Single Stage Or 2-Stage for lower PSI?

[f575gtc]

Hey guys,

I can't seem to find the right answer, I'm looking to do an overhaul on my compressor and I am looking for a new pump.

I will need a pump that can help me finish my paint job using a HVLP gun and then sandblast, but I will also need to use an air DA sander which is an air hog.

Most pressures I will be using will be between 23-50PSI for the HVLP and 90-110PSi for sand blasting. My HVLP requires 13CFM@23PSI, and the Sandblasting cabinet calls for 10CFM@100PSI.

What I got from searching so far is 2 stage is better for higher CFM at higher PSI over 150, but single stage will produce higher CFM at lower PSI. Since I will not be using anything near that pressure, and my cut off is set to 145psi anyways, am I better off with a single stage?

Or will the 2 stage will be better because of lower noise, heat, etc.?

BTW the pump I am looking at is rated for 17CFM@175PSI, can I expect at least 15CFM@90PSI with this of pump? Also this is a 60 gallon tank I am using.

Thank you for the help.

 

[PWC Repair]

The pump you are looking at will do fine but you could still add another tank and then never worry about the "air hog" tools.

 

[f575gtc]

If I were to not add another tank for the time being, will i still do fine with the pump?

 

[truckdriver]

Adding another tank will not increase your cfm. If the pump won't keep up with the blaster,an extra tank won't help at all.

 

[strutaeng]

Hey guys,

I can't seem to find the right answer, I'm looking to do an overhaul on my compressor and I am looking for a new pump.

I will need a pump that can help me finish my paint job using a HVLP gun and then sandblast, but I will also need to use an air DA sander which is an air hog.

Most pressures I will be using will be between 23-50PSI for the HVLP and 90-110PSi for sand blasting. My HVLP requires 13CFM@23PSI, and the Sandblasting cabinet calls for 10CFM@100PSI.

What I got from searching so far is 2 stage is better for higher CFM at higher PSI over 150, but single stage will produce higher CFM at lower PSI. Since I will not be using anything near that pressure, and my cut off is set to 145psi anyways, am I better off with a single stage?


Or will the 2 stage will be better because of lower noise, heat, etc.?

BTW the pump I am looking at is rated for 17CFM@175PSI, can I expect at least 15CFM@90PSI with this of pump? Also this is a 60 gallon tank I am using.

Thank you for the help.

Those were the same requirements that I had. I found a nice single-stage pump that I've coupled with a 7.5 motor set at 125psi. I think I'm getting 22-24CFM.

You should be okay with either single, or two-stage. I'm no expert, but I think a single-stage will get higher CFM at lower psi (below 150psi +/-), and a two-stage will get higher CFM at higher psi.

Two-stage compressors are usually used in a large buildings were long air lines cause excessive pressure drop. Therefore, most two-stage compressors are more industrial grade (think Quincy, Champion, Saylor-Beall, etc.), whereas most single stage are consumer grade (think Craftsman, Husky, Kobalt, etc.)

The way I see it, accessories such as magnetic starter, low RPM pump, low-oil shutdown switch, and aftercoolers indicates that an air compressor is built for dependability versus cost.

By the way, I'm a believer that adding a larger air reservoir will not increase performance for high capacity air demands.

 

[zkling]

CFM is roughly inversely proportional to PSI on a common piston compressor. So say at 175psi, you have 17CFM, you will have at least 17CFM @ 90psi, in reality a bit more than that though, more in the 20+cfm range.

Depends on what pumps you are looking at. One thing to keep in mind with a single stage, is on a smaller tank and running 90psi air tools, the pump will run more than a 2 stage pump on the same setup. A higher pressure for a fixed volume can store more ft^3 of gas at a lower pressure euivalent, back to the gas law. You will have to watch out for the duty cycle of the pump on some single stage units, not all can handle being run continuously for extended periods of time.

A good quality single stage really won't be happy running at 145psi cut off. Most of the industrial singe stage units are rated at ~110psi and less cut off. The lower end single stage units will advertise in the 140-155 psi range, but that is at a cost of efficiency and pump life. Given the choice I'd pick a nice two stage, but nothing glaringly wrong with a good single stage, my compressor is a single stage, high volume pump. Sounds like the pump you are looking at will be good for your needs. 17cfm @ 175psi is no slouch of a compressor.

 

[f575gtc]

Yeah I'm probably picking up a used 5hp rated at 24 amps running and a 1750rpm, coupled with a 730rpm pump I should have one silent compressor no?

 

[Craptain]

Yeah I'm probably picking up a used 5hp rated at 24 amps running and a 1750rpm, coupled with a 730rpm pump I should have one silent compressor no?

That will do the job, but quiet? Probably, maybe. That is also a factor of mounting, speed and a few unaccountable things. And of course quiet is a personal value. Generally the higher quality the pump the quieter it will run. Good Luck.

 

[PWC Repair]

Adding another tank will not increase your cfm. If the pump won't keep up with the blaster,an extra tank won't help at all.

No an extra tank will not change CFM at all BUT....it will allow you to operate longer without the compressor coming on. I don't like hearing my compressor over my music.

 

[f575gtc]

Quick question, this is a bit off topic but has anyone ever heard of bachmeier ? I found a 5hp 23amp 3450rpm motor but I can't find anything about the brand bachmeier.

 

[zkling]

I'm not sure what pump you have, but you will probably want a 1725RPM motor to get in the proper RPM range for the pump. As for the brand, no personal experience, I've heard of them, IIRC they are out of China.