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16 | Backup System (Optional) Thermo Fisher Scientific ULT Freezers
Backup System (Optional)
For all ultra-low temperature cold storage products, we
recommend the use of a backup system (BUS) for the
security of your samples.
When you purchase a built-in CO
2
or LN
2
optional backup
system for the freezer, backup control is integrated into the
main user interface.
Note: For stand-alone backup systems, refer to installation
instructions provided with the backup system kit.
CO
2
and LN
2
Precautions
The following are precautions for using liquid CO
2
and LN
2
backup systems.
Installation
Field installed systems are supplied with complete installation
and operating instructions. If your system is factory installed,
the freezer is shipped with a coiled length of hose to connect
the freezer to the bottles:
• 1/4" Flexible Hose with fittings for connection to the CO
2
supply.
• 1/2" Flexible Hose with fittings for connection to the LN
2
supply.
To install,
1. Straighten the coiled hose.
2. Connect one end to the labeled connection on the
freezer.
• Tighten the nut two flats past finger tight, approximately
120 degrees.
Note: For CO
2
, remove the threaded fitting from the nut on
the end of the copper tubing to access nut for connection to
the freezer. Discard the threaded fitting.
3. Attach the other end to the supply bottle or building
supply fitting.
• For CO
2
:
• Remove Nipple from adapter (NPT Connection).
Remove cable tie to release alternative nut and
CAUTION: Always purchase the cylinders which
are equipped with siphon tubes for withdrawing
liquid from the bottom of the cylinder. CO
2
cylinders must be kept at room temperature to
function properly. LN
2
bottles are functional at
any reasonable temperature.
WARNING:
If a CO
2
or LN
2
cylinder falls and a
valve is knocked off, the cylinder becomes a
deadly and completely unguided missile.
Transport the cylinders in a hand-truck 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:
CO
2
and LN
2
liquids are non-
poisonous but are very cold and will burn
unprotected skin. Always wear protective eye
wear 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 CO
2
or LN
2
are non-poisonous but displace
the oxygen in a 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 hose. 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 models ordered with factory
installed built-in backup systems, the flow of
liquid CO
2
or LN
2
will be discontinued if the
door/ lid is opened during operation of the
backup system. For units operated with free-
standing, field installed type backup system, the
flow of liquid CO
2
or LN
2
will be discontinued
upon door/ lid opening only if the switch provided
with the
free-standing package is installed on the freezer.