How would you silence an Air Compressor?
 

I'm designing a new garage and my neighborhood is quiet. I normally just stick them in a small closet that is vented to the outside. But my patio is on one side of the garage, the neighors deck is on the other.

So I'm looking at how to best isolate the noise when I build the closet it will be in. This closet will also hold the heater/ac, etc.

Suggestions?

thanks

Bob

First off get a belt drive compressor. The oilless versions are like jackhammers.

Next get a big air inlet filter and wrap open cell foam around it. Most of the noise comes from the suction side of a std compressor. Any part of the inlet filter that can resonate or vibrate will transmit the sound. You can muffle it but you still have to get air into the inlet:D

For the closet use 2x6 sill plate and top plate. Double stud with 2x4 studs and insulate with fiberglass. Check in a home handyman book about how to make soundproof walls. Sheet rock or siding on both sides. make sure you have good airflow thru the closet. If you have room line the inside of the closet with more fiberglass insulation. Spray the surface of the fiberglass lightly with some urethane spray paint to keep the dust down.

If you can get the sound to bounce around corners into fiberglass absorbing pads in any vent opening it helps also.

Remember you have to get to the compressor to service and drain it:D

A hollow core door is a big resonant sound transmitter, -very bad!

Plenty of insulation (foam type) on the walls and ceiling would help alot. Not sure if you could actually quite down the compressor itself, there may be some "low noise" compressors out there?

The Compressor is going to be one of the big, two stage, 175 PSI ones with iron lines (NO PCV) to several places. Thinking about lining the closet with ceiling tile.

Bob

Ceiling tile is OK but raw fiberglass is better. It is harder to work around tho:( Make sure you use a rubber line between the compressor and the iron line heading up the wall. Put a shutoff valve on both ends of the rubber line, but if not at least put one on the compressor side. Make a drip leg on the iron line and put a small drain valve on it. The rubber line should not touch anything. The rubber line shoud drain back into the tank or the drip leg. Secure the iron pipe very well with pipe straps.

A friend of mine assembled his own 2HP 80 gal air compressor from pieces parts. When it came to the intake filter he decided to get a little creative. He used a street elbow, a long nipple and some thin plate and and an air filter from a lawn tractor to replicate the look of an open element air cleaner from atop a carburetor, only in miniature. Somehow, he hit on just the right configuration and the compressor is so quiet you can have a normal conversation right beside it when it is running. It also pumps up in an incredibly short time for this small pump/big tank combo.

I think he essentially built a velocity stack for the pump and stumbled onto exactly the right length of inlet pipe. If you can spend some time doing some trial and error work, you can probably find the right intake pipe length for your compressor. Or if you know the formulas and can do the math to calculate the length of a velocity stack, go for it.

A couple of years ago I assembled a 2HP 10gal compressor for my dad from stuff I scavenged or bought cheap and it was really quiet, too. My own store-bought compressor is incredible clattering rattling headache. It almost drives me out of the garage when it kicks on. I've been tempted to try to duplicate Keith's intake for my own compressor, but I can't seem to find the time...

If you build yourself a closet, I have a couple of other suggestions. Use 2x6 top & bottom plates for the walls, but use 2x4 studs on 12" centers. One stud should be flush to the outside of the plate and the next flush to the inside. This way the outside wall surface and the inside wall surface are isolated and the sound pressure that moves the inside wall does not get transmitted and radiated from the outside wall. Of course the stud cavities should be filled with fiberglass batts for absorption. I would use pegboard for the inside wall surface. It will keep cleaner than bare fiberglass batts, but will not echo the sound inside the closet the way sheetrock will - echoes inside will find its way out of your air vents. Plus you can use the pegboard to hang stuff for general storage. Stuff hanging on the inside walls will also help break up the sound bouncing around inside the closet.

Good luck with your project.

