Myron L 9PTK with FCE Free Chlorine User Manual

Page 41

To continue with 3rd point calibration, use basic buffer if acidic buffer

was used in the 2nd point, or vice-versa. Again, match the display to the

known buffer value as in step 2 and continue with the following steps:

Repeat steps 3 through 6 using opposite buffer solution.

Press

to accept 3rd point of calibration, which

completes the Calibration procedure. Fill sensor well with

Myron L Storage Solution and replace protective cap.

8. ORP Calibration

ORP electrodes rarely give false readings without problems in the

reference electrode. For this reason, and because calibration solutions

for ORP are highly reactive and potentially hazardous, your Ultrameter III

has an electronic ORP calibration. This causes the zero point on the

reference electrode to be set whenever pH 7 calibration is done.

9. Temperature Calibration

Temperature calibration is not necessary in the Ultrameter III.

viii.

calibratiOn intervals

There is no simple answer as to how often one should calibrate an

instrument. The Ultrameter III is designed to not require frequent

recalibration. The most common sources of error were eliminated in

the design, and there are no mechanical adjustments. Still, to ensure

specified accuracy, any instrument must be checked against chemical

standards occasionally.

A. Suggested Intervals

On the average, we expect calibration need only be checked monthly

for the Conductivity, RES or TDS functions. The pH function should be

checked every 2 weeks to ensure accuracy. Measuring some solutions

will require more frequent intervals.

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.