Orp Electrode Check; Mv Offset - Hach EC1000 Instruction Manual

2.3.3.2

ORP Electrode Check

2.3.3.3

mV Offset

6. Keeping the ORP shorting lead in contact with the platinum disc, wait for a stable
reading and then press the
7. Press the key to return the meter to normal operations. Remove the ORP
pH/mV
shorting lead.
To ensure the ORP electrode is functioning correctly, it is necessary to check its potential
in a solution of known redox potential. The nominal potential of the Hach EC1000 ORP
electrode in Light's and ZoBell's solution are given in Table 4. Also see Table 5.
The electrode should read within ±10 mV of the nominal value. The potential of the Hach
EC1000 reference electrode is 32 ±5 mV versus SCE (Saturated Calomel Electrode) in
saturated KCl Solution.
Table 5 Potential of Zobell's Solution as a Function of Temperature
Temperature (°C)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Once it has been determined that the ORP electrode is functioning properly, a mV offset
can be performed so that the display reads values which are more familiar to the operator.
For example, if it is known that a process must be held at a set point versus SCE, then the
mV zero can be set at 430 mV when the electrode is placed into Light's Solution. Now the
display will read mV versus SCE.
1. Remove the electrode from the sample cell.
2. Place the electrode in a sample with a known mV potential.
3. Press CAL to call up the main calibration menu. The display shows:
4. Press the
UP ARROW
5. Press . The readout is an edit display with a millivolt value such as 0.0 mV.
ENTER
(The last value displayed is used.)
key twice.
ENTER
(vs. Standard Hydrogen Electrode)
EV Temperature (°C)
0.481
0.479
0.476
0.474
0.472
0.470
0.468
0.465
0.463
0.461
0.459
0.457
0.454
0.452
0.450
key. The display shows:
43
EV
16 0.448
17 0.446
18 0.443
19 0.441
20 0.439
21 0.437
22 0.435
23 0.432
24 0.430
25 0.428
26 0.426
27 0.424
28 0.421
29 0.419
30 0.417