Building the You Tube compressor intake silencer--read before you build!

[Beerhippie]

I was looking to buy an intake air silencer/muffler for our monster recip DeVilBliss back-up compressor. Sound levels in the shop when it's running vary from the high 90s to the low 80s. I hate having to wear ear protection over my ear protection when sitting at my desk.

Several of the replies I got to my query here re: best bang for the buck intake silencer/muffler were that there were several builds on You Tube that I should check out. I did. Simple enough, and I have almost all the parts on hand.



2 gal. bucket w/lid; a pile of left-over rockwool.



The black iron fittings and 1/4-20 X 1" screws and nuts were all I needed to buy. The flanges were marked down from $11 to $4, so lucked out there--and bought the last ones. Total of about $15. That's most of the tools I'll need--but something always comes up....

I cut the 1 1/4" holes in the bucket and lid with the ho' saw--then needed to pare off that raised circle. Sharp chisels are a joy to use.



Use the flange for a drilling guide:



Secure a flange inside and out with the 1/4-20 screws:



I didn't use any sealant, as the polyethylene bucket itself should make for a dandy gasket sandwiched between the two flanges. I did use red Loctite as this thing will be seeing lots of vibration.

Screw a short 1" NPT ****** to the bottom flanges:



Now it's time to make the central tube from the SS hardware cloth. Why SS hardware cloth? It was the first piece I laid eyes on.



I cut the cloth to the depth of the bucket and I'll fit it by trial and error once it's a tube. Easier than trying to measure and math the depth of the flanges.

I used a piece of 1 1/4" conduit for a mandrel to make the cloth into a tube.



After a few trial fittings,



8 1/4 was the right length--for the flanges I used.

Now you can see why I put flanges on the inside:



The boss of the flange makes centering the tube easy and keeps it there.

Now for the glass-pack:



I fluffed the rockwool up until the tube was buried.



One DIY glass-pack muffler, no internal restriction.

Now, here's where I diverge from the You Tube DIYers: I have an OSHA-approved sound pressure meter. All the videos I watched complained that the auto sound level on their cameras made it impossible to demonstrate the before/after sound level, but claimed it was significant.

A snap-shot of the sound level at my desk before installing the muffler:



It varied from about 84 to near 90 over a minute or two. I could set the meter for a longer-term average, but that would require reading the manual again.

Closer to the beast:



That would go up to almost 100 dB.

Muffler installed:



Ain't that just purty as all get-out?

Sound pressure level at my desk after installing the muffler:



Abso-f*&kin-lutely no difference. Sound levels around the shop are the same.

Now I'm thinking I need a real muffler--one with baffles. Which is quieter--a glass-pack muffler or a baffled muffler? I wonder if there's one in the metal pile at the dump that isn't blown out?

 

[b-dog]

Dang, sorry you went to all that trouble for nothing! I had about the same results with my old Craftsman Oil-less compressor when I added a DIY muffler - though mine wasn't as nice as you built. I ended up building a box around the compressor but was still obnoxious. My old compressor finally died and I upgraded to a compressor with a much slower spinning pump (660 rpm) and that helped a lot. Build a shack and just put it outside...?

 

[Beerhippie]

Dang, sorry you went to all that trouble for nothing! I had about the same results with my old Craftsman Oil-less compressor when I added a DIY muffler - though mine wasn't as nice as you built. I ended up building a box around the compressor but was still obnoxious. My old compressor finally died and I upgraded to a compressor with a much slower spinning pump (660 rpm) and that helped a lot. Build a shack and just put it outside...?

It would have to be a heated and insulated shack. It would also be one hell of a long airline and electrical run to and from where we'd have any room to build a shack.

One of my reasons for posting this was to save anyone else the time and expense of building one of these.

If I had a CNC plasma cutter, I'd consider making my own low-impedance baffled muffler (but there is some f'in math and sound engineering involved in that). But I don't have a CNC plasma cutter and the folks around here who do are mighty proud of their time.

