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Author Topic: Generator Insulation  (Read 3994 times)
DavidInWilmNC
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« on: January 09, 2007, 06:45:24 AM »

I've got the generator installed in the driver's side front bay finally.  I still need to add an air inlet for cooling and an enclosure of some sort to partition it off from the rest of the bay.  I know most use that egg-crate type of acoustic insulation, but I'm not sure where to find it.  I've also considered the type used on the engine box of my I/O boat.  It's a fairly thick, very high density black foam that's held up for years (it's a '74 boat).  I imagine the egg-crate type might be a bit more effective since it doesn't have a flat surface like the foam in my boat.  So, where's the best (quickest and cheapest) place to get heat resistant acoustic foam insulation?  Thanks for any input.

David
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DrivingMissLazy
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« Reply #1 on: January 09, 2007, 07:20:46 AM »

David, the correct term for the foam you are looking for is "convoluted" foam. I used to have it made for me in 4 by 8 ft sheets of different densities, depending on the actual use and frequencies I was trying to suppress. Sometimes used 4 inch thick and sometimes 2 inch thick. Each would yield two sheets of foam. Unfortunately, I do not remember the name of the company in California that made it for me, but maybe a search for convoluted foam would yield some information. The density of the foam as well as the thickness is information that needs to be considered.
Richard
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sivrtnge2
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« Reply #2 on: January 09, 2007, 08:16:42 AM »

My 94 Eagle has the convoluted foam. It is very brittle...every time I open the compartment door, It flakes off. I don't know if this is normal or not. May be because of the temperature inside the box. I used the insulation board used by hvac installers on another genset project, it works great I also used the aluminum tape used by hvac installers to seal all cracks as well. Just my 2 cents!!! Grin
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TomC
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« Reply #3 on: January 09, 2007, 08:45:06 AM »

Highly recommend using leaded foam.  Foam on either side of a lead sheet.  That really quiets things down.  My generator (10kw Powertech) is mounted next to the drivers seat like a front engine and is accessed from inside.  You can barely here the engine noise of the gen.  The vibration that resonates through the bus is what is noisy.  Luckily, you can barely here it from the rear bedroom.  The leaded foam with foil works very well.  Available in 1" single and 2" double lead sheet.  I got mine at Camping World, although you could most likely get it else where for cheaper.  Good Luck, TomC
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DavidInWilmNC
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« Reply #4 on: January 09, 2007, 10:52:45 AM »

Thanks for the ideas and suggestions.  So far, after about 45 minutes on Google, I've not found anything really satisfactory.  Most of the acoustic foam I'm finding is geared towards musicians.  I'm sure that would work, but I'd rather have something a bit more fireproof.  Camping World doesn't show any on their website, but may stock it in the stores.  The insulated HVAC board used to quieten compressors and blowers is an idea, though I doubt it would be as quiet as some of the thicker foam.  Anyway, the search continues!

David
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DrivingMissLazy
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« Reply #5 on: January 09, 2007, 11:10:57 AM »

Click here:

www.soundown.com/AI.htm

Richard
« Last Edit: January 09, 2007, 12:00:56 PM by DrivingMissLazy » Logged

Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body. But rather to skid in sideways, chocolate in one hand, a good Reisling in the other, body thoroughly used up, totally worn out and screaming:  WOO HOO, what a ride
Chris 85 RTS
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« Reply #6 on: January 09, 2007, 11:55:36 AM »

I used the sounddown product linked above.  But I'd hardly call it cheap, but it is effective. 
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« Reply #7 on: January 09, 2007, 12:22:23 PM »

Egg Crate Foam

Comes in 2x4 sheets

McMaster Carr 

I used it in mine for a temp sound proofing. So far two years later and still in great shape and quiets well!

Ace
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Ace Rossi
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DavidInWilmNC
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« Reply #8 on: January 09, 2007, 01:49:46 PM »

Thanks, Ace.  That's more like what I'm looking for.  The generator is an older Onan gasoline model that's fairly quiet anyway.  It'll be mounted in the first bay behind the driver and a sofa will be above it in the bus.  I think between that egg carton foam, insulation (thermal type), carpet, and the sofa, it should be relatively quiet.  How thick is the foam you used?

David
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sivrtnge2
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« Reply #9 on: January 09, 2007, 02:03:06 PM »

You would be suprised how quiet the genset is inside a box made from aluminum sided insulation. I think the sheets are 1/2" thick. If you double the insulation, it will give you a 1" barrier that is easy to work with. once you have the box the way you want it, you can spray glue over the box and cover it with an upholsery to make it look like a million dollar coach. Grin
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DrivingMissLazy
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« Reply #10 on: January 09, 2007, 02:26:30 PM »

Do you have any experience or guidance on building a low noise enclosure? If not, Dick Wright at Wrico would be a good contact I believe.
In general you need to make sure the sound makes two 90 degree bends before it exits the enclosure and be sure to make the sound path is large enough to not restrict the required air flow.
Richard
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Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body. But rather to skid in sideways, chocolate in one hand, a good Reisling in the other, body thoroughly used up, totally worn out and screaming:  WOO HOO, what a ride
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« Reply #11 on: January 09, 2007, 02:35:00 PM »

David I think it was something like 2 inches from top of peak to bottom of flat!

It works ok for a temp quieter as we used it but my plans are to re-do it in a box. I just took the bay that the gen is in and did the walls and sides. I didn't do the ceiling of the bay  which is where I get most of my noise upstairs which by the way is very little as it is!

It's pretty loud when I open the bay door but as soon as I close it, it's really quiet with the exception of the exhaust which comes out the side underneath.

Ace
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Ace Rossi
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JackConrad
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« Reply #12 on: January 09, 2007, 03:27:26 PM »

    Here is "our way". We lined the former AC condenser compartment with 1/2" high density foam, a layer of 1/2" plywood, and then a layer of noise reduction "egg crate foam". We also ran our exhaust to near the back of the bus and remoted our radiator to the spare tire compartment with an electric fan. So now the noises of the radiator fan, generator, amnd exhaust are in separate areas. Depending on where you are standing outside the bus, you hear different noises, but not all at the same time.
    I was told the "egg crate" foam absorbs more sound because the convolutions creat a greater surface are than a flat surface.  Jack
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DrivingMissLazy
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« Reply #13 on: January 09, 2007, 04:18:59 PM »

A lot depends on the frequency of the noise also. My experience is that the convoluted material is best for the higher frequencies and the lead covered foam is better for the low frequencies. There are companies with special equipment to measure the noise, and recommend the best materials for reducing it the most. This was especially helpful when building gensets for the movie industry. .
Richard
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Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body. But rather to skid in sideways, chocolate in one hand, a good Reisling in the other, body thoroughly used up, totally worn out and screaming:  WOO HOO, what a ride
Kristinsgrandpa
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« Reply #14 on: January 09, 2007, 06:04:39 PM »

This might help also.

http://www.soundproofing.org/infopages/generator.htm

Ed
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