Physitemp Instruments BFS-TC - Manual (Page 5)

3.0 OPERATING INSTRUCTIONS
3.1 Check that SENSOR INPUT is switched to B. The digital display will show the temperature
of the stage.
3.2
Depress the RUN/SET switch to SET position and hold down while adjusting the
SET TEMPERATURE knob. With this 10-turn potentiometer, adjustment may be made to any tempera-
ture between -40° and +60°C (+100°C in Extended Range versions.)
Release the RUN/SET switch and allow the stage to stabilize at set temperature. This should take 1-2
minutes.
If further slight adjustments are needed, use the same procedure.
The controller will now maintain the stage at the set temperature.
3.2 Place tissue specimen on stage. If it is dry, first moisten the surface of the stage with a few
drops of water to provide better heat conduction. The thinner the specimen, the faster it will freeze.
These powerful stages will freeze a block of tissue over 1 inch thick, but it will take several minutes to
do so. Whenever possible, tissue thickness should be limited to 2-3 mm. With this thickness, sectioning
can commence in less than two minutes.
3.3 SPECIMENS PRESERVED IN FORMALIN should be thoroughly washed in water before
attempting to freeze them. Formaldehyde depresses the freezing point of water to such an extent that the
specimen may not freeze sufficiently for sectioning even though it may be below -30°C.
3.4 If even quicker freezing is desired., a blast of CO
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can be applied when the contrroller is
switched on.
3.5 REMOVING SPECIMEN FROM STAGE
Set the stage to a warmer temperature and allow to warm up until specimen slides off easily. Wipe stage
dry.
If the stage is being used in a cryostat, it is essential to remove the water from the tubing. This is most
easily done by blowing gently into one of the tubes until air has replaced the water.
3.6 MEASURING TEMPERATURE WITH THE EXTERNAL SENSOR
The digital display of the controller may be used as a readout for the needle microprobe which is sup-
plied with BFS/TC. Any other type T thermocouple sensor may also be used. The range of the ther-
mometer circuitry is -100° to +200°C.
Connect the probe to socket marked SENSOR A - EXTERNAL. Switch SENSOR INPUT to A.
Read temperature on the digital display.
When external sensor is being used the power supply to the stage is interrupted and it will drift back
towards ambient temperature. After switching SENSOR INPUT back to B, allow stage temperature to
stabilize again.
3.7 WARNING LIGHT
Since the thermocouple modules can be damaged if allowed to overheat, audible and visible warnings of
operating failure are provided on the controller.
Fault conditions such as thermocouple sensor breakage, lack of cooling water or electronics failure will
trigger safety shutdown and lamp illumination.
SWITCH OFF IMMEDIATELY IF WARNING LIGHT COMES ON OR IF BUZZER ALARM IS
HEARD.
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