Rotary Screw Air Compressor

[Anthony Spotorno]

I currently have a Quincy QT-54 5HP piston compressor w/ 60 gal tank it's about 5yr old. It puts out about 15cfm at 100psi. I have it hooked up to an IR air dryer.

I have no issues with the compressor, except for the noise. I cannot put it outside. So I have been researching rotary screw models.

Specifically the Kaiser Airtower 5C, it comes with an air dryer built in to the unit.

It is mostly used for the CNC machine, and the Quincy cycles about every 10 min or so when the CNC is running, which can be for 10 - 15 hours straight depending upon the work.

Is this enough usage for the rotary screw? I do understand that the rotary screw compressor is substantially more than the Quincy but noise when the compressor is running would be very big motivator for switching.

[Bill Dufour]

A screw needs to run for 40-60 minutes at a time to warm up the oil and dry it out. Sounds like your air useage is too low. unless you want to dump most of the air from the screw most of the time and pay the power bill for that. I would reduce the existing compressor rpm by 75-50% but stay above the pumps minimum rpm which is probably 700rpm or so. Can you reduce then max pressure on the pump control or do you need 100psi for other stuff. Add a car muffler to the compressor intake. loose stack cinder block to make a hut around the pump. I addded an oil bath aircleaner to my compressor intake instead of a muffler.
They should make water cooled compressor heads for sound reduction.
Bil lD

[Jim Becker]

Anthony, while you can't move the unit outside, could you construct a sound deadened closet around it? I have my 60 gallon IR compressor (and cyclone) in a purpose built closet in my shop and the sound reduction is substantial. That would cost less than a new compressor if your space permits this. You'll want to have non-direct venting for the "box" for air refresh without direct transmission of sound.

[Erik Loza]

Not an expert on compressors by any means except to say that Kaesers are great. We run the whole Dallas showroom off one: Multiple CNC's, huge beam saw, several large edgebanders, 43" widebelt, etc. That being said, the vast majority of my commercial cabinet shops use tank-style compressors for their CNC machines. I assume due to cost + "who cares about noise in a commercial shop?". I like Jim's idea of enclosing it (along with the DC). Seems simpler and more cost effective. Best of luck with it.

Erik

[Adam Herman]

you may look at the small eastwood screw compressor.

https://www.eastwood.com/eastwood-elite-qst-30-60-scroll-air-compressor.html

you could plumb it into your large tank and run both if you need a ton of air, or just run the screw for normal ops. 12.7 cfm at 90 psi.

[Joe Calhoon]

Tony, I don’t think the 60 minute warm up is true with the Kassers. I would check with them to verify. I’ve been running one for almost 20 years with no ill effects and very low usage the last 3. I know of several small shops using them.

With the equipment you have you don’t want to chance contaminated air.

[Peter Kuhlman]

I would be very cautious about using a screw compressor for this. In my 30 years of using them in the oilfield I concur with Bill’s comments. Normally they work best when the oil is hot as this helps reduce moisture caused damage to the compressor screws and seals. Normal usage of a screw is continuous. We put variable speed drives on ours to maintain 24 hour runtime. Another issue with screw compressors is that there is more oil carryover to the output air than a piston style compressor so far more and better oil filtering is needed. Oil contamination of downstream equipment was always an issue.

Technology may have helped design better compressors recently and I have no experience with them since retiring 4 years ago.

[Bill Dufour]

I would mount the compressor separate on the floor in a smaller noise containment box. Then the tank can be anywhere as long as the drain is at the bottom. It is common to mount them in the attic or basement out of the way with an automatic drain. The space above the compressor can be used to store heavy items to help soak up noise.
Bil lD

[Anthony Spotorno]

Thanks for all the remarks... I've isolated it off of the floor. I've started some research on air intake mufflers...

I visited Joe Calhoon's workshop last year and he has a Kaiser, which I keep thinking about. It was so quite compared to mine and it only cycled every so often...

I have a call out to Kaiser distributor to see what they say. Their Airtower model seems like it is designed for small workshops. From what I'm seeing some of the rotary screw models have a computer to keep the tank full, but run the screw and vent the air vs storing it...

[Jeff Monson]

Anthony, Air intake mufflers work pretty well, it really doesnt have to be anything fancy. The first one we made for my shop was 3/4" hose into 2 small car mufflers. This compressor has dual air intakes so we used dual hoses and 2 mufflers, cut the noise in 1/2 at least. I recently purchased a flexilla compressor for my home use, this uses a very large air intake steel box with baffle chambers. It is remarkable quiet, I have it in my utility room which has no insulation just some osb and steel and I can hardly hear it run. Something to definitely look into for noise control.

[Bill Dufour]

A bright and shiny motorcycle muffler would look nicer then a car muffler. On my Qunicy I plumbed my air cleaner with one inch copper soft soldered together and a piece of car radiator hose

[Joe Jensen]

Two comments. 1) as another poster said screw compressors need to run a lot, enough to be hot. A friend put one in his home shop on the coast in Canada and within a year it was ruined, never ran enough to get hot. 2) I have a Quincy compressor with a model 325 pump which is very heavy cast iron with an oil pump for pressure lubrication. It can be set up with pulleys to run 900 RPM with 5HP or 440 (I think) RPM with 3HP. I never need the max air output so I put slower pulley set on and it's WAY quieter.

[Alex Zeller]

RPM is the key. The faster the louder when it comes to piston type compressors. You could, as Joe says, try to change the pulley on the motor to slow it down. Or you could look at the next level up reciprocating compressors to one that has pressurized lubrication and turns at half the speed. It's hard because until you have it in place you will not know how loud it's going to be.

[Bill Dufour]

Running a lower max pressure will help to quiet the compressor. As the pressure build up you can hear it working harder and louder. Most people do not need more then 75-90 PSI not the 125-175 factory setting.