Myron L 9PTK - Manual (Page 40)

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B. Calibration Tracking Records
To minimize your calibration effort, keep records. If adjustments you
are making are minimal for your application, you can check less often.
Changes in conductivity calibration should be recorded in percent.
Changes in pH calibration are best recorded in pH units.
Calibration is purposely limited in the Ultrameter III to ±10% for the
conductivity cell, as any change beyond that indicates damage, not drift.
Likewise, calibration changes are limited to ±1 pH unit, as any change
beyond that indicates the end of the sensor’s lifetime and replacement
is recommended.
C. Conductivity, RES, TDS, Practices to Maintain Calibration
1. Clean oily films or organic material from the cell electrodes
with foaming cleaner or mild acid. Do not scrub inside the cell.
2. Calibrate with solutions close to the measurements you make.
Readings are compensated for temperature based on the
type of solution. If you choose to measure tap water with a
KCl compensation, which is often done (ref. An Example of 2
different solution selections and the resulting compensation,
pg. 57), and you calibrate with 442 solution because it is
handy, the further away from 25°C you are, the more error
you have. Your records of calibration changes will reflect
temperature changes more than the instrument’s accuracy.
3. Rinse out the cell with pure water after taking measurements.
Allowing slow dissolving crystals to form in the cell
contaminates future samples.
4. For maximum accuracy, keep the pH sensor cap on tight so
that no fluid washes into the conductivity cell.
D. pH and ORP Practices to Maintain Calibration
1. Keep the sensor wet with Myron L Storage Solution.
2. Rinse away caustic solutions immediately after use.
ORP calibration solutions are caustic, and ±5% is considered very
accurate. By using the pH zero setting (0 mV = 7 pH) for ORP and
precision electronics for detection, the Ultrameter III delivers better
accuracy without calibration than a simpler instrument could using
calibration solutions.
iX. memOry
This feature allows up to 100 readings with their temperatures to be
stored simultaneously for later recall. At the same time, the TIME and