MVE Biological Systems
TEC 3000 Operating and Maintenance Freezer Manual
13289499 Rev H •
88
7.3.3.
Hot Gas Bypass Sensor Calibration
This section describes how to calibrate the TEC 3000 hot gas bypass sensor. There are
two calibration procedures: single point and two point calibration.
For single point calibration, the reference point is LN2. For two point calibration, the
reference points are LN2 and ice water. Unless regulations require a two point
calibration, the single point calibration procedure is recommended.
All new freezers equipped with TEC 3000 controllers and hot gas bypass have been
calibrated at the factory. The hot gas bypass sensor should only be calibrated if faulty
readings are suspected, bypass sensor has been replaced, or as a part of a preventative
maintenance schedule.
For an accurate calibration, the LN2 Saturation Temperature (Section 6.2.1.4) needs to
be correctly set based on the altitude of the freezer location.
Both the single and two point calibration procedures require a small volume of LN2;
enough to completely submerge the bypass sensor. The two point calibration also
requires an ice water bath. Proper ice water bath preparation is imperative to ensure
accuracy. It is best to add filtered water to a Styrofoam cup containing crushed ice. Allow
the solution to stand at room temperature for five minutes prior to beginning the
calibration procedure.
NOTE: Security Level 2 or higher is required to calibrate the bypass sensor.
Hot Gas Bypass Sensor Removal
CAUTION
: Removing the hot gas bypass sensor while a LN2 supply is
connected to the freezer will cause the user to be exposed to LN2. Before
beginning procedure, shut off and disconnect all LN2 supply sources. Always
wear protective gloves and face shield when handling LN2. Refer to the Safety
section of this manual.
1. Ensure all LN2 supply sources are shut off and disconnected.
2. Remove plumbing shroud or rear panel to access the plumbing assembly.
3. Locate the hot gas bypass sensor on the plumbing assembly.
4.
Using a 9/16” or small adjustable wrench, remove the sensor from the plumbing
assembly. It may be necessary to temporarily disconnect the sensor from the wire
harness to avoid over twisting of the wires. Following removal of the sensor,
reconnect the sensor wires.
5. Perform the hot gas bypass sensor calibration procedure.
6. Following calibration, reinstall the bypass sensor using new PTFE thread tape,
ensure sensor wires are connected, reinstall plumbing shroud or rear panel, and
reconnect the LN2 supply source.
Содержание MVE 1842P-150
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