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The primary purpose of the equipment is the servicing of aircraft liquid oxygen converters.

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CAUTION: The TMU-70/M is to be used only for the
storage and transfer of liquid oxygen conforming
to II, Specification MIL-O-27210. The use of liquid oxygen handling equipment with other liquified gases may contaminate the equipment and make it unfit for use with breathing oxygen.

-

The TMU-70/M is a completely self-contained unit comprised of three major components: a 50 gallon dewar storage tank, a 15 liter dewar transfer tank, and a system of transfer lines and control valves. The three components are permanently mounted on a portable three-wheel trailer, equipped with a
manually operated parking brake system and retractable caster wheel. The storage and transfer tanks are equipped with liquid level gages and pressure relief devices.

-

Working Pressure
Storage Tank 50 psig
Transfer Tank 90 psig

Relief Valve Settings
Storage Tank Vent Line 50 psig
Fill Line 75 psig.
Transfer Tank Vent Line 90 psig

Safety Device Burst Pressure
Storage Tank 75 psig.
Transfer Tank 120 psig

-

STORAGE TANK. The storage tank is a 50 gallon
(U.S.) capacity, double-walled dewar. The space between the double walls of the storage and transfer tanks is evacuated and contains a multilayer, high vacuum insulation.

-

TRANSFER TANK. The transfer tank is a 15 liter
capacity, double-walled dewar and is permanently attached to the storage tank. The transfer tank is gravity-filled from the storage tank. The transfer tank is self-contained and operates independently of the storage tank after filling. The transfer tank is equipped with a pressure buildup coil, relief
valve, rupture disc, level indicator and controls.

-

TRANSFER LINES. The transfer lines carry the
liquid from the storage tank to the transfer tank and then to the converter. The transfer lines also carry the vented oxygen gas from the converter back to the storage tank. The closed loop of the transfer lines contains the vented oxygen gas to avoid venting large volumes of gas during converter filling operations. The interconnecting liquid and return gas lines are vacuum-jacketed transfer lines wherever practical. These lines are of minimum length to
reduce cool-down and heat leak losses.

-

PIPING SYSTEM. The piping system consists of
(1) a fill line for filling the storage tank, (2) a vent system for overboard venting of excess liquid or gas, and (3) a pressure relief valve system which is connected to the vent piping system.

-

STORAGE TANK PRESSURE GAGE. The pressure gage indicates the pressure in the inner storage tank. The gage is calibrated to read from 0 to 100
psig. Safe operating pressure of 0 to 50 psig is indicated by a green band on the gage face. Unsafe pressure of 50 to 100 psig is indicated by a red band.

-

STORAGE TANK LIQUID LEVEL GAGE. The liquid level gage directly indicates the level of liquid oxygen in the inner tank when the tank is sitting level on a level surface. The gage dial is magnetically and
mechanically coupled to a float sensor inside the storage tank. The gage is calibrated in gallons. Safe operating level of up to 50 gallons is indicated in green; unsafe operating level of more than 50 gallons is indicated in red.

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CONVERTER VENT LINE SHUTOFF VALVE. The vent valve controls the flow of oxygen gas vapors from the converter being filled to the storage
tank and prevents the loss of storage tank gas when a converter is not being filled.

-

TRANSFER TANK VENT LINE SHUTOFF VALVE.The vent valve controls the flow of oxygen gas vapors from the transfer tank to the vapor space
of the storage tank.

-

TRANSFER TANK FILL LINE SHUTOFF
VALVE. The valve is used to control the gravity flow of liquid oxygen from the storage tank to the
transfer tank.

-

TRANSFER TANK PRESSURE BUILDUP
VALVE. The pressure buildup valve controls
the flow of liquid oxygen from the bottom of the
transfer tank to the pressure buildup coil (PBU). The PBU coil is a heat exchanger where the liquid oxygen is exposed to ambient temperature and is converted to gas. As the liquid changes to gas it expands. The output gas of the PBU coil is fed back to the transfer tank vapor space, providing pressure to discharge liquid to the converter. This valve is open only when pressure is required to fill the converter.

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TRANSFER TANK LIQUID LEVEL GAGE. The liquid level gage indicates the level of liquid oxygen in the transfer tank. The gage is magnetically and mechanically coupled to a float sensor inside the
transfer tank. The gage is calibrated in percent of full.

