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All air contains a certain amount of relative humidity. In
coastal locations or on high humidity days, this humidity is excessive. The
temperature of the air is increased as it is compressed. If a compressor is
running hard (continually running, without recycling or resting), the air
temperature will become excessive, leading to the compressor tank becoming very
hot to the touch. This results in a breakdown of the oil, with a resulting loss
of efficiency. The only answer is to allow the compressor to "rest"
until it cools down.
When running at high temperatures, as the moist air is compressed
and heated, it transforms into a "vapor". This vapor-laden air will
easily pass through most water separators, eventually condensing in the bottom
of the abrasive blast cabinet funnel or power gun where it is combined with the
abrasive. (Clogging results.) Also, as the nozzle orifice size increases in
size (gets larger) through wear, the compressor works harder, puts out more
moisture and the pressure starts dropping because the compressor cannot keep up
with the increased load.
In summary, for satisfactory operation when cabinet blasting or
using any air tool requiring large amounts of air, please observe the following
recommendations:
1. Change nozzles frequently -- consider going to a smaller size
to save air, or using a long-wearing Carbide Nozzle which will maintain its
orifice size for a longer period of time.
2. Do not blast continually. Take a break every 5 minutes to
allow air compressor to cool.
3. If air compressor tank feels hot (warm is normal), and is
running continually, stop operating the cabinet or air tool and allow
compressor to cool. Otherwise, compressor will overheat and eventually break
down. Compressors are not guaranteed against this condition.
4. Compressor must recycle normally on and off and run no more
than 2/3 the time. No air compressor is designed for continual operation. Know
the capacity of your compressor and the amount of air required for your air
tools, and allow a 50% overload factor for best results. (Example: Tool
requires 10 CFM air. You need 15 CFM as an overload factor.)
5. Use a minimum 3/8" ID air hose up to 25 ft, from air
compressor to cabinet and remember to consider air pressure drop as illustrated
in table below. Example: If using 25 feet of 1/4" ID air hose, at 60 lbs
pressure, you will experience a pressure drop of 19 lbs, meaning you actually
have 41 lbs working pressure.
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