Maybe It's just time to lay out the $100 or so for the real Solberg?

 

[OccupantRJ]

I have thought of trying a universal tractor muffler or small car muffler. Thanks for your test efforts.

 

[B_Bimmer]

It looked so nice, I was sad when I got to the results.

 

[Beerhippie]

I have thought of trying a universal tractor muffler or small car muffler. Thanks for your test efforts.

Please do! Let us know how that works out.

I might just be willin' to loan you the sound meter for a few days to test it out--subjective tests are, obviously, worthless after you spend time and money on something like this.

I'm just having some difficulty believing that the Solberg works any better, given its size. But maybe its just a better design?

 

[Beerhippie]

It looked so nice, I was sad when I got to the results.

Thanks. Me too.

At least I didn't waste my time making a nice housing by welding up some SS tubing, like I was thinkin' of doing.

 

[kaymccampbell]

I ducted the intakes of mine though vacuum hoses into a big dead space over the service core of the building. Took 10db right off the top.

 

[Wrench97]

In one shop we build a insulated room around the compressor and ran the air intake out the outside wall.
By room it was 3 walls and a ceiling that we moved with a forklift when we needed access to the compressor.

 

[dscheidt]

I saw a video about some other noise reducing gadget. I figured it was fake when the guy didn’t use his phone to show the sound levels.

(Phone app found meters aren’t great, but they not bad, and even if absolute numbers are wrong, the trend is pretty good.).

 

[GeoBruin]

I bought a Solberg and got similar results. That is, no results. I ultimately needed up building a compressor shed outside my shop.

 

[alfadan]

Move your desk!

 

[Beerhippie]

I bought a Solberg and got similar results. That is, no results. I ultimately needed up building a compressor shed outside my shop.

Thanks for saving me another hundred bucks!

Move your desk!

But... it's COLD outside!

 

[u3b3rg33k]

these work very well:

 

[alfadan]

Thanks for saving me another hundred bucks!

But... it's COLD outside!

Cold and quiet!

I also question whether intake air being sucked in through a mineral wool based medium is good, long term, for the pump.

 

[GeoBruin]

Thanks for saving me another hundred bucks!

Like you, I invested some time in the attempt as I had to fab an adapter to be able to thread the Solberg filter on my intake. Imagine my disappointment.

In their defense, while the one I bought is marketed as a "filter silencer", it's really just a filter. They sell dedicated inline "silencers", but these are not them.

Solberg Filter Silencer, 3/4 In MNPT, 25 CFM Max FS-10-075 | Zoro https://share.google/4C5u5QuQY12Zi9ttS

 

[Firebrick43]

I have thought of trying a universal tractor muffler or small car muffler. Thanks for your test efforts.

Universal tractor mufflers are about the crappiest mufflers there are. They are straight thru designs and lousy.

Use a small car muffler that that has 3 pipes in it.

What really works is helmholtz resonators. They are not hard to build if you know the frequency/speed of the pump

 

[Beerhippie]

Like you, I invested some time in the attempt as I had to fab an adapter to be able to thread the Solberg filter on my intake. Imagine my disappointment.

In their defense, while the one I bought is marketed as a "filter silencer", it's really just a filter. They sell dedicated inline "silencers", but these are not them.

Solberg Filter Silencer, 3/4 In MNPT, 25 CFM Max FS-10-075 | Zoro https://share.google/4C5u5QuQY12Zi9ttS

Thanks again.

The Solberg I was looking at is the silencer that goes between the filter housing and the intake. Looks like a tiny muffler.

 

[Beerhippie]

these work very well:

Yeah, and the black box costs around $700 alone.

What's with the dual air intakes on those comps? I'm used to 2 cylinder pumps being two-stage.

 

[Skyman]

An acoustic foam-lined plywood box dropped over the beast, with enough louvered openings to admit intake air, and possibly a small cooling fan on the far side - might that knock the noise down acceptably without compromising the performance or longevity of the machine?

