Tactical generator environmental modifications

[Hard Head]

Due to ice, snow, rain, pests and other things that can cause issues with a generator I decided to make some modes to my MEP-803A.

The first modification is the addition of an exhaust hood. This will prevent things such as snow and ice from accumulating in the radiator exhaust cavity.

Since all we had was some 14 gauge sheets laying around some hand bending was required. All in all day one was productive.


1) Cut out the pieces and welded them up.
2) Checked for fit
3) Added engine exhaust / hood intake
4) Sealed up edges
5) Made the exhaust screen
6) Got it ready to prime



Tomorrow:
1) Prime hot parts and hood
2) Check db levels and determine baffle placement if needed.
3) Remove riveted schematics from the doors
4) Spray Spectrum on the doors and new hood.
5) Order new door seal material


Monday:
1) Modify the air intakes
2) Make a custom high flow filter
3) Carc the hood to match the generator

 

[Korgoth1]

I am interested in db reduction from the rubberized coating, I had considered it. Are you going to coat the roof panels as well?

 

[Flyingvan911]

Looks good!

 

[Hard Head]

I may coat the entire unit inside since I am going to fix the intake area anyway. Some disassembly required! I really like the coating, it kills the noise transfer in the sheet metal. It is just expensive. Almost $300 for 5 gallons. I have the same stuff with ceramic beads mixed in it. I will use it as a second coat over the top of the muffler / engine roof area. It does great on firewalls to kill sound.

 

[robson1015]

Nice fab work Hard Head....

 

[Hard Head]

Day 2

1) Removed the doors and drilled out the rivets. looks like those shaky doors stays need some nylon washers! Will take care of that!
2) Removed the hood and cleaned up the interior of the cabinet. I will chain lift it later and fix the drain hole to prevent invasion!
3) Sanded and taped the doors and hood for coating. I am having thoughts of adding a piece of small channel to stiffen the hood just to the side of the muffler toward the fan. The sheet metal dips and I don't want it hold rain water.
4) Added a Damplifier Pro sheet (foil backed CLD vibration damper) to the metal flashing which bevels over the radiator to attach the roof screws. It doesn't make a noise now when I strike or thump it. I will put some butyl rope in the corner seams before I close the hood. I may stiffen that area too or put razor wire on the top to keep little people off!
5) I did get the exhaust hood primed!
6) Got ready to spray the doors and had an issue with my compressor smoking! Looks like I need a new one! Going to have to borrow a professionals paint booth. While I am waiting on him to return from another job, I will go purchase all new bolts and washers to replace any rusted ones that I took out.
7) I added the fuse modification to the generator since it needed it. Going to check the mounting rubber and hoses while I have the hood off. I will also add some Damplifier Pro to the sheet metal where the air filter attaches.
I believe I will go ahead and change the thermostat since it is easy to do with everything out of the way. I need a half dozen of these guys! PM me if you have some for sale.



That's about it for today.

 

[Guyfang]

This, is interesting!!!!!!!!!!!!!!!!!!!!!!!!!

 

[Another Ahab]

This, is interesting!!!!!!!!!!!!!!!!!!!!!!!!!

It's good stuff, for sure!

 

[tim292stro]

Reverberating and chassis vibration damping is for certain important, but are you doing anything to combat airborne noise too? Like mineral fiber absorbing material inside the case? How about the isolation of the unit itself from any structure that could transmit noise away from the generator? How are you "site-ing" the generator to reduce the noise impact for what does escape your acoustic controls?

I'm very interested in what your total plan is - I'm kind of a sound treatment nerd...

Also, I did have a question about your exhaust pipe modification - I see that you are piping out the exhaust through the air outlet duct you've built - how are you sealing around those pass-throughs to keep the critters out? I recall you had a Mud/Dirt Dauber issue you were concerned about...

 

[Hard Head]

I built a wire screen that is mounted in Steel U expanded metal channel. I fits inside the exhaust hood. We have several internal baffle designs we are playing around with to kill airborne sound. One of the good things about the spray on rubber compounds are that they kill vibration at 1 mm and really take a chunk out of sound at 3 mm. We are testing Open / Closed cell foams too! They ceramic coatings take up to 500 F. So around the spring tension muffler pad opening I will use ceramic. I will also RTV the silicon pad to the cabinet. The spring and plate is cool but it can get stuck and the pad can have a gap between the cabinet. Mine was stuck down when I got the gen set which left a crack. The intake is totally welded to the hood with 14 gauge material and a very heavy washer where the compression fitting attaches. It is so easy to just lift on and off. Tried it on 2 other units and it is perfect. The mass is a great heat sink too. The only thing that gets hot is the pipe. I ran 10 minutes and the hood temp is not affected. I used 2000 degree paint on the pile so it will not have any issues. I will prob stencil "HOT" on it too. Maybe I will look for some silicon pipe and give it a try.

