CARE AND MAINTENANCE
A. GENERAL INFORMATION|
9A1. Checking the system. A regular routine
of checking a refrigeration system, or systems,
should be established to insure proper care and
operation. Make a systematic check every
two weeks of all pressures and temperatures
throughout the system. Such a check determines the need for any, corrective measures
before the condition becomes acute.
9A2. Opening a charged system. Whenever
it is necessary to open a fully charged system
for investigation or repair, the final evacuation should be to a pressure slightly above
atmospheric pressure (1 to 2 pounds' gage) to
prevent air from entering the system. If the
final pressure should reach a point lower
than zero pounds' gage, sufficient refrigerant
should be admitted to the evacuated part to
raise the pressure to between 1 and 2 pounds'
gage. Connections may then be broken, and
the necessary investigation or repairs made.
If more than a few minutes must elapse after
breaking the connections, the open ends of
the system should be plugged.
When connecting the part to the system
again, make one joint first and blow out the
part under investigation with gas from the
system, then quickly finish making up the
Refrigerant charging lines, although of small
size and short length, should be purged with
refrigerant gas immediately before actual
charging is started.
9A3. Purging air from system. After a system has been open for repair, it is advisable to
check for air in the system before proceeding
with regular operation. Either of two methods
may be used for checking for air. The preferred method is as follows:
1. Close the liquid king valve from the receiver.
2. Pump down the system to 5 inches of
NOTE. While pumping down, open the
circulating water valves wide in order to run
with the lowest possible head pressure and
to condense all condensable vapors.
3. Shut down the compressor.
4. Close the discharge valve on the compressor.
5. Close the stop valve from the condenser
to the receiver.
6. Attach a small hose to the air purge valve
on the condenser.
7. Insert the other end of the hose in a glass
jar or vessel filled with water or light Freon
8. Crack the purge valve on the condenser.
If air is in the system, large air bubbles will
show in the water. When all the air is out,
small bubbles will show in the water, and a
sharp cracking sound will be heard. These
small bubbles are Freon. The purge valve
should now be closed, and the system put into
The other method of testing for air in the
system is by observation of temperatures as
1. Operate the system for 30 minutes. Observe the pressure and temperature as indicated on the high-pressure Freon 12 gage.
2. Compare the temperature corresponding
to the discharge pressure, as noted in red figures on the dial of the pressure gage, with that
shown on the liquid. If it is more than 5 degrees lower than the temperature corresponding to the discharge pressure, the system
should be purged.
3. While the system is operating, purge air
by cracking the purge valve on the condenser.
Purge at intervals until the air is expelled from
the system. This is indicated by a temperature
difference of about 5 degrees.
9A4. Testing far leaks. If leakage is suspected in any of the joints or other parts,
use the testing procedure detailed in Section
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9C1. Cleaning evaporator coils. The evaporator coils of the refrigeration system should
be cleaned only with a clean dry cloth each
time the coils are defrosted.
9C1. Starting the compressor after a prolonged shutdown. IMPORTANT. Before
starting a Freon 12 compressor that has been
idle for some time, observe the height of the
oil level in the compressor crankcase. If the
oil level is above the oil sight bull's eye, a considerable quantity of Freon 12 has been condensed in the crankcase and absorbed by the
oil. The amount of Freon 12 mixed with the
oil depends upon the temperature of the oil and
the length of the shutdown period. The oil and
Freon 12 solution may entirely fill the compressor crankcase. If the compressor is started
under such conditions, the shaft seal diaphragm may be broken or the seal assembly
distorted. Excess oil and Freon 12 solution
may be drained from the crankcase by the following procedure:
1. Temporarily connect a 3/8-inch line from
the compressor oil drain valve to the suction
pressure gage valve.
2. Close the suction stop valve.
3. Open the oil drain valve and the suction
pressure gage valve; then slowly rotate the
compressor by hand. Do not start the compressor motor. Continue rotating the compressor by hand until the oil level can be
seen in the oil sight glass.
It is expected that oil which leaves the compressor crankcase will return to the compressor
during normal operation. However, after the
system has been placed in operation, check the
oil level over a period of several hours. Do not
allow the compressor to operate with a low
oil level in the crankcase.
