Soundproofing a Dust Collection System

      Shop owners discuss ways to build sound-deadening baffles and boxes around elements of a dust collection system. March 28, 2010

I recently purchased a new, custom made machine, and would like to reduce the 88db it is producing. I'm thinking of building a sound chamber around it with 1" quilted panels (leaving the top open for air pull). Anybody else try this or have any suggestions?

Forum Responses
(Dust Collection Forum)
From contributor R:
Yes, I've done this, and it worked well. Whether it was worth my time over purchasing an attenuator is another question. For reference, I have a 20HP unit that's supposed to pull somewhere over 6000cfm. I forget the exact number. My outlet coming back into the shop is, I think, 20" diameter. I took that area and multiplied it by 50 - 100%. This was the amount of surface area I wanted at all times around the baffles. Then I made a plywood box. I'm guessing it's 4' wide, 2' tall and 8' long. The duct from the collect goes into one end. Inside are a number of plywood baffles at random places, sizes and angles. At the other end I took a 4 or 4" hole saw and drilled enough holes to get my magic surface area number. Now don't laugh too hard, but I didn't want to spend a couple of hundred on egg crate foam without knowing the idea would work. So I contact cemented fiberglass insulation to the baffles.

Works like a charm. For a couple of weeks we had tufts of insulation blowing out, then things settled down. I'm not sure how much is left, but the thing still works. Someday I'll get around to putting egg crate foam in it. The collector salesman had to grudgingly admire it. I think he was planning on selling an attenuator when we got the collector up and running.

From contributor J:
Got any pics of your Frankenstein like sound deadening system? I'd like to do something similar with my little bitty 7-1/2 hp collector. So dang noisy I hate turning it on.

From contributor R:
Here's are some pictures.

Click here for higher quality, full size image

The box around the duct is a wood blast gate. In the summer we close this and uncap a wye. It keeps the heat out in the summer and helps heat in the winter. The collector actually adds a couple of degrees (that electrical energy is converted into heat somewhere!) unless it's really cold out. And it still beats sucking all the heat out!

Click here for higher quality, full size image

I remember that we had a baffle in a couple of feet from the duct end, but after that we just scattered them about in an irregular way, always maintaining square inches of unrestricted movement.

From contributor J:
Now I'm a little confused by your setup. You've got your box surrounding the return air, but where are the filters? On my setup I've got a 12" outlet going to a plenum with 3 - 2' w x 8" h bags. So I'm pretty much contemplating a wall surrounding most of the filters and cyclone, with a layer of foam or similar material on the inside. I might be able to use some of your ideas to make it work.

From contributor T:
I had the same problem. Built a sound deadening box around the noisiest parts. Used heavy stuff for the box. MDF and drywall. Started with an MDF box, kept adding layers of drywall. Then added sound deadening foam from McMaster-Carr to the inside of the box.

It ended up being a pretty big project. Started with a box around the cyclone and barrel. That helped. Then added a box around motor and fan. That helped more. Then added some drywall/MDF around duct from fan to filters.

Not perfect, but I can hear myself think, and hold a conversation in the shop with the DC running (7.5 hp Torit). Could be that an exhaust muffler would have worked as well and been less work, but sometimes I have more time and less money. I made the box heavy to kill the low frequency sound. The sound deadening foam seems to do a good job on the higher frequency air noise. Don't have a db meter, but the sound was reduced from almost painful to almost okay.

From contributor J:
Contributor T, we've got the same DC, and sounds like you've already done what I'm thinking about. I can't see a muffler making that big a difference since so much sound radiates from the motor, cyclone, and duct, but then again I haven't seen one set up with a muffler, so who knows.

I think I'm going to build a closet-type enclosure and see how much difference it makes. Then I'll look into that sound deadening foam. Any idea if that stuff is fire resistant? I know some foams go up like tinder and I wouldn't want that in my shop. But if it's safe and can drop the sound by a few more decibels, I'm interested.

From contributor T:
It meets UL94HF-1 flammability requirements. What that is, I don't know! The stuff I got met Cal 117 flammability requirements. These seem to be flammability requirements for upholstered furniture, so probably don't apply to using the foam where a fire might burn, like inside a DC. It might be that they are self-extinguishing, but that would still leave the problem of toxic fumes in a fire.

From contributor E:
Have you ever heard of Quietrock? It would probably make your box quieter and much lighter compared to using layer after layer of drywall. This just for future reference.

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