Noise Insulation for shop compressor?

[Doofy]

So I looked into mine a bit more. Here it is with a look at the air intake. There is a pleated paper element like an old style car engine air filter and a tube sticking up inside the housing for some reason. This doesn't look far off what the "mufflers" that you see from a web search show.

View attachment 667695

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Then I used an app to measure the sound level via my phone. It averaged out around 68.5 dB at ~3'. But yet it seems louder than that to me. I'm not sure if this thing is at all calibrated, so maybe I will check it vs a sound meter we have at work. But if that is correct, then you guys with the 80+dB compressors must be in a world of hurt!

I'd borrow the meter from your work and retest. Phone apps are not very accurate as far as dB readings are concerned. I'd bet you are 80-85dB at least. 68dB is not much louder than normal conversation.

 

[dragoneggs]

I'd borrow the meter from your work and retest. Phone apps are not very accurate as far as dB readings are concerned. I'd bet you are 80-85dB at least. 68dB is not much louder than normal conversation.

Agreed. I have had mixed success with free phone Apps. I settled on and use the iPhone app called NIOSH Sound Level Meter with good success. Just went out to compare it to my quality decibel meter and they were within +/-2dB with the NIOSH fluctuating around the steady reading of 86dB on my dB meter.

 

[MossRoad]

that's the same one i use. good to establish a baseline and then look for changes.

 

[Doofy]

Agreed. I have had mixed success with free phone Apps. I settled on and use the iPhone app called NIOSH Sound Level Meter with good success. Just went out to compare it to my quality decibel meter and they were within +/-2dB with the NIOSH fluctuating around the steady reading of 86dB on my dB meter.

NIOSH is the one I am using also. 89dB at 2' and 85dB at 6'. An intake silencer should be here tomorrow but I'm not holding my breath for any great improvement in the noise level. It is just a loud and noisy beast.

 

[dstig1]

I can't find it in the Google app store. 10 trillion sound meters but I don't see that specific one. Granted i could not scroll through 10 trillion lines, but went down a couple hundred at least. I love how everyone tries to scam the search functions so you can't find the one you really want. Oh - i looked it up on the NIOSH website and it appears toe be Apple only. Figgers.

My app has a rough calibration setting (a simple offset plus or minus from what it shows) but with both meters in hand i should be able to make it more useful with that.

 

[Doofy]

NIOSH iPhone app is the same. You can calibrate it some. Look at a dB chart of normal readings and calibrate to get close to one of those. It will be close enough for testing.

 

[downsizingnow48]

Out of curiosity I found my db meter and measured the three compressors I have at 15 ft. That is the closest I would be to the machine in use, usually further than that. The 35 year old Emglo framing compressor (1.5 hp) was 73db. The 5 year old Ingersol Rand (2hp) was 75 db. The 1 year old California Air Tools (1hp) was 53 db.

 

[Doofy]

Out of curiosity I found my db meter and measured the three compressors I have at 15 ft. That is the closest I would be to the machine in use, usually further than that. The 35 year old Emglo framing compressor (1.5 hp) was 73db. The 5 year old Ingersol Rand (2hp) was 75 db. The 1 year old California Air Tools (1hp) was 53 db.

Not to shabby. I hope to get mine down to at least 75dB. That would be an improvement.

 

[TMGT]

The specs on my Quincy 20hp screw compressor is 70dba at 1meter, it's mounted high enough that you really don't even notice it.
I couldn't find any specs for the 7.5hp Ingersoll Rand reciprocating compressor, but its pretty loud/obnoxious.

Can't wait to finish hooking up the Quincy so the Ingersoll can go to backup duty!

 

[dragoneggs]

I guess those California Air Tool compressors are maybe amazingly quiet, eh? They better be as a 4hp 60gal is $3500 vs. my Husky 3.7hp 60gal at $500.

 

[downsizingnow48]

I see it at $1400 at aircompressorsdirect. The more expensive version has a dryer built in.

 

[dragoneggs]

I see it at $1400 at aircompressorsdirect. The more expensive version has a dryer built in.

Aha thanks Pat... I was not interested enough to research what the high dollar price was getting you. That makes sense. If I was doing it over again, I would probably consider the $1400 ultra quiet machine but unless I could get $500 for mine, it isn't in the cards.

 

[dragoneggs]

Adding those silencers many times will drop sound level 3dB and that amounts to HALVING the noise level.

Understanding the 3dB rule for controlling workplace noise levels

Okay a bit deeper dive into my Husky 3.7hp 60gal compressor...

Pulleys
Motor = 4in
Compressor 12in
Centers 10in

Motor = 3450rpm
Compressor = 1150rpm

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Compressor is mounted on double sheet of 3/4in plywood and HF 3in polyurethane casters.

