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Generator soundproofing — I will buy lead sheet

Question:

- Hide quoted text — Show quoted text – > I am soundproofing this generator: > http://igor.chudov.com/tmp/onan/Diesel/ > This is a followup to my question on soundproofing it. > I found some lead sheet at our local roofing supplier. 2.5 lbs per > square foot (approximately 1 mm thick), $28 per 3×3′ square, which > works out to $3.11 per square foot. I hope that combined with a 1/2" > plywood shell, (which already gives me 5dB reduction), I can > accomplish 5-10 more decibel sound reduction if I use lead sheet on 5 > sides of the enclosure (4 sides and the top), and seal the edges > better. > If I get 10 decibels total sound reduction, it will be acceptable, if > I get 15, I will be in heavens. The noise from the unshielded genset > at 10 feet is 85 dB. So, 15 dB reduction would give me 70 decibel > noise. > If anyone has a good idea why this is a stupid plan, I will be greatly > thankful if you can post your thoughts tonight, before Igo there early > tomorrow. > Thanks, as always, > i

It seems the Greater Sound Reduction (GSR) would occur at the boundary between air and solid (plywood or lead), rather than within a substance (my wag). GSR may be better if the lead squares are mounted on standoffs. A quick google did not answer whether my wag is true or false.

Response:

– Hide quoted text — Show quoted text -> I am soundproofing this generator: > http://igor.chudov.com/tmp/onan/Diesel/ > This is a followup to my question on soundproofing it. > I found some lead sheet at our local roofing supplier. 2.5 lbs per > square foot (approximately 1 mm thick), $28 per 3×3′ square, which > works out to $3.11 per square foot. I hope that combined with a 1/2" > plywood shell, (which already gives me 5dB reduction), I can > accomplish 5-10 more decibel sound reduction if I use lead sheet on 5 > sides of the enclosure (4 sides and the top), and seal the edges > better. > If I get 10 decibels total sound reduction, it will be acceptable, if > I get 15, I will be in heavens. The noise from the unshielded genset > at 10 feet is 85 dB. So, 15 dB reduction would give me 70 decibel > noise. > If anyone has a good idea why this is a stupid plan, I will be greatly > thankful if you can post your thoughts tonight, before Igo there early > tomorrow. > Thanks, as always, > i > It seems the Greater Sound Reduction (GSR) would occur at the > boundary between air and solid (plywood or lead), rather than > within a substance (my wag). GSR may be better if the lead squares > are mounted on standoffs. A quick google did not answer whether my > wag is true or false.

In sound studio construction, the dead air in double wall construction is considered key. However, lead is in a special category, because it is extraordinarily efficient at absorbing vibration. I speculate that if the lead is mounted on standoffs, fatigue cracking will appear near the points of attachment. I have not seen freestanding lead used. In movie cameras, lead is applied directly to the inside of the film magazine, right up against the aluminum casting.

Response:

[ plenty snipped ] > > I found some lead sheet at our local roofing supplier. 2.5 lbs per > > square foot (approximately 1 mm thick), $28 per 3×3′ square, which >However, lead is in a special category, because it is extraordinarily >efficient at absorbing vibration. >I have not seen freestanding lead used. >In movie cameras, lead is applied directly to the inside of the film >magazine, right up against the aluminum casting.

In the good Old Days before environmental concerns took hold, thick lead foil was commonly used as a sound baffle around pipes and other tricky and space constricted items. A favorite in NYC was wrapping it around incinerator chutes. — Knowledge may be power, but communications is the key [to foil spammers, my address has been double rot-13 encoded]

Response:

I believe this is a diesel generator and as such there are 2 things that need to be addressed before you start and that is the intake and exhaust. Did you know that most of the noise from a diesel somes from the intake and exhaust? As a matter of fact some diesel pickup trucks have a muffler on the air intake? At the Cummins school years ago they had a cummins diesel engine running at full power but the exhaust and intake were routed to outside the building. It was so quiet that one could carry on a normal conversation standing 2 feet away from the engine. Outside the building the noise level was quite impressive. Once you have the exhaust and intake directed to the outside, then you can attack if necessary the remaining noise levels of the motor. Don’t forget that the exhaust gases will get quite hot under load. Good Luck BTW Cummins and Onan are parts of the same company. Onan makes a great engine as does Cummins. r

Response:

