Advice for soundproofing a compressor

[ColeyS1]

Any thoughts on how to best soundproof this compressor please ?

I'm fairly limited for space on the sides but have 3+ inches on the back and unlimited space over it.
I recently fitted an auto drain valve on the bottom that is pretty terrifying when it hisses and let's rip. Ventilation/overheating will be my main concern. Good compressor, just very noisy when its recharging !!

Sent from my SM-G960F using Tapatalk

 

[gog64]

Is there any room outside to make a weatherproof box? Otherwise it's just a big hassle making an acoustic enclosure with sufficient airflow to keep it cool. I didn't go down that route myself, I bit the bullet and bought a dirty great big hydrovane (on our business park there was no room outside that I could use anyway). Money well spent, it made everyone much happier ! Hydrovanes just kind of hum, there's no loud "compressor" noise. Pipework was a doddle as well.

 

[ColeyS1]

If it got relocated outside it would annoy the neighbour's.

Sent from my SM-G960F using Tapatalk

 

[rafezetter]

Is there any reason why you can't make a wider enclosure in the space above the spraying booth?

Make a substantial frame bolted to the wall, if the spray booth can't take the weight, then build a proper baffled enclosure - plenty of information on hmemade version with various baffle designs and such, just remember to add an extention connector to the outlet with it's own isolating value so you can access it at ground level (again mounted to the wall?) and allow a gap underneath the compressor to access the drain, so sit the compressor on some sort of sub floor inside the enclosure.

That's what i'd do.

I'd also forget "soundproof" - best you'll get is sound reduction unless you spend quite a lot of time and money with an enclosure layered with different materials designed specifially to the task, which aren't cheap.

Just go for a rockwool box basically, not too small, give the compressor room to breath and put the baffled ports for intake and exhaust above the pumps, which MUST NOT be a straight line port or you'll be wasting your time and money.

just remember one rule - for sound, a gap of 10% can emit 50% of the sound, so close off as much as you can including where power goes in and pipes come out.

Something else you can do is mount "sound catcher" baffles nearby- essentially a wood frame with cloth over it like a canvas, and rockwool attached inside the frame - this will catch and disperse the reflected sound waves bouncing off your concrete walls, and especially off your tin roof that is aggravating the situation quite a lot.

plenty of into on those too - larger the better.

Same principle as why a room without carpet echos more than one with.

infact...... you might want to try first to just make a couple of those and stand one in front of the compressor and one above it to reduce the sound waves coming out of that alcove the compressor is in, but make them so the edges of the frames meet the walls and each other - or again sound will escape from the gaps.

 

[toolsntat]

Have you tried simply introducing some baffles?
I've heard of some garden fence designs that capture the vibrations and absorb the sounds in angular protrusions.
At this point I have in my mind a flush door with the (eggbox) core exposed.
Perhaps you need not close it off completely but just stand/position the baffles to create an interference for the sound waves.
Cheers Andy

 

[rafezetter]

Have you tried simply introducing some baffles?
I've heard of some garden fence designs that capture the vibrations and absorb the sounds in angular protrusions.
At this point I have in my mind a flush door with the (eggbox) core exposed.
Perhaps you need not close it off completely but just stand/position the baffles to create an interference for the sound waves.
Cheers Andy

There's all sorts of ways this can be done - some easy, some not. Theres a famous sculpture of a set of steel pipes stood vertically, a person standing on one side CANNOT HEAR a person talking on the other, because it's been designed to throw off any direct sound waves; this is what I was talking about to make sure any inlet port is baffled and not a straight run.

Like I said plenty of websites and info on how to make an enclosure with very low sound wave propagation.

 

[ColeyS1]

Is there any reason why you can't make a wider enclosure in the space above the spraying booth?

Make a substantial frame bolted to the wall, if the spray booth can't take the weight, then build a proper baffled enclosure - plenty of information on hmemade version with various baffle designs and such, just remember to add an extention connector to the outlet with it's own isolating value so you can access it at ground level (again mounted to the wall?) and allow a gap underneath the compressor to access the drain, so sit the compressor on some sort of sub floor inside the enclosure.

