Quiet compressors

[newbury]

I used to have a Kobalt 26 gal oil free compressor. I always hated how loud that thing was. It scared me so bad the first time it turned on. It broke and I was tired of fixing it.

I love the belt driven compressors, but they are much more expensive. I picked one of these:

29 gal. 2 HP 150 PSI Cast Iron Vertical Air Compressor

It has been great so far. Time will tell how good it is. It is much quieter than my old compressor and more powerful.

I did similar - I had an old HF model 94667, 115 PSI, 4.9 SCFM@90 psi. I wanted more oomph with less BANG. Bought the 150 PSI linked, more air, less noise. Just checked the noise level 80 dB@ 10ft. That was with ambient noise level in a tin roof shed with moderate rain was at 67 dB.

So not a quiet compressor but for $330 it fit my needs.

VERY PLEASED.

 

[ray66v]

Compressors, and most air tools do not have to be loud, to be powerful.

It has a lot more to do with how much the manufacturer cares about operating sound level.

I always made it a rule to never buy an air tool, without hearing it run. That was easy, when I bought them off of tool trucks. They would always let you try it.

If you buy a compressor, or a tool, and find out it's a screamer, take it back, and choose a different one.

Many people eventually develop tinnitus, and or hearing loss. Don't needlessly add to it.

 

[bigtiller]

The pump RPM, block thickness and muffler size are good indicators of noise levels if the owners manual isn't available when shopping for new compressors.

 

[ultrarunner]

Good point, I agree. And this applies as much to my original idea (tracking run time on all compressors and forcing them to run an equal amount) as it does to the "designated failer." So maybe the best way to go about this is the simplest way. Just connect all the compressors in parallel straight out of the box without any adjustments to pressure switches, and let them kick on, run, shut off, last forever, or prematurely fail in whatever order they are destined to, as predicated by their inconsistent quality.

In the shop/hospital we have lead/lag boilers, pumps and compressors... the idea is they do not have equal hours...

 

[nimblemotors]

Given this is in the Build Yourself forum, I want to try building a quiet compressor using refridgerator compressors. They are designed to be very quiet! But not a lot of airflow,
so to have one be sufficient to run an air sander (which I need to do), the idea is to gang a bunch of them together. You can get old fridges free all the time.
There are some videos on people making them into compressors, there are some issues, not trivial project.

 

[tjkubota93]

Given this is in the Build Yourself forum, I want to try building a quiet compressor using refridgerator compressors. They are designed to be very quiet! But not a lot of airflow,
so to have one be sufficient to run an air sander (which I need to do), the idea is to gang a bunch of them together. You can get old fridges free all the time.
There are some videos on people making them into compressors, there are some issues, not trivial project.

I had a fridge compressor I made onto a vacuum pump for ac work. Worked great until it stopped. I think it didn't like running stuff through it that didn't contain lubricant.

 

[strantor]

On the larger compressors, 5HP plus, like the big 80gal quincy upright types, what makes them loud? Is it the speed? Or is it the intake/exhaust?
I know that's a poorly worded question; I can't think of a way to word it better. Maybe it would help if I explain the reason behind the question (Another idea that just occurred to me)... It's been said a few times here that the belt-drive pumps with low speed are quieter. Could any old loud pump be made quiet by slowing it down?

Here's the new idea... get a big belt-drive compressor with a 3-phase motor on it (or replace existing single phase motor with 3-phase) and put a VFD on it. Replace the on/off pressure switch with an analog pressure sensor, wired back to the VFD with to an inverted analog input. The VFD will read a higher pressure signal as a lower speed command, and lower pressure signal as a higher speed command. When it gets to max pressure the motor will stop.

The way I'm hoping that would work, is that if pressure goes just a little bit low because I just used an airgun for a few seconds to blow off my worktable, instead of slamming the contactor closed and throwing the compressor to full (loud) speed instantly and scaring the daylights out of me, it will just slowly begin to creep in circles until max pressure is reacquired. If I run an air tool for a minute and deplete the tank to 75%, the motor will run half- speed. If I run several air tools for several minutes and deplete the tank below 50%, motor will run full speed. So it will at times be loud, but not suddenly and startlingly (which is the main problem).

What I don't know, is if that will make a difference. Does an 1800rpm/85db compressor make less noise if ran at 10rpm? or does it make (10) 85db "pops" per minute?