I had a insulation installation company bring in for repair a trailer mounted insulation blower once. It was inside a 10×10x30 foot long trailer, and the engine, a B+S vanguard v-twin was about 6 feet inside the trailer rear door. The engine installer did a good job unstalling a duct in the floor to the cooling air inlet at the flywheel screen, and all was well until one day one of the workers knocked off the duct while moving supplies or something, we never found out. This missing duct allowed the engine cooling air to "recycle", i.e. the hot cooling air exhaust went back in to the cooling air intake. This was with a 10′x10′ door open only six feet away, mind you. After almost a full day with inadequate cooling the engine oil looked like tar and was about as thick. Total engine destruction due to inadequate cooling was the result. I hope you have provided a way for the engine to cool itself, the box you are describing sounds a lot like that trailer. Air cooled engines make about the same watts in heat as the generator makes electrical power, i.e. 5 kw generator makes 5 kw heated air Scott

Response:

[snip] > that I plan on addressing with some baffling. > I am also thinking of spraying or gluing some vibration absorber to > the sheet metal pieces on the engine. Would it make sense to you? > i

I have a feeling that the intense vibration would cause the stuff to degrade at an accelerated rate. Perhaps it would be manageable.

Response:

Some years back, our company had to soundproof some industrial machinery that emitted wide spectrum of noise. Local supplier of soundproofing material provided sheets of material with layers of ~.060" lead, ~.100" foam, ~.030" plastic (like vinyl). Lead side would face out (free of skin of machine.) This was surprisingly effective, but don’t ask for specific db reduction at freq. At least it enabled us to meet customer rqmts., deliver, and collect. John

Response:

You don’t want to staple it. The staples will transfer the vibrations and therefore noise to the plywood. The best answer is some sort of glue like liquid nails. .

– Hide quoted text — Show quoted text -> Some years back, our company had to soundproof some industrial > machinery that emitted wide spectrum of noise. Local supplier of > soundproofing material provided sheets of material with layers of > ~.060" lead, ~.100" foam, ~.030" plastic (like vinyl). Lead side would > face out (free of skin of machine.) > This was surprisingly effective, but don’t ask for specific db > reduction at freq. At least it enabled us to meet customer rqmts., > deliver, and collect. > Thanks. My own insulation will be 1/2" of plywood, coupled with 1 mm > thick lead sheet. 1mm is approximately 0.04". > i

Response:

3M spray on adhesive is great for that. – Hide quoted text — Show quoted text – > You don’t want to staple it. The staples will transfer the vibrations and > therefore noise to the plywood. The best answer is some sort of glue like > liquid nails. > . > > Some years back, our company had to soundproof some industrial > > machinery that emitted wide spectrum of noise. Local supplier of > > soundproofing material provided sheets of material with layers of > > ~.060" lead, ~.100" foam, ~.030" plastic (like vinyl). Lead side would > > face out (free of skin of machine.) > > This was surprisingly effective, but don’t ask for specific db > > reduction at freq. At least it enabled us to meet customer rqmts., > > deliver, and collect. > Thanks. My own insulation will be 1/2" of plywood, coupled with 1 mm > thick lead sheet. 1mm is approximately 0.04". > i

Response:

A soft inside is important. You need to actually absorb the sound energy and turn it into heat. A hard enclosure will just bounce the sound around more until it comes out anyways. Some DIY audio shops sell a mat made to line the insides of speakers. It works very well on top of dense wood to absorb sound energy.

Response:

I’m surprised they still sell it, much less for exterior use where runoff goes into the ground and polutes the groundwater. My employer is spending millions of dollars to get rid of less than an ounce of lead in our products, and you are going out and exposing several pounds of it to the elements? Hope you don’t have any small children or animals in the vicinity. Shaking head in amazement.

Response:

> I’m surprised they still sell it, much less for exterior use where > runoff goes into the ground and polutes the groundwater. > My employer is spending millions of dollars to get rid of > less than an ounce of lead in our products, and you are going > out and exposing several pounds of it to the elements? Hope > you don’t have any small children or animals in the vicinity. > Shaking head in amazement. > The lead will be inside the plywood compartment, not exposed to > elements.

Riiiiight.

Response:

- Hide quoted text — Show quoted text ->> I’m surprised they still sell it, much less for exterior use where >> runoff goes into the ground and polutes the groundwater. >> My employer is spending millions of dollars to get rid of >> less than an ounce of lead in our products, and you are going >> out and exposing several pounds of it to the elements? Hope >> you don’t have any small children or animals in the vicinity. >> Shaking head in amazement. > The lead will be inside the plywood compartment, not exposed to > elements. > Riiiiight.

Lead is still used AFAIK as a roofing material. Very much in evidence on historic buildings. Also concider the number of houses STILL served by lead waterpipes. Does it degrade at all? Is this not one of the big problems with the stuff?

