BACK-UP SYSTEM
WARNING
As with any equipment that uses N
2
gas, there is a likelihood of oxygen depletion in the vicinity of
the equipment. It is important that you assess the work site to endure there is suitable and
sufficient ventilation. If restricted ventilation is suspected, then other methods of ensuring a safe
environment must be considered. These may include atmosphere monitoring and warning
devices.
The freezer is provided with an automatic liquid N
2
injection device as a back-up system. This freezer
prevents the chamber temperature from going up by injecting the liquid N
2
gas when the power supply is
disconnected (power failure, disconnection of power cord, breaker OFF) or in the case of failure of freezer
itself. The liquid N
2
gas is injected with the activation of solenoid valve energized by battery when the
chamber temperature reaches the alarm temperature.
Following shows the procedure for setting the back up system.
Solenoid valve
Liquid N
2
gas cylinder
Pipe
Rough scheme
1.
Connect the liquid N
2
cylinder with the back-up
system joint by using the pipeline and the joint
attached with this freezer. This work should be
done by high pressure gas works specialists.
The pressure of liquid N
2
cylinder should be
regulated at 0.5 kg/cm
2
G.
2. Operate the freezer until the freezer temperature
reaches the required level.
3. Set the warning indicator of the recorder at 15
o
C
higher than the freezer temperature.
4. Switch on the liquid N
2
back-up. This
completes the back-up system setting.
5. Make sure that liquid N
2
spouts into the freezing
room with the liquid N
2
back-up test switch.
6. This completes the setting of the tank for automatic spouting in case the freezer temperature should
match the alarm set temperature.
Note:
• The liquid N
2
gas cylinder is to use an exclusive cylinder.
• There is to be a pressure regulator, and a liquid N
2
gas cylinder is to use the thing that 68.6
〜
49.0 kPaG
(0.7
〜
0.5 kg/cm
2
G) can adjust pressure.
• Use the pipe encloses with the freezer for the setting. (The extension of the pipe is not permitted
because of cooling capacity.)
• Turn off a back-up switch when the operation of the freezer is suspended and when a back-up system is
not used. A battery for the back-up system discharges electricity with on.
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