units
Metric Units
Q = Volume flow rate
ft
3
/min
m
3
/s
A = Cross-section area
ft
2
m
2
V = Average duct velocity
ft/min
m/s