Response:

3M is the leader in adhesives. <http://products3.3m.com/catalog/us/en001/manufacturing_industry/engin… MWH6QPge/gvel_VJ9R6TT0WDgl/theme_us_adhesivetape_3_0/command_AbcPageHandler /output_html> or Marine products http://products3.3m.com/catalog/us/en001/manufacturing_industry/engin… – Hide quoted text — Show quoted text -> You don’t want to staple it. The staples will transfer the vibrations and > therefore noise to the plywood. The best answer is some sort of glue like > liquid nails. > Thanks. I would like to know what is the source of your knowledge. > Specifically, how do you know that liquid nails would in fact hold > lead and would not separate. > i > . >> > Some years back, our company had to soundproof some industrial >> > machinery that emitted wide spectrum of noise. Local supplier of >> > soundproofing material provided sheets of material with layers of >> > ~.060" lead, ~.100" foam, ~.030" plastic (like vinyl). Lead side would >> > face out (free of skin of machine.) >> > This was surprisingly effective, but don’t ask for specific db >> > reduction at freq. At least it enabled us to meet customer rqmts., >> > deliver, and collect. >> Thanks. My own insulation will be 1/2" of plywood, coupled with 1 mm >> thick lead sheet. 1mm is approximately 0.04". >> i > —

Response:

The glue type was a shot in the dark. The no holes came from an acoustical engineer on a bus conversion my father and grandfather did and the lead was on the floor so holding it in position was easy. The engineer did say if you must have nails, glue a small piece of lead over the heads.

– Hide quoted text — Show quoted text -> You don’t want to staple it. The staples will transfer the vibrations and > therefore noise to the plywood. The best answer is some sort of glue like > liquid nails. > Thanks. I would like to know what is the source of your knowledge. > Specifically, how do you know that liquid nails would in fact hold > lead and would not separate. > i > .

– Hide quoted text — Show quoted text ->> > Some years back, our company had to soundproof some industrial >> > machinery that emitted wide spectrum of noise. Local supplier of >> > soundproofing material provided sheets of material with layers of >> > ~.060" lead, ~.100" foam, ~.030" plastic (like vinyl). Lead side would >> > face out (free of skin of machine.) >> > This was surprisingly effective, but don’t ask for specific db >> > reduction at freq. At least it enabled us to meet customer rqmts., >> > deliver, and collect. >> Thanks. My own insulation will be 1/2" of plywood, coupled with 1 mm >> thick lead sheet. 1mm is approximately 0.04". >> i > —

Response:

The reason they are getting rid of it in solder has to do with the inability to insure correct disposal of electronic devices, not the presence of lead in operating ones. I’m skeptical that dripping water could carry off a dangerous amount of it.

Response:

– Hide quoted text — Show quoted text -> I’m surprised they still sell it, much less for exterior use where > runoff goes into the ground and polutes the groundwater. > My employer is spending millions of dollars to get rid of > less than an ounce of lead in our products, and you are going > out and exposing several pounds of it to the elements? Hope > you don’t have any small children or animals in the vicinity. > Shaking head in amazement. > The reason they are getting rid of it in solder has to do with the > inability > to insure correct disposal of electronic devices, not the presence of > lead > in operating ones. > I’m skeptical that dripping water could carry off a dangerous amount > of it.

And yet seeping water in landfills is exactly why the EU is making it illegal. Go figure.

Response:

> I’m skeptical that dripping water could carry off a dangerous amount of it.

Response:

– Hide quoted text — Show quoted text -> I’m surprised they still sell it, much less for exterior use where > runoff goes into the ground and polutes the groundwater. > My employer is spending millions of dollars to get rid of > less than an ounce of lead in our products, and you are going > out and exposing several pounds of it to the elements? Hope > you don’t have any small children or animals in the vicinity. > Shaking head in amazement. > The reason they are getting rid of it in solder has to do with the > inability to insure correct disposal of electronic devices, not the > presence of lead in operating ones. > I’m skeptical that dripping water could carry off a dangerous amount > of it.

Could give these guys a try instead of lead: http://www.dynamat.com/ -Bruce

Response:

> I’m surprised they still sell it, much less for exterior use where > runoff goes into the ground and polutes the groundwater. > My employer is spending millions of dollars to get rid of less than an > ounce of lead in our products, and you are going out and exposing several > pounds of it to the elements? Hope > you don’t have any small children or animals in the vicinity. > Shaking head in amazement.

Lead occurs in nature. What was God thinking???

