Air compressor speed

[bowtieboy77]

I have purchased a replacement 5hp compressor pump. The maximum stated pump speed is 1050rpm. My 5hp motor has a pulley size of 9 3/4. According to the pump calculations the motor requires a 8 3/4 pulley. The difference is a 1" which is a difference of 120rpms. My question is should I try to find a 8 3/4 pulley or will a increase of 120 rpms really make much difference?

 

[pattenp]

I can't second guess the manufacturer and say it's okay to go beyond the max rpm's by 120. If it was me I'd try to find a smaller pulley.

 

[larry_g]

Your missing a few important pieces of data.
What is the motor RPM's?
What is the hp input required to spin the pump at 1050"
What is the minimum RPM of the pump?

Can you provide a link to the pump specs?

Most pumps have a power curve between the min and max rpm. Your pump could have a 3-5hp rating where a 3 hp motor will spin it at 650 rpm and a 5 hp will spin it at 1050. Or you could have a pump rated 5-7hp and it requires 7 hp to spin it at 1050 and a 5 hp motor will only spin it 650 rpm.

So with out knowing the power curve of the pump any information given is a guess and probably wrong.

lg
no neat sig line

 

[bowtieboy77]

Well I am in luck I was able to get the proper size pulley to put my pump speed in a appropriate range. Thanks for the opinions.

 

[strutaeng]

Well I am in luck I was able to get the proper size pulley to put my pump speed in a appropriate range. Thanks for the opinions.

That's good. I was just going to add that if you spin the pump faster, you will also draw more amps through the motor and that may be a problem. The pump will produce more work (air), but the system will draw more power. You know, "no free lunch" in physics...

I tried to run a 7.5-10HP compressor pump with a 5HP I had laying around with the minimum RPM per the manufacturer, and would trip the thermal overloads on the magnetic starter on the motor.

I wound up getting a 10HP motor, but ratcheted the RPM such that the CFM (and power consumption) was more like a 7.5HP. I hardly use it, but the lights sort of flicker a bit when I run it, LOL.

 

[GRB]

See larry_g post. You are missing lots of data. Don't know if you figured it out and just didn't include it or don't understand what you are getting into.
The pump should have data that shows how much power is capable of spinning it at what RPM. You can go below that for a sacrifice in air output with less noise, but you can't go above that.
He has it pretty well nailed.