Keep Full Mode
In KEEP FULL mode, the CryoWiz™ maintains the primary source valve in the open condition and
the reserve source valve in the closed position. In KEEP FULL mode, the system will purge the
primary and reserve inlets when necessary to maintain liquid at both source valves. This ensures that
liquid is instantaneously available from either side should there be a demand for it. When the
CryoWiz™ senses that liquid is no longer present at the primary inlet; it will automatically switch to the
reserve source and continue delivering LN2 to the outlet. In a high demand or continual use
application, the amount of LN2 consumed by purging will be minimal relative to that used to supply
the demand. It is recommended that in this mode, vacuum jacked (VJ) supply hoses and vacuum
jacketed downstream piping be used to minimize heat transfer and product loss. KEEP FULL mode is
not recommended for installations where demand is sporadic, as the automatic purging may lead to
excessive product loss.
Display When in Keep Full Mode
When configured for KEEP FULL mode, a green light indicating KEEP FULL and a green light for
FILLING will illuminate. The FILLING light will blink for a period of time before illuminating
continuously. The side selected to be primary will be indicated by a green SELECTED light. The
reserve side SELECTED light will remain off. If the CryoWiz™ senses liquid at the source valves
on both sides, the primary and reserve LIQUID lights will be illuminated green.
If liquid is not sensed at a source valve, the LIQUID light will illuminate yellow and the PURGE light
will illuminate green until the system has purged hot gas from that side. When the CryoWiz™ senses
that liquid has returned at the source valve, the LIQUID light will turn green and the PURGE light will
turn off. For short periods of time during normal operation, the purge light on either side may
illuminate indicating that the purge valve on that side has opened to expel hot gas and maintain
continuous liquid supply. The LIQUID lights will switch from green to yellow during purging.
During a purge, if liquid does not return to the source valve on the selected side within a specified
period of time (referred to as the PURGE TIMEOUT), the selected side LIQUID light will be
extinguished, the red REPLACE light will illuminate, and the audible alarm will sound. The
CryoWiz™ will switch to the reserve side, close the depleted side source valve, and open the
reserve side source valve. The reserve side SELECTED light will illuminate. If liquid is not detected
at the reserve side source valve, the reserve side purge light will remain on until liquid is detected. At
that point, the reserve side LIQUID light will turn from yellow to green, and the purge light will turn
off.
When the empty dewars are removed from the depleted side and full dewars are connected with
their valves opened, the RESET button on the front graphic must be pushed. The CryoWiz™ will
then detect the new source, turn on the LIQUID light for it, extinguish the REPLACE light, and cut
off the audible alarm.
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