New, to me, air compressor noise questions - PeachParts Mercedes-Benz Forum

Nate · #1 12-27-2010, 12:53 AM

Hey everyone, I got a myself a 3.5hp 20 gal direct drive air compressor off CL for cheap. It works well, and will do everything I want it to do... But It's noisy.

First noise thing is the regulator? When it is "full" the on/off lever trips what looks a safety valve, and starts to relieve air (1psi per min) The air compressor is off, but you hear an annoyingly loud hissing from the valve. It already has an over pressure "pop off" valve, so I was wondering If I could remove the other valve.

Second noise is from the intake, I put a filter on it, from the fast and furious isle of Advance auto parts, and it seamed to quiet it down a bit. The problem is that the air intake is 1/2" cast aluminum pipe, with no threads. Only option is a clamp on one. Is there a better filter to quiet it down more?

Lastly, I understand it's direct drive, and WILL be noisy. I have an "upstairs" to my 2.5 car garage. It's open, but has 1/2" plywood between the rafters, so you can walk up there. There's an outlet for the garage opener, and it's rated for 15 amps, so the compressor will be fine if I dont want to open the garage when It's running...

Wondering if I can put it upstairs, with some insulation foam under it? Hoping to make it quieter, worried it will turn the plywood decking into a sound board, and actually amplify the noise...

Any ideas?

Thank you!
~Nate

Aquaticedge · #2 12-27-2010, 12:59 AM

I would not put a compressor overhead unless it's small. those things vibrate and shake and you dont want to be around when they crash through

Nate · #3 12-27-2010, 01:02 AM

Seems to weigh around 50-75lbs. For sure dont want to be near it falling nearly 8 feet.
The plywood is 1/2" thick, screwed ontop of 2x4 rafters. I was planning on securing it with rope to prevent movement. I wasn't concerned with it falling through. Should I be?

~Nate

jplinville · #4 12-27-2010, 06:01 AM

You could build a box, of sorts, to contain the compressor. Make sure to have vents to prevent overheating, and have the air intake plumbed to the exterior of the box, so it gets fresh air. You can insulate the interior walls to cut down on noise.

It's never going to be quiet...but you can quiet it down some...

layback40 · #5 12-27-2010, 06:41 AM

Quote:

Originally Posted by Nate

Hey everyone, I got a myself a 3.5hp 20 gal direct drive air compressor off CL for cheap. It works well, and will do everything I want it to do... But It's noisy.

First noise thing is the regulator? When it is "full" the on/off lever trips what looks a safety valve, and starts to relieve air (1psi per min) The air compressor is off, but you hear an annoyingly loud hissing from the valve. It already has an over pressure "pop off" valve, so I was wondering If I could remove the other valve.

Second noise is from the intake, I put a filter on it, from the fast and furious isle of Advance auto parts, and it seamed to quiet it down a bit. The problem is that the air intake is 1/2" cast aluminum pipe, with no threads. Only option is a clamp on one. Is there a better filter to quiet it down more?

Lastly, I understand it's direct drive, and WILL be noisy. I have an "upstairs" to my 2.5 car garage. It's open, but has 1/2" plywood between the rafters, so you can walk up there. There's an outlet for the garage opener, and it's rated for 15 amps, so the compressor will be fine if I dont want to open the garage when It's running...

Wondering if I can put it upstairs, with some insulation foam under it? Hoping to make it quieter, worried it will turn the plywood decking into a sound board, and actually amplify the noise...

Any ideas?

Thank you!
~Nate

The hiss could be from the line bleed. It should not leak like that. There is a check valve where the air line from the compressor goes into the tank, its built into the fitting, that line is empty so the comp doesnt try & start against pressure.
There is a safety valve near the reg, it normally has a ring through its pin. If you pull the pin it releases air. It can sometimes be reseated by pulling the ring & letting it snap back.
1/2" ply is a bit weak to mount it. If you bolt it to the beams, it will transfer the vibration. Best only have it on only while you need it. They need good air flow as they do get warm. Make sure you drain the condensation out of the tank regularly.

Chris W. · #6 12-27-2010, 09:31 AM

IMHO the hiss should occur but stop after a few seconds. That is the unloader which allows the compressor not to start against compression next time it starts.

If it is hissing for minutes you have a problem.

Rgds,
Chris W.

LUVMBDiesels · #7 12-27-2010, 10:23 AM

If the noise is really bothering you build the box, but put it outside the garage.
You can plumb a hard line through the garage wall and put a quick connect fitting on the garage wall.

Any compressor will be loud but it should not be obnoxiously so.

If you do build the box, make it at least twice the size of the unit and then head to Best Buy or a similar store and ask for the foam that comes in computer boxes. a lot of it looks like eggshell acoustic foam. Use that to line the inside of the box

Nate · #8 12-29-2010, 10:22 PM

As a follow up to this post, I'm adding the following information:

I've been doing some research, and I appear to have found the problem. The "pressure switch" is sticking, causing the "unloader valve" to stay depressed at all times unless the compressor is calling for power.

I'm going to attempt repair of the "pressure switch", but more likly it will need replacement. A replacement is around $20 (

http://cgi.ebay.com/AIR-COMPRESSOR-PRESSURE-SWITCH-CONTROL-VALVE-95-125-PSI-/220666894277?pt=LH_DefaultDomain_0&hash=item3360c597c5 )

Oh, and the $17 harbor freight air gun cannot break loose lugnuts. The $25 one struggles with it, but can. Currently looking for a good used one from craigslist...

More to follow.
~Nate

tbomachines · #9 12-29-2010, 11:16 PM

Quote:

Originally Posted by Nate

Oh, and the $17 harbor freight air gun cannot break loose lugnuts. The $25 one struggles with it, but can. Currently looking for a good used one from craigslist...

More to follow.
~Nate

This usually has more to do with the compressor and air supply than the impact gun itself, most pancake compressors would struggle with the volume and pressure of an impact wrench, but 20gal should be fine.

Pooka · #10 12-30-2010, 12:00 AM

I would recommend replacing the air regulator and filter with Norgren units. They are high priced for items such as that, but the overall cost is low no matter what you buy so I would go with the best.

The filter should also have a water trap in the bottom you can bleed out without cutting off the air to it. Look at a few online and you will see what I mean.

If there is a good pneumatic supply house near you I would go to them and tell them what you are trying to do. Their advice should be free and they will take a lot of the guess work out of your set-up.

If you buy a quality brand, such as Norgren, it will last for many years and you will be able to rebuild it when it wears out. They are no more difficult to rebuilt than the door lock actuators on a 123.