Bright Instruments
20
5. General Maintenance
Cont.
5.5 SERVICING & REPAIRS CONT.
Calibrating the Microtome (Cont.):
d. Engage the pawl. Operate one complete
cutting and return cycle. Then slowly do a
downward cutting stroke observing pawl
movement (clicks) in and out of teeth on
ratchet wheel (14), 1 click = 2µm. If otherwise,
adjust screw (88), clockwise for fewer clicks.
NOTE:
Before adjusting screw (88), loosen
the locking nut (106) beneath (88) and
tighten after each adjustment.
e. When you have finished, replace cover, put
the microtome back into the cryostat and
check it under refrigerated conditions. I may
be necessary to alter the calibration once the
microtome is cold, particularly if a hand wheel
is fitted.
5.6 DECONTAMINATION
It is the responsibility of the user to ensure
that a decontamination procedure is employed
which is appropriate to the nature of the work
carried out.
The cryostat chamber, freezer assembly
and accessible parts of the microtome are
constructed of corrosion-resistant materials,
and the following decontamination procedures
can be used. Hypochlorite (bleach) solutions
are corrosive to many metals and should be
avoided.
5.6.1 FORMALDEHYDE DECONTAMINATION
This method is recommended in the Howie
Code on the prevention of infection in medical
laboratories and more recently in the “Code
of Practise for the Prevention of Infection in
Clinical Laboratories and Post-mortem Rooms”,
ISBN 0 11 320464 7
a. Defrost the cryostat completely (after
removing knife)
b. Place 50ml of formalin BP in a flat dish in
the cabinet. Fit the insulating plug.
c. Leave for at least 24 hours and preferably
48 hours.
d. Remove the insulating plug briefly and
place a beaker containing 10ml of ammonia
SG.880 in the chamber.
e. Leave for 1 hour. The cryostat is then ready
for cleaning.
5.6.2 VIRKON DECONTAMINATION
‘Virkon’ is a virucidal disinfectant made
by Antec International and widely used in
microbiological and clinical departments.
a. Defrost the cryostat completely.
b. Remove the microtome (Section 3.3.3)