9C2. Stop valves. If the stop valves on the
compressor are of the double packed type, the
valve stem is packed with a conventional
stuffing box and a steel cap is provided to
screw over the stem as a second seal against
leakage around the stem. This seal cap seats
on the top face of the valve body with a copper ring gasket or fiber gasket between.
9C3. Operation of stop valves. In order to
manipulate the stop valves, it is necessary to
remove the seal cap. To permit the valve
stem to operate freely, loosen the valve stem
packing gland. When opening or closing the
valve by means of a wrench on the valve stem,
or when tightening the internal packing gland
with a wrench, it is essential to exercise every
precaution not to scratch or otherwise mar the
gasket seat which is the top edge of the valve
body. Remember that valves made of brass are
soft as compared to the steel used in the
wrenches. Any scratches or burrs raised on
this gasket seat by careless operation of the
wrench are certain to impair the efficiency of
the gasket joint.
If a valve of this type is manipulated frequently, the gasket should be inspected occasionally to see that it is in good condition.
If this gasket shows signs of flattening or of
being scored, it should be renewed. The seal
cap over the valve stem should provide an
absolute seal against leakage, providing the
gasket surface is not damaged and providing
the gasket is in first-class condition.
IMPORTANT. Each time the valve is
manipulated, the packing gland should be
tightened, the seal cap drawn tight, and the
gasket joint tested for leakage.
CAUTION. If the internal packing gland
on the stop valve stems is not kept properly
tightened, it is possible in opening the valve
to back out the stem far enough to compress
this packing from the inside and thus raise
the valve stem higher than the normal full
open position. The seal cap might then bear
hard against the valve stem where the valve
is open farther than normal, before it would
seat properly on the gasket. Therefore, care
should be taken to see that the internal packing gland is tight, and that the valve is not
open farther than its normal full open position.
9C4. Difficulty of checking the oil level. As
stated in Section 7B16, the greater the amount
of Freon 12 absorbed by the oil, the higher
the apparent oil level. The amount of refrigerant in the mixture is greater after a prolonged
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shutdown period. Therefore, a check of the oil
level immediately after a prolonged shutdown
is worthless for determining the actual working oil level.
9C6. Best time to check the oil level. The
best time to check the oil level is after a prolonged period of operation, because then there
is the least amount of refrigerant mixed with
the oil. During the period of operation, the refrigerant is pumped out of the oil until only
the normal quantity remains in solution. This
check should be made with the compressor
9C6. Checking the oil level after a prolonged shutdown. If the apparent oil level is
observed after a prolonged shutdown period
and is above the sight glass in the side of the
compressor, it is a good indication that a
considerable amount of Freon 12 has been
absorbed by the oil while the compressor has
not been running. If this is the case, start the
compressor as described in Section 8B4. If the
oil level is lower than 1/4 up on the glass, it is
almost certain that the actual working oil
level is far too low. Add sufficient oil to raise
the oil level to 3/4 up on the glass in the side
of the crankcase. The compressor should now
be started and checked as described in Section
9C7. Checking the oil level when running.
To check the oil level when the compressor
has been running on its normal cycle with no
1. Wait until the end of a period of operation, or if the operation is continuous, wait
until it has operated at least half an hour.
2. As soon as the compressor stops, turn
the flywheel until the two tapped holes for the
flywheel puller are in a vertical line and observe the oil level in the bull's-eye sight glass.
It nay be necessary to wait a few minutes
until the oil settles in the crankcase.
The ideal oil level is from 1/2 to 3/4 up in the
glass, checked as outlined above.
CAUTION. Do not remove oil from the
crankcase because of an apparent high level
unless it is known that too much oil has been
added previously. If the oil level, checked as
above, is lower than 1/4 up the glass, add oil.
In adding oil, it is recommended that the level
be raised only 3/4 up the glass.
9C8. Adding oil. To add oil to the compressor
crankcase, use the small oil pump designed for
this purpose and proceed as follows:
1. Remove the protector cap from the end
of the oil pump and wipe the pump cylinder
2. Insert the oil pump into the can of oil to
3. Connect the pump discharge hose to the
compressor crankcase oil charging valve, but
do not tighten.
4. Hold the pump firmly, being careful not
to strike the bottom of the oil can hard enough
to puncture it. Displace the air in the oil pump
connections by several strokes of the pump
handle until oil appears at the oil charging
valve. Then tighten the flare nut attaching
the oil hose to the charging valve and open
IMPORTANT. Use Navy Oil, Symbol No.