 

[Citation]

Beerhippie,
Just a few thoughts. First, if the rest of your compressor is noisy, you can only do so much. Consider holding your hand over the intake (without the muffler attached). How much quieter does it get? That's basically all you can achieve with an intake muffler. The rest of the noise is other parts of the system.

Second, in my experience on of the best ways to reduce the noise is something like rubber hose. Notice those quiet boxes use a rubber hose as part of the intake. That was a trick I learned form California Air Tools. In a lot of pictures you will notice what looks like a short bit of "fish aquarium" tubing sticking out of the air filter inlet. That stupid bit of tubing really makes a difference. I learned that when I fired up my CAT compressor sans any air filter. It was much louder than I recalled. Then I added the filter... that helped. Then I added that stupid little tube... damn, that helped too!

Here is what I've done on my non-CAT compressor and it works well. Mine is a belt drive Campbell Hausfeld thing.
I've got an intake filter housing that looks like this thing

https://www.amazon.com/Element-VH901700AV-Campbell-Hausfeld-MP333200SJ?tag=atomicindus08-20

I've added a bit over a foot of rubber hose on the inlet side of things. That's it. The rubber hose really helps.
My system is basically this thumbnail minus the can at the end. Just the filter housing and rubber hose.

What would I try in your position? Try running about 2-3' of say radiator hose between the compressor inlet and your bucket thing (have the filter in there somewhere too).

Again, that should help the inlet a lot. It doesn't help if the other parts of your system are rattling.

 

[engineer2]

I used a small muffler I found online. Measured before and after with my dB meter as you did. Similar results: not much difference.
Found most of the noise is from the mechanical workings of the compressor pump.

 

[Beerhippie]

Beerhippie,
Just a few thoughts. First, if the rest of your compressor is noisy, you can only do so much. Consider holding your hand over the intake (without the muffler attached). How much quieter does it get? That's basically all you can achieve with an intake muffler. The rest of the noise is other parts of the system.

Second, in my experience on of the best ways to reduce the noise is something like rubber hose. Notice those quiet boxes use a rubber hose as part of the intake. That was a trick I learned form California Air Tools. In a lot of pictures you will notice what looks like a short bit of "fish aquarium" tubing sticking out of the air filter inlet. That stupid bit of tubing really makes a difference. I learned that when I fired up my CAT compressor sans any air filter. It was much louder than I recalled. Then I added the filter... that helped. Then I added that stupid little tube... damn, that helped too!

Here is what I've done on my non-CAT compressor and it works well. Mine is a belt drive Campbell Hausfeld thing.
I've got an intake filter housing that looks like this thing

https://www.amazon.com/Element-VH901700AV-Campbell-Hausfeld-MP333200SJ?tag=atomicindus08-20

I've added a bit over a foot of rubber hose on the inlet side of things. That's it. The rubber hose really helps.
My system is basically this thumbnail minus the can at the end. Just the filter housing and rubber hose.

What would I try in your position? Try running about 2-3' of say radiator hose between the compressor inlet and your bucket thing (have the filter in there somewhere too).

Again, that should help the inlet a lot. It doesn't help if the other parts of your system are rattling.

I did try that--but, being older and wiser, I had a coworker do it for me. It only took about half a day to get most of him cleaned out of our air system.

We do miss that guy... great guy, laugh a minute... kinda gullible, 'though, if you know what I mean.

 

[Citation]

I did try that--but, being older and wiser, I had a coworker do it for me. It only took about half a day to get most of him cleaned out of our air system.

We do miss that guy... great guy, laugh a minute... kinda gullible, 'though, if you know what I mean.

You can do it with a block of rubber. It does depend on the size of the air intake but with my pump it's well under 1"^2 so no issues with getting sucked in. You could also just put a pipe cap over the intake if you are that worried about it.

 

[DavidR8]

My compressor was loud as hell. I built a lean-to on the side of my shop. Insulated the heck out of it with Rockwool and now I can barely hear it when it kicks in. Best thing I ever did.

