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Airflows measurements

Several methods are existing to measure firefighting fan airflow. Discover these methods to realize tests with realistic measurements that meet as near conditions found on the fire ground.

I. Nominal Airflow

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The nominal airflow is the volume of air which passes through the fan. We measure it at the outlet of the units shroud (without reference to its distance from the door opening).

 


II. Full airflow

Description: The fan is positioned at distance « d » from a measurement gate.

The “full airflow” is the air ​​blown by the fan (nominal airflow) added to the air entrained (this  effect varies according to the speed and the shape of the jet at the fan outlet).



Advantage: It gives an indication of the full flow capacity of the fan.
 

Disadvantage : This airflow is not representative of any effective airflow during a PPV operation. Indeed, it
does not take into account the restriction due to a doorway entrance and obstacles, which influence a lot the airflow
efficiency value.

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III. Airflow according to AMCA 240 standard

 debitdairphoto1448Description:
Airflow through a test chamber allowing adjustable pressure – Method according to AMCA 240 standard:

- The chamber is made up of 3 volumes: C1, C2 and C3.
- A fan is positioned at a distance « d » from the chamber and it blows into C1 through an entrance of 0.91 to 2.03m in width.
- A wall system built between C1 and C2 allows blending the air movement to make it uniform.
- A second wall system made up of calibrated holes and built between C2 and C3 allows airflows calculation via the pressure difference between C2 and C3. Taking into account the size of the calibrated holes we can conclude the airflow at a time « t ».
- An extraction fan positioned at the end of C3 allows varying the pressure in it and so varying the speed and so the airflow between C2 and C3.
-The static pressure is measured in C1.

 
illustration methode amca 240 eng 500x300

 

 

 

 

 

 

 










By varying the speed of the extraction fan, we obtain then a series of results that we write down on a graph to draw a curve (airflow in X-axis and variation of pressure p in Y-axis).

The airflow of the ventilator tested according to AMCA standard is found at p = zero, is when the curve crosses the X-axis.

Curve example after an AMCA test - Airflow vs. Static pressure curve (SI)

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Advantage: This AMCA 240 method considers the restriction due to the cross sectional area of the entrance. 

Disadvantage: Manufacturers give AMCA airflows at zero pressure. This AMCA airflow “at free air” is not representative of the effective airflow during a PPV operation. Indeed, it does not take into consideration the overpressure (positive pressure) generated by the air stream inside the test chamber. 


IV. Airflow according to ULH method

Description :
Airflow through a positive-pressure test chamber - ULH method (University of Le Havre):

  • The chamber is made up of 2 volumes C1 and C2.
  • A fan is positioned at a distance « d » from the chamber and it blows into C1.
  • A wall system built between C1 and C2 allows blending the air movement to make it uniform.
  • An outgoing is created at the end of C2. It is here that the speed measurement is done to calculate the airflow.

 

 illustration methode ulh eng 500x300




 

 

 

 

 

 

 

 
 

 

 

Advantage: this method takes into consideration the restriction due to a doorway entrance and the overpressure (positive pressure) created by the airstream inside the test chamber.

This positive-pressure method is not linked to a standard as AMCA 240; so several sizes of entrance and outgoing can be tested to go deeper in studies.

This is the most realistic measurement method that meets ground operating conditions.  

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This is the measurement method adopted by LEADER for their tests. LEADER has built its own Test House to support R&D and allows the company to validate its Easy Pow’Air Technology effectiveness.