Leica Biosystems LN22 - Manual (Page 8)

8 Instructions for Use V1.2, RevB – 10/2012
Safety measures in cryopreparation
Provided that the safety measures outlined in the present chapter are
observed, using all safety devices of the instrument as described, there
is no significant accident risk involved in cryopreparation. For this rea-
son, please make sure at all times when working with the LN22 system
that the few, but decisive, rules for safety listed in this chapter are fol-
lowed.
When handling liquid nitrogen (LN
2
), please bear in mind the following:
• LN
2
is extremely cold and boils at -196°C. As a consequence, also ni-
trogen gas (GN
2
) escapes from boiling LN
2
at a very low temperature.
Bear in mind, that LN
2
and/or GN
2
as well as objects which are in con-
tact with LN
2
/ GN
2
(pipe joints, valves, pipes, containers or stoppers)
can cause severe frost bite on skin and eyes.
• When evaporating, LN
2
expands at a ratio of approximately 1 : 700,
i.e. 1 liter of liquid nitrogen produces almost 1 m 3 of nitrogen gas
(GN
2
). Therefore, please make sure that the working area is kept well
ventilated when larger quantities of liquid nitrogen evaporate (e.g.
when pouring LN
2
from one container into another). LN
2
residues from
containers may only be emptied outdoors: Useful for disposing of liq-
uid nitrogen is a gravel-filled container or pit, where LN
2
will evapo-
rate quickly and safely.
• Nitrogen gas (GN
2
) is odorless and has no taste so it cannot be distin-
guished from normal air when inhaled. GN
2
is nontoxic as a sub-
stance. Still, a higher GN
2
content (normal ratio: about 78 % GN
2
to
21 % of oxygen) in the air will cause the oxygen level to diminish, thus
causing sudden fainting and deep unconsciousness without any pre-
ceding warning symptoms (such as numbness, dizziness).
In case of doubt about the oxygen level in the air it is advisable to use
a gas analyzer with an oxygen level indication range of 0 to 25 %.
There is danger when the oxygen level drops below 18 %.
2. Safety