Measurements & Conversions

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An AMCA Standard 210 double chamber is used to accurately measure air volume
and static pressure.

Air Volume and Staic Air Pressure Chamber

Maximum static pressure: As
shown in the figure, when closing the nozzle, the pressure in
the A chamber will reach the maximum. This differential
pressure (Ps) between the air pressure and the pressure in the A chamber can be called
the maximum static pressure.

Maximum air flow: When opening
the nozzle and absorbing the air using the auxiliary blower to
make the static pressure zero (Ps = 0), the differential pressure (Pn) between A chamber and B chamber will reach the maximum. The air flow
obtained by applying the differential pressure (Pn) to the above equation can be called the maximum air flow.

Note : Fan performance is calculated using the data obtained from this equipment
according to the following formula:

The Equation : Air flow Airflow Formula

C : Coefficient of nozzle air flow
D : Diameter of nozzle (m)
r : Air density Air Density Formula
t : Temperature (oC)
P : Air pressure (hPa)
Pn : Differential pressure of air flow (Pa)
g : 9.8m/s2

Use the tables of multipliers below to convert between units.


CFM m3/min m3/hr L/sec
1 0.028 1.7 0.47
35.3 1 60 16.7
0.59 0.017 1 0.28
2.12 0.06 3.6 1

       Example: To convert from CFM to m3/hr multiply by 1.7.

         Static Pressure

in H2O mm H2O Pa
1 25.4 249
0.039 1 9.81
0.004 0.1 1

To convert from Pa to in.H2O multiply by 0.004.