Metrohm 767 Calibrated Reference - Manual (Page 12)

3 Procedure for checking instruments
8
767 Calibrated Reference Instructions for Use
3.2.2 Polarization current and voltage source
carry out on instrument or sen-
sor:
carry out on Calibrated
Reference:
compare display
with:
remarks
1. screw off cable at sensor close cover place sensor in
storage tube
2. connect sensor cable to
socket (5)
3. set instrument to function Upol or
Ipol
cover always remains closed calculate R value
(5) according to
equation, see be-
low
compare with per-
mitted tolerance;
take display resolu-
tion into account
If the variation of the measured values is too large then first exchange
the original sensor cable against the reference cable in the accessories.
Equations for the calculation:
U pol: I = (U/R) = selected Upol potential / Ω value (5)
I pol: U = (IxR) = selected Ipol current x Ω value (5)
For different instruments the different control limits according to the in-
dividual technical data must be observed → observe overload display.
Example:
1 µA x 14 345 Ω = 14.345 mV
Consider resolution of display!
3.2.3 Temperature (Pt 100/Pt 1000)
carry out on instrument or sen-
sor: carry out on Calibrated
Reference: compare display
with: remarks
1. remove cable (with sensor) from
instrument
close cover
2. connect temperature measuring
input to Calibrated Reference with
2x banana cables (6.2150.000)
depending on sensor, con-
nect:
Pt 100 : sockets (1) (2)
Pt 1000: sockets (2) (3)
3. set instrument to temperature func-
tion
Pt 100 : sockets (1) (2) →
Pt 1000: sockets (2) (3) → °C value (1)(2)
°C value (2)(3) compare with per-
mitted tolerance
Note
During the pH measurement the two Pt 100 / Pt 1000 resistances at
sockets (1)....(3) can also be used at the same time with the pH mea-
surement (see above). Please note that the measuring temperature of
the instrument to be tested is approx. 0°C, while the information in the
table refers to 25°C. This must be converted accordingly.
For the Pt 1000 measuring input the following applies: value between
sockets (1) and (3) (R-Pt100 and R-Pt1000 in series) corresponds ap-
proximately to 25°C (for the exact individual value see certificate for
767.0010).