Thermo Scientific CRYO Plus 1 Operating And Maintenance Manual page 57

Section 9
Appendix
9-2 7007400 Cryoplus
The safety precautions in this manual must be followed to avoid potential
injury or damage which could result from these two characteristics. Do not
attempt to handle liquid nitrogen until you read and fully understand the
potential hazards, their consequences, and the related safety precautions.
Keep this booklet handy for ready reference and review.
Note Because argon is an inert gas whose physical properties are very similar
to those of nitrogen, the precautions and safe practices for the handling and
use of liquid argon are the same as those for liquid nitrogen.
Use containers designed for low temperature liquids.
Cryogenic containers are specifically designed and made of materials that
can withstand the rapid changes and extreme temperature differences
encountered in working with liquid nitrogen. Even these special contain-
ers should be filled SLOWLY to minimize the internal stresses that occur
when any material is cooled. Excessive internal stresses can damage the
container.
Do not cover or plug the entrance opening of any liquid nitrogen refrigera-
tor or dewar. Do not use any stopper or other device that would inter-
fere with venting of gas.
These cryogenic liquid containers are generally designed to operate with
little or no internal pressure. Inadequate venting can result in excessive gas
pressure which could damage or burst the container. Use only the loose-
fitting necktube core supplied or one of the approved accessories for clos-
ing the necktube. Check the unit periodically to be sure that venting is
not restricted by accumulated ice or frost.
Use proper transfer equipment.
Use a phase separator or special filling funnel to prevent splashing and
spilling when transferring liquid nitrogen into or from a dewar or refrigera-
tor. The top of the funnel should be partly covered to reduce splashing.
Use only small, easily-handled dewars for pouring liquid. For the larger,
heavier containers, use a cryogenic liquid withdrawal device to transfer liq-
uid from one container to another. Be sure to follow instructions supplied
with the withdrawal device. When liquid cylinders or other large storage
containers are used for filling, follow the instructions supplied with those
units and their accessories.
Do not overfill containers.
Filling above the bottom of the necktube (or specified maximum level)
can result in overflow and spillage of liquid when the necktube core or
cover is placed in the opening.
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