Helmer Scientific i.Series
®
Ultra-Low Freezer
Service and Maintenance Manual
360173-A/C
9
2.7 Back-up Refrigeration Systems (optional)
A back-up refrigeration system may be installed to ensure the chamber temperature remains below a critical level in the event of
an extended power failure or an equipment failure. If the chamber temperature rises to a pre-determined setpoint, the back-up
refrigeration system will inject carbon dioxide (CO
2
) or liquid nitrogen (LN
2
) into the chamber to keep the chamber temperature within a
specified range.
NOTICE
• The temperature setpoint for the CO
2
/ LN
2
injection should be set to a value within the freezer operating range
(-50 °C to -86 °C).
• Do not drill holes in the cabinet. Drilling holes may damage the insulation in models equipped with vacuum-insulated
panels, or may damage the evaporator coil, causing a loss of refrigerant.
Install Optional Back-up Refrigeration System
Follow the back-up refrigeration system manufacturer’s directions to install the back-up system.
Notes
• Helmer recommends installing the back-up refrigeration system door switch along the handle-side of the door. This will
prevent the door switch from interfering with the vacuum port, located near the top of the door.
• External sensors for the back-up refrigeration system may be installed through ports in the side or rear of the
freezer cabinet.
• Three threaded screw holes have been provided on the interior back wall of the cabinet to assist in installing and routing the
back-up refrigeration system. Holes are #8-32 thread, with Phillips screws temporarily installed.
• Back-up CO
2
and LN
2
Refrigeration Systems are available from Helmer Scientific.
Threaded screw holes and distribution port
for back-up refrigeration system installation
2.8
Back-up System Contacts
Remote contacts are provided on the back of the freezer for the back-up refrigeration system. The back-up system may be connected
to the i.C³ monitoring and control system with the remote contacts. If the back-up system is activated, the system activation will be
communicated to the i.C³ through the remote contacts. An icon will be displayed on the i.C³ to indicate that the back-up system has
been activated.
NOTICE
The i.C³ monitoring and control system does not control the operation of the back-up refrigeration system.
