Operation
16 Installation and Operation Manual
Thermo Scientific Cryogenic Storage Freezers
6.4.1 LN
2
Precautions
The following are precautions for using liquid LN
2
backup systems.
WARNING!
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!
LN
2
liquid is non-poisonous but it is very cold and will burn
unprotected skin. Always wear protective eyewear 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 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 tubing. 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!
The flow of liquid LN
2
will be discontinued if the lid is
opened during operation of the backup system. For units operated with
free-standing, field installed type backup system, the flow of liquid LN
2
will
be discontinued upon lid opening only if the switch provided with the
free-standing package is installed on the freezer.
6.4.2 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 tubing to connect the freezer to the bottles:
•
5/8 in. OD copper tubing covered with Armaflex™ insulating tubing for
connection to the LN
2
supply.
Straighten the coiled tubing and connect one end to the labeled connection
on the freezer and the other end to the supply bottle or building supply
fitting.
