Leica Biosystems LN22 - Manual (Page 35)

35 Leica LN22
2. Remove the pump from the Dewar, cover the
pump immediately with the yellow protection
cap, place it on the corresponding supporting
device and refill the Dewar. Before the pump
is re-immersed into the Dewar it has to be thor-
oughly dry.
This second method is very time-consuming
and can take up to several hours. To simplify
the process the use of a second Dewar ves-
sel is recommended. Once a Dewar is empty,
immediately place it into the second (full)
Dewar.
The pump must always be held in UP-
RIGHT position to prevent melt water and
humid air from entering the pump valve.
After taking the pump out of the Dewar, immedi-
ately cover the Dewar and cover the pump with
the yellow protective cap.
Humidity will cause icing of the pump valves dur-
ing the following refrigeration process thus inter-
fering with the pumping process. Pumping trou-
ble is easy to recognize: in spite of the pumping
motor being activated, no nitrogen will be pumped
from the Dewar. To eliminate this problem, please
proceed as described in chapter 5.2.4.
4.13 Heating up the chamber
During operation, metal surfaces and components inside the
cryochamber can reach temperatures from as low as -196°C up to
as hot as +110°C! Touching these extremely cold or respectively
hot parts can cause severe injury!
For that reason, for any type of manipulations inside the
cryochamber you may use only the special tools which come as
part of the standard delivery and the use of which is described in
detail in the present manual.
Transfer of frozen specimens may also only be done by means of
the corresponding special tools.
• Remove specimens and cryo-tools from the
cryochamber.
• Remove sectioning waste since it will fuse
during heating.
• Press button (H) on the control unit (9, Fig. 18c).
After pressing button (H) the temperature of both
knife and specimen holder will rise quickly to ap-
proximately +100°C. After about 45 minutes the
heating process is completed.
At that point, any residual water inside the cham-
ber should have been evaporated.
The control unit automatically switches off the
heating function once a certain chamber tem-
perature has been reached. This means that the
instrument can be left in the H-mode overnight.
The pump can remain in the Dewar vessel due to
its low liquid nitrogen consumption while not in
operation.
•
To restart the instrument, simply press the
START button (11, Fig. 18c).
4. Startup