29
BACK-UP SYSTEM for AT type
WARNING
As with any equipment that uses CO
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 AT type is provided with an automatic liquid CO
2
gas injection device as a back-up system.
This freezer prevents the chamber temperature from going up by injecting the liquid CO
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 CO
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.
1. Setting of liquid CO
2
cylinder
By using the joint and connect tube enclosed with
the freezer, connect the liquid CO
2
cylinder to the
joint of the back-up system. For this setting,
consult with a qualified gas supplier or Sanyo sales
representative agent.
2. After setting the liquid CO
2
cylinder, operate the
freezer until the chamber temperature reaches the
required level.
3. Set the warning indicator of the temperature
recorder at the temperature higher than -70
o
C.
The back-up system is operated continuously if the
warning indicator is set at the temperature lower
than -70
o
C. This means the liquid CO
2
is
consumed very quickly.
4. Switch on the back-up system.
5. Make sure that CO
2
spouts into the freezer chamber by pressing the CO
2
back-up test switch.
Note:
• The liquid CO
2
cylinder loses its cooling capacity at speed when the ambient temperature is over 31
o
C.
Install the liquid CO
2
cylinder in the cool environment. And the duration of back-up time per one liquid
CO
2
cylinder varies depending on the ambient temperature. Refer to “Installation of back-up system”
enclosed with the freezer for the available back-up time.
• The liquid CO
2
cylinder should be a siphon type.
• Use the connect tube enclosed with the freezer for the setting. (The extension of the pipe is not
permitted because of cooling capacity.)
Rough scheme
Connect
tube
Solenoid valve
Liquid CO2
cylinder
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