2135, or equivalent.
5. Pump oil into the compressor crankcase
until the oil covers 4 of the bull's-eye sight
6. Close the charging valve tightly, replace
the valve seal cap, and disconnect the pump
hose, taking care not to spill oil on the deck.
Replace the flare seal cap on the oil charging
7. Place the protector cap on the oil charging pump when the pump is not in use.
NOTE. When steel or iron pipes and fittings are used for Freon 12 mains, condenser,
or evaporator, a sample of oil from the crankcase should be taken at least every six months,
and if it proves to be contaminated with scale
or foreign matter, all the oil must be removed.
If clean copper tubing is used for the Freon
12 mains, condenser, and evaporator, and reasonable care has been exercised against dirt
entering the system during its installation, the
oil in the compressor crankcase probably is
not contaminated sufficiently to require renewal between overhaul periods; but if the compressor is ever disassembled and left open to
the atmosphere longer than six hours, the oil
must be renewed, since it will have absorbed
sufficient water from the atmosphere to make
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renewal necessary. The cleanness of used oil
is easily determined by observation. Pour a
sample of oil into a glass and allow it to stand
for a few minutes until the oil foam has dissolved.
If particles of scale or foreign matter
are visible either on the surface or in suspension, the oil is dirty and should not be used,
Drain the crankcase and add new oil.
9D1. Condenser shutdown. If there is a
possibility of obtaining a freezing temperature
in the condenser compartment during the
shutdown period of any condenser, it is necessary that the condenser be thoroughly drained
of water, to prevent a freeze-up that would
damage the condenser tubes.
9D2. Cleaning the condenser. The condenser
tubes should be inspected every three months,
to determine whether or not cleaning is
All condensers should be cleaned before the
vessel leaves the harbor for war patrol.
To clean the condenser tubes, shut off the
water supply and discharge valves and drain
the tubes; then remove the heads.
Use a water lance and soft rubber plugs to
clean the condenser tubes. Care must be taken
that the protective film of corrosion-resisting
preparation on the inner surfaces of the tubes
is not destroyed during the cleaning process.
Inspect the zinc fingers at regular monthly
intervals. Renew the fingers when they show
30 percent deterioration.
These instructions have been taken from the
York instruction book, but in actual operation
it has been found that the condenser gives very
little trouble, and if the system has not been
operated in shallow waters, there is little
chance of the condenser becoming dirty. The
operating temperatures are low enough so that
scale does not form in the tubes. Unless there
is a definite indication that the condenser is
plugged up, it is opened only for inspection at
regular overhaul periods.
9D3. Defecting condenser leaks. In order to
prevent serious loss of refrigerant through
leaky tubes, it is advisable to test the condensers for leakage once every two weeks.
The test should always be conducted on a
condenser that has not been in use for at least
12 hours. There is always a small air pocket
in the top of the heads. Slowly open the vent
valves on the water side, one at a time, and
insert the exploring tube of a leak detector. If
this simple test shows the presence of Freon 12
gas, the exact location of the leak or leaks may
be determined as follows:
1. Remove the water heads and listen at
each section for the hissing sound that indicates gas leakage. This assists in locating the
section of tubes to be further investigated. If
the location is not definite, all the tubes must
be investigated. If the probable location of the
leaky tubes is determined, treat that section in
the following manner
2. Wash the tube heads, and with a cloth or
a ball of cotton, clean all the tubes (while wet)
until the inner walls are dry and shining; then
hold the exploring tube in one end of each
condenser tube long enough (about 10 seconds)
to draw in fresh air. As soon as fresh air is
drawn into the tube, drive a cork into each
end of the tube. Repeat this with all the other
tubes in the suspected section, or if necessary,
with all the tubes in the condenser. Then let
the condenser remain in this condition for 48
hours before doing anything further.
NOTE. It is against submarine instructions to have carbon tetrachloride on board.
However, the condenser may be overhauled or
tested outside the submarine. If the condenser
is being tested for leaks outside the submarine,
carbon tetrachloride should not be used in
cleaning the tube heads or tubes, as its fumes
give the same flame discoloration as Freon 12,
and serve only to confuse the investigation.
