Specifications

60
16
SERVICE AND MAINTENANCE
Reliquefying Solid CO
2
In the event the Dura-Cyl HP/Cryo-Cyl HP loses pressure
and the contents become solidified, the following pro-
cedure should be used:
1. Locate and correct the reason for the pressure
loss; refer to the troubleshooting tables above.
2. Connect the proper gas source to the vent
valve on the frozen Dura-Cyl HP/Cryo-Cyl HP.
3. Open the vent and gas source valve on the
frozen liquid cylinder and monitor its pressure.
4. Pressure in a frozen Dura-Cyl HP/Cryo-Cyl HP
should rise to 60 psig (4.1 bar) and remain
there. When the pressure starts to rise above
60 psig, it is an indication that the solid has
reliquefied. Continue to raise the pressure to
200 to 300 psig (13.8 to 20.7 bar).
Note:
Depending on length of time contents have been
frozen, the time to reliquefy could last from six min-
utes to two weeks. This should be done as soon as
possible. It could take up to two full liquid cylinders
to reliquefy a fully solidified tank.
Changing The Service Pressure
The inner pressure vessels used in the Dura-Cyl/
Cryo-Cyl Series liquid cylinders are designed and
rated to a maximum operating pressure by the DOT.
All of the vessels have been proof tested for that rat-
ing. The maximum pressure rating is shown in the
specification, section 5, and on the liquid cylinders
data plate, figure G on page 10. DO NOT install a
relief valve with a higher pressure than specified.
Lower pressures are commonly used for limiting the
maximum pressure of the liquid.
The relief valve can be changed in the following manner:
1. Open the vent valve and release all pressure
from the vessel. If the liquid cylinder is in CO
2
service the vessel must be emptied of product.
2. Remove the relief valve. DO NOT attempt to
repair or reset the relief valve.
3. Remove the metal identification tag.
4.
Install the new identification tag and relief
valve; use oxygen compatible thread sealant
or teflon tape.
5.
Pressurize the container and leak test with
oxygen compatible snoop solution.
The following relief valve parts list shows the various
pressure settings that are offered. The relief valves
that are marked for CO
2
and N
2
O are specially
designed for those gas products.
Rego Relief Valve Generant Pressure Range
Part No. Part No. (PSIG)
1810012 11884770 22
1810022 – 35
1
810032 – 50
1810042 – 100
1810652 – 125
1811412 11884796 230
1810462 11884788 350
1812712 11892956 500
* Standard relief valves currently supplied are Generant.
The above Rego valves are also supplied upon request.
Changing Operating Pressure
The Dura-Cyl/Cryo-Cyl Series containers have preset
operating pressures and preset pressure building and
economizer regulators. These settings can be
changed using the procedures that follow.
For Dura-Cyl MCR with Combo Regulator in Gas
Service
When a container is dedicated to a gas withdrawal
service, change of operation pressure requires ad-
justment as follows.
1. Release pressure in the container by opening
the vent valve.
2. If the desired pressure setting is not within the
regulator's range the regulator will have to be
replaced as shown on page 62.
3. With liquid in the container, open the pressure
building valve and observe the pressure gauge
until it stops rising. The gauge will then indi-
cate the pressure control regulator setting.
4. Turn the pressure control regulator screw clock-
wise to increase the pressure. Use the calibrated
scale to approximate the desired setting. The
pressure gauge will stop rising at the new regulator
setting.
5. Continue adjusting the regulator until the desired
pressure has been reached.
6.
Vent the tank pressure and allow it to build up to
confirm the pressure setting.