Sanyo MDF-793AT - Manual (Page 21)

20
OPERATING INSTRUCTIONS
Back-up system
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
gas cylinder
By using the joint and pipe enclosed with the
freezer, connect the liquid CO
2
gas cylinder to the
joint of the back-up system. For this setting,
consult with a qualified gas supplier or Sanyo sales
agency.
2. After setting the liquid CO
2
gas cylinder, operate
the freezer until the chamber temperature reaches
the required level.
3. Set the warning indicator of the 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
gas is consumed very
quickly.
4. Switch on the back-up system.
5. Make sure that liquid CO
2
gas spouts into the freezer chamber by pressing the CO2 back-up test
switch.
Note:
• The liquid CO
2
gas cylinder loses its cooling capacity at speed when the ambient temperature is over
31
o
C. Install the liquid CO
2
gas cylinder in the cool environment. And the duration of back-up time per
one liquid CO
2
gas 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
gas cylinder should be a siphon type.
• Use the pipe enclosed with the freezer for the setting. (The extension of the pipe is not permitted
Rough scheme
Pipe
Liquid CO2
gas cylinder
Solenoid valve