a single bundle of tubes enclosed in a cylindrical shell.
The air to be cooled passes through the tubes while the
water circulates around the outside of the tubes
absorbing the heat from the compressed air. The
baffles are used to direct the water flow across the heat
exchanger tubes in the most efficient manner. The
intercooler is located between the discharge of one
cylinder and the intake of the next cylinder on a
multistage compressor. The intercooler reduces the
temperature and volume of the compressed air for
delivery to the next compression stage. The aftercooler
is located at the discharge of the last cylinder to cool
the air, to reduce the volume, and to liquify any
AIR RECEIVERS.The receiver is nothing
more than a tank designed to hold the -air that is
compressed to meet supply peak demands that are in
excess of the compressor capacity.
receivers function as pulsation dampers on reci-
procating compressor installations. Figure 6-47 shows
an air receiver.
SEPARATORS.Separators remove oil and
water from compressed air. Figure 6-45 shows a
centrifugal moisture separator. The air enters the unit
in a swir ling motion. Centrifugal action forces the
moisture to the walls of the separator and then the
moisture drains to the bottom of the separator.
Another type of separator is the baffle type. This
separator causes the air entering the separator to make
sudden changes in direction, causing the heavier
moisture particles to strike the baffles and walls and
drain to the bottom.
moisture from intercoolers, aftercoolers, receivers,
and distribution piping. Common traps used are the
ball float, the bucket, and the inverted bucket traps
DRYERS.Dryers remove moisture from
compressed air that would condense in air lines, air
tools, and pneumatic instruments. Condensation can
cause damage to equipment by corrosion, freezing, and
water hammer, and will cause instruments to
malfunction. The three types of dryers are adsorption,
deliquescent, and refrigeration.
The adsorptive dryer is made of some type of
desiccant, such as silica gel or activated alumina. The
desiccant adsorbs and holds the water vapor from the
air. Adsorption-type dryers (fig. 6-48) consist of two
drying towers, each containing an adsorbent, plumed
in parallel. The drying towers are cycled manually or
automatically, so one tower is on stream and the other
tower is being reactivated. Reactivation is accom-
plished by heating the desiccant which drives the
moisture out to waste.
Only one type of dryer was discussed in this
chapter. Other types of dryers, maintenance,
operation of controls, and other interesting
information about compressors can be found in
NAVFAC MO-206, Maintenance and Operation of
Listed below are some safety tips on how you can
avoid air compressor accidents.
Keep the hose connections on portable air
compressors tight, and inspect these connections
often to ensure they remain tight.
Check the safety valves and gauges frequently to
make sure they are working correctly.
Use fixed tow bars, not chains or ropes, when
moving portable air compressors.
Check the wheels of portable air compressor
carriages to ensure proper operation.
When an air compressor is started, check the
safety valves, the pressure controls, and the
regulators to determine that they are working
DO NOT leave the area of an operating
compressor unless you are sure that the control,
Figure 6-45.Centrifugal moisture separator.