That's what i'd do.

I'd also forget "soundproof" - best you'll get is sound reduction unless you spend quite a lot of time and money with an enclosure layered with different materials designed specifially to the task, which aren't cheap.

Just go for a rockwool box basically, not too small, give the compressor room to breath and put the baffled ports for intake and exhaust above the pumps, which MUST NOT be a straight line port or you'll be wasting your time and money.

just remember one rule - for sound, a gap of 10% can emit 50% of the sound, so close off as much as you can including where power goes in and pipes come out.

Something else you can do is mount "sound catcher" baffles nearby- essentially a wood frame with cloth over it like a canvas, and rockwool attached inside the frame - this will catch and disperse the reflected sound waves bouncing off your concrete walls, and especially off your tin roof that is aggravating the situation quite a lot.

plenty of into on those too - larger the better.

Same principle as why a room without carpet echos more than one with.

infact...... you might want to try first to just make a couple of those and stand one in front of the compressor and one above it to reduce the sound waves coming out of that alcove the compressor is in, but make them so the edges of the frames meet the walls and each other - or again sound will escape from the gaps.

Moving the compressor over the top of the booth is certainly an option. It would take a bit of time to do it. I was hoping I could perhaps chuck £150 ish at buying some soundproofing materials. I've plenty of wood sheets to build an enclosure.
I'll look into the sound catcher baffles you mention- I've not heard of them before. Thanks

Sent from my SM-G960F using Tapatalk

 

[ColeyS1]

Have you tried simply introducing some baffles?
I've heard of some garden fence designs that capture the vibrations and absorb the sounds in angular protrusions.
At this point I have in my mind a flush door with the (eggbox) core exposed.
Perhaps you need not close it off completely but just stand/position the baffles to create an interference for the sound waves.
Cheers Andy

The baffles will be the first thing I research. Thanks guys.

Sent from my SM-G960F using Tapatalk

 

[topchippytom]

can you just box it in and vent it

 

[rafezetter]

can you just box it in and vent it

Well yes, but as I said in my post, if it's just a basic box with holes, that will be pretty ineffective and will actually compound the issue, as the sound waves bouncing around inside the box will turn the walls of the box into vibration amplifiers, and the holes will let out 50% of the sound.

Sound PROOFING is quite a complex science; vibrations, sympathetic oscillations, physical conduction from the object and between the walls, different materials to combat each frequency group etc etc, each requiring a different solution, and no single approach will get the job done, while sound reduction is more easily (relatively) attainable as long as you follow some basic principles.

I made a wooden computer "forever" case, big enough to house whatever I want to throw in there even multiple GPU's, with just such principles applied; each side, top and bottom is physically isolated from the others via rubber gaskets (no vibrational conduction), the inlets and exhaust ports for the 200mm fans are baffled and lined with foam and carpet (for different frequencies), the walls are made from concrete board and again lined (density for low frequncies, lined for higher frequencies), and all the wire entries go through another isolation system.

It's silent. Even when all the 8 fans are going full throttle.

I did this as a "test" for a compressor enclosure as it drives me (and the other tenantss) nuts too - just haven't got around to it (and I use it less than I did)

 

[minilathe22]

I did see a video of someone who got an old car engine air filter unit, and replaced the small inlet filter on their air compressor. I assume the car air filter being oversized means the air is moving very slowly, and therefore quietly. Made a big difference to the induction noise! Although you would also need to box the whole unit in as suggested by others.

 

[RobinBHM]

A cheap solution is to put some dense material + insulation on the spraybooth outer face -its a netal sheet and eill be transmitting the noise like a drum.

You could booard the front and and angled roof -much higher up and deflect the noise to the rear wall

 

[ColeyS1]

A cheap solution is to put some dense material + insulation on the spraybooth outer face -its a netal sheet and eill be transmitting the noise like a drum.