Noise (pretty much against wall)

88dB @3ft
85dB @6ft

Noise (compressor 3ft from wall and rotated 90deg so front/back not facing wall)

86dB @3ft
83dB @6ft

Compressor intake on top with filter on side. 2 intake ports about 1.25in by .5in (a little smaller but couldn't fit my calipers)

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Well my little redneck experiment didn't yield much but I dropped the sound a bit by adding some sound proofing material on the adjacent cabinet sides and 'roof' and a wool throw rug hung on the back (drywall) wall. Also wrapped a HF moving blanket around the tank.



And the results...

Noise (pretty much against wall w/o any insulation)

88dB @3ft
85dB @6ft

Noise (pretty much against wall w/ some back and side insulation along with wrapping the tank with HF moving blanket)

87dB @3ft
84dB @6ft

Does seem just a little muted and not as high pitched (a little easier on the ears). Didn't cost me much. Not as quiet as pulling away from the wall but a duller sound. It's better.

Now I'm thinking of a heavy blanket hanging between earshot and the compressor. Stay tuned.

 

[MossRoad]

...
Now I'm thinking of a heavy blanket hanging between earshot and the compressor. Stay tuned.

That's what I thought you were going to do when you mentioned a blanket or moving quilt. Temp tacking it up in front of it and see what it muffles.

 

[dragoneggs]

That's what I thought you were going to do when you mentioned a blanket or moving quilt. Temp tacking it up in front of it and see what it muffles.

Tacked up a cheap HF moving blanket to serve as a curtain so now enclosed on all but one side left open for air/ventilation. A face on view and a view 'behind the curtain'.



Noise from front (w/ some back and side insulation along with wrapping the tank with HF moving blanket)

87dB @3ft
84dB @6ft

Noise from front (w/ added hanging blanket partially enclosed)

84dB @3ft
82dB @6ft

Some definite muffling going on. The frequency seems a less piercing as well. Still louder than desired but this is encouraging. Now I am on a pursuit for a heavier/thicker blanket that could be a short term solution. It isn't ideal from an ergonomics standpoint though. I can't easily see my on/off and pressure gauges and it is kinda in the way of things.

Have dropped the levels by 4dB so far but I am running out 'in place' ideas other than a heavier curtain. I could move it to the far corner of the shop but that would be a real pain to move other shelving and reroute the plumbing.

 

[Doofy]

Tacked up a cheap HF moving blanket to serve as a curtain so now enclosed on all but one side left open for air/ventilation. A face on view and a view 'behind the curtain'.

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Noise from front (w/ some back and side insulation along with wrapping the tank with HF moving blanket)

87dB @3ft
84dB @6ft

Noise from front (w/ added hanging blanket partially enclosed)

84dB @3ft
82dB @6ft

Some definite muffling going on. The frequency seems a less piercing as well. Still louder than desired but this is encouraging. Now I am on a pursuit for a heavier/thicker blanket that could be a short term solution. It isn't ideal from an ergonomics standpoint though. I can't easily see my on/off and pressure gauges and it is kinda in the way of things.

Have dropped the levels by 4dB so far but I am running out 'in place' ideas other than a heavier curtain. I could move it to the far corner of the shop but that would be a real pain to move other shelving and reroute the plumbing.

I see egg carton shaped acoustical sound deadening foam on Amazon so if your moving blanket helped then perhaps the foam would really work well. I have a heavyweight moving blanket to try also.

 

[dragoneggs]

I see egg carton shaped acoustical sound deadening foam on Amazon so if your moving blanket helped then perhaps the foam would really work well. I have a heavyweight moving blanket to try also.

I have two concerns with the egg crate foam.

1. Very flammable
2. Dust trap

I think heavy wool/cotton is probably better than foam for these reasons but more expensive too.

 

[Doofy]

Perhaps they make fire resistant acoustical foam? I would box the compressor in, line box with foam and perhaps duct in a little outside air for cooling. It all depends on how the heavy moving blanket works. I want to get the sound down to 75-76dB or close.

 

[dragoneggs]

Okay, for chits and giggles, I tacked up a second HF blanket, this time closing off the open end and wrapping it most of the way around giving me a double wall facing the shop. Now the only fresh air will pull and escape from the 24in gap at the bottom.

Noise from front (w/ added hanging blanket partially enclosed)

84dB @3ft
82dB @6ft

Noise from front (w/ added 2nd hanging blanket and fully enclosed except for bottom)

81dB @3ft
79dB @6ft

A further 3dB drop! :dance1: For a total loss of 7dB. I think that is pretty good.

Again, noticeable and even more pleasant sounding (muffled) if that makes sense. The higher pitches are welcomely absent.

Now my concern is the temperature of the compressor head. I would like to know if with repeated cycling, the temp is much hotter than the default. I should have measured that before I got started with this MacGyver project.

 

[MossRoad]

Just for a couple minutes, make it all the way to the floor, so it's enclosed on all 4 sides, the top, and the bottom and take some quick measurements. It would be interesting to see how much sound escapes that bottom. I'm happy to hear the higher pitches are noticeable less.