How to Silence / Quieten a Generator

raind33r said:
Best place to buy rockwool? Dont see it listed at builder's and Takealot only has the grow medium
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Yeah, this has been my issue as well - there are some suppliers but they seem allergic to sending out quotes or information.
 
Grouter said:
A 12 kva 1500 rpm diesel, in a concrete block housing, surrounded by old mattresses.

View attachment 1464757

Exhaust down through the slab, running into two underground concrete mufflers.
A few old mattresses suspended above it with an old coolroom wall for a lid.

View attachment 1464759

The other side of that vibracrete fence, in the street, you can't hear the generator. Can't hear it in the house either. The 1 amp solar panel keeps the starting battery happy.

View attachment 1464763
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Nice solution. But the concrete walls are doing all of the work. At best those mattresses are only absorbing some high frequencies. Swap those out for rockwool bats (80kg/sq 100mm thick) and they’d be doing some work for you. The mattresses are potentially a fire hazard.
 
The Darkness said:
Nice solution. But the concrete walls are doing all of the work. At best those mattresses are only absorbing some high frequencies. Swap those out for rockwool bats (80kg/sq 100mm thick) and they’d be doing some work for you. The mattresses are potentially a fire hazard.
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Acoustic attenuation, simply put, is mostly about two things: Trying to bounce back sound waves (reflection) towards the source (achieved by the walls) and then trying to convert those sound waves into heat via a medium (open cell foam mattresses) through absorption into that medium.
Without the mattresses, the neighbours can hear the generator running. With them, not.

It's an ex-marine diesel, and I'm a retired marine diesel engineer (on a budget). It hasn't caught fire in nearly twenty years. I figure it's fine.
 
D said:
Jeez! Price for a loaf of bread has bounced off the charts in the Grouter household!
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SWAMBO: "I wish we had a bigger inverter. I want toast"
GROUTER: "Just starting the generator, darling. 2 secs."

Just haven't yet gotten around to getting one of those gas camping toasters yet.
 
Grouter said:
SWAMBO: "I wish we had a bigger inverter. I want toast"
GROUTER: "Just starting the generator, darling. 2 secs."

Just haven't yet gotten around to getting one of those gas camping toasters yet.
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What you need is an electronic start so that when the toast tray goes down, the generator goes on. Solution! :giggle:
 
Grouter said:
Acoustic attenuation, simply put, is mostly about two things: Trying to bounce back sound waves (reflection) towards the source (achieved by the walls) and then trying to convert those sound waves into heat via a medium (open cell foam mattresses) through absorption into that medium.
Without the mattresses, the neighbours can hear the generator running. With them, not.

It's an ex-marine diesel, and I'm a retired marine diesel engineer (on a budget). It hasn't caught fire in nearly twenty years. I figure it's fine.
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Not how sound works. The cancellation from a standing wave will conversely also have points along the wave that will increase. These too vary at all wavelengths, however the fundamental frequency of the sound source in this case your generator will dominate the path and decision to attenuate it. The best way I can describe this is if you are in a nightclub you’ll find areas with attenuated bass (along with other frequencies) and likewise those with positively augmented bass.
Open cell foam has a very low NRC and would only be marginally effective at higher frequencies normally from around 3kHz upwards. What absorbs low frequencies is mass. This is why rockwool is effective, even more so if you mounted it with a gap behind it away from the wall. While the conversion to heat assumption is marginally true, this is only best effected using limp mass absorbers, which is an entirely different concept. Anyway, I’m glad your solution is effective in assuaging your neighbours.
 
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