I have a sound engineer who has been reviewing for weak spots. The air exhaust hood is designed this large since you have to account for acoustical material and screening in order to keep the combined airflow to equal to or greater what it was before the hood. Therefore a large hood was needed. The airflow / design was calculated by a hood design engineering firm. Just testing the hood raw there is not that great of a db difference at the hood opening.

I currently use precast AC pads with a horse stall mat on top for vibration dampening. It works but it would be easier to change fluids and prevent ant invasion if I elevate it and isolated the platform legs. I will attack this too. I have seen so many great ideas on this site. It got me inspired to make something to further automate the use of generators. I don't want to have to manually remove covers or clean out snow and ice before cranking it or open and run when wasps attack when you open a panel. I want automated testing and a home panel showing the condition of the set. As we go the design it is being captured in CAD and it can be Laser cut for the next half dozen I plan to do before Spring. This will save a couple hours of fabrication work and make it prefect! There are a lot of great minds on this site with years of experience that you don't get from just reading reading a TM manual!!!! If only the younger folks could understand that we are just trying to share experience! Been there, done that!

I really appreciate your opinion and interest! Guess I had better get of the computer and get to work done to post today! FYI, I need some parts! Coolant temp sender and thermostats.

 

[Another Ahab]

I currently use precast AC pads with a horse stall mat on top for vibration dampening.

It is very impressive the level of detail you are going to here; my hat's off to you.

And I don't know if any material is publicly available from the USN, but if you want to know about vibration dampening/ sound-deadening, nothing beats the systems on board the fleet's subs; that's the state-of-the-art.

 

[Hard Head]

Ok, didn't get as much done as I wanted to since I have to fix my truck today

1) Put Damplifier Pro on the rear plate where the air filter is mounted.
2) Put the first coat of Spectrum on the doors, roof, and new hood.
3) Made a stiffener for the top of the generator. Got to add some secret material to the 1/4 inch plate to bring the top slightly higher in the middle.
4) Put some paint on the screen

I am going to put 2 more coats of Spectrum on the doors and exhaust hood; and 1 more coat on the roof piece. Then I will put a coat of ceramic on the roof. I have to wait a few days for the rubber to cure enough before I can coat with the ceramic. That is ok since I have to fix the intakes and put better seals on every opening in the unit. They don't seal good enough in the corners which allows for critter issues. Heck there is a major gap on the control panel cover. Taking care of that too! There will be no more easy entry points.

 

[kloppk]

.... I want automated testing and a home panel showing the condition of the set. ....

I've been working on that very feature since early December. Wireless genset start/stop with remote parameter monitoring.
Prototype is working. Will be posting up once I tweek the firmware, shoot some pics and a video.

 

[Hard Head]

Hi Ahab, Looked into it and the Navy touts the material to be equal to 12" of poured concrete. They also allowed a commercial company to produce it for commercial use. Well I found the same specs and 12" claim on a NASA spin off company named Acoustiblok and they are located in FL.

http://www.acoustiblok.com/acoustiblok-soundproofing-demonstration.php

The only catch is that the more limp they are the better they convert sound waves into energy. You have to seal every crack or the sound will escape also. I am going to see if I can get some to test.

 

[Another Ahab]

That video clip is VERY convincing; wow.

That product does the job by all appearances. The question is:

- What's the cost?

 

[Hard Head]

I just looked a a home movie theater install that stated the cost @$2 a square ft for 1200 sq ft. It must be decoupled with special spacers in order for it to vibrate with sound waves to convert the sound into energy. If you could make a box to cover the entire generator you would never hear it run! Problem is you need air in and out! The price is not terrible since mass loaded butyl sheets with aluminum facing (the stuff I used on the generator) run around $4 to $6 a sq ft. Spectrum is around $6 a foot when applied @3 mm buying it by the gallon 10 sq ft for $68 + shipping and tax.

 

[tim292stro]

...I don't know if any material is publicly available from the USN, but if you want to know about vibration dampening/ sound-deadening, nothing beats the systems on board the fleet's subs; that's the state-of-the-art.

Sylomer, used all over the place, not just Naval subs - also used to isolate entire buildings or industrial machinery from foundations. Think of how bad it would be to have a skyscraper next to a subway line, or a quiet office next to a building that has a 1000-ton stamp press...

