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30012009, 11:05 PM #1
How to calculate the Flow rate of air blower(centrifugal type)
Please tell me the formula of flow rate of air blower (centrifugal type).
Regards
Nadeem

30012009, 11:45 PM #2
Re: How to calculate the Flow rate of air blower(centrifugal type)
Sorry, we are not manufacturers of ventilation fans here.
I suggest you ask somewhere else as this is a refrigeration forum.Brian  Torquay, Devon, UK
I have to stop saying "how stupid can you be?" to my coworkers.
They're starting to take it as a challenge...
BASIC MAINTENANCE. If it doesn't move and it should then use WD40. If it moves but it shouldn't then use Duct Tape.

20022009, 10:40 AM #3
Re: How to calculate the Flow rate of air blower(centrifugal type)
There are generally two possibilities that i know. One is to measure the air velocitiy in the attached duct work. Using the formula volume flow=hydraulic area (ductwork)* measured velocity, will give you the answer. The other possibilty is to utilize the the absorbed power vs. volume flow / differential pressure chart of the fan manufacturer. Therefore you have to measure the absorbed power of the fan motor. Hope that helps.
regards
EntropieRTFM always thoroughly!
Vacuum sucks!
Sience rules!

22022009, 10:02 AM #4
Re: How to calculate the Flow rate of air blower(centrifugal type)
hi all
the formula is Pt= Ps+Pv
Pressure total = Pressure staitis + pressure velocity
or
quantity= area*volume
if the duct is 2 metres by 2 metres volume is 2 metres/second
= 2x2=4 x 2m/sec= 8 cubic metres/second x that by 1000 = 8 litres a second

22022009, 08:57 PM #5
Re: How to calculate the Flow rate of air blower(centrifugal type)

22022009, 09:23 PM #6
Re: How to calculate the Flow rate of air blower(centrifugal type)
CFM = Q/1.08 x TD
Q = Total BTU or another way is this:
http://www.1728.com/flowrate.htm

22022009, 11:58 PM #7
Re: How to calculate the Flow rate of air blower(centrifugal type)
His question is how much air will a centrifugal fan produce, not how to measure it in a duct.
Brian  Torquay, Devon, UK
I have to stop saying "how stupid can you be?" to my coworkers.
They're starting to take it as a challenge...
BASIC MAINTENANCE. If it doesn't move and it should then use WD40. If it moves but it shouldn't then use Duct Tape.

30032009, 07:58 AM #8
Re: How to calculate the Flow rate of air blower(centrifugal type)
Volume flow rate = Area of the duct X velocity
remember area = pie X diameter squared/ 4

30032009, 06:46 PM #9
Re: How to calculate the Flow rate of air blower(centrifugal type)

26062009, 07:53 AM #10
Re: How to calculate the Flow rate of air blower(centrifugal type)
i too have an blower...its 550 cub.mt per min, and t manufacturer says a value 60mmAq...
I am not sure as to what pressure value to be taken if I use ideal gas law to calculate mass/molar flow rate to calculate air velocity
pls suggest
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