looking conversion formula

[evans]

hello,
in my plan, my flowbench is not using restriction valve or air bleed. so i'm logging the flow and the testing pressure. so, the testing is bigger or smaller than 28"H2O. is there any formula to compensate the flow from the testing pressure that i've got (bigger or smaller than 28"H2O) to the flow based on 28"H2O?
thanks

[86rocco]

To standardize your readings to 28" multiply the reading by the square root of (your test pressure/28).

[200cfm]

I think it is this formula: New CFM Flow = the square root of the New Pressure divided by the Old Pressure X the old CFM flow.

[evans]

can you give me the clue or the website that can i use to derive that formula?? and how about the temperature compensation? should we calculate the changes of density compare to testing pressure?

[200cfm]

On an orifice design bench if the air passes through the measuring orifice plate before it passes through the suction motors then no temperature compensation is required. But if the air passes through the motors first and gets heated before it is measured by the orifice plates, then a temperature compensation is required. That is my understanding on this. Like you I am new at all this but I recall that statement in my research. Hope this helps.