Because the consumption air is not enough to prevent overheating. Besides,
air is heated when compressed.
Everything has to be put into proper perspective. Every compressor has a
duty cycle. It may be 30%, but could be 100%. Industrial compressors
sometimes go 24/7 for a year at a time. The 150 HP IR that we run will have
air temperatures in the range of 240 degrees and the cooling water can reach
115 on a very hot day even with two fans running on the cooling tower.
Our 75 HP Quincy screw has a factory enclosure to keep noise down. There is
also a large fan and vent to the outside about 2' square for the exhaust.
In the case of Upscale, he is looking at running about 10 minutes a few
times a week. It will not even be up to normal operating temperature in
that time so an enclosure is not a problem with cooling air.
As acoustics are often part of electrical engineering, (it spills over
into architecture) the core of the discipline are simple, basic physics.
Once a noise is air-bound, only two things will kill it: mass and
dissipation. In both cases, the energy is converted into heat (as
infinitesimally small that heat may be)
Transmitted (through a body other than air) noise obeys those same rules.
Parking your compressor on a heavy slab (like a patio stone they're
cheap enough) will have an immediate, positive result. If you then also
isolate the patio stone from the floor via a dissipating medium, like
four tennis balls, not a whole lot will get to the floor. You will feel
the immediate difference in your feet standing beside the running
compressor. Cut 4 pieces of 3/4" x 1-1/2 PVC drain pipe to use as rings
to put the tennis balls in so they won't roll around.
IF you're going to hang the unit from the ceiling, the noise will be
transmitted to the people upstairs...unless you use rubber bungee cords.
Egg cartons will dissipate some reflective sound, but in a very narrow
band of frequencies. basically useless for your problem as the
compressor puts out wide-bandwidth energy. The absorption of a medium is
measurable by the thickness as it is a multiple of the wave-length.
Therefore, carpet will only kill very small (high) frequencies. The
thicker, the better.
A box with a muffin fan... yup.. works for me.
I finally replaced my free craftsman 30 gal amazing 5.5hp compressor
with a nice small 4 gal non oiless compressor. the noise was so bad
even with hearing protection it was horrible. I guess it got jealous
as it died the next time I tried using it two weeks later (G) took the
pump off and hooked it to my smaller compressor. the smaller one will
actually fill it's tank and the 30 gallon tank faster then the
affordable handmade wooden planes
No, not so far. I feel that the once or twice weekly, 10 minutes use of the
compressor in the daytime is not of long enough duration that I need do so.
Hell the fire alarm in the building goes off much more often that I use my
compressor. That doesn't stop me from being aware of my neighbour's comfort.
Better to think about it too much than not enough as far as I'm concerned.
However, if I could abate some of the potential for noise, I'm sure I could
find increased usage for the compressor.
I have made my compressor significantly quieter by boxing it in. I have
it under a bench and enclosed it with Pegboard. Two doors on the front,
framed pegboard. I don't know the mechanics of why it works but it does
and the Pegboard allows plenty of airflow. I have my scroll saw on top
the bench and when working it and the compressor kicks into life it's
fine. Before the enclosure it scared the sh@t out of me every time :)
I also have the none wheeled end sitting on some 1/4" insertion rubber
just a piece about 6" square.
I tried placing egg cartons on the back wall (Shed), but they made no
difference. It is significantly louder where there are gaps in the doors
etc. The overall effects are quite comfortable with the peg board.
Thanks, I'll give it a try. Pegboard is really cheap so the worst that can
happen is that I waste $15 for what at the very least, would be a learning
experience. Providing it produces a noticeable diminishing of sound volume,
I'd hazard a guess that the holes in the pegboard diffuse the sound enough
to prevent a measure of resonance.
What would work even better, is two layers of peg-board, 1" apart with
the holes off-set from each other with a thin layer of fibre glass
insulation in between. That how I designed soundproof operators
enclosures for Ontario Hydro's RL Hearn Generating Station (The one at
the Leslie Spit).
Peckover's in Concord will sell you perforated metal. Easy to cut and
fold. Use 3/8" holes on the inner enclosure, 1" hard fibreglass
insulation and 1/4" holes on the outside. (You'd still need a muffin fan
though, as the rigid insulation isn't very "airy")
That would be the fire-proof version. The upside of the rigid insulation
would be that the inner and outer enclosures would not have to be
mechanically connected, again stopping noise from transmitting.
I'll keep it in mind. As a start, I can try the single layer peg board
version and if that doesn't produce sufficient noise abatement, then I can
consider going with the second layer as you've laid out above.
Generally speaking, the oil-less compressors seems louder than non oil-less.
We used to keep the shop compressor just outside in an old full-height
freezer. And when the compressor exploded one day, we think the
freezer may have reduced the amount of shrapnel that came though the wall.
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