The quietest ones will normally be "ALL" Cast Iron and oil lubricated. When
shopping take magnet with you to check the cylinder and head and if possible
ask to listen to the unit running. Typically the lower rpm units will be
On Fri, 10 Dec 2004 00:39:26 -0800, "Joseph Connors"
No such thing. Compressors are noisy by their nature. You may want to
consider running the compressor in an area where noise is not an issue
and run a pipeline to where you need the air. The oiless compressors
generally have more noise than the one's that have an oil reservoir.
That's a rather blunt assessment. There are drastic differences in
noise levels between compressors. A cast iron oiled compressor might
run in low to mid 80 db noise level. An oil free aluminum might run in
the mid 90's. Given that every 3 db increase in sound level equals a
100% increase, that would mean that the the oil less compressor might
be 16 times as loud as a cast iron. Many people would anecdotally say
"its at least that much louder".
I agree that none of them would be considered quiet, but the cast irons
are generally tolerable, while the oil less are intolerable.
I have a little compressor called a Jun Air. My boss gave it to me because I
wanted one for my nail gun but didn't want one of those big loud things.
This compressor is almost silent. It is the size of a pancake but you can
hardly hear it and the output is fantastic. My boss says they cost almost
$1000. The photographic and medical communities use them.
I work in the photo industry repairing industrial and darkroom equipment. I
get a lot of cool stuff as the industry slowly dies. I have all sorts of
columns, motors, gears and other stuff that I build in to tools.
Oh yeah, I have thousands and thousands of negs, B/w and color.
I've found that in the better made compressors (oilers, cast iron
pumps) that the main noise is the intake. Put a muffler on that and
you barely notice the thing running.
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This "3 dB = twice as loud" error is frequently made. Alexander Graham
Bell was, among other things, an audiologist. He did empirical studies
of loudness, and codified a relative loudness scale Bel(l)s. 1 Bel
represents a doubling (or halving) of sound pressure level. A decibel
is 1/10 of a bel, therefore 10 decibels is required for a doubling of a
perceived sound pressure level (on average - these are based on
empirical data). To generate a 3 dB increase in sound pressure level,
on a stereo for example, requires a doubling of power. I believe it is
this latter relationship that is often confused with the former.
Stepping off peeve-box....
A true 6hp compressor would draw approximately 4,500 watts, or 40 amps
on a 115v circuit, so you are oviously in the realm of 220+ v units.
I would look at the Eaton compressors (www.eatoncompressor.com) for
what appears to be a well-made unit.
On 10 Dec 2004 20:17:08 -0800, email@example.com wrote:
I'll add that distance can affect sound level in a huge way. Placing
the irritant as far from the source of irritation as possible can also
Most compressors can easily be placed in a convenient spot and plumbed
to the area where the air is needed. They don't need to be right next
to the user, or right under the wife's TV room.
What is your concern about noise? In that size of compressor I don't
believe there are any 'quiet' ones.
If this is a neighbor concern, I doubt if it will be that big of a deal. I
have a 6HP CH in my garage. When it starts while I am in the garage I am
occasionally startled. Outside, with the door down, I can barely hear it.
I can also hear it in the house but it is not disturbing. Beside that,
unless you are spraying, running air sanders or doing other things that
require constant flow, the compressor seldom runs for more than a minute or
so at a time. For normal use (nailing, occasional impact wrench use, some
other air tools, etc.) a larger tank will usually mean less startups.
As others say, oiled compressors are generally quieter. In addition to
being noiser, the oil-less machines run at a frequency that makes my hair
Search for "dental compressor". I recently bought a military surplus
used $7,790 dental compressor for $400. It was very quiet indeed, and
has air dryers and whatnot. I resold it for $1,250, as it was too big
for me anyway. The buyer was a dentist. It required 220V to run
Check out "Air Techniques AirStar 50" at www.airtechniques.com.
You can reduce about 75% of the noise if you take the motor and pump off the
tank and mount it to another platform. Of course that would be a pump that
uses oil. You will have to have someone hook up the tubing for you, unless
you can fabricate it yourself.
On Fri, 10 Dec 2004 00:39:26 -0800, "Joseph Connors"
the quietest ones that I've heard about are the new generation of
pancake compressors, which are usually smaller than you need..
I can't remember who had them, maybe PC, but they were oiled and low
rpm for lower noise level.. about double the price of the normal ones,
[ Not what you asked for - but, hey this is Usenet, where we excel at
answering questions you didn't ask, but we're all damned sure that's what
you meant: ]
One day to get my 2Gal oiless pancake out-of-the-way, I stuck it in the base
of an all 3/4" MDF cabinet, and closed the door. Out of curiousity, I
plugged it in, and was shocked by the amount of noise reduction. Actually
muffled down to Small 1HP Dust Collector levels (dbs in high 70's, low
I does get hot in there, so I don't run it long with the door closed, but it
has made it a usable tool now at all hours rather than only during daylight
Thanks everyone for the ideas. I think I am going to build an enclosure for
my existing compressor (6HP 30 gal upright Sears - oilless) using plywood,
2x4's, soundboard, and insulation. Just a box with openings for access to
controls and air and power (plus some ventilation as well). Thanks again!
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