Metrohm 767 Calibrated Reference - Manual (Page 14)

3 Procedure for checking instruments
10
767 Calibrated Reference Instructions for Use
3.3.2 Temperature
Checking the temperature, see chapter 3.2.3.
Note
During the measurement the two Pt 100 / Pt 1000 resistances at sock-
ets (1)....(3) can also be used at the same time as the conductance
measurement (see further up). Please note that the measuring tem-
perature of the instrument to be tested is approx. 0°C, while the infor-
mation in the table refers to 20°C. This must be converted accord-
ingly.
When the test is finished the cell constant, temperature coefficient and
the temperature must be set again to their current values.
3.3.3 Tolerances
Instruments with digital display:
G value (5) ± 0.1 µS/cm
G value (6) ± 0.7 µS/cm
Temperature ± 0.5 °C
Instruments with analog display:
The tolerance lies within the reading accuracy.
If the measurements lie outside the tolerances they should be repeated
with the reference cable from the accessories case.
If the measurements are still outside the tolerance range please contact
your local Metrohm agency to arrange for the instrument to be serviced.
3.4 Rancimat 617 and 679
The Rancimat carries out conductivity measurements via the measuring
channels. The function of the measuring channels and the presentation
on the printer can be checked channel by channel by means of the
Calibrated Reference. The conductance can be read off from the dis-
play. By variation of the conductance the sensitivity of the measurement
can be shown on the printer in approximately the correct scale. The
temperature of the heating block plays no role in the following meas-
urements (if the instrument has reached the operating temperature the
check can be started immediately). If this is not the case then the start
condition should be achieved (for 679: > 50°C).
The following test can be used as a functionality test.
carry out on instrument or sen-
sor: carry out on Calibrated
Reference: compare display
with: remarks
1. unplug sensor from instrument close cover (Sensor can remain
in the measuring
vessel)
2. plug in cable 6.2150.010 instead of
the sensor
Plug in cable according to
diagram (see Fig. 7, p. 11)
so that 15.3 kΩ is obtained