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TRANSFER TANK PRESSURE GAGE. The pressure gage indicates the pressure in the
transfer tank. The pressure in the transfer tank must be greater than the pressure in the storage tank to effect transfer of liquid since the converter is vented into the storage tank during converter fill operations. The gage is calibrated to read from zero to 160 psig. Safe operating pressure of 0-90 psig is indicated by a green band; unsafe pressure of 90 to 160 psig is indicated by a red band.

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CONVERTER FULL INDICATOR GAGE. The full indicator gage (marked LIQUID-GAS) is a vapor pressure thermometer that monitors the converter
vent line temperature. During transfer of liquid to a converter the gage indicates GAS temperature in the converter fill line. When the converter is full, the vent line is filled with liquid oxygen overflow. The converter vent line temperature drops and the gage indicator moves to the LIQUID position that indicates a full converter.

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CAUTION: The fill-drain line shutoff valve is not used to control flow. Restricting transfer flow may
create a dangerous back pressure on the supply
line used for filling. Control of transfer flow
shall be maintained with the service valve of
the central supply tank.

-

FILL-DRAIN LINE SHUTOFF VALVE . The fill valve is used during the storage tank filling operation to permit the flow of oxygen from a central supply tank. The shutoff valve is opened completely during the filling function and then closed after the transfer
has been completed.

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STORAGE TANK VENT LINE SHUTOFF
VALVE. The vent valve is used to control the release of gaseous vapors from the storage tank to the
vent piping manifold. The valve is open during filling to vent all pressure from the storage tank. During normal idle storage, the valve is left in the open position to vent all vapors generated by normal liquid oxygen boil off. In flight line service, the valve is left closed to prevent oxygen contact with flammable liquids or vapors.

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PROPERTIES OF LIQUID OXYGEN.
- Liquid oxygen is a pale blue, nonviscous water-like
fluid. Liquid oxygen boils at -183 degrees Celsius (-297 degrees Fahrenheit). At atmospheric pressure it is 1.14 times heavier than water and weighs 9.527 pounds per gallon.

- Liquid oxygen, when converted to gaseous oxygen
at ambient temperature, expands to about 860 times its original volume.

--

WARNING: Observe all safety precautions to assure safe and easy handling of cryogenic liquids.
NAVAIR 06-30-501, NAVAIR 00-80T-96.

-

LIQUID OXYGEN HANDLING PRECAUTIONS.
- The following precautions must be observed when handling liquid oxygen.

a. Never allow liquid oxygen to contact the skin. The
extreme low temperature of the liquid quickly freezes the area and severe frost bite results. If the skin is splashed with the cold liquid, immediately flush the area with cold water and then obtain medical attention.

b. Always store liquid oxygen with the vent valve
open. Relief valves furnished on the tank are provided to protect the tank in case of malfunction and are not to be used as pressure regulators.

c. Never confine liquid oxygen in any piping or
container without adequate safety devices. The pressure built up when the liquid expands to gas will rupture most piping, tubing or containers.

d. Comply with all safety directives. Fifty feet has
been established as the safe distance criterion for oxygen equipment. Assure painting and markings on the tank are maintained as required. Oxygen gas does not burn but it supports combustion of any material that burns.

e. Keep liquid oxygen away from absorbent
materials, loose clothing or rags. These materials can trap oxygen gas and later be ignited by a spark, cigarette or match.


f. When liquid oxygen equipment is in use, keep it in
a well-ventilated area away from all gasoline, kerosene, oil, grease and other hydrocarbons. These substances are not compatible with liquid oxygen. Spontaneous ignition may result from contact with these substances.

g. Always wear required protective clothing when
handling cryogenic fluids.

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Principles Of Operation
- The annular space between the double walls of the
storage tank and internal transfer lines is evacuated to 5 microns or lower. The evacuated space contains a multilayer high vacuum insulation to minimize heat gain and boil off of the liquid oxygen.

- The TMU-70/M closed loop transfer system is
designed to retain oxygen vapors caused by heat gain during transfer to the aircraft converter. The gaseous oxygen vapors vented from the transfer tank and the converter are returned to the storage tank for cool down and retention.

