MAINTENANCE OF
the upper discharge valve. As the piston
AIR COMPRESSORS
moves downward, air is drawn into the upper
cylinder; likewise, air in the lower cylinder
As a GSE or a GSM, you must be thoroughly
is being compressed and forced out the lower
familiar with the operational and safety
discharge valve. Compressed air leaves the first-
stage discharge valves and flows through the first-
procedures for operating or maintaining an
air compressor. Always use the correct EOP
stage intercooler, and into the first-stage moisture
when operating an air compressor. Before
separator.
starting any maintenance or repair work,
you should consult the MRCs and the manu-
The first-stage separator has a small tank
facturers' technical manuals. These materials con-
mounted on the side of the compressor frame
tain information concerning specifications,
below the gauge panel and has a holding tank
clearances, procedural steps, and troubleshoot-
mounted below the cooler rack. The separators
ing techniques. Compressed air is potentially
for the remaining stages handle smaller volumes
very dangerous. Remember that cleanliness
of air due to compression, and as a result the
is of greatest importance in all maintenance
separators and holding chambers are smaller and
that requires the opening of compressed air
are integrated into one tank. Condensate is
systems.
removed from the air as it collides with the
internal tank baffles and collects in the holding
chamber.
SAFETY PRECAUTIONS
Air from the first-stage separator is drawn into
Many hazards are associated with pres-
the single-acting, second-stage cylinder on the
surized air, particularly air under high pres-
upward stroke of the piston. As the piston travels
sure. Dangerous explosions have occurred in
downward, the air is compressed and forced out
high-pressure air systems because of DIESEL
the discharge valve. The second-stage discharge
EFFECT. If a portion of an unpressurized
air passes through the second-stage intercooler
system or component is suddenly and rapidly
into the second separator.
pressurized with high-pressure air, a large
amount of heat is produced. If the heat is
The third stage draws air from the second
excessive, the air may reach the ignition
separator and compresses it in the same manner
temperature of the impurities (oil, dust, and
as in the second stage. Third-stage air enters a
s o forth) present in the air and piping.
pulsation bottle before passing through the third
When the ignition temperature is reached,
interstage cooler. Pulsation bottles are used after
a violent explosion will occur as these impurities
the third and fifth compression stages to minimize
ignite. Ignition temperatures may also result from
the shock effect of inlet and discharge pulses as
other causes, such as rapid pressurization of a low-
well as pressure changes due to condensate
pressure, dead-end portion of the piping system,
draining.
malfunctioning of compressor aftercoolers, and
leaky or dirty valves.
After passing through the third interstage
cooler and moisture separator, the air is
Air compressor accidents have also been
drawn into the fourth-stage cylinder on the
caused by improper maintenance procedures.
downstroke of the piston. As the piston
These accidents can happen when you disconnect
travels upward, the air is compressed and
parts under pressure, replace parts with units
forced out the discharge valve. Then it passes
designed for lower pressures, and install stop
through the fourth-stage intercooler and moisture
separator.
valves or check valves in improper locations.
Improper operating procedures have resulted in
air compressor accidents with serious injury to
Air is drawn into the fifth-stage cylinder on
personnel and damage to equipment.
the piston downstroke and is compressed and
discharged on the upstroke. The discharge air
passes through the fifth-stage pulsation bottle, the
You must take every possible step to minimize
the hazards inherent in the process of compres-
aftercooler, the moisture separator, a back-
sion and in the use of compressed air. Strictly
pressure valve, and a check valve before entering
follow all safety precautions outlined in the
the ship's HP piping.
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