CFM to Pascal

B

Thread Starter

Burak

I have to install a new system. System data sheet need exhaust flow as "60cfm"

But i can't measure that, so i need to convert this to pascal..
Are there any special program for this? Or how can i convert cfm to pascal?

My fluid is air
 
A

Allard Gilles

You can't. Period!
CFM (cubic feet per minute) is a flow unit while Pascal is a pressure unit. There is no direct relation between the two.
 
CFM is calculated using differential pressure (i.e. The high and low of either side of a VAV damper). DP is measured in in/wc (English) or pascals (metric). However the calculation depends on something called a Kfactor. The Kfactor and the formula for calculating cfm is dependent on the size duct, shape of the duct, and the manufacturer. That is why a balancer comes and measures the actual flow and then adjust the multiplier (Kfactor) to be as accurate as possible. There is a chart that shows the calibration curve of measuring cfm on the outside of all VAV enclosures; and each company calibration chart is slightly different. That's why it is not a direct conversion. We are a Distech and Siemens dealer, and Distechs programming application called GFX has a programming block meant to calculate cfm.
 
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