Thermo Scientific Cryo 740 Series, Руководство по эксплуатации и техническому обслуживанию

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Dip Level Test (continued)
Dip Tests should be made and the LN
2
level monitored about every
seven to ten days. Many labs continuously monitor and keep perma-
nent LN
2
consumption records.
Tank Switcher Outlet
Press Manual Fill while checking the tank switcher outlet with a volt
meter. Line voltage will be present when the unit is filling.
Alarm and LED Validation (not required at installation)
To perform the following test, it is necessary to remove the temperature
probes from the sensor tube. To adjust the probes, follow the procedures
in Section 2 of this manual. An LN
2
sample in a small insulated cup, or
the LN
2
supply already in the freezer can be used.
Warning Protective gloves, eye wear, and apron should be worn when
performing this test. ▲
1. Referring to Figure 1-6, remove the access panel and remove clamp.
2. Pull the probe sets toward the top of the tube until resistance is felt.
3. Power up the unit with the sensors out of the LN
2
. The solenoid valve
LED will light.
Caution
When the probes are near the top of the sensor tube and
resistance is felt, it may be necessary to wait a few minutes to allow the
probes to warm up before removing them completely.
▲
4. The Low Level alarm LED and the audible alarm activate in about 10
minutes. The remote alarm contacts activate in about 30 minutes.
Note If the low level probe is not submerged in LN
2
within approximately
one hour, the low level shutdown alarm activates. See Section 2. ▲
5. To shut off the audible alarm, press the Silence button.
6. Submerge the Low Level Sensor into the LN
2
. The Low Level alarm
LED will go out.
7. Press the Manual Fill button. The solenoid LED lights. When the unit
is full, release the button, the fill stops, and the LED goes out.
1-8 7000740r7 Cryo Series Thermo Scientific
Section 1
Quick Start-Up
Installation Validation
(continued)
Alarm and LED Test