 

[Cheep]

I built a giant box over mine in the corner of the shop, 60 gal 5 hp Devilbis, not able to stand the damn thing before the box, now, tolerable.

 

[mm08822]

I was looking to buy an intake air silencer/muffler for our monster recip DeVilBliss back-up compressor. Sound levels in the shop when it's running vary from the high 90s to the low 80s. I hate having to wear ear protection over my ear protection when sitting at my desk.

Several of the replies I got to my query here re: best bang for the buck intake silencer/muffler were that there were several builds on You Tube that I should check out. I did. Simple enough, and I have almost all the parts on hand.



2 gal. bucket w/lid; a pile of left-over rockwool.



The black iron fittings and 1/4-20 X 1" screws and nuts were all I needed to buy. The flanges were marked down from $11 to $4, so lucked out there--and bought the last ones. Total of about $15. That's most of the tools I'll need--but something always comes up....

I cut the 1 1/4" holes in the bucket and lid with the ho' saw--then needed to pare off that raised circle. Sharp chisels are a joy to use.



Use the flange for a drilling guide:



Secure a flange inside and out with the 1/4-20 screws:



I didn't use any sealant, as the polyethylene bucket itself should make for a dandy gasket sandwiched between the two flanges. I did use red Loctite as this thing will be seeing lots of vibration.

Screw a short 1" NPT ****** to the bottom flanges:



Now it's time to make the central tube from the SS hardware cloth. Why SS hardware cloth? It was the first piece I laid eyes on.



I cut the cloth to the depth of the bucket and I'll fit it by trial and error once it's a tube. Easier than trying to measure and math the depth of the flanges.

I used a piece of 1 1/4" conduit for a mandrel to make the cloth into a tube.



After a few trial fittings,



8 1/4 was the right length--for the flanges I used.

Now you can see why I put flanges on the inside:



The boss of the flange makes centering the tube easy and keeps it there.

Now for the glass-pack:



I fluffed the rockwool up until the tube was buried.



One DIY glass-pack muffler, no internal restriction.

Now, here's where I diverge from the You Tube DIYers: I have an OSHA-approved sound pressure meter. All the videos I watched complained that the auto sound level on their cameras made it impossible to demonstrate the before/after sound level, but claimed it was significant.

A snap-shot of the sound level at my desk before installing the muffler:



It varied from about 84 to near 90 over a minute or two. I could set the meter for a longer-term average, but that would require reading the manual again.

Closer to the beast:



That would go up to almost 100 dB.

Muffler installed:



Ain't that just purty as all get-out?

Sound pressure level at my desk after installing the muffler:



Abso-f*&kin-lutely no difference. Sound levels around the shop are the same.

Now I'm thinking I need a real muffler--one with baffles. Which is quieter--a glass-pack muffler or a baffled muffler? I wonder if there's one in the metal pile at the dump that isn't blown out?

Since you have already made something, try and modify it. Nothing to loose, just maybe some noise.
Try this:
Remove the wool,
Drill multiple rows of 1/2" in the wall of bucket,
Shorten the inner basket 2",
Repack the wool,
Add wool over the basket and next to lid,
Attach cover.

If it works you will need to monitor air temp, wool compressing against while running, and wool blinding over with dust at the holes.

I agree others that the casting and it's cooling fins are good sound transmitters. Even the tank and floor it sits on.

 

[Wrench-Polisher]

A muffler with a threaded pipe ends eh? Better hide your dogs.

 

[txvwnut]

Try extending the run between the filter and the muffler, maybe a couple feet and test again. You might be getting noise reversion out of the filter.

 

[GeoBruin]

I guess I have more to add. This was my original shed build. I had already built a shed so I wanted this one to match, and I could use the extra storage. So I built it larger than needed but I built a "trap door" to isolate the compressor. I added an air inlet being the flywheel, plus a soffit vent in the front and a solar attic fan on the top. I lined the interior with acoustic foam and the door with an acoustic wall panel.

