# Room Difference pressure

1. Jan 28, 2008

### enmuaxuan

I have a room 6x6x3 m
I want to maintain the Difference pressure between the room and outside area 30Pa.
How can i calculate the rate of supply and exhaust air flow to do it?
is there a formular to calculate?
Pls help me.

2. Jan 28, 2008

### mervincris

Use Q = 0.83AP^-n, where Q = net flow rate, A = effective area of leakage, P = differential pressure, and n = 1 to 2 (1.6 for cracks around windows, 2 for large openings such as doors and windows).

3. Jan 28, 2008

### Staff: Mentor

Estimating leakage is extremely difficult. You may need to do it experimentally.

4. Jan 28, 2008

### mervincris

construction standards may also be used as a reference. they have an approximate measurement on leakage areas based on the type or quality of construction of the building, or room for the case of enmuaxuan. try british standards, specifically BS EN 12101-6:2005. the equation i have given you is also found there.

5. Jan 31, 2008

### enmuaxuan

Thanks.
Mervincris, could you give the detail of EN 12101-6:2005?
Thank you again.
enmuaxuan

6. Jan 31, 2008

### mervincris

no prob. it is specifies the standard for pressure differential systems to prevent the smoke, during fire, from entering critical spaces. usually, these critical spaces are stairwells which are used as means of escape during fire.

7. Feb 20, 2008

### mervincris

correction: ...it specifies...