# How to measure open air quantity?



## bemegopi (Mar 24, 2014)

I have using 604 cfm air compressor.In some of our applications (like cleaning) we also used that compressed air by the way of 8 mm hose.

My question,

I used compressed air for cleaning purpose
air pressure- 5 bar
cleaning time- 8 min (for one hour study)
hose end size - 8mm

it is possible to find out how much air consumption it takes?? like cfm


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## David (Apr 11, 2014)

Hi,

You can measure the air flow using the following steps :

> Isolate the compressor along with its individual receiver that are to be taken for a test from the main compressed air system by tightly closing the isolation valve or blanking it, thus closing the receiver outlet. Measure the storage volume in m3 (V) which includes receiver, after coller and delivery piping.
> Open the water drain valve and drain out water fully and empty the receiver and the pipeline. Make sure that the water trap line is tightly closed once again to start the test.
> Start the compressor and activate the stopwatch.
> Note the time (t) taken to attain the normal operational pressure (P2) (in the receiver) from initial pressure (P1).
> Measure the ambiant temperature (T2);
> Measure the compressed air temperature at discharge (T1)
> Calculate the capacity as per the formulae given below :

Q = V x (P2-P1) / (P0 x t) 

Correct by the factor : (273.15 + T1) / (273.15 + T2)

Where :
P1, P2, P0 (atmospheric pressure): kg/cm²a
V : m3
T : minutes
Q : m3/minutes

Then convert in free air or Nm3 or cfm as you want.


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## shanonmethod (Nov 13, 2013)

David said:


> Hi,
> 
> You can measure the air flow using the following steps :
> 
> ...


Hii David I admire your way of explaining this concept.Mathematical equations can easily solve the any air measurement issues.


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## nillsons (May 4, 2014)

well,if you know how big the tank is, let it fill up, turn it off, run it empty, and repeat for 8 minutes. If you dont want to count the time it's refilling, then just count the time you are emptying it.


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