however, they may become contaminated or burst and
After installing a new filter and purifier cartridge,
need to be changed early.
you should charge the nitrogen servicing cart and
check for leaks with leak detection compound.
CAUTION
VALVES AND OTHER COMPONENTS.--
Most valves on the nitrogen servicing unit are
Relieve all pressure from the nitrogen cylinders
considered not repairable; however, you may have to
before disconnecting any tubing and before
clean them with an approved cleaning solvent to
removing the filter element or purifier cartridge of
improve their functionality until a new replacement
desiccants. Disassemble only to the extent
item can be obtained.
necessary for replacing defective components.
CAUTION
Changing The Filter.--The filter, shown in figure
Do not allow dry-cleaning solvent to contact
9-10, can be removed by unscrewing the bowl and
rubber parts, as this causes rubber to deteriorate.
pulling it down. When installing a new filter, install a
Clean all metal parts with dry-cleaning solvent or
new O-ring in the bowl. Be careful not to overtighten
carbon tetrachloride. Remove hard crust and minor
the bowl. It is the O-ring that makes the seal, not the
corrosion with a bristle brush dipped in
tightness of the bowl.
dry-cleaning solvent. Then, wipe dry with a clean,
Changing The Purifier Cartridge.--When
lint-free cloth or dry with compressed air.
changing the purifier cartridge, shown in figure 9-11,
ensure that all pressure is relieved in the system and
Cracked lines are a common problem, and nuts
that all cylinder valves are closed. Replace all O-rings
often become corroded. After valves have been
at the time of cartridge replacement.
repeatedly opened too fast, a burst of high-pressure
nitrogen may cause a device to fail from the surge in
WARNING
pressure. Extreme cold or heat can also take a toll.
Never attempt to remove or install a purifier
Oddly enough, the most severe source of heat isn't the
cartridge until the unit is properly secured and the
sun, but jet exhaust. Occasionally, taxiing jet aircraft
components are relieved of pressure. Gases under
will stop in a position where the jet exhaust is pointing
high pressure, such as are encountered in this
toward a servicing cart. The rapid expansion of metal
equipment, are extremely dangerous to both
due to heating may cause a crack to develop.
personnel and equipment if improperly handled.
NOTE: Fluid Power, NAVEDTRA 14105,
contains a detailed discussion on the fundamentals of
HEAD
NIPPLE
O-RING
O-RING
ELEMENT
BACKUP
RING
VALVE
BOWL
SPRING
LOCK
WASHER
ASf09010
Figure 9-10.--Filter assembly.
9-16
