Where to find guidelines for building generator compartment?

[belfert]

I am going to need to build a generator compartment for my new WRICO 12.5 KW generator.  Where can I find some guidelines for building a generator compartment to make it quiet?

I want this to be at least as quiet as my Powertech enclosed generator is now.  I have found some Youtube videos of bus conversion diesel generators running and they are loud compared to my Powertech.

[richard5933]

Here's where I got the material I used to replace the soundproofing on my coach.

https://www.soundproofcow.com/

They have a few how-to videos and blog entries about this. Poke around their site and see what you can glean from it.

My experience says that there are three aspects to reducing the sound from a generator.

1) Engine noise.
2) Engine vibration.
3) Air flow noise from radiator/cooling system.

You have to address all three to make this work.

[luvrbus]

The air intake makes the most noise,lead lined sheet rock makes the best sound proofing but you need  to cover it to prevent damage,Sun Down is ok but all foam will deteriorate over time.I used the egg crate lead foam on my bus and after so long I was always removing pieces from my air cleaner on the generator

[Jim Blackwood]

It has to be isolated from the bus, and sometimes the existing isolator pads are not compliant enough. McMasterCarr sells a wide variety of isolators.

Jim

[luvrbus]

It has to be isolated from the bus, and sometimes the existing isolator pads are not compliant enough. McMasterCarr sells a wide variety of isolators.

Jim

He can buy the gel or air bags from Dick they work really well

[chessie4905]

The Marathon Prevost has air bags on the 17 kw Martin diesel. On a slide out.

[belfert]

The air intake makes the most noise,lead lined sheet rock makes the best sound proofing but you need  to cover it to prevent damage,Sun Down is ok but all foam will deteriorate over time.I used the egg crate lead foam on my bus and after so long I was always removing pieces from my air cleaner on the generator

Isn't drywall really heavy for a bus?  How you stop it from cracking?

[luvrbus]

 People use sheet rock all the time on the interior and it doesn't crack,all depends on how you attach it.The people I know that has used the lead lined sheet rock covered it with FRP and hose the compartment out without problems one for 20+ years and yes  it is heavy but so is Granite counter tops 

[belfert]

I am looking for where to find design principles like how to design air intakes to reduce sound transmission.

[Jim Blackwood]

A no-restrictions design would have a well muffled and insulated exhaust which exits above the roof, possibly contained in an air stack with an open bottom and top. Triple-wall stainless stove pipe comes to mind, with the exhaust running up the center.

There have been advances in fans in recent years to reduce sound levels, that would also be a good place to look.

Jim

[richard5933]

Custom Coach used lead sheeting on the floor of the bus, with a layer of cork over the top of it. Both were done to provide a sound barrier to the generator below it.

They lined the generator compartment itself with a multi-layered material - heavy vinyl layer between two layers of foam, with a metallic layer facing the generator. All of this is held in place with expanded steel mesh (which protects the foam and also keeps the sound from penetrating.)

The air flow comes in from the driver's side, across the bay in a sound-protected channel, and then through the radiator which is mid-ships. The air is then sucked across the genset and out through the floor of the generator bay with a large squirrel fan moving the air. You can see the intake in the photo, with the radiator at the back of the intake tunnel.

I did install new vibration isolation mounts when I got the bus as the old ones were collapsing. They come in both two-directional and three-directional dampening. I got the three-directional ones. Just upgrading the mounts made a big difference.

[belfert]

A no-restrictions design would have a well muffled and insulated exhaust which exits above the roof, possibly contained in an air stack with an open bottom and top. Triple-wall stainless stove pipe comes to mind, with the exhaust running up the center.

Unfortunately, I probably won't be able to run the exhaust to the roof in an already built interior.  What sound benefit is provided by doing this?  Is there a possibility of too much back pressure?

[belfert]

Here is what I am dealing with for a generator compartment.  My bay is 57" wide, 32" deep, and 36" high.  Door opening is 49" wide.  The rest of the luggage bay behind the generator is full of fresh water and waste tanks.

I have heard that if air makes a turn it will be quieter, but I am trying to find something that actually states that.  I tried searching here, but I gave up after a while as I wasn't finding anything useful.

[Jim Blackwood]

The answer is that it depends on the configuration. You have to get into sonic wave transmission formulas to really nail it down and it is very dependent on frequency. But because a generator runs at a more or less fixed speed that effort can pay off. Essentially what you would be trying to do is create a sound trap where the wave bounces off a wall and cancels out the next incoming wave, then you would put your intake or exit at the cancellation point which is somewhere back up the duct or tube. Sort of like waveguide theory. That's about the limit of my ability to help with this, but yes, it is possible to get some benefit. How much I couldn't say, and I don't know how large this structure would have to be. Again, pretty much dependent on frequency, but also on air flow requirements.

Jim

[Busted Knuckle]

Brian don't worry about running the stack up thru the finished interior of your coach just build one of the removable stacks that slides on it when parked the guys you haul out to the desert build rockets so a simple exhaust stack ought to be a piece of cake for them to do in a short time while sitting around bs'ing about the days activities!
  BK