Clean The Ph/Orp Sensor - Hach MP-4 User Manual

Maintenance
1 Temperature sensor
2 Conductivity cell (built-in electrodes) 6 Reference junction under glass pH
3 ORP electrode
4 pH/ORP sensor (replaceable)
5.4.2

Clean the pH/ORP sensor

The pH/ORP sensor in the MP series meters is non-refillable and features a porous
liquid junction. It should not be allowed to dry out. If it does dry out, the sensor can
sometimes be restored by following the steps below.
Clean the sensor cup with isopropyl alcohol.
1.
Rinse well. Do not scrub or wipe the pH/ORP sensor.
2.
Follow the hot solution method described below:
3.
Pour a hot salt solution ~60 ºC (140 ºF), such as pH storage solution in the
a.
sensor cup.
Allow the liquid to cool.
b.
Retest.
c.
If the hot solution method does not work, follow the Deionized (DI) water
4.
method below:
Pour DI water into the sensor cup.
a.
Figure 7 Model MP-6 sensor cups
5 pH glass electrode
bulb
7 pH/ORP sensor protective cap
39