Re: Air compressors vs. canned air
* Chris Jones <cjns1989@gmail.com> [100214 02:35]:
> Has anyone with real world experience in the area of computer cleaning
> tried such solutions as the MetroVac duster line and might be able to
> comment on the respective merits of air compressors vs. air cans..?
The telephone company uses dry nitrogen to purge telephone cables
(sealed conduits which contain hundreds of twisted pairs).
The short answer: There is no practical way for a small user to
produce compressed air which is free from oil vapour and moisture; the
proper solution is dry nitrogen.
More detail: In petrochemical plants, from time to time there is an
air line fire in which combustion takes place within the line; the
steel pipe of the line (which may run hundreds of feet) grows red-hot
and sags in the pipe rack as the combustion progresses from one end of
the line to the other. This can happen when the oil vapour is not
removed after the air exits the compressor, and when a large
compressor is in continuous service. The oil comes from the
compressor lubrication system. The amount of oil coming out of a
small home compressor generally is too small to be hazardous. The oil
problem does not exist with small diaphragm-type compressors.
Water is another matter. Almost every mechanic has experienced a slug
of water which makes its way down the line and out a nozzle or into a
pneumatic wrench. This is because condensate traps are not perfect,
and they don't always get emptied routinely. Water is bad enough, but
hardly anything makes a worse mess than a spray of oily water.
I doubt that it is possible to get a computer board or power supply
cleaned properly up after being sprayed with oily water; the only hope
would be immersion in a capacitor-safe, plastic-safe solvent such as
freon, and even that would ruin the fan bearings.
How-to: Any welding supply house can sell you a tank (2000 psi) and
regulator with gages for dry nitrogen, just like the telephone company
uses. And they can fix you up with a hose and nozzle with a
pushbutton valve. When you finally empty the tank, you haul it back
to be refilled.
Just make sure that the tank which you purchase is one which is
intended to be privately-owned and make sure that you hang onto the
receipt. Many tanks have a welding supply company name forged or
deeply stamped into the neck of the tank. So, for example, if you
have a tank stamped "FOO Welding Supply" and you take it to BAR
Welding Supply to be refilled, BAR may refuse to fill the tank; this
is because theft of tanks is a major problem; that's why the expensive
markings are manufactured into tanks. So ask about third-party
refilling before you purchase a tank.
Rental of a tank is too expensive for the individual user; this is because
a daily "demurrage" charge accrues after the first 30 days.
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