Myron L PH1 - Manual (Page 6)

4. Press to verify the pH calibration. (If the display reads 7.00,
skip the pH Zero Calibration and proceed to section b. pH Gain
Calibration. If reading is not acceptable, continue.
5. Remove cap plug labeled ZERO CAL on bottom of Instrument.
N O T E : If the pH reading displayed will not adjust to the proper reading,
the sensor well needs additional rinsing or fresh buffer solution, or the pH
sensor is bad and needs to be replaced. (ref. Troubleshooting Chart, pg.
12)
6. Refill sensor well again with 7 buffer solution.
7. While pressing the key, adjust ZERO CAL Control with
finger until the display reads 7.0.
8. Replace bottom cap plug securely to maintain water resistance.
The pH Z E R O Calibration procedure is now complete. You may continue
with pH Gain Calibration or stop and replace with storage solution & pH cap.
b. pH Gain Calibration
IMPORTANT: Always calibrate or verify your pH1 with a pH 7 buffer
solution before adjusting the gain with acid or base buffers, i.e., 4 and/or
10, etc. The pH gain calibration is performed in the same manner as the
ZERO. For maximum accuracy use a buffer value closest to instrument’s
normal area of use, i.e., if you normally measure acidic solutions, use “4”
buffer.
1. Rinse the sensor well 3 times with acid or base buffer solution.
2. Refill sensor well again with same buffer solution.
3. Press key. If reading is acceptable, end procedure. If
not, continue.
4. Remove cap plug labeled GAIN CAL on bottom of Instrument.
5. Refill sensor well again with same buffer solution.
6. While pressing the , adjust GAIN CAL Control with
finger until reading agrees with buffer solution.
7. If the instrument will be used to read both acids and bases,
repeat steps 1 and 6 using opposite buffer solution.
8. If reading is different by more than is acceptable, split the
difference with the previous setting. (If it is not possible to
adjust Gain, it is an indication of bad buffers or a deteriorating
or damaged pH sensor).
9. Replace bottom cap plug securely to maintain water resistance.
The pH GAIN Calibration procedure is now complete.
VI. CALIBRATION INTERVALS
There is no simple answer as to how often one should calibrate an
instrument. The pH1 is designed to not require frequent recalibration.
The most common sources of error were eliminated in the design, and
there are simple electromechanical adjustments. Still, to ensure specified
accuracy, any instrument has to be checked against chemical standards
occasionally.
A. Suggested Intervals
On the average, calibration 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 pH calibration are best recorded in pH units. Calibration is
purposely limited in the pH1 to approximately ±1 pH unit because more
than that indicates the end of the sensor lifetime, and it should be
replaced.
C. Practices to Maintain Calibration.
1. Keep the sensor wet with pH storage solution .
2. Rinse away caustic solutions immediately after use.
VII. CHANGING from CENTIGRADE to FAHRENHEIT
(Note: °F to °C is the reverse)
1. Dry Instrument THOROUGHLY.
2. Remove the 4 bottom screws and carefully open Instrument.
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