Metrohm 773 pH/mV Simulator - Manual (Page 6)

2.1. Aligning/Checking the potential U/mV
773 pH/mV Simulator
4
2.1 Aligning/Checking the potential U/mV
773 pH/mV Simulator
x100
x10
x1
-
-
14,3k PT1000 PT100 RE WE WE ON/OFF
pH U/mV
- +
20
6
4
2 18
16
14
12 10 8
0
+ +
0
20
25 40 60 80
100 C
1000 ~0,002
pH=7
U=0mV
i R /M
1. Connect the socket "WE" of the 773 pH/mV Simulator with the
measuring input of the instrument with the 6.2150.040 Cable.
For instruments with an E-plug (e.g. 670, 636) use the 6.2150.030 Cable.
For checking the instrument and its electrode cable:
Screw off the cable from the sensor and insert it in socket "WE" of the 773
pH/mV Simulator.
If you normally work with separate electrodes then remove the cable from the
reference electrode and insert it in socket "RE" of the 773.
2. Switch on the 773 pH/mV Simulator; the pilot lamp lights up.
3. Set the instrument to be checked to "Measure U".
4. Select the required factor and sign for U (switch 6).
Example with measurement switch on "2":
Switch setting Measured value
+ x1 2 mV
- x100 -200 mV
5. Set impedance switch R
i
to 0.002 M Ω .
6. Set the required value with the measurement switch and read off
the measured value on the instrument being checked.
Compare this measured value with the value given in the table.
Please take into account both the resolution of your instrument’s
display and the information about tolerances given in the
‘Instructions for Use’ for your instrument.
7. Set impedance switch R
i
to 1000 M Ω . The measured value on the
instrument being checked should differ from the value obtained in
step 6 by less than 1 mV.
Examples:
Set on pH Simulator Read off on instrument
1500 mV, Ri= ≈ 0.002 M Ω 1495 mV
1500 mV, Ri= 1000 M Ω 1494.9 mV
⇒ alignment poor, high-impedance OK.
Set on pH Simulator Read off on instrument
1500 mV, Ri= ≈ 0.002 M Ω 1500 mV
1500 mV, Ri= 1000 M Ω 1494.9 mV
⇒ alignment OK, high-impedance poor. Check the electrode cable!
Note: the value 0 mV can also be set directly with switch (9) (setting 0 mV).
6.2150.040 Cable