Pump up equation? 1

[imjasper]

I am trying to determine how long it would take to pump air into an open bottomed barrel(100 cubic feet) in a tank of water 230 feet deep. (Say a silo)
I know that the psi at that depth is approx 100 psi.
The pump will be located below the tank so there will be minimal amount of hose needed.
I have a 25hp pump pushing 100 CFPM.
How do I calculate this???
any help would be greatly appreciated.

 

[bandrsntch]

Answer depends on what pressure the pump operates at. If less than 100psi, you can never fill the barrel. Of course you must have just over 100psi, otherwise the air would never have enough pressure to overcome the water pressure. Now assuming you have just enough pressure, with a 100cfpm pump it would theoretically take 1 minute to fill a 100 cubic foot barrel. If you have a higher pressure output it would take less time, in which case you should be able to use the perfect gas law to figure(P1*V1/T1=P2*V2/T2. Do you know what pressure out put of pump is? If pump pressure output was 200psi, then its equivalent volume in the barrrel would be twice that in the pipe. Effectively you could fill the barrel in half the time. This is all theorectical and there will some friction losses, but it should get you in the ball park. How close do you need? Answer would be: Time= Volume of barrel/(CFM of Pump * Pressure OutPut of Pump/Pressure in barrel).

 

[imjasper]

Thank you very much. That answers my question completely.
I even went so far as to contact a few air pump manufacturers and was told by the chief engineer (which I highly doubt) that all it would do is aeriate the water........LOL.
Again, thank you very much.