With the vent valve closed, use the pressure build-up
contamination, the container must be drained and the
LOX wash test repeated.
coil to pressurize the container to 30 to 40 psig, and
then dump the LOX. Repeat this procedure for a total
PURGING.--When repeated LOX washing fails
of three cycles.
to decontaminate a LOX trailer, the trailer is shipped to
a depot-level activity that has the proper equipment to
Collecting a Sample for Testing.--With the vent
perform a hot nitrogen purge.
valve still closed, partially fill the container with
enough LOX to permit a sample of the liquid to be
Purging of aircraft converters is done locally. Part
withdrawn for analysis. The sample will be sent to a
of your job as an AS is to maintain the equipment that
"O" level activities use to purge aircraft converters
designated ABO test site, which may or may not be on
with hot nitrogen. This text covers the Aiel
board your station. Results are returned within 1
Corporation's aircraft liquid oxygen system gas
working day of submission.
purging set (fig. 10-11).
Samples are collected in the cryogenic sampler,
This LOX purging set is designed to use gaseous
shown in figure 10-10. Use and maintenance of the
nitrogen or gaseous oxygen for purging (oxygen is
sampler are covered in-depth in Cryogenic Sampler,
used only when nitrogen is not available). In the set, the
Model FCS 2001, AG-115SL-OMP-000.
gas is super heated by an electric heater to 225°F ±25°
If testing indicates that the LOX sample is
for the purging process. The hot gas is forced through
acceptable, the container may be filled and put into
the contaminated unit, where it mixes with the
service. If testing indicates an unacceptable level of
contamination and is vented to the atmosphere.
LO2 AND LN2
HOSE
CHARGING
ASSEMBLIES
MANIFOLD
(TWO HOSES)
ASSEMBLY
CYLINDER
ASSEMBLY
SAMPLE CASE
BASE / COVER
SPARES
KIT
ASf10010
Figure 10-10.--FCS 2001 cryogenic sampler.
10-20