Cheers.
Eric

when you have something as loud as a compressor the vibrations will just travel through the studs so regular insulation alone won't do much. the best thing to do is hang RC channel across your studs then hang soundboard to that and sheetrock over that the RC will stop the vibrations from coming from the studs to the sheetrock and into the room if you want it almost totally soundproof do this on both sides of the walls

Well that's two of us now that have suggested that 2x6 top and bottom with 2x4 stud walls. It is a common construction technique. Check in that handyman book for specifics like I suggested above. It wouldn't be a bad idea to do your whole garage like that in case you do any banging around in there.

A fake ceiling or insulation in the roof will help dampen transmission thru that structure also. That RC channel construction mentioned by utbroncodriver would even be better.

That pegboard would allow the sound pulses to dissipate into the fiberglass inside the wall.

I have made a number of machine enclosures over the years for industrial machinery. I never tried pegboard inside them because I couldn't use it for flammability reasons. I have used expanded metal over the fiberglass.

i thgouth they made silencers for compressors?

I worked installing equipment in dental offices for a few years, including compressors. Most manufacturers made silencing hoods that would fit over the compressor. We also would heavily insulate the closet (or area) where the compressor was installed. The hoods were metal, with fiberglass insulation inside. These hoods were lined of course to keep the fiberglass contained. So, I would recommend both insulating the closet, build a loose hood that fits over the compressor yet allows free air flow to the intake. One other consideration is to use rubber isolation feet on the tank. By isolating the tank from the floor you will reduce both vibration and noise levels. Some offices where noise was a serious issue, we also used sound deadening foam panels, especially where the compressor room shared a common wall with another space.

Hope this is of some help to you.....

Hockey pucks make good isolation feet for air compressors. I used some under a 10 HP 120 gal unit at work. I snugged the anchor bolt nuts to the concrete floor first, so I counter-bored the underside of the pucks to clear the nuts. The compressor then sat on fender washers on the pucks. The anchor bolts went through the tank feet and were fitted with a washer and double-nutted loose to the feet. The double nuts and washers were there to stop the compressor from tipping, but were not tight to the compressor feet so vibrations would not get coupled to the floor.

It worked extremely well. When the compressor was pumping, you could barely feel any vibrations when standing right beside it.

Hockey pucks are surprisingly easy to drill (the rubber curls off the drill quite nicely) and cost about a buck each, which is really reasonable for a chunk of rubber one inch thick and three inches in diameter.

Cheers,
Eric

Great thread! I've got one of the diaphram compressors and it's so noisy it does drive me out of the garage, so I've been thinking about a soundproof enclosure, too. I've got all my materials for a good plumbed air suppy system, but I need to find a permenant place to quiet the thing down.

The wall ideas so far sound great. I've been trying to figure out a good vent system for the closet. The pegboard posted idea kind of clicked. If I was to frame an opening and then build a baffle inside, using multiple layers of pegboard, staggered, with about a 3/8 airspace between, it might do the trick. The pegboard I have has 3/16 holes on 1 inch centers. Anyone know how to calc. how small that opening can be? Like a rough square meter/cfm or something?

rather than fiberglass insul, I would reccomend using Acousti-blok which you can look up online, They have, in my opinion, the best sound dampening material on the market for the price. its something to look at.

a 2 stage 175 psi compressor will make a huge amount of heat. You will need to keep the unit cool to help with the longevity of the pump and motor and to increase eficiancy.
I have a 25 cfm Champion. It turns a slower rpm than my old sears compressor, and is quieter. But it will heat a 6X14 compressor shed +15degrees in a half hour. Stick it in a closet and it would cook the pump in no time.

The "quieter" compressors run at 1750 rpm or less. The lower priced compressors run at 3450 rpm and make 100% more noise and heat. Make sure you put the compressor on rubber pads to stop the noise from transfering thru the floor, use a flexible line from the compressor to the piping in the garage if you plumb it in and if you have an attic above the garage you can extend the air intake thru the ceiling and put the air filter up there. I just did this with my Saylor-Beal 2 stage and I am very happy with the noise level. I was going to put the whole unit in the attic but at 700 lbs. I canned the idea. I would try this first before I wasted time making a room for it. The heat and a/c will already waste enough garage space. Besides when the neighbors get used to the sound of impacts,grinders and muffler cutters that you run with the air compressor the compressor itself will be music to their ears!