Dust collector noise reduction

[Thomas Wilson80]

I am just getting my basement shop put together and just got my CV1800 DC set up - the motor and cyclone are in a separate cold storage room with the filters/ductwork in the shop going through a cement wall to keep the shop temperatures stable. I thought this would also keep the noise from the DC down but it seems like the loudest part of the DC is at the filters.

Now I am planning on building a small enclosure for the filter stack with soundproof material lining the inside of the enclosure and an access door to clean out the filters with a small baffle at the bottom to let the air back into the shop. Any advice on materials for the inside of the filter enclosure - I’m specifically looking at rockwool 2” sheets verses foam acoustic panels but I’m getting conflicting info online on which would be better. One article says the Rockwell panels are better at blocking sound and the foam panels are better at absorbing sound - does this mean I should line the enclosure with rockwool but put foam panels in the baffle?

any tips or advice would be appreciated. It’s a tiny room (15x11) so the noise is pretty deafening and I really need to do something to decrease it.

thanks
Tom

[Rush Paul]

Tom, one challenge you will have in building an enclosure for the filters such a small space is making sure you don't restrict the air flow out of the filters. If you build walls around them with only a small exhaust opening, you can easily restrict the flow enough to create back pressure that will reduce the effectiveness of your entire dust collection system. Generally, you should have at least 2 times the area of your intake duct for your exhaust, and 3 times is safer. For a 6" intake, that would mean an exhaust duct with an area of at least 28.27 square inches.

If you run the exhaust through a baffle (e.g., force the air through a channel that makes the air flow across a couple 90-degree turns), you can significantly reduce the noise coming out of the exhaust. But since those 90-degree turns add resistance, you need to increase the exhaust cross section to 3x or 4x your intake.

As to insulation (your original question), I suggest first trying a double layer of 5/8" fire rated sheet rock for the walls. Mass is your friend and will provide more sound dampening than any of the foams or fiber insulation panels.

Another thing that may help the noise in your room is adding some acoustic panels on the walls and ceiling of the shop itself. The Owens Corning 703 acoustic panels are good and easy to use. I suggest 2" thick. You can put them in wood frames and cover with cloth or burlap.

[Dan Gaylin]

I agree with Rush's statements, particularly mass is your friend. Too often, people think that soft acoustic panels will do the job. You actually need a noise barrier (something dense and hard, and ideally thick) and THEN something that dampens the sound. There is a lot of online information that talks about the details of soundproofing, but this is one the key points.

One thing you will find though: a 4" or 6" "tunnel" (the hose or pipe) from the source of the noise to your tool is always going to let a lot of noise into your work area, no matter how good your soundproofing of the unit it.

[Thomas Wilson80]

Thanks so much for the info Rush and Dan. Things that I hadn't considered....I'll definitely spend some more time researching things but I think I could make a baffle 3-4x the size of my intake and I'll definitely look into the different materials you mentioned.

Tom

[Thomas Wilson80]

Has anyone used Quietrock for the soundproofing Sheetrock? Online, several websites say that it is significantly better for soundproofing but it’s much more expensive ($72 per sheet in my area). Is it worth it?

[Chris Fairbanks]

Thomas, I enclosed my CV Max with just a standard 2x4 wall. The outside of the wall, which is facing towards the inside of my shop, is two layers standard 5/8” Sheetrock with green glue sound glue between the two layers. Between the studs I used Roxul safe and sound insulation bats and left that inside of the wall open to the dust collector. I had some left over screen door netting around so I stapled that up to make sure the batting did not fall down. The door to the closet is 3/4” of plywood I had hanging around and to that I green glued and screwed two pieces of. 5/8” Sheetrock to it that is facing the inside towards the dust collector. Finally I left about a 2’x2’ square opening through the wall near the ceiling as the air return to the shop. I planned on building some sort of sound insulated baffle to help cut down the noise coming from the return but since it’s up high, about the height of the cvmax motor, surprisingly not that much noise comes through it. It’s about the same noise level right now as my old jet canister dust collector. I’ll eventually get around to doing the baffle but it’s not loud enough to be high on my priority list. Now, if I open the door up that’s a whole different story and the full roar of the CV max is on display for my neighbors to hear. . Hopefully that helps.

[John K Jordan]

Tom,

One thing people do (which should help if you have the space) is wrap the exhaust duct with insulation, effectively making a muffler - some found much of the noise was coming from the exhaust port and not from the filters. You might still find posts about this on the ClearVue forum with a search. If you have room in your cold storage room you might try moving the filters inside and wrapping insulation around your flex duct then building a baffled air return.

I built my sound reduction closet (for the cyclone and big air compressor) with a staggered stud wall which I read was sometimes used in sound studios. I used 2x4 studs on a 6" plate and alternated them so the wall (I used 1/2" plywood) was only fastened to every other one, inside and out. Then I snaked insulation between the studs. Staggering the studs keeps the sound from being conducted from one "sound board" to another. For an existing wall, an air gap or soft insulation with a hard surface might do the same. I have no experience with how much sound a cement wall transmits.

staggered_studs_IMG_2013071.jpg

My access door is on the side of the closet away from the shop, opening into another area. I used a 5' wide double door.

In addition, I built a baffled air return to the shop, built from plywood and taking the air up into spaces between roof trusses. I insulated around the outside of the baffle and sprayed a rubberized coating inside. I can hear no sound coming through the outlet in the shop ceiling.

This is my duct design drawing. The duct has a number of sharp turns and several baffles designed to prevent direct sound travel. The top is sloped to fit under the roof and the cross section at all points was enough to keep from constricting the airflow.