-

FILLING. The storage tank is filled from a central
supply tank through fill-drain line coupling C-1. The input LOX flows through filter LF-1 (2) and shutoff valve LV-1 (3) to the storage tank. Relief valve RV-3 (4) is provided to prevent excessive pressure if the
fill drain line shutoff valve and the service valve of the
central supply tank are closed with cold gas or liquid
trapped within the supply line. The relief valve RV-3 is connected to the vent line discharge for safe discharge overboard. Vent valve GV-6 (5) is opened during filling and normal storage where safe overboard discharge is provided. Storage tank conditions are monitored and indicated by liquid level gage LG-1 (6) and pressure gage P-1 (7). Relief valve RV-1 (8) and rupture disc SD-1 (9) are provided in case of excessive pressure in the storage tank.

-

TRANSFER. The flow of LOX from the storage tank
to the aircraft converter is accomplished as follows.

- The liquid oxygen flows by gravity through transfer
tank fill line shut-off valve LV-2 (10) to the transfer tank. During the process of filling the transfer tank, the gaseous oxygen produced by cool down of the tank is vented back to the storage tank through vent valve GV-3 (11). Transfer tank conditions are monitored and indicated by pressure gage P-2 (12) and liquid level gage LG-2 (13). Relief valve
RV-2 (14) and rupture disc SD-3 (15) are provided in case of excessive pressure in the transfer tank. When the transfer tank is filled to the desired level, as indicated by liquid level gage LG-2, valves LV-2 and GV-3 are to be manually closed.

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The transfer tank is equipped with a pressure
buildup (PBU) coil. The PBU coil is used to increase the pressure in the transfer tank to the converter. The PBU coil is operated by opening transfer tank pressure buildup valve GV-5 (21). As LOX flows through the PBU coil, it changes to vapor and expands to create pressure in the transfer tank
and increase LOX flow to the converter. The transfer tank pressure is raised to approximately 90 psig; converter vent line shutoff valve GV-5 is regulated as required to maintain as much transfer pressure as possible.

-

- A liquid sensing element in the converter full
indicator gage F1 (19) indicates when the converter is full by sensing LOX overflow from the converter. The overflow is returned to the storage tank.

- Disconnect the filler valve C-2 (17). Close transfer
tank pressure buildup valve GV-5 (21), if necessary, and vent valve GV-4 (20). Bypass check valve CV-1 (18) opens to prevent pressure buildup when
vent valve GV-4 (20) is closed and vent line connector C-3 (16) is still connected. Vent line connector C-3 is then disconnected.

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- The preceding process is repeated until storage tank pressure approaches the operating pressure, as indicated on storage tank pressure gage P-1 (7), or the LOX supply is exhausted.

- Relief valves are installed to relieve excessive
pressure in the storage tank and transfer tank. The relief valves are set to operate at a predetermined pressure. In case of a malfunctioning relief valve, rupture discs are installed as a backup safety precaution. The evacuated annular space of the storage tank is protected against pressure buildup (due to inner shell leakage) by outer shell relief device SC-2 (22).

-

NOTE:
Refer to NAVAIR 13-1-6.4 for assembly instructions
of test pressure gage/relief valve test
fixture. The test pressure gage relief valve test fixture
shall be forwarded to the intermediate maintenance
activity every 6 months for pressure gage calibration and relief valve adjustment and leakage test.

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WARNING:
The rate of pressure buildup depends on the
liquid level in the transfer tank. On a full transfer tank, the pressure will build extremely fast because of the small amount of vapor space to be filled. Use extreme caution in building the pressure and never allow the pressure to exceed 90 psig. If observation of the rate of pressure buildup indicates it will exceed 90 psig, open transfer tank vent valve GV-3 (11) to relieve the pressure into the storage tank. This will
avoid the unnecessary opening of relief valve
RV-2 (14) and the resultant undesirable discharge
of gaseous oxygen from the vent line.

-

NOTE:
When disconnecting servicing trailer "NOTE
TIME" time noted is beginning of buildup time
test. Immediately attach pressure gage/relief
valve test fixture. Observe pressure gage,
record time it takes converter assembly to build
to a working pressure of 55 to 90 psig, max. time shall not exceed 5 minutes.

-

WARNING:
Increased pressure can occur from multiple
transfers to converters.

-

WARNING:
If pressure fails to stabilize, drain the LOX converter and forward to intermediate maintenance for unscheduled maintenance.

