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My diy oilless compressor muffler/silencer

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PWC Repair

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I had to repair a leak on my EXTREMELY noisy oilless air compressor so while I was at it I thought I'd build a muffler. Cost of parts would be about $12 but I already had most of this. I figured since they use sound wave cancellation on chambered car mufflers then it should work for the intake noise as well....right?

Parts list:

1 pc. 3" PVC pipe 6" long
2 pc 3/4 PVC cut 7" long
2 3" PVC test caps
1 3/4 slip x 1/2 MPT PVC adapter
1 1/2 FPTxFPT PVC 90
1 1/2x3 galvanized pipe fitting

Drill holes in a 4x3 pattern around only half of each 3/4" pipe. Cut out a 1" hole in each 3" cap. Glue the caps to the 3" PVC with the holes 180 degrees from each other. Slide the 3/4 pipe in (drilled hole half first) until it bottoms and mark it at the cap with a pencil. Pull it back out and put some glue on the end and around the 3/4 pipe just before your pencil mark. Now slide the 3/4" pipe back in and the end will be glued inside on the cap and also around the hole you inserted it through. Do the other side the same way. Let the glue set up good and install it onto your compressor intake. There is enough 3/4" pipe stubbed out to clamp on a small filter.
Here is a short vid showing the comparison.

It might not sound like much in the vid but there is about a 50% noise reduction in my little 12x18 shop. The remaining noise is of the compressor mechanicals and plastic rattling (also soon to be addressed). I can also tell you that with nothing on the intake energy is emitted as a loud, annoying humm. With my muffler the sound energy is cancelled and the energy can be felt "blowing" out of the muffler as pressure pulses in the air. The energy is still there but is not in the form of sound anymore....YAY!
 

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navymech

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In the video it sounds louder with the muffler on... :wtf:

Maybe not the best demonstration lol Pretty sweet ingenuity if it works in person though.
 
OP
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PWC Repair

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The deeper drone sound is the intake. The rattling noise is the housing and that air nozzle vibrating. The noise from those doesn't get any louder, the overall sound just gets quieter so you notice the housing rattling more. Maybe I can take a vid from across the shop so the camera isn't right next to the rattling of the housing.
 
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cheechi

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I assume you will be attaching a filter to yours? I'd like to see/hear it with the filter, and if you link which you use that would be helpful too.

I'd be interested in a before/after times for this mod to see if it makes filling the tank take longer. I understand in this situation it wasn't an option due to the leaking.
 
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gtg082y

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Very interesting. I've though often of doing something similar. My compressor when new was the biggest 115v oilless unit sold at Sears and it is painfully loud.
 
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LEVE

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Use your (or someone else's) smartphone to take a before and after sound test with a DB app. I like the idea you've come up with. I think I'll try it.
 
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airdale

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Oregon
rice rocket said:
So you know there's an actual science to this, right? Did you actually do the calculations to figure out chamber size, port diameter, port length, etc?
Click to expand...

Wouldn't you need to know the frequencies + resonant frequencies of the pump to make those calculations worthwhile?

OP - I like your ingenuity. You could neck down the end pipe to add a cheap aftermarket filter/silencer. Don't know how much more it would quiet it though.

Edit: Or use some insulation batting in the chamber. Glass Packs :)
 
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rice rocket

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airdale said:
Wouldn't you need to know the frequencies + resonant frequencies of the pump to make those calculations worthwhile?
Click to expand...

For sure, it all can all be measured with basic equipment though, which you can then plug into the equations.

Or have multiple mufflers of varying sizes for better effect. :)
 
OP
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PWC Repair

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I did not use any sort of math. The only thing I took into account was that it had to breathe better than the 1/2" pipe inlet so I wouldn't restrict the airflow. Everything else was just a guess. It seems to fill in the same amount of time it always has..........slow, compared to my twin cylinder Speedaire Commercial Duty. I will find an app for db measurement and try that!

Yes, I'm adding a little clamp on filter I robbed off a Chinese ATV.
 
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CHADD

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St Louis, MO
Nice setup. Ive seen ppl run the 3/4" pipe straight through the larger. Drill holes all the way around. Then fill the larger pipe with steel wool.

Sent from my SCH-I535 using Tapatalk
 
OP
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PWC Repair

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OK put an App called "noise meter" on my wife's S4 and measured right at 4db reduction on the intake. BUT.....I don't know how accurate trying to measure sound pressure through a microphone is?? You can scream at it at the top of your lungs and it only reads 82db??

Anyway I feel like I'm working around a standard pushmower now instead of a 20hp riding mower as far as in shop noise goes.
 
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bsaint

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Manchester, CT
PWC Repair said:
OK put an App called "noise meter" on my wife's S4 and measured right at 4db reduction on the intake. BUT.....I don't know how accurate trying to measure sound pressure through a microphone is?? You can scream at it at the top of your lungs and it only reads 82db??

Anyway I feel like I'm working around a standard pushmower now instead of a 20hp riding mower as far as in shop noise goes.
Click to expand...

Im pretty sure most smartphones have soundwave amplitude modulation for their mic and/or earpiece. If probably maxed out at 82db
 
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