Response:

– Hide quoted text — Show quoted text ->> I am soundproofing this generator: >> http://igor.chudov.com/tmp/onan/Diesel/ >> This is a followup to my question on soundproofing it. >> I found some lead sheet at our local roofing supplier. 2.5 lbs per >> square foot (approximately 1 mm thick), $28 per 3×3′ square, which >> works out to $3.11 per square foot. I hope that combined with a 1/2" >> plywood shell, (which already gives me 5dB reduction), I can >> accomplish 5-10 more decibel sound reduction if I use lead sheet on 5 >> sides of the enclosure (4 sides and the top), and seal the edges >> better. >> If I get 10 decibels total sound reduction, it will be acceptable, if >> I get 15, I will be in heavens. The noise from the unshielded genset >> at 10 feet is 85 dB. So, 15 dB reduction would give me 70 decibel >> noise. >> If anyone has a good idea why this is a stupid plan, I will be greatly >> thankful if you can post your thoughts tonight, before Igo there early >> tomorrow. >> Thanks, as always, >> i > I believe this is a diesel generator and as such there are 2 things > that need to be addressed before you start and that is the intake and > exhaust. Did you know that most of the noise from a diesel somes from > the intake and exhaust? > The exhaust issue has been addressed. I have a tractor muffler that is > surprisingly quiet. I ran my genset in the garage and routed exhaust > outside. It was almost completely quiet. > The intake of air is a good question, but, given relatively low HP and > volume (70 ci, 1800 RPM), it is not much.

Whatever goes out must come in, so I would route the air intake from the outside as well. That should reduce noise a significant amount. > What is much more serious is the fact that this engine is > aircooled. It sucks cold air in from the side that says ONAN in big > letters, and exhausts warm air from the back. I route that air > outside with the help of some HVAC stuff.

Not only is the engine air cooled, so is the alternator. The fan noise would be rather loud. If it were me, I would build a "dog house" for it outside. When I needed it I would take the doors off and fire it up. – Hide quoted text — Show quoted text -> As a matter of fact some diesel pickup trucks have a muffler on > the air intake? At the Cummins school years ago they had a cummins > diesel engine running at full power but the exhaust and intake were > routed to outside the building. It was so quiet that one could carry > on a normal conversation standing 2 feet away from the engine. Outside > the building the noise level was quite impressive. Once you have the > exhaust and intake directed to the outside, then you can attack if > necessary the remaining noise levels of the motor. Don’t forget that > the exhaust gases will get quite hot under load. > Thanks. Exhaust has been taken care of. Cooling is an open question > that I plan on addressing with some baffling. > I am also thinking of spraying or gluing some vibration absorber to > the sheet metal pieces on the engine. Would it make sense to you? > i

What seems obvious sometimes isn’t the solution. It will take some careful analysis to properly quite down the critter. There is a reason why all the data centers I have seen have their generators outside and isolated from the main buiilding. I assume you are determined to keep it indoors. When you get it to the point where the fan noise is most of what you hear, you are getting close. A cheap RS SPL meter might help locate the noise sources. When you get it to the point where the fan noise is the primary culprit, you will likely have to build a sound isolation booth for it with proper air intake and exhaust for cooling the alternator and engine. Don’t forget to calculate back pressure on the exhaust system. One elbow is the equivalent of adding something like 10 to 20 feet of pipe. Too little backpressure is as bad as not enough. Applying sound absorbant material to the engine covers might be helpful in reducing valve train noise but that could be detrimental to the proper cooling of an engine. When we would dyno test 871 GMC diesels it would be before the engine was painted. After painting the engine, we would test it once more and the coolant temp would go up about 15 degrees when under full load. I keep imagining an old printer sound booth only on a bigger scale for your application. You might try wrapping the exhaust pipe with some asbestos like wrap to keep the noise down as well. Tap it with a screwdriver and see if it rings. Sound travels through steel much faster than through air. Did you call you local Onan dealer to see if Onan makes a low noise kit for that genpack? You could call the factory and see what they have to say about it. They like talking to customers. My son talked to the founders son or grandson and he is a nice guy. He was also the current head honcho at the time. r

Response:

> I’m surprised they still sell it, much less for exterior use where > runoff goes into the ground and polutes the groundwater. > My employer is spending millions of dollars to get rid of less than > an ounce of lead in our products, and you are going out and exposing > several pounds of it to the elements? Hope > you don’t have any small children or animals in the vicinity. > Shaking head in amazement. > Lead occurs in nature. What was God thinking???

And Arsenic and Ebola and the radioactive isotopes all occur in nature as well. But God didn’t refine them or displace them to the point of being dangerous. We did that to ourselves.