3. After the tubes have been corked up for
48 hours, get three men on the job, one to
remove corks at one end, one to remove corks
at the other end and handle the exploring
tube, and the third man to watch the color of
the flame in, the lamp. Start with the top row
of tubes in the section being investigated,
remove the corks simultaneously at each end
of the tube, and insert the exploring tube for
5 seconds; this is long enough to draw into the
lamp any Freon 12 gas that is bottled up in
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4. Mark any leaky tubes for later identification.
5. Leakage of any of the tube joints is indicated by the presence of oil at the joint after
tire 48-hour period.
The procedure described is a laborious one,
but it is the only method found to date that can
give conclusive evidence, and it has given satisfactory results in most cases in which it has
E. THERMOSTATIC EXPANSION VALVE|
9E1. Indications of need of cleaning. When
the thermostatic expansion valve is working
properly, the temperature of the pipe on the
outlet side of the valve is much lower than
the temperature of the pipe on the inlet side.
if this temperature difference does not exist
when the plant is in operation, it is an indication that the valve seat is dirty and clogged
with foreign matter.
9E2. Cleaning. If the valve seat is dirty or
clogged, the best remedy is to close the stop
valves on each side of the thermostatic expansion valve and remove the valve bonnet assembly from the valve body to obtain access to the
internal parts. Do not pinch the small remote
Use the manually operated bypass valve to
admit liquid to the evaporator coils during the
period required for repairs, being careful not
to open the bypass wide enough to allow liquid
Freon 12 to carry over to the compressor.
After the necessary repairs have been made,
be sure that all internal parts are thoroughly
clean and dry. Place the valve bonnet assembly
on the valve body and pull up the bolts hand
tight. Open slightly the stop valves on each
side of the thermostatic expansion valve long
enough to expel the air from the line, and bolt
the valve together securely.
After all connections have been made and
tested for leakage, close the manually operated
bypass valve tightly. Open the stop valves on
each side of the thermostatic expansion valve
and operate as usual through the thermostatic
F. SUCTION LINE STRAINER|
9F1. Cleaning the suction strainer. The suction vapor strainer in the suction line at the
compressor serves to prevent scale or foreign
matter from entering the compressor. To clean
the strainer screen proceed as follows:
1. Pump out the compressor.
CAUTION. Before the strainer is opened,
be sure the gage shows slightly above atmospheric pressure. Use accurate gages.
2. Mark the strainer body cover so that it
can be replaced in its original position. The
gasket should also be replaced in its original
3 Remove the strainer body cover, with
draw the strainer, and immediately replace the
cover on the strainer body to prevent foreign
matter or moisture from the air from getting
into the system.
4. Clean the strainer and spring by washing
them in approved cleaning solvent; dry them in
5. Clean the strainer seat inside the strainer
body, being careful to wipe out any particles
that may drop down into the strainer body.
Use only chamois or lint-free cloth. If this
strainer seat is dirty, the screen does not seat
properly and dirt may pass through into the
6. Reassemble the strainer in the body with
the spring in place.
7. See that the cover gasket is in good condition.
8. Bolt the cover on the body, drawing up
the capscrews evenly.
G. CARE OF V-BELTS|
9G1. Alignment and tension. To insure long
life and satisfactory operation of the V-belts,
the motor pulley and flywheel must be in exact
alignment and the belts must be under proper
The main steps used to align and apply the
V-belts are as follows:
1. Preparatory to aligning the drive, find
the magnetic center of the rotor. This may be
done by running the motor idle and measuring
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from the inside face of the motor pulley to
some fixed point on the motor frame. This
distance must be maintained during the alignment procedure.
2. Loosen the bolts that hold the motor to
3. Move the motor on the rail base forward
far enough for the belts to slip over the pulley
and flywheel without stretching.
4. Proceed with the alignment, keeping in
mind that the face of the motor pulley must
be parallel with the face of the flywheel, that
the belt grooves must be in alignment, and
that the rotor must be on its magnetic center.
5. By means of the adjusting screws on the
motor base, move the motor back until the
belts are reasonably tight. To have the proper
tension, a belt should have about a 1-inch
sag when applying thumb pressure halfway
between the pulley and the flywheel. When
this condition is obtained, tighten the bolts
holding the motor to the base. Belt dressing
should not be used on the belts and the belts
should never be cut and spliced.
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Copyright (C) 2004 Maritime Park Association
All Rights Reserved
Version 1.10, 22 Oct 04