-

CAUTION:
Open storage tank vent line shutoff valve GV-6
(5). If there is no indication of storage tank pressure, the unit must be purged prior to filling with LOX.

-

WARNING:
Do not position the TMU-70/M on macadam
(black top) surface.

-

CAUTION:
Pressure should not be allowed to rise above 50
psig in the storage tank. Monitor storage tank
pressure gage P-1 (7) closely during cool down.

-

NOTE:
Observe the time required to fill the storage tank. Filling time varies with each supply tank and supply line system. However, with a transfer pressure of 30 psig and under normal conditions, the storage tank should be filled within a period of five to ten minutes. Each using activity should determine an average time with the equipment at hand. Abnormal deviation
from the average filling time should be cause for investigation.

-

CAUTION:
Use extreme caution when disconnecting the
transfer hose. Even though the hose has been
drained and pressure relieved, some LOX will
still remain. Do not direct the hose toward
personnel or equipment.

-

WARNING:
Vent the TMU-70/M overboard off to a safe area
where oxygen vapors from the vent manifold will not
contact flammable materials or cause a hazard to personnel.

-

NOTE:
All parts of the TMU-70/M are designed to resist and are protected from corrosion. No further protection is required or should be attempted.

-

WARNING:
To protect against damage or injury, ensure that
areas onto which LOX is discharged are free
from all hydrocarbons (oils, greases, lumber or
wood, macadam, grass, etc.). Hydrocarbons are
not compatible with LOX and spontaneous
combustion or explosion may result. Observe
all safety precautions including the wearing of
protective clothing to prevent bodily contact
with LOX or surfaces cooled to subfreezing
temperatures.

-

WARNING:
When the storage tank LOX level is low, do not
raise the lunette end of the storage tank to fill
the transfer tank. Foreign particles in the bottom of the storage tank may be introduced into the transfer tank.

-

WARNING:
Ensure transfer and storage tanks are empty prior to steam cleaning

-

CAUTION:
Do not tighten joints or flanges while tank is under pressure or while component is below approximately 32 degrees Fahrenheit (freezing temperature).

-

The system must not be left open to the atmosphere
for extended periods of time unless the entire system is to be cleaned. In order to preserve the integrity of the equipment, it must be free of contamination. Always protect open systems against possible contamination. Use clean polyethylene bags and sheet material, and polyethylene pressure sensitive tape to wrap and seal all disassembled
parts, subassemblies and assemblies. If possible store disassembled items in a clean room until required for assembly.

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TROUBLESHOOTING

-

PRESSURE GAGE INDICATES ABOVE NORMAL

Probable cause:
- Pressure relief valve not operating. This is a dangerous condition and immediate action must be taken to vent the excess pressure. Pressure gage indicating incorrectly.
Pressure buildup valve GV-5 in open position.

Checking Procedure:
- Visually check pressure relief valve.
- Check calibration.
-Check pressure buildup

Remedy:
- Replace valve.
- Calibrate or replace gage
- Close valve

TANK BURST DISC BLOWS AT LESS THAN
RATED PRESSURE

Probable cause:
- The applicable pressure relief valve has failed to
operate.
- Incorrect or faulty burst disc.

Checking Procedure:
- Check valve setting.
- Compare with replacement disc.

Remedy:
- Replace disc.

PRESSURE GAGE MALFUNCTION

Probable cause:
- Ice or foreign matter in line.
- Gage incorrectly calibrated. Gage defective

Checking Procedure:
- Disconnect gage line and visually inspect.
- Determine that calibration is impossible.

Remedy:
- Remove line and clean. Dry entire system.Calibrate.
- Replace.

EXCESSIVE FROST OR CONDENSATION ON
LINES

Probable cause:
- Automatic opening of relief valve.
- Tank not level. Piping end down.
- Valves leaking.
- Vacuum deterioration

Checking Procedure:
- Wait to see if condition is temporary.
- Visual.
- Check for escaping gas.
- Check evaporation loss rate

Remedy:
- Abnormal condition will disappear.
- Level tank or put piping end up.
- Repair or replace.
- Locate and repair leak and reevaluate tank.

