Roots Vacuum pump noise

[cip]

Has anyone devised a really effective way to insulate a Roots vac pump? If so can you give some details?

[Gary Campbell]

Mike...
The proper installation procedure is:
In the barn, 50 yd from the shop

There are a few noise control posts on here, but I cant tell you if they were specifically aimed at the roots blower.
Gary

[harryball]

I've heard one run before, sounded like a small jet engine to me. The only thing I could think of is burying it under the floor in a pit as I know a guy that converted an old autoshop to wood working and it had a grease pit in it.

Beyond that, like Gary said... move it outside the shop.

/RB

[gpari]

I built a sound enclosure for our 15hp roots blower. It measures 94 dBa from 20' without the enclosure. With the enclosure it measures 86 dBa. Very noticeable difference. The enclosure is basically a "party wall" design. Two separate walls with offset studs and insulation between them. Then I added egg crate foam on the inside. The box is force fed ventilation air and has a truck muffler on the exhaust. It's not pretty
But it works pretty good.

We are moving to a new location, and our new shop has a more strict sound ordinance. We are getting quotes from acoustical enclosure companies (there is a business for everything!!), they claim they can get us well below the 80 dBa limit for our new location. So far it seems the enclosure will run about $2K. I will post up some pics and contact info when/if we get the box built.

There is definitely some engineering put into these boxes, they look pretty slick.

Gabe

[dana_swift]

Gabe - if you have to make huge drops in sound.. check out Sonex acoustical tiles, they are one of the most sound absorbent things made since they stopped making leaded foam.

You could probably build an enclosure using the tiles on the inside and out that would meet the 80db requirement and be less than the $2k.

Good luck with your move.

D

[bcammack]

The home theater business has some good tricks, too. They have some channels that let you "float" one layer of drywall over another with a narrow airgap that will allow the "outer" (inner in your case) layer of drywall to move and dissipate sound energy through not only it's mass, but through friction with its mounting channels.

[erik_f]

Make a box within a box. Make the cavity between the two boxes about 3 inches and fill in all the walls with sand.

[gabepari]

I haven't had a problem coming up with a multitude of ideas for the construction of the actual enclosure. Ours is basically a box within a box, the air cavity filled with insulation. The issue comes with the required penetrations. You need fresh air pumped through to keep the motor and pump cool, and the exhaust is LOUD. The tricky part is getting the porting and baffling right on the penetrations so that it effectively cancels out the offending noise. Like a band-pass filter, but backwards I guess


I was into speaker theory in highschool, but don't remember anything, and don't have time to fiddle. I don't need any neighbors calling code enforcement on us at the new shop, I'll let the experts handle it



Gabe

[erik_f]

For exhaust why not use a truck muffler? Or create a box with baffles and fill it with some sort of stuffing.

[gabepari]

We have a truck muffler now. Works pretty good. I think routing the exhaust about 10-15' up and having it exhaust straight up would help dissipate the sound as well.

To be honest, the city is relocating us because of a public works project and they are willing to pay for upgrades to meet any new conditions on the new location. SO, if I can get a fancy box built by a "fancy box building company", why not


Thanks,

Gabe