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Page Title:
Cooling systems for submarine air compressors |
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|  MIL-C-18419B(SHIPS)
3. 3.19.2 Cooling systems for submarine air
straight tubes with a single return bend. For air
compressors. -
pressures of 250 p. s. i. g. or higher, air shall flow
through the cooler tubes and water flow over and
3. 3.19.2.1 For submarine service the cooling
around the tubes. For air pressures below 250
system shall be designed for the use of fresh water
p. s. i. g. air may flow either through or around the
supplied [rem an unpressurized! shipbuilder fur-
tubes at the manufacturers option. Cooler tubes
nished, closed cooling water heat exchanger system.
shall be roiled, welded or brazed into tube sheets
The coolIng system shall be designed for a maximum
or headers, except that roiled tubes shall not be
pressure of 50 p. s. i. and shall have an attached cir-
used for pressures above 250 p. s. i. g. Provision
culating water pump driven by the compressor or by
shall be made for prevention of damage due to the
Independent means, and capable of supplying ade-
expansion of tube nests. Stay rods as necessary
quate flow through the compressor cooling system
shall be provided for support of tube sheets and
plus an additional dynamic head of 8 p. s. i. g. at the
air heads. Each cooler tube nest shall be a self-
required flow rate for external system drop through
contained unit so that it may be easily removed
the ship's piping and heat exchanger. When the
from the compressor as a unit for inspection and
pump is independently driven it shall be arranged to
cleaning. Suitable air relief valves shall be
automatically stop and start with the compressor,
fitted on or after each air cooler. Suitable water
relief valves shall be fitted at the high point of the
3. 3.19.3 Cooling systems for surface ships. -
water side of each air cooler except for first and
second stage coolers. Water relief valves shall be
3. 3.19.3.1 For surface ship service all parts of
set at 60 p. s. i. for submarines and at 185 p. s. i.
the cooling system shall be of corrosion resisting
for surface ships (see 3.3. 24).
material and shall be designed for the use of salt
(sea) water supplied from the ship's flushing or fire
3.3.20 Condensate drainage system. -
mains at a maximum working pressure of 175 p.s. i.g.
3. 3.20.1 Efficient moisture separators shall be
The cooling system shall include an attached valve
for positive and automatic control of the cooling
provided after each intercooler and aftercooler for
removing free moisture and oil from the air. Each
water so that the water flow is maintained while the
compressor is running and is stopped when the
separator shall be sized to require drainage not
compressor is not running. The water flow should
oftener than every 30 minutes under the maximum
stop within 10 seconds after the compressor is
condition of 100 percent relative humidity and
temperature of intake air, and the minimum
stopped. A solenoid type valve shall not be used.
condition of 28 "F. cooling water temperature.
3. 3.19.3.2 The cooling system shall be pro-
3.3. 20.2 Each separator shall have a
tected from electrolytic action by the insertion of
drain connection at its low point leading to
replaceable zinc anodes designed to MIL-A-18001.
an automatic separator drain device mechan-
The zinc anodes shall have as large a surface area
ically or electrically timed to completely d.rain
as is practicable for maximum electrolytic protec-
each separator in sequence from first to final
tion without causing excessive turbulence. The
stage, Drainage from the automatic drain device
zinc anodes shall be easily removable for inspection
shall be led to an attached condensate accumulator
and replacement.
to be stored under pressure until all stages have
3. 3.19.3.3 The Bureau of Ships will give con-
been drained, after which the automatic drain de-
vice shall permit the pressurized accumulator to
sideration to a closed cooling system employing
discharge to ambient pressure through a single
liquids other than sea water, provided it can be
demonstrated that there will be a saving thereby in
drain connection on the compressor. This drain
weight or cost, or other definite advantages. In any
connection shall be suitable for attachment, either
case the ultimate heat sink will be sea water and the
directly or through flexible hose, to ships piping
heat exchanger shall be furnished integral with the
for drainage disposal. Means shall be incorpo-
compressor. If an alternate design is proposed,
rated for automatic discharge of the condensate
accumulator each time the compressor stops, in
then all departures from specification requirements
order to avoid full or partial pressurization of the
shall be thoroughly described giving reasons and
drain system during shut down.
advantages to be expected.
3. 3.19.4 Lubricating oil coolers furnished as
3.3.20.3 Each drain line between the separator
separate accessories shall conform to MIL-C-
and the automatic valve shall be provided with a
15730. Such coolers fabricated as an integral part
suitable sight flow indicator, a check valve to pre-
vent backflow during possible malfunction, and a
of the compressor shall conform to the basic re-
quirements of MIL-C-15730.
manually operated valve to bypass the automatic
device thus permitting manual drainage direct to the
3. 3.19.5 Air coolers. - Inter and aftercoolers
drain connection. Each element of the condensate
shall be of the straight-tube type, or of a type having
drain system, regardless of the stage, shall be
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