What is normal Tank fill time for a 5 HP 30 gallon tank

by SG 1
(Hamilton Ontario)

Hi all. I received a 5 peak HP (scam) 30 gallon Campbell Hausfeld Compressor from my brother in law. He said that the reed valves need changing. Before I changed them it took 190 seconds to fill from empty. After I changed them it took 196 seconds (sigh). I then replaced the seals on both ends of the copper fill tube. Now down to 186 seconds. So it appears non of these components were defective. If it was the rings I think the crank case would pressurize and force the oil out. Is this a normal fill time for this compressor.


Thank you

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Jan 05, 2015
power ratings
by: Doug in s.d.ca

Yeah, was same thing with audio amps in the 60's.

It's simply ignoring that power over time is RMS volts times amps. For a sine wave, like AC power, that's the real power. The "peak" is around 1.7 times that, so a 3HP motor becomes 3X1.7=5.1 peak, which is meaningless.

Jan 03, 2015
motor FLA vs HP
by: SG 1

Looking in my electrical motor books, a 3 HP, split phase,dual cap, 220V motor has a FLA of about 15 Amp. A 5 HP of the same type is about 20 FLA. I am use to dealing with 3 Phase 600 VAC motors. Those are 1 amp per HP for a typical motor.

Jan 03, 2015
fill time
by: SG1

Thanks for your reply. He's had it for about 30 years. not sure why. Maybe be thought over the years it took longer to fill. Mind you I believe he always kept the tank charged as I do. Maybe the final test would be to run the compressor then shut off the power at the panel. This way the compressor and fill tube will not unload. I can now do the soap test on everything. Kind of hard to do this with it running because the cooling fans is blowing.

Current wise it is a 3 HP dual cap motor. I am an industrial electrician and first came across this "peak HP rating" when my brother in law bought the new 5 HP 60 Gallon compressor. For my labor to hook it up and some wire I got his old one. His new 5 HP draws 20 FLA amps. The old was a 5 peak HP FLA 15A. Did some goggling and this is a scam to inflate the rating of the compressor

Dec 31, 2014
fill time
by: Doug in s.d.ca

Well, we generally figure about 4CFM/HP;

30 gallons is about 4 cubic feet.

We can round off your time and say it's 3 minutes.

4CF at 8 bar (115PSI) would be 36CF of free air, divided by the 3 mins is 12CFM, which we would expect from a "true" 3HP compressor.

So, your machine seems to be operating OK, depending on how the "5HP" rating was arrived at.

Any idea why bro thought it needed new reeds?

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