Specifications

15
TROUBLESHOOTING
55
The troubleshooting section of this manual deals with
the normal operating conditions and the problems that
may occur with the Dura-Cyl/Cryo-Cyl Series liquid
c
ylinders. The troubleshooting guide assumes that the
tank is in its normal operating environment having a
cooled down inner vessel and a reasonable vacuum.
Before troubleshooting an operational problem, the
liquid cylinder should be examined for vacuum.
Loss of Vacuum
The loss of vacuum on a liquid cylinder is usually as-
sociated with excessive cylinder frosting or rapid
pressure rise. Excessive pressure rise, however, can
be normal. A new liquid cylinder or one that has not
been used recently is considered to have a warm in-
ner vessel. Warm cylinders will build pressure fast
after filling and vent off the excess. A liquid cylinder
that has been filled and not used will build pressure
and vent the excess off. The higher the pressure was
in the storage tank at the time of filling the faster the
liquid cylinder will vent off.
Excessive pressure rise can also be an indication of
vacuum loss. The Dura-Cyl/Cryo-Cyl Series liquid
cylinders are equipped with a pump-out plug that is
expelled from the pump-out body if there is a loss of
vacuum. This indicates an inner vessel leak. The
pump-out body and plug are covered by a black plas-
tic cap to protect them from the environment and
tampering. If it is determined that the pump-out plug
is properly seated in the pump-out body, but a loss
of vacuum is still suspected, an evaporative loss rate
test should be performed.
Vented Evaporation Loss Test
The vented evaporation loss test should be used on
liquid cylinders that are in nitrogen, oxygen or argon
service. It should be done over a period of 3 to 4 days.
1. Fill the container to the half full mark using the
same product the container previously contained.
2. Verify that the pressure building, gas use, and
liquid withdrawal valves are all closed.
3. Allow container to vent for approximately 24 hours.
4. Weigh the container as accurately as possible.
5.
Allow the container to continue venting for an
additional 48 hours.
6. Weigh the container as accurately as possible.
7. Calculate the difference between the two weights
obtained in steps 3 and 5. A weight loss of more
than 16 lbs. (7.3 kg) in 48 hours is considered
e
xcessive; contact your local Chart distributor or
the factory for appropriate disposition.
8. If the weight loss is not excessive, proceed
with pressurized evaporation loss test.
Pressurized Evaporation Loss Test
The pressurized evaporation loss test should be
used on liquid cylinders that passed the vented loss
test or are in CO
2
or N
2
O service. It will take longer
than a vented test since the pressure must rise by
evaporation only.
1.
Pressurize the unit to 50 psig (3.4 BAR) and
check for any plumbing leaks.
2. Vent and then fill the unit with it's designated
service product. Maintain pressure in the liq-
uid cylinder while filling. Do not vent after filling.
3. Verify that all valves are tightly closed.
4. Observe pressure rise to relief valve setting.
(This could take up to 6 days for a typical cylinder.)
5. Once the unit is at relief valve pressure, weigh
it as accurately as possible.
6. Check weight a second time after 24 hours.
7. Calculate the difference between the two weights
obtained in steps 5 and 6. A weight loss of more
than 10 lbs. (4.5 kg) in 24 hours is considered
excessive; contact your local Chart distributor or
the factory for appropriate disposition.
8. If the weight loss is not excessive, the liquid
cylinder is considered to have the proper vacuum
level.
Follow the troubleshooting guide and the repair
procedures found in section 16. If there are any
other questions, contact Chart's Technical Service
Department at:
1-800-400-4683
1-952-758-4484