Compressor Stuff

[Matty]

well, went to the dump today and found this old school compressor, i will get pics up later but for now....its an electric motor and belt drive to the compressor motor.  I didnt think it would put out enough psi so we hooked it up to a pressure gauge and it stopped pumping around 125 psi which is plenty to run any air tools that we would want.  so then we had spare hose and stuff and hooked it up to the tank and it would only pump it to about 20 psi and took a while and this was a small 5 gallon tank.  is there a reason for this? if we stepped the motor up would it be any better? and i forgot where the posts where about you guys running on board air, but what do you use for that? and if i hooked this compressor to my belts would it put out enough pressure for anything?  i know you might not be able to know without really seeing and know what it is, but any info will help, thanks guys

[Matty]

anybody any ideas??

[whiteman]

How long did you leave it hooked up to the tank?  I had the same problem when i tried to put my electric compressor on a larger tank. 

I went from 25gal to 40gal and it would not build pressure. I was sure i had no leaks.  I could never figure it out either.

[Matty]

probably had it hooked up for like 15 min it got to 20 psi pretty fast and would just hold itself there.  we mocked it up and had one minor leak would that cause it to only stay at 20 psi, and the other thing was that we just hooked it up to a 7 gal tank.  my buddy was trying to convince me that the fittings on it have small openings so it would take longer to pump and stay at a low psi or something, but that shouldnt affect it right?

[CTENG in KS]

The pump will put out 120 psi at atmospheric pressure, but as the tank fills the pressure in the tank creates "backpressure" against the compressor...the compressor will only be able to pressurize the tank until the backpressure becomes more than it can work against.  In your case the compressor isn't strong enough to overcome more than 20 psi...
You could try cranking the motor up to allow the compressor to increase its mass flow rate, however the harder you crank the more chance you will burn out the motor.  You could give it a shot with some air tools, but I would suggest a larger compressor.

[RHG]

HF has some cheapo compresors that you could hook up