Why do air motors have an icing problem in the first place?
Air motors operate on compressed air from 20 to 180 psi and exhaust the same air at approxi-
mately 14.7 psi or atmospheric pressure. This is an extremely high percentage pressure drop
that occurs in a short period of time. Exhausted air temperatures will be well below freezing at
times on exit. Moisture in the air freezes and crystallizes at these low temperatures. This is the
same basic principle as a household refrigerator.
Icing is a problem that is inherent to all air motors. Many factors can
Compressed air temperature.
Compressed air dew point.
Compressed air pressure.
Compressed air volume flow rate.
Air quality due to contaminants.
Ambient air temperature.
Ambient air dew point.
Ambient air flow.
Motor air valve material.
Motor air valve geometry.
Cycle rate of motor.
Exhaust port restrictions such as a muffler.
Any one of these factors can cause icing. These factors can interact in unpredictable ways
and can be temporary, which is especially true with seasonal fluctuations in relative humidity.
How do you know if you have an icing problem?
Before you try to fix an icing problem, you should be reasonably sure that icing is the problem.
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You likely have an icing problem if the following conditions exist:
The pump has erratic pressure fluctuations.
The air motor stops but will restart after the ice melts. This may
take an extended period of time.
The motor or muffler is heavily frosted.
The compressed air you are using is moisture laden because little or no drying
equipment is installed.
Icing can also show up in subtle ways. Icing may be the problem if you need to do air supply
or fluid control adjustments to maintain a constant cycle rate. The problem may be temporary
if it is a seasonal fluctuation in humidity.
Air Motor Icing:
What is it and what can be done to eliminate it!
Air Motor Icing: What is it