Response:

– Hide quoted text — Show quoted text ->>>> I am soundproofing this generator: >>>> http://igor.chudov.com/tmp/onan/Diesel/ >>>> This is a followup to my question on soundproofing it. >>>> I found some lead sheet at our local roofing supplier. 2.5 lbs per >>>> square foot (approximately 1 mm thick), $28 per 3×3′ square, which >>>> works out to $3.11 per square foot. I hope that combined with a 1/2" >>>> plywood shell, (which already gives me 5dB reduction), I can >>>> accomplish 5-10 more decibel sound reduction if I use lead sheet on >>>> 5 sides of the enclosure (4 sides and the top), and seal the edges >>>> better. >>>> If I get 10 decibels total sound reduction, it will be acceptable, >>>> if I get 15, I will be in heavens. The noise from the unshielded >>>> genset at 10 feet is 85 dB. So, 15 dB reduction would give me 70 >>>> decibel noise. >>>> If anyone has a good idea why this is a stupid plan, I will be >>>> greatly thankful if you can post your thoughts tonight, before Igo >>>> there early tomorrow. >>>> Thanks, as always, >>>> i >>> I believe this is a diesel generator and as such there are 2 things >>> that need to be addressed before you start and that is the intake and >>> exhaust. Did you know that most of the noise from a diesel somes >>> from the intake and exhaust? >> The exhaust issue has been addressed. I have a tractor muffler that is >> surprisingly quiet. I ran my genset in the garage and routed exhaust >> outside. It was almost completely quiet. >> The intake of air is a good question, but, given relatively low HP and >> volume (70 ci, 1800 RPM), it is not much. > Whatever goes out must come in, so I would route the air intake from > the outside as well. That should reduce noise a significant amount. > Agreed. >> What is much more serious is the fact that this engine is >> aircooled. It sucks cold air in from the side that says ONAN in big >> letters, and exhausts warm air from the back. I route that air >> outside with the help of some HVAC stuff. > Not only is the engine air cooled, so is the alternator. The fan noise > would be rather loud. If it were me, I would build a "dog house" for > it outside. When I needed it I would take the doors off and fire it > up. > Yes, it will be outside, and I did build the dog house > see > http://igor.chudov.com/tmp/onan/Diesel/Enclosure

Great pics. – Hide quoted text — Show quoted text ->>> As a matter of fact some diesel pickup trucks have a muffler on >>> the air intake? At the Cummins school years ago they had a cummins >>> diesel engine running at full power but the exhaust and intake were >>> routed to outside the building. It was so quiet that one could carry >>> on a normal conversation standing 2 feet away from the engine. >>> Outside the building the noise level was quite impressive. Once you >>> have the exhaust and intake directed to the outside, then you can >>> attack if necessary the remaining noise levels of the motor. Don’t >>> forget that the exhaust gases will get quite hot under load. >> Thanks. Exhaust has been taken care of. Cooling is an open question >> that I plan on addressing with some baffling. >> I am also thinking of spraying or gluing some vibration absorber to >> the sheet metal pieces on the engine. Would it make sense to you? >> i > What seems obvious sometimes isn’t the solution. It will take some > careful analysis to properly quite down the critter. There is a reason > why all the data centers I have seen have their generators outside and > isolated from the main buiilding. I assume you are determined to keep > it indoors. > No, I am determined to keep it outdoors.

my apologies…i misunderstood. > When you get it to the point where the fan noise is most of what > you hear, you are getting close. A cheap RS SPL meter might help > locate the noise sources. > I have a digital SPL meter.

that will work fine. Point it at different areas and see what needs work. Some thick foam rubber will quiet down your plywood enclosure. Maybe some syrofoam insulboard will work. > All I know is that Onan parts for my 26 year old genset are very > expensive. > i

Onan parts are expensive no matter what. Thankfully they don’t break often. There were 3rd party parts suppliers but I don’t know if they still exist. I have an 18 Hp Onan gas engine on my lawn tractor. Runs great and will likely outlast me. I had to buy 2 exhaust pipes and two mufflers for it this year. Cost me in excess of $120.00. I almost made the pipes myself but I needed it in a hurry. r

Response:

207.115.63.158: > Air cooled engines make about the same watts in heat as the generator makes > electrical power, i.e. 5 kw generator makes 5 kw heated air > Scott

Yes, that is true. We would figure the electric bill for computers and add that same dollar amount for AC to keep it cool. It was within pennies of each other. r

Response:

> 207.115.63.158: > Air cooled engines make about the same watts in heat as the generator > makes > electrical power, i.e. 5 kw generator makes 5 kw heated air > Scott > Yes, that is true. > We would figure the electric bill for computers and add that same > dollar > amount for AC to keep it cool. It was within pennies of each other.

Well, ALL of the power that goes into computer equipment ultimately leaves the other end of the equation as heat.