User Guide

pH mV pH mV pH mV pH mV pH mV

0 990 1 920 2 860 3 800 4 740

5 680 6 640 7 580 8 520 9 460

10 400 11 340 12 280 13 220 14 160

Reducing pretreatment: immerse the electrode for a few min-

utes in HI 7091.

Oxidizing pretreatment: immerse the electrode for a few min-

utes in HI 7092.

If the pretreatment is not performed, the electrode will take

significantly longer to respond.

As with pH electrodes, gel-filled redox electrodes are more

suitable for industrial applications due to lesser mainte-

nance requirements. However, if working with refillable

electrodes, the electrolyte level should not fall more than

2½ cm (1") below the fill hole and topped up if necessary.

Use HI 7071 Refill Solution for single junction and HI 7082

for double junction electrodes.

In the event that measurements are performed with solu-

tions containing sulfides or proteins, the cleaning of the

diaphragm of the reference electrode must be performed

more often to maintain the proper functioning of the ORP

electrode. Therefore, immerse it into HI 7020 and mea-

sure the response; the obtained value should be within

200 and 275 mV.

After this functional test, it is suggested to wash the elec-

trode thoroughly with water and proceed to the oxidizing

or reducing pretreatment before taking measurements.

When not in use, the electrode tip should be kept moist

and far from any type of mechanical stress which might

cause damage. This can be achieved by installing the elec-

trode in such a way that it is constantly in a well filled with

the sample (stream or tank). The protective cap can also

be filled with HI 70300 Storage Solution if the electrode is

not being used at all.

Note With industrial applications, it is always recommended to

keep at least one spare electrode handy. When anomalies

are not resolved with a simple maintenance, change the elec-

trode to see if the problem is alleviated.