 

[dr_clyde]

I solved this problem by getting a screw compressor.

Seriously though, the only real way I've found to reduce compressor noise is to isolate the machine in a room or cabinet, then line the room with sound deadening material.

Even a simple plywood box lined with acoustic foam would do wonders. Angling the air intake of the box through a series of corners that had foam in it allows the box to breathe and keep the compressor cool while not allowing noise out into the space. An exhaust fan mounted to the box pointed away from the area that pulls air through the system keeps everything from overheating.

We had to make an insulated sound proof box for a generator at one point, and it was a good exercise in geometry, vibration isolation, exhaust and intake muffling, as well as heat management. It worked very well, but wasn't cheap.

Remember, sound waves will lose energy when they are reflected off surfaces, and will cancel if they can crash into each other at the right angles. Having absorbent surfaces that are angled to reflect sound back onto itself will do more than you think.

 

[aka Larry]

Abso-f*&kin-lutely no difference. Sound levels around the shop are the same.

Thanks for taking the time to post your failure so someone else could learn from your efforts.

I went down a similar rabbit hole with my compressor. I toyed with the idea of plumbing the intake to the exterior of my shop, but wondered how my neighbors would like it. I ended up with a Solberg, which was (marginally) better than the OE filter, so I decided that if one was good, two Solberg's would be better. Spoiler alert, it was not, and a complete waste of money.

I've considered boxing mine in also, but it's not running all that often so I haven't bothered.

 

[larry_g]

https://www.reddit.com/r/CarAV/comments/1glcpls
At our plant we had to add a small compressor to one of our machines. To reduce the noise an engineer designed a labyrinth sound enclosure that worked really well. Basically removed all the noise. The link above is for audio the box was similar. He explained to me that sound travels in a straight line so having the air to the compressor go threw the labyrinth the air flowed freely and the sound did not. The inside of the box and all surfaces were lined with sound attenuating foam.

lg
no neat sig line

 

[Citation]

https://www.reddit.com/r/CarAV/comments/1glcpls
At our plant we had to add a small compressor to one of our machines. To reduce the noise an engineer designed a labyrinth sound enclosure that worked really well. Basically removed all the noise. The link above is for audio the box was similar. He explained to me that sound travels in a straight line so having the air to the compressor go threw the labyrinth the air flowed freely and the sound did not. The inside of the box and all surfaces were lined with sound attenuating foam.

lg
no neat sig line

This is why I like the rubber hose and suspect it plays a not insignificant part in the Eaton setup's noise reduction. Get a few feet of hose, make a roll and try it.

 

[Citation]

You can do it with a block of rubber. It does depend on the size of the air intake but with my pump it's well under 1"^2 so no issues with getting sucked in. You could also just put a pipe cap over the intake if you are that worried about it.

Just figured I would run some quick math on this...

My compressor is no more that a 1/2” inlet. With no more than 14.7 psi of pressure acting over 1/2” diameter opening. That's less than 1.5lb of force pushing my hand into the intake. But what if you have a 1" ID pipe? Well that's 5.8lb. Going to 1.5" ID is 13lb. If your intake is 2"ID then your at 23lb. Basically if you have a less than 1" ID intake getting "sucked in" is a non issue.

 

[GeoBruin]

https://www.reddit.com/r/CarAV/comments/1glcpls
At our plant we had to add a small compressor to one of our machines. To reduce the noise an engineer designed a labyrinth sound enclosure that worked really well. Basically removed all the noise. The link above is for audio the box was similar. He explained to me that sound travels in a straight line so having the air to the compressor go threw the labyrinth the air flowed freely and the sound did not. The inside of the box and all surfaces were lined with sound attenuating foam.

lg
no neat sig line

I suspect this is similar to what is hanging on the side of the Eaton silent compressors.

 

[Beerhippie]

I solved this problem by getting a screw compressor.

....

