PAC Alcor JFTOT II Manual page 96

2.32.1 The heater stays on and controls the
temperature at 357°C for no more than
2.5 minutes. If the next step (2.33) is
not started within the 2.5 minutes, an
error message is displayed and the
Lead Calibration procedure must be
repeated (proceed to step 2.39).
2.33 Press ENTER to find the freezing point
(eutectic) of Lead (327°C). The heater will
turn off.
2.34 The JFTOT will begin LOOKING for freezing
point of Lead. The current temperature of
356°C is used here as an example.
2.35 The temperature will drop, then abruptly
increase (to about 327°C), and then pause a
few seconds. This pause period constitutes the
freezing point, the change of state from liquid
to solid Lead. The JFTOT will detect this
pause period and record the temperature as the
detected freezing point. The drop in tempera-
ture below the freezing point and the abrupt
reversal is due to the super-cooling characteris-
tic of Lead. If the temperature does not remain
constant long enough, the freezing point will not
be found. In that case, the Lead is probably
contaminated and should be replaced. See
ROUTINE MAINTENANCE in the Mainte-
nance Manual for replacement instructions,
then restart the AUTOCAL TC procedure.
Page 10
2.35.1 If the freezing point is detected, the
heater will turn on automatically to
melt the Lead so that the thermocouple
can be removed; proceed to Step 2.36.
2.35.2 If the freezing point is not detected, an
error message is displayed. The Lead
Calibration must be repeated, go to
Step 2.39.
2.36 The thermocouple may be removed when the
temperature reaches 357°C. The display will
display the prompt "REMOVE THERMO-
COUPLE" and an alarm will sound to alert the
operator that the thermocouple can be re-
moved. The temperature value of 364°C is
used here as an example.
JFTOT II Calibration Manual Rev. C