Interestingly, it's what the floor-floating "pucks" are made from for sound isolated rooms, then rebranded by the various reseller companies.

Hi Ahab, Looked into it and the Navy touts the material to be equal to 12" of poured concrete...

Installation methods affect how this works, and it's not a single product you need, as it does little for reflection/reverberation - so still need a diffusing/absorbing layer of some other material. This is especially important if you have machinery or people who need to breath in the enclosed space. It's very easy to sound seal a room if there is nothing that needs air circulation...

...They also allowed a commercial company to produce it for commercial use. Well I found the same specs and 12" claim on a NASA spin off company named Acoustiblok and they are located in FL.

http://www.acoustiblok.com/acoustiblok-soundproofing-demonstration.php

The only catch is that the more limp they are the better they convert sound waves into energy. You have to seal every crack or the sound will escape also. I am going to see if I can get some to test.

That video clip is VERY convincing; wow. That product does the job by all appearances.

Their product is a common lead sheet replacement, boron impregnated vinyl, boron being the high mass element they "load" the vinyl with - thus "mass loaded vinyl". Not magic, and I worry about just about any company that claims to be a spin-off on the heading of their website... I dug a bit deeper into their "NASA Registered Spin-Off" thing once I saw that emblazoned on their page, they are not registered for their use of NASA derived sound deadening technology, they are registered for Thermablok product, which uses an Aspen Aerogel insulation package in a plastic carrier (not "novel" either, other companies do that too but don't feel the need to drag NASA into it). The loading of vinyl with boron can actually be traced back to radiation shielding in the 50's, since high mass is required for good ray and neutrino radiation shielding properties and the list of non-reactive elements with high mass is rather small...

The Acoustiblok people talk a really big game IMHO

I just looked at a home movie theater install that stated the cost @$2 a square ft for 1200 sq ft. It must be decoupled with special spacers in order for it to vibrate with sound waves to convert the sound into energy. If you could make a box to cover the entire generator you would never hear it run! Problem is you need air in and out! The price is not terrible since mass loaded butyl sheets with aluminum facing (the stuff I used on the generator) run around $4 to $6 a sq ft. Spectrum is around $6 a foot when applied @3 mm buying it by the gallon 10 sq ft for $68 + shipping and tax.

I have done home theater installations from 1995-2000, and have done some work with THX commercial theaters and industrial noise control. This technology was around back then and we bought from a company called Auralex (and many others) - only they call it SheetBlok (important to understand that AcoustiBlok/SheetBlok are Brand names, mass loaded vinyl is a Trade name - like Sheetrock is a brand name and drywall is a tradename)

They has been a company for about a decade called QuietRock which is drywall that has a mass loaded vinyl layer pre-installed in the panel's sandwich. They also make RF shielding panels for SCIF rooms and other uses when you need to worry about TEMPEST compatibility.

Acoustiblok's sound-source viewer is actually a widely available noise source device - it works on the same principal as phased array radar (the kind that doesn't move). It just works on time of arrival across a known measurement of small array and uses some math to figure out which direction an impulse came from. Incidentally this is the reverse of how the GPS system works - many impulses are sent from known locations and back calculating where the possible intersections are (rejecting the improbable ones).

My point is, there are tons of companies and their "solutions" out there for sound/noise control, and it's not a new industry (most of the new guys are just rehashing old stuff). I believe it's important not to get hung up on a product or a flashy demo by a marketing guy (even a CEO touting his company's product is engaging in marketing...) - good sound control is done through good engineering and construction using hard earned science which is very well documented. I only brought this up because of pricing being brought up - that leads down a dangerous path of assuming that you only need so much of a given product no matter the condition of the space or type of noise problem. I'm not trying to single anyone out, or claim anyone is a charlatan, I merely quoted posts to bring some calm logic and experience to the thread. As many will agree, it's been my long standing intent to bring more understanding and insight to threads rather than to get into arguments or wandering into potential product battles - I think we are all better for it when we all actually start to be knowledgeable with what we are talking about

If you're reading this thread looking for good generator enclosure or shed construction information, do a Google search for "STC 70 Wall assembly". There are tons of practical resources that will instruct (at no charge) a lot of the best practices of building sound isolating structures - in fact the Green Building Council is starting to consider environmental noise as part of their building guidelines, so newer homes, offices, and buildings in general will be quieter.

