air flow coefficient through an orifice plate

[rotor]

How can I find the air flow coefficient and air density which must be used to calculating the volumetric flow rate through an orifice plate (flange) in an air pipe? thanks lot

[PipeFlowCalcs]

Hope orifice plate calculator can help. Use absolute pressures in calculations.

[bad66cp]

Yes, I have a similar question about unsteady air flow through a valve. I have a question about using your flow equations. I'm thinking I can get the flow started using newtonian flow (F=m*a) for very small time increments, the known pressure on either side of the valve, and the pressure loss due to friction. Where the total force = (p1-p2-gravity*headLoss*density)*area. I assume the area is pi*(d1/2)^2, where d1 is the smallest diameter of the contraction and expansion. The mass can be computed from the density*volume, where the volume is between p1 and p2. I think I can compute the headLoss from (k1+k2)*velocity^2/(2*gravity), where k1 is for contraction and k2 for expansion and functions only of the ratio of the diameters. Is the velocity in this equation the velocity at the smaller diameter d1? Then I'm thinking I can compute at the same time what the steady-state flow rate (q) would be for this valve from your "The rate of flow of any fluid through a orifice or nozzle...". Ideally, I should be able to run the newtonian flow with loss with a small delta t and reach the calculated steady-state flow rate smoothly after some settling time.

Do you think this would be fairly accurate and did I interpret the equations correctly?

Thanks for the help,

Brandt