Anne Hunt on thu 30 nov 00
'Lo, all --
Some very dear friends, who are not on the list, now have a kaflooey air
compressor; I believe the switch has burnt out, or some such. Am forwarding
on part of her query, knowing that ya'll's collective expertise will help
with the problem.
"Unless you know the answer to this, I need to know a web page address that
can answer the following question: What is the recommended psi and hp for an
air compressor that will spray glazes; and is the same psi used to spray
stains? We will get a new compressor and we are trying to
find the smallest one that will do a good job. The old compressor will be
up for grabs if you know anyone who wants to fool with it... any mechanical
types."
Thanks for the assist,
anne & the cats.
vince pitelka on mon 4 dec 00
Anne -
There have been a number of discussions of air compressors on the list over
the years, so you could no doubt find information in the archives. But no
one else has responded to your query, so I'll take a stab at it.
When you say that the switch has burnt out, that doesn't say much. But at
any rate, it is no problem to replace the switch. Most decent compressors
have an automatic pressure switch, which starts and stops the compressor
automatically in order to maintain a preset pressure range in the tank. If
that is all that is wrong with the unit it would be a shame to replace the
whole thing. However, if it is old and tired, or underpowered, then a new
one is in order.
There are several things to look for in a good studio compressor, depending
on the size of the studio. For an independent potter spraying glazes and
occasionally using air tools for brief periods, a one to two horsepower
compressor is adequate. For a larger studio doing lots of glaze spraying
and other tasks with a compressor, a unit of at least five horsepower is
appropriate. In either case, be sure to always get a compressor with at
least a 10-gallon storage tank (preferrably 20-gallon or 30-gallon), and
make sure it has an automatic pressure switch. A good compressor with an
automatic switch will pump the storage tank up to the preset cutoff pressure
(usually around 110 lbs.), and then shut the motor off. If the system is
tightly sealed the tank will remain pressurized, ready for your needs. On
the output there will be a regulator, and you can regulate the air pressure
down to your needs. When you use air, and the pressure drops below the
cut-in pressure, the motor starts up again and pumps up the tank. In other
words, the only time you have to listen to the thing much is when you are
using a lot of air. Also, with such an automated compressor, you have the
option to install it in a remote location (outside under a shed, for
example) where you will not have to listen to it at all.
Whenever considering purchase of a compressor, always get one with a
separate motor and compressor unit, with a belt drive between the two, and
always make sure your compressor has a cast iron barrel, or at least a cast
iron sleeve inside an aluminum barrel, and make sure it has an oil-bath
crank-case. Drain the air condensation from the tank weekly, and change the
oil in the compressor sump as recommended by the manufacturer.
Always avoid the direct drive compressors where the motor is connected
directly to the compressor shaft, especially the ones advertised as
"maintenance-free." They are a scam. Maintenance free just means that you
cannot do anything to prolongue the life of the machine. The compressor
unit turns at motor speed, and has no oil sump. It usually relies on a
teflon-lined aluminum barrel to work smoothly and dissipate the rapid heat
buildup. But they are throwaway compressors, with limited life, especially
if used heavily.
In contrast, if you buy a unit with a cast iron cylinder or sleeve and an
oil-bath crank-case, with proper maintenance it will last almost
indefinitely. Any of the good compressor makers like Quincy, Speedaire,
DeVilbiss, Ingersol-Rand, and Chicago Pneumatic make great cast iron
compressors. Campbell Hausfield makes good ones too for very reasonable
prices, advertised as their "Cast Iron Line." You can see them at
www.grizzlyindustrial.com or at www.campbellhausfeld.com
You can get a 5 HP Campbell Hausfield cast iron air compressor with a
vertical 30-gallon tank (takes up less space), automatic pressure switch,
and air regulator from Grizzly Industrial for $422, including freight
anywhere in the 48 states. That is one hell of a deal.
Best wishes -
- Vince
Vince Pitelka
Home - vpitelka@dekalb.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
http://www.craftcenter.tntech.edu/
Jonathan Kaplan on tue 5 dec 00
Vince's tretise on air compressors is quite complete and to the point.
A few things to add.
If you are using air on a fairly continuous basis consider a 2 stage
compressor. Most compressors are single stage and if you need lots of air,
a single stage compressor will run all the time and wear out quicker.
Doulbe stage compressors cost more though.
Make sure your compressor is in a ventillated area. It needs air also!
A filter regulator is essential. You don't want to draw high pressure air
for use right off the tank. A filter regulator not only takes out some of
the crud in the air, but also offers an adjustable output for your tools,
spray gun etc.
Also consider, regardless of which compressor you buy, purchasing a
coalescing filter and some sort of dessicant filter. Compressed air is
loaded with mositure and oil residue from the compressor head. These small
filters will insure that the air you use will be relatively contaminant
free! Dessicant filters are an ok solution for moisture in the air stream
and the dessicant material does need to be replaced periodically. There are
other solutions that are quite involved using aftercoolers and other
devices, but these are really high tech solutions
The Grainger's catalog is full of all sorts of stuff for air systems as
well as having quite a good section on air requirements, equipment needed,
piping requirements, etc.
Another good brand is Curtis-Toledo from St. Louis MO. A compressor is a
valuable piecve of equipment. If you treat it well, it will last a life
time.
BTW, remember to check the oil level and add oil as necessary!
Best
Jonathan
Jonathan Kaplan, president
Ceramic Design Group
PO Box 775112
Steamboat Springs CO 80477
voice and fax 970 879-9139
jonathan@csn,net
http://www.sni.net/ceramicdesign
Plant Location:
1280 13th Street Unit 13
Steamboat Springs CO 80487
(please use this address for all deliveries via UPS, comman carrier, FEd
Ex, etc.)
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