static pressure 2

[mab3013]

Hi there,
I would like to calculate static pressure using air flow, can anyone give me an idea how to do that. I have air quantity of 10,000 L/s and an area of 11m2. I want to check the static pressure using these values.
Thanks and regards.

 

[willard3]

Total pressure = velocity pressure + static pressure

You only know velocity pressure with what you have given and it can all be converted to static pressure.

As you loose pressure from friction, you will begin to have a static pressure number and the velocity pressure and velocity will decrease.

In the USA, velocity pressure = (V/4005)^2
velocity in ft/min

 

[ChasBean1]

I'd assume you're looking at pressure buildup resulting from 10,000 l/s flow through an 11 m2 open area?

What I'd posted in the past was using a simplified leakage equation (posted by ASHRAE, from a more complex orifice equation). Please note that the units are in English:

Q = 2610 * A * dP^.5

Q is flow in cfm (difference between supply and exhaust to/from the space)
A is net area of cracks/openings in ft2
dP is in inches water column

Converting everything I get .0047 in. w.c. (or about 1.2 Pa). Very small due to the large open area.

I've found in practice you can get pretty close with this estimation. Hopefully it helps.

CB