Leica Biosystems LN22 - Manual (Page 34)

34 Instructions for Use V1.2, RevB – 10/2012
4.12 Refilling the Dewar vessel
Use caution when handling liquid nitrogen!
Please refer to the safety instructions in chapter 2.
can be started to help reach a stable specimen temperature through the
regular immersion of the cold bridge of the cryo specimen arm into the
liquid nitrogen. The LED above the START button flashes until the knife
temperature has reached the preselected value.
If you want to change the temperature during a work session, e.g. from
-70°C to -120°C, it is recommendable to press the START button once
again as this ensures that the new temperature is reached as fast as
possible, since otherwise the instrument will approach the new tempera-
ture value only very slowly.
The cryochamber of the LN22 liquid nitrogen freezing device is an open
chamber system, which can be covered with a lid when relative air hu-
midity is high or during breaks. It is advisable to cover the chamber dur-
ing the refrigeration process and reopen it before starting to section. An
appropriate plastic lid for the chamber comes as part of standard deliv-
ery.
While not in operation or while collecting the specimens, always
move the cryo specimen arm to the lowest position to maintain the
selected specimen temperature at a constant level.
The 25 liter Dewar vessel contains enough liquid
nitrogen to work without interruption for more
than 8 hours. We advise you to leave the pump in
the Dewar until the nitrogen content is exhausted.
The liquid nitrogen consumption of the pump while
not in use is less than 1 liter / day.
The Dewar can be filled in two different ways:
Press the LN
2
STOP button (7, Fig. 18c) and wait a
few minutes until the pump tubing has thawed and
can thus be bent without difficulty:
Do NOT remove the LN
2
connecting tube from the
pump. This way you avoid formation of conden-
sation water inside the upper pump valve.
1. Slightly lift the pump and refill the Dewar from
a LN
2
storage tank without removing the pump
entirely.
4. Startup