soundproof generator box

to davert (Dave)

I have just sent you a Private Message to your Mailbox.

Sound proofing of structures could be done using double-walled construction, with sheet lead from each side, the opposing sheets not touching each other, but a gap between.

The above is expensive, also heavy, of course, but is the standard method of making soundproof chambers.

You will need to have cooling for the petrol engine too, and that means noise will get out, unless your engine is watercooled, with a radiator external to the enclosure.

There are noise reducing foam products available, try your local PARA shop, because they should be able to source/supply.

Other sources would be car clubs, engine tuners and the like.

Advise your progress here, with

Kind Regards....

Thanks for that will try para as weight is a criteria

Regards dave

I have considered this same thing for housing a little genny for boats. I will construct my version out of Plywood, covered in Fiberglass Fabric laid in Epoxy. Ordinary Automotive Body Shop materials would also suffice. To Sound Proof the box I plan to line it with a Marine style material that is a Mylar covered Foam sandwich with a sheet lead core. All these materials are available via Internet stores.

Thanks for you info, I would have to leave out the lead as weight is a criteria

Regards Dave

that's interesting a NZ company supplied us with noise attenuation panels for our power plant. i took apart one to see the construction, the panel was constructed from light gauge sheet steel 18-20AWG or to your discretion, the thickness vary's some panels are 4" some are 6"...inside is the noise attenuation material very similar to pink bats used in homes. the inside panel facing the sound source is peforated, the idea per the company the noise enters the perforations and absorbed by the insulation material. you can use this concept to work up something maybe even of wood. we used 100$ silicone for all the joints and seams, the box/panels where riveted.

yes the heat is something you need to address.

cheers

The fiberglass insulation and perforated metal previously mentioned should work fine. Another material you might want to consider, is duct liner you would probably have to go to an HVAC supply to obtain this, basically a higher consistency fiberglass. As far as cooling whether or not it's a water cooled engine some air circulation is required for the compartment, when insulating the compartment to prevent sound transfer, you are also preventing heat transfer.

Heat from the internal combustion engine and the electrical generation section would be trapped within the compartment, the temperatures could quickly get out of hand if the compartment is completely sealed. A ventilation fan could be mounted at one end, and air intake at the other of the enclosure.90° elbows insulated in the same way as the rest of the enclosure , could be placed over the discharge from the exhaust fan, and the air to intake. The elbow should be reasonably effective in preventing sound transfer

Hi,

In a good design, of Noiseless Machine, Sound emanates because of lubricant for Engine rotations and Contaminants in fuel impede smooth running of machine.

I suggest Make your Engine work Smoother and Efficiently as originally designed.

Place a Nano (100mG) dose of BIOSANITIZER, Non-Perishable Catalyst, which will Improve Productivity of Fuel with contaminants removed, and Offering lubrication for smoother Running, which would make it Noiseless.

Contact me in Bangalore India to fetch LIFE LONG remedy for improving Quality of your Petrol Generator first from Sound level based issue. You can protect Engine with much simpler covering (with Heat dissipation & Dust, Rain,Sun protection taken Note of) costing much lower than getting HiFi Outdoor Enclosure for your generator.

Regards:Kishor <kishorekaikini@gmail.com>

Objective is not feasible. The BEST you can achieve is a reduction in perceived noise by SHIELDING the listener(s) from direct transmission of noise. Engine & Generator ventilation for cooling is essential. One CAN fabricate a lightweight 'box enclosure' out of foil faced insulation board, with one side open (similar to an Igloo, pointing away from listeners). The engine exhaust and cooling air must freely flow out the open end--and fresh air easily enter. Dividing the opening into two levels with a simple horizontal baffle may be sufficient to allow hot gases out the top, cool air in the bottom.

3M has a product dedicated to fireproofing and sound reduction for engine

compartments.It's not cheap - a 3' x 3' piece costs $127.00 CAN , it's a

foam and foil flexible 1" thick sticky backed mattress type of thing.

Here is another possible alternative to this that is a little cheaper. It is still pricey though. (69.95 US for a 32"X54" sheet) It is a Dynamat Product made for the underside of car hoods. Dynamat products, in case you are not familiar with the name, are designed for car audio sound deadening. Their products are popular amongst professional car audio intallers and are supposed to be pretty effective. Here is a link for their heat resistant underhood material: http://store.summitracing.com/partdetail.asp?autofilter=1&part=DYC%2D11905&N=700+115&autoview=sku

PS I am not associated with Dynamat or Summit Racing equipment. I merely have used this product in my own vehicles and it seems to work well, though and holds up well. I too was considering using it to silence a generator, but have not done do yet. So I cannot say if it will do the job or not. Just a thought.

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I have a noisy generator as well and was wondering if an adapted car muffler would quieten the engine noise without damaging the engine. Would that type muffler trap too much heat in an aircooled engine?

I have already tried it on a 5KW aircooled Homelite. It did not seem to harm the engine but it was only moderatly effective. Most of the sound from these aircooled generators is mechanical noise from the engine, not the exhaust note.

Granted the exhaust noise will have to be dealt with at some point, but only after the mechanical noise from the engine itself is dealt with, as it is only part of the overall noise picture and not the largest part.

Antoher point. If you are going to go the car muffler route, make sure that the pipe that you use has a larger diameter that the stock exhaust. That way you minimize the amount of added back pressure created by the larger muffler and longer exhaust. Also if you are adding any considerable length of exhaust to the engine, use flexible pipe to connect to the engine, to allow the engine some movement, or else your pipe will break or you will crack the engine block (or head depending upon where the exhaust port is) The other problem you may encounter is, that the larger pipe will have a trumpet effect, which could actually make the generator even louder. Maybe use a Supertrap muffler at the end of the pipe.

Thanks for the reply. It sounds like a sound reduction box might be the only way to go.

Leave it to engineers to overcomplicate things.

A few years ago, one of my fellow hams made a sound reducing box for his generator. He made it out of plywood to cover the top and 3 sides, lined it with old carpet. He used hinges to make it collapsible and easier to move and store.

Yes, we do tend to overcomplicate things.

KISS is a proven strategy, allthough it's not as much fun!

Sounds like my sort of solution, will let you know how it goes

Regards Dave

Why not use Green glue soundproofing compound? Green glue is a new soundproofing product available in the market that is capable of eliminating a wide range of frequency, much wider than the traditional STC range. Green glue is considered as a water barrier and you can apply it in between two layers of water resistant gypsum board. Use Green Glue should be good enough for your soundproofing generator box.

Green Glue is not a water / vapor barrier. It may or may not be an appropriate material, depending on the frequency of the sound and if it is airborne or conducted through the slab