|
OPERATING
INSTRUCTIONS FOR CMC/CRC DISCHARGE DEVICE
Introduction
The Cryofab
CMC/CRC Discharge Device is designed to facilitate withdrawal
of cryogens from Cryofab CFN and CFL Series dewars. The device
consists of a manual shut-off valve (CMC only), or solenoid
valve (CRC only), a manual pressurizing valve, a pressure
gauge and 10 psig relief valve.
Installation
The Discharge
Device may be installed in a dewar whether it is full or empty
by placing the seal on the dewar flange and inserting the
siphon tube down the neck tube of the dewar. If the dewar
is full, use caution and insert the tube slowly. Once in place,
fasten the device to the dewar with the wing nut clamp provided.
Close the liquid valve (top) and leave the vent valve (lower)
open unless another operation is planned. For the CRC Discharge
Device, plug the power cord of the solenoid valve into the
appropriate outlet of the controller.
WARNING
Never
loosen the wing nut clamp unless the dewar is completely depressurized.
Filling
The recommended
and safest way to fill the dewar is to remove the Discharge
Device completely. Then attach a suitable transfer line to
a pressurized liquid source and insert the discharge end of
the line, terminating with a tube extension, down the neck
of the dewar. To prevent the transfer line from being ejected
during the initial pressure surge, ensure the line is secured
in some fashion.
If the
above is not possible, the dewar can be filled through the
Discharge Device by attaching a suitable transfer line, from
a pressurized liquid source, to the liquid valve (or solenoid
valve) on the Discharge Device.
CAUTION
For the
greatest safety all transfer lines used with this device should
be equipped with a relief device.
Open the
vent valve and the liquid valve. To begin the transfer, slowly
open the valve at the liquid source to admit the LN2. Throttle
the flow, if necessary, to keep the dewar from over pressurizing
above the relief valve setting until the dewar has cooled
down and the pressure peak has subsided.
WARNING
Keep
clear of cold exhaust stream from vent valve.
When the
dewar is full, liquid will start to exit from the vent valve.
At this point, shut off the liquid source valve. When the
transfer line has warmed, disconnect it and shut off the fill/withdrawal
valve. Leave the vent valve open unless a withdrawal is planned.
For CRC Discharge Devices, the solenoid valve is normally
closed so it must be energized n order to open it for filling.
If your controller does not have an override switch to open
the solenoid valve manually then plug the power cord into
an appropriate outlet.
Withdrawal
In order
to transfer liquid from the dewar, pressurization is required.
Introduce room temperature gas of the same composition as
the contents, at 5 psig from a regulated source, through the
vent valve.
Attach
a suitable transfer line to the liquid valve or solenoid valve.
Open the liquid valve as far as necessary to obtain the desired
flow rate. When the transfer is complete, close the fill/withdrawal
valve, disconnect the transfer line and depressurize the dewar
through the vent valve leaving the vent valve open. For CRC
Discharge Device, please refer to the operating manual of
your level controller for instructions on setting up the automated
level control system.
CAUTION
Before
operating any cryogenic vessels, please read thoroughly, "Precautions
for the Safe Handling and Storage of Liquefied Gases"
included with these instructions, for additional precautions
and good practice regarding cryogens and equipment.
|
