Old Compressor CFM?

[Iplayfarmer]

I got an old compressor off Craig's List. It is a single cylinder unit with a fairly large tank. I'm hoping someone here can help me figure out the CFM based on the tank size and how long it takes to fill up.

The tank is 27 gallons roughly measured (~15" X ~36"). It takes 30 minutes to reach the shut off pressure of 150 PSI. Anyone dare take a SWAG at the SCFM?

 

[jenkinsph]

Might be worn out I think, I have my compressor with a 30 gal tank set for 175psi and it will pump up from zero to 175 in about 1 minute or so. Mine is 19cfm @ 90 psi as I recall. Ingersoll T30 12hp Kohler motor.

 

[RPW]

Compressor sounds like it's worn out. You can get a replacement compressor from many sources on the internet for a reasonable cost. I have a 60gal 13cfm that take about 5 minutes from a complete drain of the tank.

 

[Iplayfarmer]

I'm sure it's worn, but it's just a small 110v motor. I think I read that it was 1/2 hp. I'll have to check tomorrow. I'm hoping to get some indication of the CFM to get a guess on how worn out the pump is.

The tank is in great shape, but I don't think it's worth replacing the pump. It may be worth an attempt at re-building the pump. I've had success with rebuilding newer pumps. I'd hope this older one would be easy to rebuild too.

 

[dex3361]

Being a single cylinder/stage unit it should probably be set to cut off at 125 PSI. Test the empty to off time then. A single stage pump may be nearly dead heading at that pressure.

 

[Iplayfarmer]

Being a single cylinder/stage unit it should probably be set to cut off at 125 PSI. Test the empty to off time then. A single stage pump may be nearly dead heading at that pressure.

I just happened to check the time when the PSI was a little below 125, and it was 16 minutes. Still not the best.

 

[dex3361]

Unless the belt was slipping or it has a bad valve, I would have to agree with the others its gonna have to be rebuilt.

 

[SPYDERLK]

I got an old compressor off Craig's List. It is a single cylinder unit with a fairly large tank. I'm hoping someone here can help me figure out the CFM based on the tank size and how long it takes to fill up.

The tank is 27 gallons roughly measured (~15" X ~36"). It takes 30 minutes to reach the shut off pressure of 150 PSI. Anyone dare take a SWAG at the SCFM?

A cubic foot is roughly 8 gallons so you have about a 3.4CF tank. 150 psigauge is about 10:1 compression so you have to add about 34CF to the tank for 150 cutoff pressure. That makes it 34/30 ~ 1.15CFM Average over the pressure range. Those single stage compressors can hardly breathe at 150 so your last 10psi its probably only delivering around 1/2 cfm.
larry

 

[Bird]

My compressor is a vertical 30 gallon tank, 2 cylinder, vertical compressor, 1.8 running hp, 120 volt motor pulling 15 amps, working pressure of 125-155 psi, 7.0 CFM at 40 psi, 5.7 CFM at 90 psi, but I've never timed it from empty to full since it hasn't been emptied in the last 4 years.

Well, you aroused my curiosity. So I dumped ALL the air from my compressor tank and refilled it. It took 5 minutes 45 seconds to get the gauges from zero to 125 psi and 6 minutes 30 seconds zero to 149 where it cut off instead of 155 psi, assuming the two gauges are accurate (at least they were together). That was to fill the tank and a 60' 3/8" air hose.

 

[BHD]

most likely about 1.5 to 2 cfm most likely closer to the 1.5 maybe even a little less,

Pump, Compressor - Air Compressor Pumps - Air Compressors and Vacuum Pumps - Pneumatics & Hydraulics : Grainger Industrial Supply

the pump in the URL is for 1/2 to 3/4 hp, and only 1.4 cfm at 120 psi, if you have a Half horse motor I would not expect any thing more,

my dads first air compressor was a small half horse motor and small pump only about a 12 gallon tank and it seemed to take what seemed like 10 to 15 Min's to fill if empty, it was slow, but it sure beat a hand pump to pump up a car tire or on an implement,