We did, too. The recip is our original and is supposed to be back-up only. However, the 5 hp IR screw comp is barely enough to keep up with the canning line if everything is tight. We use air for controls all over the brewery, so there are lots of little leaks to chase down continuously. I found and fixed a fairly major one yesterday, so maybe we can can without the beast running.

Just figured I would run some quick math on this...

My compressor is no more that a 1/2” inlet. With no more than 14.7 psi of pressure acting over 1/2” diameter opening. That's less than 1.5lb of force pushing my hand into the intake. But what if you have a 1" ID pipe? Well that's 5.8lb. Going to 1.5" ID is 13lb. If your intake is 2"ID then your at 23lb. Basically if you have a less than 1" ID intake getting "sucked in" is a non issue.

No, you won't get sucked in--that's what we call sarcasm. But you will get one hell of a hickie! I forgot to check the air filter for a while once, and pulling the lid off the air filter enclosure with the comp running was near took both hands. The top of the filter is 4.5" dia, so it has 16 sqin of area. Multiply that by 15 lb/sqin (a little less up here), and you have near 240 lb of force! As there was still some air going through the filter, I was able to get the lid off and filter replaced.

 

[Citation]

These links should give you an idea what's in the Eaton mufflers

Intake Noise Suppressor Installation Manual by Eaton Compressor - SlideServe

Here are the installation instructions for Intake Noise Suppressor in Whisper 100 compressors along with the parts list. You will start by removing existing filter assembly/assemblies from compressor pump. For full procedure, refer: https://www.eatoncompressor.com/whisper-100

www.slideserve.com

https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://eatoncompressor.com/wp-content/uploads/2024/10/CHANGE-THE-FILTERS-ON-SILENT-AIR-COMPRESSORS.pdf&ved=2ahUKEwi8royAwduQAxWQl4kEHfxdAFwQFnoECBEQAQ&usg=AOvVaw2CAEU62F9wVdusp-6pVly3

Basically a box with internal shelves. The top has the standard air filter housings with hoses to the pump. It should be relatively easy to recreate with 1/4” plywood.

 

[Citation]

We did, too. The recip is our original and is supposed to be back-up only. However, the 5 hp IR screw comp is barely enough to keep up with the canning line if everything is tight. We use air for controls all over the brewery, so there are lots of little leaks to chase down continuously. I found and fixed a fairly major one yesterday, so maybe we can can without the beast running.

No, you won't get sucked in--that's what we call sarcasm. But you will get one hell of a hickie! I forgot to check the air filter for a while once, and pulling the lid off the air filter enclosure with the comp running was near took both hands. The top of the filter is 4.5" dia, so it has 16 sqin of area. Multiply that by 15 lb/sqin (a little less up here), and you have near 240 lb of force! As there was still some air going through the filter, I was able to get the lid off and filter replaced.

Yeah, didn't let your parents see it (or use your neck to seal it )

 

[Beerhippie]

These links should give you an idea what's in the Eaton mufflers

Intake Noise Suppressor Installation Manual by Eaton Compressor - SlideServe

Here are the installation instructions for Intake Noise Suppressor in Whisper 100 compressors along with the parts list. You will start by removing existing filter assembly/assemblies from compressor pump. For full procedure, refer: https://www.eatoncompressor.com/whisper-100

www.slideserve.com

https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://eatoncompressor.com/wp-content/uploads/2024/10/CHANGE-THE-FILTERS-ON-SILENT-AIR-COMPRESSORS.pdf&ved=2ahUKEwi8royAwduQAxWQl4kEHfxdAFwQFnoECBEQAQ&usg=AOvVaw2CAEU62F9wVdusp-6pVly3

Basically a box with internal shelves. The top has the standard air filter housings with hoses to the pump. It should be relatively easy to recreate with 1/4” plywood.

OK, so now I just need to get some of that loose glass mat.

I still don't quite grasp the dual intakes, 'though--is that an HVLP compressor with two single-stages?