Taylor-Wharton 24K w/ AutoTend - Manual (Page 17)

This section of the operating manual is for Taylor-Wharton approved equipment that
uses the KRYOS controller. For models that use the Mark IL controller refer to
operating manual TW-303, P/N 7950-8303, for the Mark 3 controller refer to operating
manual TW-291, P/N 7950-8291, for the Mark 2L controller refer to operating manual
TW-290, P/N 7950-8290.
Introduction
The KRYOS temperature and LN
2
level controller is designed for easy operation and
uninterrupted, reliable service. This controller will maintain the selected temperature
and liquid level range of LN
2
in your refrigerator as well as provide audible and visual
alarms for any alarm conditions that may occur. An “alarm” is any off-normal condi-
tion, such as a sensor short or open circuit, a temperature outside of the limit set by
the user, or any other condition that would cause the controller to enter the ALARM
mode. “Events” are lid openings and closings, solenoid valve openings and closing,
and operation of the controller’s relay for remote alarm indication. “Data” refers to
periodic alarm and event logging available at the “Data Output” connection.
The KRYOS controller should require no additional attention to control temperature
and maintain liquid level if an adequate source supply of liquid nitrogen is maintained.
If your protocol calls for you to “top-off” the cryostorage system at the end of a work
day or work week, press the FILL button. The unit will fill to the upper allowable liquid
level and stop automatically. You may choose to manually stop the fill by pressing the
STOP FILLING BUTTON at anytime during the fill.
Normal Fill Cycle
When the refrigerator is filled and the controller is operating, the LOW LEVEL and
LOW ALARM sensors are immersed in liquid nitrogen. Their resistance values are
interpreted by the controller as “in liquid”. At the same time, the FUL LEVEL and the
HIGH LARM sensors are above the liquid pool, sending the controller an “above
liquid” signal. As liquid nitrogen evaporates, the liquid level in the refrigerator drops
slowly until the LOW LEVEL sensor is above the liquid and sends a different signal to
the controller. After a delay sufficient to ensure the signal, the controller interprets this
condition as low liquid and opens the fill solenoid, admitting more liquid nitrogen from
the supply source.
The refrigerator will fill slowly. The fill continues until the STOP FILL SENSOR
SENDS THE CONTROLLER A SIGNAL THAT IT IS NOW IN LIQUID. The controller
will close the liquid supply solenoid to stop the fill. As liquid evaporates, the display
will indicate the liquid is at a normal level as the cycle begins again.
The KRYOS temperature and liquid level controller is designed to support a remote
alarm. Connections are provided on the bottom of the controller chassis for the 38K
and on the back of the refrigerator for the 10K and 24K. See Figure 13.
Power
The control can be turned on and off by pressing the Power button followed by
“42”, as instructed on the display panel. The two-step shutdown is a precaution
against accidental shutdown. Shutdown can also be password protected to prevent
users from turning the system on and off under the security section of this manual.
CONTROL OPERATION