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Thermo Scientific Revco Cryogenic Storage Freezers
You can press the Audio Silence pad to silence the alarm but the
alarm will ring back in five to seven minutes. You can silence the
alarm in this manner as many times as necessary until the sensor
cools below the warm alarm temperature. The alarm quits
automatically when the sensor cools below the warm alarm
value.
There is a limit on the alarm test feature. The alarm test
Note:
will not commence if the warm alarm setpoint is more
than 15 degrees warmer than the operating temperature
setpoint.
6.3 Backup System (Optional)
When you purchase a built-in LN
the freezer, the backup system control panel is located behind a
hinged panel adjacent to the grill (refer to Figure 3).
Always purchase the cylinders which are equipped with
Note:
siphon tubes for withdrawing liquid from the bottom of
the cylinder. LN
bottles are functional at any reasonable
2
temperature.
Use this panel to set the backup initiation temperature, usually
10 to 15°C warmer than the operating setpoint.
Digital Temperature
Display
TEMPERATURE °C
POWER
OFF
ON
Power
Temperature Control
Switch
Set Button
Figure 3. Control Panel for Optional
Built-In Backup System
optional backup system for
2
Temperature Control
Setpoint Screw
PUSH
TO SET
SETPOINT
ADJUST
6.3.1 LN
Precautions
2
The following are precautions for using liquid LN
systems.
WARNING!
If an LN
knocked off, the cylinder becomes a deadly and
completely unguided missile. Transport the cylinders
in a handtruck or cart with secure chain ties for the
cylinder. After cylinders are connected to the
equipment, securely attach them with chains to a
solid, stationary object such as a building column.
WARNING!
LN
very cold and will burn unprotected skin. Always wear
protective eyewear and clothing when changing
cylinders or working on the piping systems attached to
an active source of liquid refrigerant.
WARNING!
The gases produced by evaporation of
LN
are non-poisonous but displace the oxygen in a
2
confined space and can cause asphyxiation. Do not
store the cylinders in subsurface or enclosed areas.
CAUTION!
When closing the cylinder valve, make
sure that the injection solenoid is energized to allow all
the liquid to bleed off instead of being trapped in the
supply tubing. Failure to do this results in activation of
the pressure relief device, which could damage the
freezer and requires replacing if it is activated.
CAUTION!
For chest models ordered with factory
installed built-in backup systems, the flow of liquid LN
will be discontinued if the door or lid is opened during
operation of the backup system. For units operated
with free-standing, field installed type backup system,
the flow of liquid LN
lid opening
only
free-standing package is installed on the freezer.
Installation and Operation
backup
2
cylinder falls and a valve is
2
liquid is non-poisonous but it is
2
will be discontinued upon door or
2
if the switch provided with the
2
5
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