You could booard the front and and angled roof -much higher up and deflect the noise to the rear wall

I reckon I've got about 30mm between compressor and spraybooth face. It is starting to seem that the easiest way might be to relocate it and make a box/baffle arrangement. Proper soundproofing foam certainly isn't cheap...... Do you think a box lined with-

Would make much difference?
Would 'dense material' include 25mm mdf? P
The worst part about it is doing alot of work and spending alot of money without really knowing if it'll make much difference.

Sent from my SM-G960F using Tapatalk

 

[rafezetter]

In answer to your question Coley - yes those *ahem* "sound proofing" foam sheets will make a difference, by dispersing the energy of the sound waves.

If you think of sound waves as physical shock waves, that give you that *thump* in the chest, open cell foams and stuff like rockwool break up the wave into smaller waves - it cannot actually negate them as the first law of thermodynamics proves, it just breaks them up so the kinetic energy is more dispersed, this in turn lowers the magnitude of power, and in turn reduces the decibels.

But - this is less effective on lower frequencies - where density is more effective.....

But - it's not just density - RIGIDITY plays a factor ... lol I did say it was complicated stuff. Dense but "flexible" (in relative terms) will just turn the material being hit by the soundwaves into a vibrating soundingboard, ala your tin roof (I think I mentioned that), and dense but hard will just bounce them off entirely, like your concrete walls.

I'm not 100% certain but I'm reasonably sure that what's happening in your shop is the sound is being concentrated in the gap, by bouncing off the concrete walls and firing those waves directly at your tin roof, in one direction and another concrete wall (I assume) in the other. Did you ever read about those sound system "speakers" that were essentially just a pair of drivers (no cones) and cables and you attached them to a window or glass table? Same principle.

Next time your are there, take a shoe off and put your foot next to the compressor when it's on, if you can feel the vibrations, it's also transmitting sound through your concrete floor, which going by the feeble rubber pads on the feet I'm certain it is - they need to be AT LEAST rubber doorstop thickness, 40mm+ and not hard rubber but something softer.

Going back to the MDF question, I did have a table of materials that showed the relative densities vs thickness etc etc but can't find it atm - it did make me choose cementboard, the stuff tilers use as a backer in wet rooms, over MDF despite the added cost because iirc it gave a bigger sound reduction per £ spent than MDF.

Compressor sound is also a lower frequency, which density is the better factor for material to use to counteract it.

Here's one page I used that might help - it lays out the basic principles of material types and what they do to sound waves.

https://www.phelpsgaskets.com/blog/mate ... -dampening

Edit - re-reading it, the bit about CORK, sounds like the perfect solution, until you note that it turns sound energy into VIBRATIONAL energy, and we're back to the soundingboard problem - so you need an additional solution to combat that...

and so it goes on

I guess at the end of the day you need to decide how far you want the sound reduced...

nothing 90+ dB (typical compressor dB output)
Take the edge off - 80 dB
Annoying but tolerable hum you can hear even with the radio on - 70dB
Discernable hum if you concentrate with the radio on - 60dB
Background hum that can be ignored in a quiet room - 50dB

https://www.alarmgrid.com/faq/how-loud- ... ity-system

each 10dB drop will require an additional material or method.

I've probably re-stated a few things I've said before, but hope that gives you enough info to decide

 

[Rich C]

You should be looking at mass loaded vinyl. It's designed for preventing machine noise transmission and is much thinner than those foam sheets so easier to fit into the space.
If you wanted to apply it directly to the walls around the compressor though, you'd be best off using fgoam backed MLV (or a sheet of foam between it and the wall) to avoid it just transmitting vibration to the wall.

 

[thetyreman]

there are two basic types of noise, vibrational or structural and airborne noise, I would also use a layer of mass loaded vinyl, for example Tecsound S100 is as dense as lead, sandwitched between two layers of say MDF of different thicknesses or plywood, this is how I remember a pro studio I once worked in was constructed, but they went a step further than that and removed all flanking paths of noise and also built a room within a room, even 30-50Hz frequencies weren't coming into that room, it was amazing and very quiet, the best book to read on the subject is the master handbook of acoustics if you want to get into serious detail, which was required reading when I studied music at uni.