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Noise reduction for Dust Collector

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Forum topic by leftcoaster posted 04-03-2017 03:40 PM 772 views 0 times favorited 3 replies Add to Favorites Watch
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leftcoaster

189 posts in 709 days


04-03-2017 03:40 PM

Hi,

I have a Laguna C|Flux 1.5 horse dust collector.

I keep it in an alcove that is 6’ deep and 3.5’ wide. THat’s just enough for me to access the side of it for a bag change at the rear. The chip bin is easily pulled forward and out for more frequent emptying.

I have ABS ducting exiting at the ceiling.

I’d like to do “whatever it takes” to reduce noise from this thing.

Air in the shop is not conditioned. I can not put the unit outside.

I can build a bifold door at the front of the alcove and load it with Roxul rock wool insulation: the door would be hinged 16” 1×4 bays on casters. I had good results with Roxul in a shop vac box.

I can hang more Roxul filled panels on the walls of the alcove.

I built a few of these already and tried them around the filter and where a door would go (I did not build the whole thing). I saw no reduction in dB.

The ducting exiting the alcove at the ceiling is an issue—I can’t really enclose that very effectively. I guess I could put some kind of non-folding header up there and stuff Roxul around the ducting.

I do need a place for air to return: perhaps there would be enough space under casters on the bifold?

What can I reasonably expect to achieve by doing this and am I overlooking other more obvious opportunities? For example, should I build a smaller, baffled crate around the collector. I’m worried about overheating in that way.

Sorry this is overly long—grateful for ideas!


3 replies so far

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leftcoaster

189 posts in 709 days


#1 posted 04-03-2017 03:42 PM

PS, it has to be a bifold door—I can’t tie up the area outside the alcove with clearance for the arc of a full door.

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Hermit

139 posts in 1158 days


#2 posted 04-03-2017 07:53 PM

A picture of your area would be helpful

-- I'm like the farmer's duck. If it don't rain, I'll walk.

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JBrow

1269 posts in 753 days


#3 posted 04-04-2017 02:17 AM

Leftcoaster,

Mufflers sold or included with cyclone dust collectors seem to universally reside between the impeller housing and the filter. It makes sense to me that most of the noise originates at the impeller and is carried mostly by exiting air. Oneida sells a muffler and their claim is 3 db to 6 db noise reduction while Grizzly simply claims “significant” noise reduction. However I do not think these products would work for you but do demonstrate where manufacturers focus some of their noise abatement efforts. Since our central vacuum system is outfitted with a muffler, I can say for sure that a muffler at the exhaust reduces noise by an impressive amount. As a result, this would be a good place to start.

The Laguna dust collector does not make inserting a muffler between the impeller and the filters very easy. Perhaps wrapping the impeller housing (leaving plenty of room for the motor to breath) and the connection of the impeller to the filters (plenum?) with sound abating insulation may be worth a first try; before proceeding with your plan. If lucky, that may be enough to get the noise reduction to want. Although I have not seen or heard of anyone doing so, attaching a layer of rubber to the impeller housing, plenum, and perhaps even to the cyclone body before insulating could absorb some noise before it reaches the insulation.

If noise abatement at the impeller and exhaust is not enough, I have to believe that applying insulation inside the closet would help, including to the bi-fold doors.

I doubt that the 1” to 2” crack at the bottom of the bi-fold doors would be enough to return air to the shop and maintain performance. According to Laguna specs, the inlet is 6” in diameter. That requires a minimum of 29 square inches (.2 sq. ft.) of return air space. However, this absolute minimum air return may not be enough to allow air to freely flow out of the 48 square feet of filter area. Unfortunately I am at a loss as to the proper size of the air return, but I would make it a large as possible

If there is room, air could be returned to the shop by forcing the low velocity exhaust to make a 90 degree turn as it exits the area at the filter on its way back to the shop. This could be done by cutting a fairly large rectangle in the bi-fold doors, where the doors are insulated. Then a piece of insulated plywood a few inches larger than the size of the rectangle in the door could be attached over the opening in the door, but with stand-off bushings. This creates a channel around the perimeter of the plywood cover through which air from the filters can escape.

I cannot say that insulating the cyclone body makes much difference, but if you are undertaking a major effort to reduce noise, wrapping the cyclone body in insulation would probably be a good idea. My thinking is that even though air is being drawn out of the cyclone into the impeller, the metal cyclone body is connected directly to the impeller. I have to believe some noise is transmitted from the impeller to the cyclone body; I am just not sure how much.

I am unclear whether the ducting in the joist bay above the dust collector is the home’s HVAC or dust collector piping. Either way, stuffing sound abating insulation up there might help reduce noise in the rest of the house if it is HVAC piping.

For what it is worth, I tamed the cyclone noise so that a conversation can be held in the shop with the dust collector on and it makes less noise than the table saw (I did not measure before and after sound levels but from what I can learn from others, unabated noise from my cyclone is around 100 db). I enclosed my cyclone in an enclosure just large enough to house the cyclone body. The enclosure was stuffed with insulation. The impeller exhaust was wrapped in insulation and insulation was applied to the adjacent two shop walls (a corner) and some 1’ x 1’ x 1” acoustical panels on top of the impeller housing (leaving space for air to flow around the motor) and to the ceiling. I used denim batt insulation rather than mineral wool because I recall it was a little better than mineral wool insulation for sound. But as I recall the difference was not a lot. I had originally planned to use Roxul.

Lastly, if you want more topic specific discussion concerning dust collector noise abatement, Clear Vue offers a forum similar to LJ. There may be some ideas on that forum that may be helpful. From what I gather a number of people utilize a closet to tame Clear Vue cyclone noise.

http://www.clearvuecyclones.com/forum/forum/clearvue-cyclones/noise-control

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