BURST DISC FAILS TO BLOW ABOVE RATED
PRESSURE

Probable cause:
- This is a dangerous condition. Lines are obstructed by foreign material or ice. Also the applicable pressure relief
valve has failed to operate. Reduce pressure by opening
vent valve.
- Wrong burst disc assembly.

Checking Procedure:
- Check lines for foreign material. Check setting of
pressure relief valve.
- Compare with replacement disc assembly.

Remedy:
- Clear or thaw lines. Replace relief valve.
Purge entire system.
- Replace with correct disc assembly.

PRESSURE RELIEF VALVES DO NOT OPEN
ABOVE RATED PRESSURE

Probable cause:
- Pressure gage faulty or incorrectly calibrated.
- Valve faulty or incorrectly set.
- Valve frozen

Checking Procedure:
- Check calibration.
- Build up tank pressure and recheck valve.
- Visual or manual.

Remedy:
- Perform calibration procedures. If gage cannot be calibrated, replace.
- Replace relief valve.
- Thaw valve.

PRESSURE RELIEF VALVES OPEN AT LESS
THAN RATED PRESSURE

Probable cause:
- Pressure gage faulty or incorrectly calibrated.
- Relief valve faulty or incorrectly set.

Checking Procedure:
- Check calibration.
- Build up tank pressure and recheck valve.

Remedy:
- Perform calibration procedures. If gage cannot be calibrated, replace.
- Replace relief valve

EXCESSIVE RELIEF VALVE LEAKAGE BELOW RESEAL PRESSURE (36 psig for P/N 22385, 54 psig for P/N 22387, and 71 psig for P/N 2236 and 22386-1)

Probable cause:
- Ice in valve seat.
- Foreign material or object lodged in valve.
- Faulty relief valve.

Checking Procedure
- Bubble check relief valve outlet.

Remedy:
- Warm valve to ambient temperature.
- Replace relief valve

VALVE SEAT LEAKING

Probable cause:
- Valve not fully closed.
- False indication. Leakage is in another part of system.
- Ice or foreign material lodged in valve seat.
- Valve seat warped or worn

Checking Procedure
- Check system carefully.
- Disassemble as far as possible to determine if valve is leaking.
- Empty system and warm interior to ambient.
- Disassemble valve and examine seat thoroughly.

Remedy:
- Disassemble valve and examine seating surfaces
thoroughly.
- Purge entire system.
- Replace removable seat. Lap seat if necessary.

LEAKING VALVE STEM PACKING

Probable cause:
- Valve packing loose.
- Loose packing spring (toggle valves).

Checking Procedure:
- Visual.
- Check packing spring adjustment

Remedy:
- Tighten packing nuts.
- Readjust packing spring

VALVE STEM PACKING LEAKS AFTER TIGHTENING PACKING NUT OR ADJUSTING
PACKING SPRING

Probable cause:
- Packings excessively worn

Checking Procedure:
- Disassemble valve and examine thoroughly

Remedy:
- Replace packing.

VALVE STICKING OR HARD TO TURN

Probable cause:
- Bent or damaged valve stem.
- Ice or foreign material lodged in valve stem.

Checking Procedure:
- Disassemble and examine carefully.

Remedy:
- Repair or replace faulty parts.
- Clean and dry parts carefully before reassembly

COUPLINGS WILL NOT MATE WITH COUPLINGS ON OTHER EQUIPMENT

Probable cause:
- Ice or other foreign material on mating surfaces.
- Improper couplings on mating equipment

Checking Procedure:
- Visual.
- Check coupling applicability.

Remedy:
- Thaw out and examine carefully.
- Use mating equipment or install proper couplings

COUPLINGS LEAK OR CANNOT BE REMOVED
FROM MATING EQUIPMENT

Probable cause:
- Worn couplings.
- Lines twisted and binding couplings.
- Coupling iced up internally.

Checking Procedure:
- Examine carefully.
- Relieve tension.
- Thaw with warm water or allow to warm naturally.

Remedy:
- Replace worn parts. Reorient mating lines to
eliminate binding.
- Purge couplings and lines thoroughly.

BRAKES NOT APPLIED EVENLY, DO NOT LOCK
OR DRAG WHEN RELEASED

Probable cause:
- Brakes improperly adjusted.
- Brake shoes worn out. (Brake in ON position while towing unit).
- Brake mechanism twisted, bent or broken.

