Leica Biosystems LN22 - Manual (Page 33)

33
4.10 Preparing the pumping system
Use caution when handling liquid nitrogen!
Prior to filling the Dewar vessel with LN
2
, please refer to the safety
instructions in chapter 2.
• Slowly lower the pump into the Dewar vessel if the liquid boils over
and LN
2
escapes from the Dewar, lift the pump partly back out until
the boiling over stops, then continue to lower the pump carefully until
it is completely immersed into the Dewar.
The LN
2
connecting pipe consists of an outer insulation tube (1) with a
polyamide filling tube (2) inside.
• Connect the polyamide tube (2) to the cryochamber (Fig. 29 a), and
press the insulation tube (1) completely into the corresponding open-
ing in the cryochamber wall.
• Place the Dewar vessel close.
• Open the protective lid (3) and connect the other end of the polya-
mide tube to the pump (Fig. 29b).
The polyamide and insulation tube are both delivered overlength and can
be shortened according to the needs at the installation site. Always
make sure, however, that both ends of the polyamide tube are covered
entirely by the outer insulation tube.
4. Startup
2
1
2
1
3
Fig. 29
a
b
4.11 Refrigerating
• Before starting with your cryopreparation work, set the desired tem-
perature values for specimen and knife.
• Start the pump by pressing the START button (11, Fig. 18c).
• Move the cryospecimen arm to the lowest position to ensure the
quickest possible refrigeration time.
The reservoir in the cryochamber is filled up with LN
2
. Once the appropriate level is reached, the filling
level is maintained constant by means of a level sensor which controls the LN
2
pump. When the speci-
men temperature has reached the selected value, the motorized sectioning function of the microtome