# Soundproofing for Air Compressor



## Proud_Poppa_of_2 (Feb 16, 2008)

I have a Porter-Cable six gallon pancake air compressor that makes a racket when doing its job.  My question is whether anyone has managed to construct a viable chamber of any sort to dampen the noise substantially while permitting sufficient airflow to the compressor. If so, would you mind sharing your design?


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## England14 (Feb 16, 2008)

Put my compressor in a storage shed about twenty feet away from shop and ran air line underground to shop.  I can still here the compressor but not like it was when in the same room.


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## alamocdc (Feb 16, 2008)

I haven't made one, Mike, but I recently saw an article (online somewhere) whre a fellow built a sound dampening box for his shop vac and said it worked quite well. I would imagine the same thing could be done for a compressor, but I'd be worried about heat.


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## leehljp (Feb 16, 2008)

Here is a link that I did for a Dust Collector and within that link is a link to a "box" that quietens the DC system. One thing that I learned was that the best sound dampening comes when ALL sections including INLET AND OUTLET edges for the box's air flow are covered. 

http://www.penturners.org/forum/topic.asp?TOPIC_ID=33477

For you, I think you will need some kind of small fan to pull air in and push air out of the box to remove the heat. Do this in a baffled inlet and exhaust for the greatest noise reduction.  In baffles and edges, I used a very thick felt carpet that construction people use to place on finished floors to walk over.

In placing carpet on the inside walls, I used mostly carpet squares and the easiest way to attach them were with 3M type of spray adhesives.

On the box that I made, (unlike an air compressor box) The air is exhausted into a small bag INSIDE the box in a chamber under the DC itself. The exhausting air flows out of the bag, up and over the DC unit and out the baffled exhaust, pulling all heat with it.

ADDED NOTE: IF you placed it in a box about 4 feet tall, with carpeted exhaust openings at the top - with say - the top raised 2 or 3 inches above the walls with corner braces of 2x2, all heat could escape without the need of a fan. If all inside surfaces were covered with carpet, the dampening effect would be considerable. IF you cover the outside too, it would cut down even more on noise. 

Solid surfaces either _reflect_ or become a _sounding board_ increasing the noise effect, but totally covered, they cut down considerably.


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## Proud_Poppa_of_2 (Feb 16, 2008)

Johnny - I wish  had a shed. 

Billy - sounds like you might be referring to Hank's post.

Hank - I remember your post now.  I wasn't thinking about my air compressor when I first read it, but I can see how it would work.  I'm wondering if, instead of carpet, I could use styrofoam insulation panels.  The appeal is that they're cheap, easy to get and easy to install.    Also, since your suggestion is in the context of a dust collector, and since my air compressor sits adjacent to my DC, I might just make a bigger compartment that houses both units.  The advantage is that there would be more space for the heat to dissipate, more space to create baffles for air intake and outflow, and room for a fan, if necessary.

Thanks to each of you for responding.


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## leehljp (Feb 16, 2008)

I will be curious about the styrofoam panels. I bought a 1 inch panel 3 ft by 6 ft and started to use it.  But it didn't seem to have the sound deadening effect of carpet and felt. It is a great insulator concerning heat but it does seem to reflect sound more than carpet does. For that reason, I just went to carpet. I wanted to use a layer of styrofoam and carpet on top but that began to eat up the space in the box that I had, and I didn't have room for a larger box.

ANOTHER ADDENDUM:
Let me add that as in my original post on the DC system itself, I needed to get the sound WAY down to the point that normal conversations could be heard with only a slight elevation in voice levels. My side neighbor's bedrooms were only 8 feet from my shed and my rear neighbor's bedroom is only 6 feet away, so I have to either quiet everything down considerably or not turn at all.

IF your requirements are not that stringent, then styrofoam will probably do well.


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## WWAtty (Feb 16, 2008)

I have the exact same compressor, and it is loud.  I built a plywood box with a hinged lid, lined it with 3/4" thick styrofoam and drilled some holes for ventilation and to run the hose out.  The box reduces the noise to the point where it is at least bearable.  It strikes a good compromise between sound attenuation and heat dissipation--I haven't had any problems with the compressor overheating.

Cheers.


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## alamocdc (Feb 16, 2008)

Yep, it was Hank's post. Sorry I couldn't remember the source, Hank![:I]


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## Daniel (Feb 17, 2008)

A good material for dampening sound are egg cartons. the basic idea is that the cartons bounce the sound off in many directions. I had a musician friend cover the walls of his apartment with them so the neighbors could not hear him pratice his sax. but the best sound profing i have ever seen is foam pyramids. they are about 3 feet tall though so the box would have to be huge. nothing gets through them though. They use them at the University to stop echos of microwaves in one of there labs. The music department uses them in there recording studio as well. possibly a smaller version would go a long way toward knocking down the decibles. the only other thing I have seen that is really good about reducing noise is a double wall with a space in between. if you can put something like the egg carton idea in the space it works even better. the idea of the double wall is the sound gets trapped between the walls. I think DC's are harder to quite down because there noise is low frequency. it goes through everything. the compressor could give you the same problem.


