Vacuum chamber vent time

[GT35]

Hi all,
What is the simplest method for calculating the vent up time to atmosphere in this application:

Chamber volume: 5 cubic metres
Base pressure: 50mtorr

3 vent valves in paralell
150psig N2 inlet pressure
cv of each valve 0.23

That is all I have to go on!

 

[btrueblood]

You can't get there from here; the Cv value of the valve does not apply when the flow is sonic (which it will be for that pressure ratio). You could try and back-calculate the flow area of the valve...if you knew details of the seat geometry and had decent guesses for that geometry's flow coefficient(s) at the Reynold's number for which the Cv value was measured, if it was ever measured....

 

[Occupant]

You need the X_T for the valves from the manufacturer then you can do it per attached.