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how hot should an piston air compressor get

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Ashton Crusher

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Oct 12, 2009, 9:54:49 PM10/12/09
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My old Monkey Wards 2 piston, single stage, 6 gallon (guessing), 1 hp,
120V air compressor runs as hot as 180 degrees on the cylinder head
when I'm using it a lot. Is that a normal temperature for this kind
of compressor?

Ed Pawlowski

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Oct 12, 2009, 10:10:24 PM10/12/09
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"Ashton Crusher" <de...@moore.net> wrote in message
news:can7d5hf2dk4n7ta5...@4ax.com...


Yes. Compressing air heats it up. Many industrial compressors are water
cooled and then the air goes through a chiller to remove the moisture. Our
150 hp at work will have cooling water temperatures up to 120, air
temperatures over 250.

Be sure you have enough oil in the machine as that aids in cooling.


Nate Nagel

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Oct 12, 2009, 10:25:48 PM10/12/09
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well, pv=nrt so it will get quite hot simply through adiabatic
compression alone. If you know the compression ratio of the cylinders,
you can calculate the theoretical pressure of the fully compressed air
with the piston at the top of the stroke. Obviously it shouldn't get
any hotter than that, and likely will stabilize at a lower temperature
due to the cooling fins radiating some of the heat to the atmosphere.

That said, that does seem a little warm; your average compressor will
get "hot" but I don't recall using any where it was significantly warmer
than, say, domestic hot water even after heavy use, but then again I
don't recall using any smaller than your typical roll-around 20 gallon
or so jobs.

nate

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Red Green

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Oct 12, 2009, 10:57:30 PM10/12/09
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Ashton Crusher <de...@moore.net> wrote in
news:can7d5hf2dk4n7ta5...@4ax.com:

If you run it a lot higher than the rated duty cycle it's gonna be
abnormally hot I would think.

fftt

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Oct 13, 2009, 2:42:40 AM10/13/09
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the important question is "duty cycle"........

how much "on" time? how much "off" time?

180 is hot but if you're working this puppy hard, its to be expected

either use less air (cfm's) or set up a fan to help cool it


cheers
Bob

Hustlin' Hank

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Oct 13, 2009, 4:37:01 AM10/13/09
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It is basically the same thing as a car engine without the fuel to
burn to make it hotter. Car engines need cooling because of the added
heat from the fuel being burned. They cool car engines down to 180-
200 degrees, which is the normal temp. I am just guessing, but I would
think 180 is about right.

Hank

tra...@optonline.net

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Oct 13, 2009, 8:09:45 AM10/13/09
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It's not the same or similar to a car engine. In a car engine
without fuel, the air would be compressed on the compression stoke,
then immediately decompressed on the power stroke in the cylinder.
When you compress it, it gets hot. When you decompress it, it gets
cold. In an air compressor, the cylinders are strictly
COMPRESSING. The decompression takes place elsewhere, eg where it's
being used in a tool, or blowout gun, etc.


Hustlin' Hank

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Oct 13, 2009, 1:13:43 PM10/13/09
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Kinda picky aren't ya? I was trying to keep it simple in the fact it
is only a piston that moves up and down. But since you want to get all
techy on me.........When the outlet valve (think exhaust )of the
compressor closes (piston going down) the intake valve opens and
brings in cool air that also helps cool the cylinder, along with the
cooling fins. Altho there is significant heat built up in regards to
compressing the air, it still isn't a match for fuel being burnt also.

Hank

John Gilmer

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Oct 13, 2009, 11:11:27 PM10/13/09
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A single stage air compressor can easily get hot enough to cause a 2nd
degree (blisters) level burn on the skin.

If you can to get "scientific" that find out what happens when you compress
air from 0 psig to 135 psig under adiabatic conditions. (Add about 15 psi
to convert to psia.)


Steve Barker

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Oct 14, 2009, 1:42:06 PM10/14/09
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Upon failure, we disassembled a large compressor at the autoshop i
worked at. There was carbon on top the pistons.

s

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