Calculating negative pressure

[emalsyd]

Is there a calculation to determine how much exhaust is needed in a space to get a desired negative pressure. We have a room with 1200 supply cfm. They are looking for the room to always be a minimum of .01 wc negative. Need to determine how much cfm to exhaust.

 

[willard3]

Search this forum, this is a common question.

 

[chicopee]

Obviously, you have to exhaust more the 1200 CFM. Use the first law of thermo. developed for isothermal condition and such equation can be found in fluid dynamics textbooks; then you can use an inclined manometer to figure out how much of pressure differential you have between inside and outside the room.

 

[BronYrAur]

I know this doesn't answer your question, but it all depends. If you have a room full of holes, you will never get the desired negative pressure. This article from ASHRAE should help you.

 

[MintJulep]

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