Checking Procedure:
- Remove wheel and brake drum and inspect linings.
- Visually inspect handbrake and cross shaft assembly.

Remedy:
- Adjust per handbrake assembly procedure.
- Replace worn or defective parts.
- Repair or replace

WHEELS NOISY, TEND TO WOBBLE OR SWAY,
OR TRAILER DOES NOT TRACK PROPERLY

Probable cause:
- Wheel bearings loose or worn.
- Brake shoes dragging.

Checking Procedure:
- Disassemble wheel assembly as required per disassembly
procedure and examine for faulty or worn parts.

Remedy:
- Adjust or replace worn or faulty parts as required. Assemble and repack per assembly procedure.

LIQUID LEVEL GAGE DOES NOT INDICATE

Probable cause:
- No liquid in tank. Liquid level very low.
- Level gage float damaged, jammed or frozen on bottom
of tank.
- Level gage travel stop is worn or float arm is bent.
- Level gage float gears jammed with ice or foreign
material.
- Defective dial gage.
- Level gage shaft or magnetic coupling defective.

Checking Procedure:
- Verify liquid in tank.
- Tap lightly on flange where level gage enters tank.
- Remove level gage dial, loosen level gage flange
bolts, and gage to free float.
- Remove level gage dial, loosen level gage flange
bolts, and shake gage to free float.
- Remove dial gage and gage mount. Place gage back into
position without mount.
- Rotate gage to check operation of magnetic coupling movement. Drain tank, remove gage mechanism, and operate
mechanism manually. Check magnetic coupling operation.

Remedy:
- Refill as required.
- Drain tank, remove level gage mechanism and inspect
carefully.
- Replace parts as required

STORAGE TANK FILLING TIME ABNORMALLY LONG

Probable cause:
- Central supply pressure too low or transfer line unable
to deliver sufficient liquid. Ice or foreign material obstructing fill line filter. Fill, vent or supply valve not fully opened.

Checking Procedure:
- Check out storage transfer system carefully. Refer to
supply tank manual. Remove and inspect filter carefully. Check valves carefully.

Remedy:
- Thaw and clean or replace as required. See previous
procedure on leaking, sticking or hard to turn valves.

TRANSFER TANK FILLING TIME ABNORMALLY LONG

Probable cause:
- Storage tank does not contain enough liquid. Pressure buildup valve open. Storage tank not level.
- Transfer tank fill and vent valves not fully open or defective.
- Operator using wrong filling procedure.
- Defective liquid level indicator.

Checking Procedure:
- Check storage tank liquid level.
- Check attitude of trailer.
- Check valve position and adjustment or disassemble
and examine.

Remedy:
- Fill storage tank.
- Close pressure buildup valve.
- Level unit as required for filling.
- Adjust or replace as required.
- Repeat fill procedure following operating instructions carefully.

TRANSFER TANK DOES NOT PRESSURIZE
WITHIN TWO MINUTES

Probable cause:
- Transfer tank fill or vent open.
- Liquid level in transfer tank low.
- Pressure buildup line excessively frosted from recent or frequent use.
- Faulty pressure gage.
- Transfer tank relief valve leaking.
- Transfer tank rupture disc leaking or blown.
- Transfer tank fill valve leaking. Transfer tank vent line valve leaking.
- Converter vent line check valve leaking. Gross external leak.

Checking Procedure:
- Check valve positions.
- Check liquid level.
- Make visual inspection.
- Check gage calibration.
- Close storage tank vent valve and check for gas into vent manifold.
- Close storage tank vent valve and check for gas leakage into vent manifold.
- Close storage tank vent valve and monitor storage tank pressure gage for pressure buildup.
- Check for gas venting from converter vent line coupling.
Make visual inspection of transfer tank and all piping. Make bubble check.

Remedy:
- Close valves.
- Fill transfer tank as required.
- Thaw piping or allow to warm to ambient temperature.
- Replace gage as required.
- Replace relief valve.
- Replace rupture disc assembly.
- Drain tank. Disassemble fill toggle valve and inspect
carefully for worn or damaged seat.
- Replace check valve.
- Repair as required.

CONVERTER DOES NOT FILL WITHIN FIVE
MINUTES

Probable cause:
- Pressure buildup valve not open.
- Converter fill coupling valve not fully actuated.
- Converter vent line shutoff valve not fully open.
- Low transfer tank liquid level.
- Defective converter.
- Defective converter full indicator.

