Orifice pressure

[evanmars]

I have a 36" x 72" x 1.75" box with an air input of 100CFM at approximately 70 degrees F. One surface has 2275 0.0625" diameter orifices in it. How do I calculate the pressure at each orifice? The orifice depth is approximately 0.0625".

 

[chicopee]

When you stated at each orifice, how many orifices do you have? Are the orifices on the outside walls separating an air plenum from ambient air or do you have intermediate chambers in the box and orifices positioned on the chamber respective separating walls?
If you can measure the air velocity from the orifice you can calculate air velocity pressure as follows: Pv=C*V^2/2g and the result will have the unit in ft or inches. C is a constant for the orifice and V is air velocity. For static pressure use a manometer.

 

[evanmars]

It is basically a box with 2275 orifices of .0625" diameter on the top side. Ambient pressure outside. I guess what I am actually trying to calculate is the velocity at each orifice, since I think I will know the required pressure.
Is there a table that you could point me to for the orifice constant value?
I'm trying to figure out the required CFM of a blower for a specific pressure.
The setup is basically an air-hockey table. I have a known weight for the puck and the minimum number of orifices beneath it at any given time. I need to calculate a blower with enough CFM to float the puck.

 

[fredb]

Hello,

See: Flow of Fluids Through Valves, Fittings, and Pipe.
Crane Technical Paper No. 410. page 2-14.
Flow of gases and vapors: