Chapter 7AUXILIARY MACHINERY
5. When the cooling water system of the com-
pressor is being refilled, the water inlet valve
should be opened slightly to allow the water to
rise slowly in the cooler shell and water jackets.
Also, the vent valves which are fitted to the water
spaces should be opened to permit entrapped air
to escape, and thus prevent the formation of air
pockets in the system.
CARE AND MAINTENANCE OF
AIR SYSTEM EQUIPMENT
The air flasks and separators of surface ships
must be given a surface inspection every 3 months
to determine if there is any external corrosion or
damage to flasks or piping.
Because of the coating of zinc chromate
primer, corrosion is seldom a source of trouble
on the internal surfaces of air flasks; however,
corrosion may take place on the external surfaces
of air flasks and may be sufficiently serious to
weaken the material, especially in high-pressure
flasks. Surface corrosion usually occurs at points
which cannot be easily reached for proper
cleaning and painting.
Drainage of air system equipment must be suf-
ficiently frequent to prevent excessive accumula-
tions of moisture and oil. Such accumulations not
only cause internal corrosion and fouling of
moving parts, but also create a serious hazard
since any excessive oil accumulation may result
in an explosion.
All high-pressure flasks and separators must
be inspected, cleaned, tested, and repainted at
prescribed intervals by a repair activity. For sur-
face ships, the initial and subsequent intervals
should not exceed 6 years. Although inspection
intervals for separator flasks are approximately
3 years, if there is reason to believe that serious
corrosion of either the exterior or the interior of
air flasks is taking place, before the lapse of the
normal interval, the flasks should be inspected and
tested at once.
Periodic examinations are essential to deter-
mine the condition of air system equipment; these
examinations should include not only a complete
inspection of the interior and the exterior of flasks
and separators, but also ultrasonic inspections and
hydrostatic tests. After a thorough cleaning, the
flasks which successfully pass the hydrostatic test
are given the prescribed internal protective
coating, and when necessary, the exterior is
painted. Further information on the details of the
inspections and maintenance performed by repair
activities can be found in chapter 551, section
VIII, of Naval Ships Technical Manual.
INSPECTIONS AND TESTS
The minimum maintenance requirements for
the performance of inspections and tests of com-
pressed air plants are given in figure 7-1. It is the
responsibility of the engineer officer to determine
if the condition of the equipment, hours of
service, or operating conditions necessitate more
frequent inspections and tests. Details for each
test and inspection are obtained from the PMS
Manual, or the appropriate manufacturers
technical manual.
SAFETY PRECAUTIONS
Competent personnel operating and maintain-
ing any machine keep it performing as efficiently
as possible. In order to achieve peak performance
from a compressed air plant, they take steps to
prevent or minimize the occurrence of any con-
dition which might reduce plant capacity or result
in serious damage. All personnel should take every
possible precaution to prevent potential explo-
sions, especially when operating high pressure
systems. Safety precautions which will aid you in
preventing explosions and in maintaining a plant
in satisfactory operating condition are listed
below.
1. Minimize the possibility of explosions in
an air compressor, discharge line, or receiver by
taking steps to prevent or eliminate the following:
a. Dust-laden intake air.
b. Presence of oil vapor in compressor or
receiver.
c. Leaking or dirty valves.
2. Make sure that the compressor intake
receives only cool, dry air.
3. Use only prescribed agents for cleaning
compressor intake filters, cylinders, or air
passages. DO NOT use benzene, kerosene, or
7-5