 

[Hard Head]

Hi Tim,
I agree with where you are going with structural enclosures but for my requirements I only have the space allocated inside the unit to work with. I want it as quite as possible and I will add some sound absorbing material next. My goal is to not increase the sound, lower it if possible, keep out critters, snow, rain, etc. while maintaining portability. I want to disconnect, hoist and go in 30 minutes of less. I am not going to put any structure over the generator or put it in one. All my external structures have to match the architecture of the home ( must be brick), (yes we have neighborhood agents that keep up with everything we have or do in the subdivision). I cannot leave it on a trailer in the yard unless it is temporary and attached to a vehicle at all times. So temporary on the ground backup power hidden by a shrub is allowed and not a problem. I would have never started this thread if I was just doing a permanent placement of a generator. As you have indicated you can just put in sound deadening products in a building and there are lots of great ways documented about building them in. I wanted to correct issues I have encountered with the MEP-80X generators. I have used the acoustic products in this thread in automobiles and trucks to not only reduce road noise but also stop vibrations in doors, etc. where audio components of very high output physically move the metal, create rattles like mad, and ruin the sound. I also had a challenge to take a vehicle that had a gas engine replaced by a diesel and substantially reduce the diesel sound in the cabin (2003 Land Rover Cummins 4BT conversion). The materials I am using here were utilized but were not the only materials used. When finished we dropped 15 db in the cab . It was worth the effort. Kind of funny you mentioned RF products. I think I have some type of RF shielding material in one room in my house. It is dead to cell phone and wireless signals with the doors closed. From what I can tell there are three layers of material in the walls and ceiling. Cool but aggravating when you are on the phone going from one side of the house to the other! I think the previous owner had some issue and had that room modified. Pretty much a Faraday cage. What would you recommend for 1 to 2 inches of absorption materials for use in the cabinet?

 

[tim292stro]

...Kind of funny you mentioned RF products. I think I have some type of RF shielding material in one room in my house. It is dead to cell phone and wireless signals with the doors closed. From what I can tell there are three layers of material in the walls and ceiling. Cool but aggravating when you are on the phone going from one side of the house to the other! I think the previous owner had some issue and had that room modified. Pretty much a Faraday cage...

Slick - I have some kind of "fantasy" for a home that is all Faraday cage... That previous owner sounds like a kindred spirit of sorts

...I would have never started this thread if I was just doing a permanent placement of a generator. As you have indicated you can just put in sound deadening products in a building and there are lots of great ways documented about building them in. I wanted to correct issues I have encountered with the MEP-80X generators...

Indeed, the same things you will find the building suggestions are applicable to the MEP line of generators too - double wall the housing, put absorptive material between layers, mechanically isolate the machinery from the cabinet/skid, and then break up the standing waves inside so that the air flow paths don't have lot of extra sound to attenuate.

...What would you recommend for 1 to 2 inches of absorption materials for use in the cabinet?...

1/2" closed cell polyethylene foam sheet glued to the steel case, 2lb/sqft mass loaded vinyl glued to the closed cell foam, 0.5"-1.5" mineral fiber glued to the mass loaded vinyl. Doing this will still result in relatively flat (yet absorptive) surfaces inside the enclosure. The standing waves can be further broken up by pieces of 2"x2"x0.25" aluminum t-bar in the wall, and sticking out 2" thick diffusers from surfaces directly around the engine and generator head air-flow holes. The aluminum t-bar gives some structure and floating mass to the partition segments.


Also check the isolators for the engine and generator head - they should be nice and soft. If you can't reach into the case through a door and wiggle the engine and generator, you may want to change them out. Also take a look at plumbing and wiring - they can transmit vibration to the case.

If you're trying to "go for broke" with sound deadening, putting a thermal/acoustic blanket on the exhaust and muffler inside the case will keep more of the energy contained in the pipe. That bent pipe you have going out the the exhaust hood is a convenient place to add a large attenuation chamber or a higher grade secondary muffler.

 

[Hard Head]

The vibration mounts look brand new! No issues with them. Put silicon on the rubber parts. I will have to mock up the pattern you suggested in the fiber board. There is very little room directly above the muffler. Maybe an inch. I added a steel stiffener since the cabinet dips there and holds water. I think it will be a convenient item to handle mounting some material varying in height and width to diffuse sound. I did find an airflow restriction issue on the right side of the unit. A little storage box modification should fix that. I am testing a silencer on the exhaust. Very little back pressure! Noticeable difference! A great thing about the changes is the current top exhaust noise can easily be heard in the two bedrooms directly above the generator on the second floor. That should make a big difference!