Noise enclosure tips for a 1/2HP compressor pump

[ESTinker]

I don't know much about noise reduction, got any advise on reducing the noise on a 1/2HP compressor pump?

The pump weighs 20 pounds and mounted on 4 isolation mounts each rated at 35 pounds. I plan on make an enclosure with 1/4" noise insulation foam on all 6 sides with cut outs for the fan holes on the front and back where cold air gets blown in and at the top put either a big hole or a bunch of small ones to vent out the hot air.

So any advice on the best way to remove as much noise? Not really sure if it make any difference to have a bunch of small holes or 1 big one.

 

[GregLocock]

make sure you cover any holes with additional baffles so there is no line of sight to the interior


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Your bushing spec is meaningless, it needs to be very soft.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[Tmoose]

Got pictures of the finished installation?
Is it constant speed ?

Is this a reciprocating compressor? If so, intake pulsing is a BIG noise source. A well done commercial intake silencer made a startling and wonderful improvement on my old 3 HP Frankenstein Curtis compressor. The silencer/filter was a yard sale find. Solberg, I think, and probably significantly oversized because I had to use radical pipe reducer fitting to neck it down a couple of pipe sizes to fit the compressor's pipe thread inlet. I found a replacement automotive pleated paper filter that fit well, filters very well, and probably vast flow capacity.
The keys are a large volume "expansion chamber" (10X piston displacement would be nice), cylindrical with thick or shaped end caps to resist "panting" and resulting sound "break out" in response to the powerful intake pressure pulsations , with 1 to 3 small streamlined inlet holes.

No compromise required of sound reduction vs cooling of the compressor either, unlike an enclosure would.

The mechanical noises that are left over would be easier to tame with an absorptive enclosure, if necessary.

 

[ESTinker]

Its an oil-less rocking piston twin pump runs at constant speed 1750RPM

 

[Strong]

Start with improving the compressor mounting! The intermediate sheet metal base is nothing more than an extra sound radiator, so remove it. The vibration isolators/mounts should be attached directly to the compressor feet (see picture in Gast catalog). The isolator load rating should be 5-lb. each (20-lb. total); to keep mount stiffness as soft as possible for effective isolation. The base frame the mounts are attached to should be as rigid and massive, as possible.

Second, install suction and discharge silencers/mufflers to reduce low frequency pulsation sound.

Third, is the sound enclosure to reduce case radiated and cooling fan sound. The enclosure must have 6-sides, so bottom is included. The enclosure must have mass, either metal or fabric with mass layer. The enclosure should be lined with sound absorbing material (foam or Fiberglas) at least 1" thick to reduce reverberation and improve Noise Reduction. The enclosure must have sound isolated ventilation openings, either custom air silencers or tortuous path for air flow. A 1% area opening with direct line of sight will nullify any benefit of the enclosure. The enclosure penetrations for electrical, instrumentation, suction and discharge should be well sealed. Air tight is sound tight! The enclosure should be easily removeable or have access panels for inspection and maintenance. It may be worthwhile to reroute all of the penetrations to one area, such as near the base, to allow enclosure (5-sides) to be lifted off. The connected items (see penetrations) may require vibration isolation, or be flexible, to avoid vibration/sound short circuits that reduce enclosure effectiveness.

Some Internet searches for sound and vibration control and discussion with other experts will help you towards an effective result. You have a small machine, but the fundamentals are the same as for a large machine.

Walt -- Sound & Vibration Control