I have a new shop and need to run my own air compressor again. I still have my 20 year old 220v 5hp unit that still works but is very very loud.
I've bought a couple hf 2hp units to get 120v, they are loud too. I actually bought a cal-air-tools ultra quiet unit for like $300 (looks like they are $200 now),
and it was quiet (but not ultra-quiet :) but the scfm could not run my air tools, i'd need at least two of them, and so I sold that thing.
I ended up putting my 5hp outside in an enclosure and that was much better, but I am revisiting this topic. I was thinking of converting a/c compressors since I seem to have a lot of them from all my dismantled cars. Or I also have a 4-cyl 50hp two stroke outboard motor I was thinking I can make into an electric driven compressor, or I also have a dead RX8 motor and that looks like it might work?
I am sure I am not the first to think through these things, most all I've found don't fit the need of high volume air AND quiet AND low-budget.
For the 120v stuff, find one that's belt driven and oil lubed. They're still noisy, but MUCH quieter than the cheaper direct drive / oilless stuff.
Look for a used Jun-Air dental compressor. I have two. New ones are crazy expensive. Dentists need to replace them every ten years or so. Mine are so quiet that I thought they weren't working until I saw the pressure gauge moving up.
Another vote for oiled. Also, I find mine is quieter when bolted to the ground instead of sitting on a pallet.
My Emglow belt driven oil cooled is super quiet. They aren't cheap to buy new, but if you know anyone that works on fire systems, you can get a used one cheap or free when they replace one on a sprinkler line.
Mine was free because it leaks a little air, if I fill it up, it will kick on again after 18 hours or so. No good for a sprinkler system, but perfectly fine for a home shop.
I just won an auction for a item that is $16,000 new with some non-working parts that didn't matter to me, for $120.
But I don't have time to wait a year to find something I need now.
What design is the Jun-air that makes it quiet? I would not think a dentist needs a lot of CFM.
In reply to nimblemotorsports :
Reply
A fridge compressor is quiet because it has diddle-squat for cfm.
I tried to find out how the quiet ones work, they use a really big bore and a small stroke, not sure why that makes it quiet, but that is how they are built.
I think a wankel rotary engine will work.
Make the first spark plug the output port for the compression 'stroke', and use the second plug as the input port for the 'exhaust' stroke,
and now we get two output pulses per rev. Then I think fill in the rotor cup to make it have higher compression. Water cooled so can run it at high rpm without overheating,
and get LOTS of cfm. Just need to dig out my rx8 motor and got the damn front bolt out, maybe I just cut it off now if going with a compressor build. :)
In reply to nimblemotorsports :
A quiet rotary?
I've always thought it would be fun to take a small dohc engine, cut the cams between the lobes, flip them 180° and re weld them so they compress on every stroke. I'd be very curious to see how a water cooled compressor would work.
The noise from an air compressor is generally from the intake. Routing the intake with a rubber hose into a air filter box will reduce the noise.
In reply to Woody :
They still make engine air compressors. Look at Grimer Schmidt. They had 2 different models when I sold them. One was 1/2 a 302 V8 the other 1/2 a 460 V8.
Natural gas companies use them for CNG delivery.
I've heard of ACVW engines being used as air compressors. Two cylinders to drive it and two cylinders to compress air. Cheap if you already have a few Bug engines laying around. Dunno about quiet....
Running a gas motor is not going to be quiet!
While i think the rotary will work, using a car a/c compressor seems better in that anyone can easily and cheaply duplicate the work if I get it to work,
so I will try that. The twin swashplate designs look like they can keep the oil out of the piston top.
Not low budget but 63 decibels!
We have a 15hp Ingersol Rand at the shop which is marginally quieter at 60db and it is a marvel. Feeds an entire shop including the air hungry body shop tools and you can stand right next to it and have a conversation without raising your voice.
C'mon guys, the suggestions are either loud, expensive, or low-cfm, I don't need help with bad options, google finds those all day.
Next suggestion will be a LS swap... lol
In reply to nimblemotorsports :
Convert the rotary to an air compressor and power it with an LS?
Ian F
MegaDork
4/29/19 7:29 a.m.
In reply to nimblemotorsports :
If a 220V 5 hp compressor (likely a belt-driven, oil piston compressor) is too loud for you, then either something is wrong with that compressor or you are going to have to spend $$$ for something less noisy. By most standards those are quiet.
My brother-in-law works as an installer for industrial sprinkler systems. It came to my attention that they get working but deprecated air compressors all the time. I dropped him a note and he's going to try to set one aside for me for when I go visit in July.
I'm going to need a tank. I'm thinking 40 gallon or larger. I see that Northern tool, Lowe's and the other retailers have plenty of smaller, portable tanks, and then they jump up to like 200 gallon tanks. Besides looking on Craigslist and in FB marketplace for compressors with good tanks and bad power units, where can I find a tank?
RevRico said:
Cheap. Quiet. High CFM.
Pick two.
Up until Jumper K shared how quiet that twin screw is, I'd have said "pick one" LOL.
Brother got me an ingersoll rand service station two stage compressor. Head was rebuilt, but had no motor. Picked up a 5hp Baldor for it. Much quieter than the vertical tank twin cylinder it replaced.
So Jumper's scroll compressor has me wondering if you could take a supercharger and power it electrically to make a quiet compressor. The pictures make me think of the G-Lader. Who's up for it?
