MVE Biological Systems
TEC 3000 Operating and Maintenance Freezer Manual
13289499 Rev H •
33
7.1.2.
Automatic Liquid Nitrogen Level Control
The TEC 3000 is equipped with a fully automated LN2 level control system. This level control
system is based on user-defined parameters that can be adjusted to maintain a LN2 level in a
freezer over a range of 3.0 inches (76 mm) up to 48.0 inches (1219 mm). Since this control
system utilizes the differential pressure system described previously, these parameters can be
adjusted electronically using the TEC 3000 keypad or remotely through a networked computer.
This automatic fill control feature can be disabled. Below is a brief explanation of the four user-
defined level control parameters. For instructions on accessing and adjusting the level control
settings, see the Liquid Level Setpoints and Alarms section.
•
High Level Alarm
– If the LN2 level in a freezer reaches or exceeds this setting, a
High Level Alarm will result. This audible/visual alarm will cause the High Level discrete
contact and the global remote to switch to alarm state.
•
High Level Setpoint
–
When the LN2 level in a freezer reaches this setting (with or
without automatic fill enabled) the controller will close the fill valves and terminate the
fill.
•
Low Level Setpoint
– When the LN2 level is at or below this setting (with automatic fill
enabled) the controller will initiate a filling cycle.
•
Low Level Alarm
– If the LN2 level in a freezer is at or below this setting, a Low Level
Alarm will result. This audible/visual alarm will cause the Low Level discrete contact
and the global remote to switch to alarm state.
NOTE: Certain events can tempo
rarily disable Auto Fill Control. Pressing “Stop Fill”
will disable Auto Fill Control for 30 minutes. In the event of a Hot Gas Bypass Alarm or
a Fill Time Alarm, Auto Fill Control will be disabled until the respective alarm is cleared
by pressing “Alarm Mute” or restarting the controller.
Overfill Protection
The overfill protection (Software Version 2.03) will prevent an automatic fill if the
LN2 level reading is 0 or if the level reading suddenly drops to 0. This prevents an
overfill scenario in any situation where the TEC3000 loses its ability to measure the
LN2 level.
Figure 5:
Example of automatic level control parameters
Note: Pressing Stop Fill will
temporarily terminate TEC3000’s automatic fill function for 30
minutes.
High Level Alarm
High Level Setpoint
Low Level Setpoint
Low Level Alarm
Содержание MVE 1842P-150
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