Dust_collector_baffle_small.jpg

The baffled return wouldn't have to be above the ceiling but it would probably need to be well insulated.

I forget what the dB measurement is but with all this I can hear a whisper in the shop and easily carry on normal conversation.

JKJ

[Thomas Wilson80]

Thanks for the detailed info John. I could move my filters to the cold storage but I think I would need to make the air return hole through the cement wall much larger as it is only 8”.

what kind of insulation did you use on your staggered stud wall? And what kind of spray foam for the baffle?

I’ve got some days off this week so will try to figure something out. Thanks again,
Tom

[John K Jordan]

Thanks for the detailed info John. I could move my filters to the cold storage but I think I would need to make the air return hole through the cement wall much larger as it is only 8”.

what kind of insulation did you use on your staggered stud wall? And what kind of spray foam for the baffle?

I’ve got some days off this week so will try to figure something out. Thanks again,
Tom

Yes, a larger duct could prevent back pressure but I suspect keeping it the size of the outlet from the cyclone might be sufficient.

I found a ruberized compound in a spray can at the hardware store. Don't recall the brand. It's not foam but a soft rubber. I sprayed it while constructing so I can't tell what difference it made, if any. I figured it wouldn't hurt. I did wrap the return duct in the ceiling with insulation.

I used standard insulation (fiberglass?), the same stuff I bought in bats or rolls to insulate the walls of the shop. It has a relatively high R value since every shop wall is 6" thick. Some of the stuff made specifically for sound insulation might be better but I didn't try any. You might find info on the web - that's how I found out about the staggered stud walls.

Another thing that is said to transmit a significant amount of sound is vibration from mounting the cyclone itself on the other side of a shop wall. I mounted mine on an outside shop wall. I can hear it from outside the building but I live on a farm and the llamas don't seem to mind. I've read where some people built independent stands to support the cyclone to minimize contact with walls.

This is my shop layout showing the location and orientation of the sound-reduction closet. BTW, I put all controls for the DC and air compressor (disconnects, remotes, valves and gauges) outside the closet, accessible from the main shop.

shop_floorplan.jpg

What's this "some days off" concept?. This is difficult to understand, perhaps since I retired 15 years ago.

JKJ

[Tim Tucker]

DC cabinet.jpegDC cabinet interior.jpeg
Is it possible to locate the DC outside and pipe it back into the bldg./shop? It was the best answer for my application. And - it does reduce the sound level in the shop- tho the direct connection to the interior ( plenum) could be muffled and reduce sound even more I suppose. I was more concerned with saving space in the shop, and returning clean air to the shop. So - the cabinet with double seals, and the shaker motor and collection box att eh bottom. It works well and with no leaks.

[Thomas Wilson80]

Is it possible to locate the DC outside and pipe it back into the bldg./shop? It was the best answer for my application. And - it does reduce the sound level in the shop- tho the direct connection to the interior ( plenum) could be muffled and reduce sound even more I suppose. I was more concerned with saving space in the shop, and returning clean air to the shop. So - the cabinet with double seals, and the shaker motor and collection box att eh bottom. It works well and with no leaks.

I like your setup a lot Tim and wish I would have sone something like that - I have the cyclone in another room but it would now be a lot of work to move the DC/cyclone/ducting and make room for the filters there too and I wonder if I would need a hole through the cement wall larger than the 8” hole currently for the exhaust duct. I called Clearvue before the install and they said I should have the filters in my shop to keep the temperate air from being replaced. I was under the impression that the noisy part was the motor/cyclone so now I am kind of scrambling to try to adequately enclose my filters in a crowded corner in my very small shop. As is, the noise from the filters is too loud in the shop and even in the entire basement.

I plan on enclosing the filters with a staggered stud wall with quietrock sheetrock lining the interior with a baffle with soundproofing foam releasing the air back into the shop. I may take the enclosure up over the entire 8” duct Connecting the DC to the filters instead of just to the top of the filters as I’ve read that that can be the source of a lot of noise too, though right now it is so loud I’m having trouble telling where specifically the noise is coming from.

I’m not much for non-turning woodworking so my goal is to make it functional even if not pretty. We’ll see! Thanks for the input and photos - your enclosure is beautiful!

Tom

[Tim Tucker]

Tom
The holes I drilled thru the concrete walls are 10” which allows for isolation of any vibration/hum/ harmonics that the cyclone may produce. It is sealed with insulation foam. The cabinet for the filters acts to conserve the “conditioned air” to the shop. As the shop is my basement, you can imagine how fast running a 5hp cyclone would suck the conditioned air out of the shop AND house. So, that is when I got out the calculator to size the interior of the cabinet and to draw the return plenum so that neither would be an impediment to air flow while saving the conditioned air. Bill Pence is a such a resource on dust collection. He is incredibly generous with his time, and I would encourage you to reach out to him for any additional advice that he can offer on your project. Best of luck on your project!

[John Lifer]

I don't know if you've done it, but I would disconnect the flex at the DC and cover up that hole with a bit of ply and then see how loud it really is without return into the filters.
If it is quieter, then it is sound out of the filters/hose. If it is not significantly quieter, you are having sound come through the wall. (which I doubt).
I would probably build another box for the filter and put simple insulation inside. Give an exhaust facing back towards the wall and even put some insulation on that wall to dampen anything coming out of the other return.
You can get fancier and make a double box and insulate between and have air return come in say at top and leave at the bottom. That would help a lot, but is more work to build.