Calibration must be carried out annually, or whenever the performance of the
apparatus is suspected e.g. when similar successive test produce markedly
divergent results.
The apparatus must either be returned to the dealer for calibration, or
calibration must be carried out in the following manner, using Calibration Kit
AZ6730 and the standard chemicals Carbazole (AZ9118) and P-nitrotoluene
(AZ9218).
To check if the unit is still in calibration proceed as follows:-
a) Switch the unit on and ensure the instrument components are in the
stable condition as described in Section 4 or 18.
b) Perform a melt with each standard chemicals and note the reading.
c) Compare the results obtained with the melting points shown on the
certificates supplied with each chemical and ascertain whether the unit
performs within acceptable limits.
d) If it is decided that re-calibration is required proceed as follows:-
1. Switch off the unit and allow it to cool.
2. Disconnect Power supply from the rear of the unit.
3. Invert the unit and remove the three screws securing the base
plate to the body.
4. Place the unit on the bench the correct way up taking care not to
let the base fall from the unit. Lift the body from the base plate.
5. Turn the body on its side and placed it on the bench to the right of
the base plate.
6. Remove the two pin connector from PL1 2A on the printed circuit
board.
7. Plug in the calibration box into pin connector PL 12A.
8. Switch the selector switch to the LO position.
9. Insert the power plug on the instrument and switch on.
10. Allow the instrument to re-stabilise. It should not be necessary to
go through the „Set-point‟ procedure again at this stage. 2 to 3
minutes should suffice to ensure stabilisation.
11. Adjust the LO knob until the display shows the actual melting point
obtained in b) above for the standard sample of p-nitrotoluene.
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