Sper Scientific 850055 pH Meter - Advanced - Manual (Page 29)

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MAINTENANCE
2. Put the probe in a buffer solution of pH 7.00 with sat-
urated quinhydrone.
3. Stir; mV reading (E1) should be 86 ±15mV.
4. Rinse the probe with distilled water between each use.
Keep the ORP probe wet. If not in use for long periods,
it should be rinsed and stored in the soaker bottle filled
with the saturated KCL solution.
ORP Probe Cleaning
A contaminated sensing element can result in a slow
response and/or inaccurate reading.
 If contamination is a mineral matter, put the sensing
element in a HCl solution 0.1 N for 10 minutes. Then
rinse in distilled water.
 If contamination is oil or grease, clean with a mild
detergent. Then rinse with distilled water.
Upon completion of either cleaning method, immerse the
probe in a saturated buffer solution with pH 4.01 for 15
minutes and rinse with distilled water.
Probe Performance
The sensing element of an ORP probe is made of a high
purity metal. Slow response time and inaccurate readings
may be caused by the sensing element previously having
been soaked in a solution for a long period of time. An ox-
idation reduction coating may have formed on the surface
of the sensing element. Resolve by cleaning the element.