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## Proud_Poppa_of_2 (Feb 17, 2008)

This is a good discussion.  Daniel points out that the sound problem can be attacked through absorption, dissipation or a combination of the two strategies.  The heat problem can be addressed by a dissipation strategy.  

As for the sound problem, I needn't look beyond Hank's solution as my requirements are less than his (i.e., I do not have to appease neighbors located six feet away) and the solution is straightforward enough.  The air compressor, however, has a greater heat dissipation need than the dust collector.  Ventilating the box with air holes compromises the sound attenuation as it permits sound to escape before the absorption/dissipation process is applied.  Baffles, as suggested in Hank's earlier post could help.

If I built a box that enclosed both my dust collector and air compressor, I'm thinking I could get enough air circulation within to assist with heat dissipation.  I could add to that an exhaust chimney made of 4" PVC with styrofoam baffles glued to the interior.  And, I could add a similar fan-assisted intake chimney with a temperature-actuated switch to draw fresh air into the chamber as needed.  Since my chamber is adjacent to an exterior window, I could draw the intake air from the outside.  The exhaust could be directed outside or inside depending on the season.

Assuming the above is practical, the other challenge is to build the chamber in a way the permits easy access to the switches for the DC and air compressor, as well as the waste bag for the DC, without compromising the sound absorption/dissipation qualities.

Further comments?


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## IPD_Mrs (Feb 17, 2008)

Just dump the air compressor and invite Ed over, he is a windbag![]
Mike


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## Proud_Poppa_of_2 (Feb 17, 2008)

> _Originally posted by MLKWoodWorking_
> 
> Just dump the air compressor and invite Ed over, he is a windbag![]
> Mike



But, is he quieter than my air compressor?  And, I don't have to feed my air compressor.  And, my air compressor doesn't have a mustache and a goofy grin.


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## rixstix (Feb 17, 2008)

FWIW, I read a report several years ago about soundproofing and it said that carpet and carpet padding has a higher acoustic insulating value than styrofoam.  Styrofoam on the other hand has a higher thermal insulation value than carpet.

Very similar to Hank's solution, I built a frame from 2x4 lumber with a solid OSB top, then used a staplegun to hang interior and exterior walls of carpet.  The top is also covered with carpet and became a table on which I put a 6ft Gorilla rack.  The carpet stops 4 inches shy of the floor and has ventflaps cut near the top on the interior and exterior walls.  A small muffin fan is currently strapped to the compressor fins but originally was mounted, blowing outward, near the top ventflaps.  The theory being that hanging carpet absorb more sound than carpet glued to a hard surface.  The door is the end where I only stapled the carpet along the top so that I can just swing it up to get to the compressor

It works for us in our retail space, though it is still less than perfect to attempt a telephone conversation beside the box while the compressor is running.


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## Proud_Poppa_of_2 (Feb 17, 2008)

Thanks for chiming in, Rick.  What you say about styrofoam versus carpet makes sense to me due to the density of the styrofoam.  I also agree with hanging the carpet as opposed to affixing it to the panels if there is room to do so, although I'm not sure I will have that much space.

I'm rethinking my air intake/outflow design based on convection principles.  My thought is that the chamber willl have a raised floor of about 6" or so, with vents on three sides.  (The fourth side is the brick foundation wall of the garage.)  Within this area will be baffles.  The floor panel of the chamber will have sufficient air holes to draw air from the area below. Airflow will be fan-assisted and thermostatically actuated.  The top of the chamber will have a chimney exhaust that leads to an exterior window.


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## bjnash (Feb 18, 2008)

> _Originally posted by Proud_Poppa_of_2_
> 
> I have a Porter-Cable six gallon pancake air compressor that makes a racket when doing its job.  My question is whether anyone has managed to construct a viable chamber of any sort to dampen the noise substantially while permitting sufficient airflow to the compressor. If so, would you mind sharing your design?


Simple sliding boxes (but effective) lined with soundproofing material is shown at
http://soundproofing.org/infopages/generator.htm


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## Proud_Poppa_of_2 (Feb 18, 2008)

> _Originally posted by bjnash_
> 
> Simple sliding boxes (but effective) lined with soundproofing material is shown at
> http://soundproofing.org/infopages/generator.htm



Thanks for the link, BJ.  I learned something from it, too.


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## walking_tall (Feb 19, 2008)

The article on making a noise containment box for your shop vac is in Fine Woodworking's Annual Tools & Shops Pg. 84. It might give you some further ideas


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## Randy_ (Feb 19, 2008)

I figured out that a lot of the noise from my little 5 gallon compressor was coming from the exhaust port.  The stock muffler was nothing more than a thin piece of foam rubber.  I cobbled up a muffler out of an old bathroom towel and a 2 litter Coke bottle.  Cut the noise level in half.  The compressor is by no means quiet; but the noise level inside a closed garage is now tolerable.  I feel pretty confident that a box enclosing the compressor and insulated with 1" styrofoam would prove to be a very acceptable solution.


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