Checking Procedure:
- Open valve fully.
- Disconnect and reconnect fill coupling, making sure
valve is actuated.
- Check for proper operation of valve.
- Check transfer tank liquid level.
- Fill test another converter. Check operation of indicator
per following procedures

Remedy:
- Fill transfer tank.
- Replace if defective

CONVERTER FULL INDICATOR DEFECTIVE

Probable cause:
- Faulty indicator gage.
- Faulty converter full indicator assembly. (Assembly has lost oxygen charge.)

Checking Procedure:
- Check operation of gage during converter filling. Indicator needle should point to a position corresponding to 3 or 4
o'clock on full indicator dial when assembly is at ambient
temperature. Remove assembly and check at ambient temperature.

Remedy:
- Replace converter full indicator assembly

STORAGE TANK FAILS EVAPORATION LOSS
TEST

Probable cause:
- Tank boil off high due to recent filling.
- Transfer tank fill or vent valve open or leaking.
- Transfer tank full at beginning of test.
- Scale used to weigh tank inaccurate.
- Vacuum deterioration.

Checking Procedure:
- Recheck after 24 hour period.
- Check for properly closed and adjusted valves.
- Check transfer tank liquid level gage.
- Check scale calibration and repeatability.
- Check for vacuum leak per paragraph 4-196.

Remedy:
- Drain transfer tank and retest.
- Retest.
- Repair leak and evacuate tank. Retest

As an added precaution, the TMU-70/M may be shipped with a positive pressure not to exceed 25 psig.

...

Do not position on macadam (black top) surface.


Ensure transfer and storage tanks are empty prior to steam cleaning.

Ensure that the unit is empty and purged before welding.

Caster: Inflate tire to 12-15 psi

Use teflon tape on all pipe threads; start tape on the third thread to prevent contamination

...

Clean all parts that will come in contact with liquid oxygen in accordance with Oxygen Nitrogen Systems Manual, NAVAIR 06-30-501

Use Ultrasonic Cleaning System in accordance with NAVAIR 06-30-501 for the cleaning of components that come in contact with liquid oxygen.

Cleanliness inspections are performed after the tank has been filled with liquid nitrogen.

...

DO NOT raise the transfer tank pressure above
106 psig as the rupture disc may rupture
causing the entire unit to be disabled.

...

Do not tighten joints or flanges while tank is under pressure or while component is below approximately 32 degrees Fahrenheit (freezing temperature).

...

Prior to maintenance on the liquid system unit,
it must be purged using the procedures addressed in paragraph 3-32.

...

The system must not be left open to the atmosphere
for extended periods of time unless the entire system is to be cleaned. In order to preserve the integrity of the equipment, it must be free of contamination. Always protect open systems against possible contamination. Use clean polyethylene bags and sheet material, and polyethylene pressure sensitive tape to wrap and seal all disassembled parts, subassemblies and assemblies. If possible store disassembled items in a clean room until required for assembly.

...

The exterior should be inspected for the presence of
hydrocarbons prior to entry into the liquid oxygen or
vacuum systems.

...

When jacking main wheels only jack one side at a time.

...

Inspect bearings in accordance with NAVAIR
01-1A-503.

...

Adjustment of the relief valves in the liquid oxygen system is not recommended because of the high
safety hazard involved. If a relief valve does not operate as described in paragraph 4-29, the valve must be replaced.

...

Ensure that the unit is empty and purged before
welding.

...

SURFACE PREPARATION. All surfaces to be
painted shall be cleaned free from dirt, grease, oil, solder flux, welding flux, sand, visible rust, scale or oxide, and all other debris that might interfere with the intimate application of the finish. Sandblasting is the preferred method of cleaning. Grinding, chipping, scraping and solvent cleaning may be necessary before sandblasting. Sandblast to near white condition.

...

Hydrocarbon contamination, if noted by ultraviolet light inspection, should be removed by steam
cleaning or by wiping with a lint-free cloth moistened with solvent (MIL-PRF-680).

...

The following moisture test procedure shall be
performed only after overhaul and/or cleaning
per the applicable procedure. The condition of
the storage tank should be empty of LOX and
warmed to ambient temperature.

...

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