YSI YSI 556 MPS, Set-Up, Operation & Calibration

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pH / ORP (Stage 2)
•
NOTE: If good pH and/or ORP response is still not restored by the above procedure,
perform the following additional procedure:
•
Soak the sensor for 30-60 minutes in one molar (1 M) hydrochloric acid (HCl). This
reagent can be purchased from most distributors. Be sure to follow the safety
instructions included with the acid.
•
GENTLY clean the glass bulb and platinum button by rubbing with a cotton swab
soaked in the acid.
•
Rinse the sensor in clean water, wipe with a cotton swab saturated with clean water,
and then re-rinse with clean water. To be certain that all traces of the acid are
removed from the sensor crevices, soak the sensor in clean water for about an hour
with occasional stirring.