User manual HANNA INSTRUMENTS HI 98128

[. . . ] Avoid touching the glass bulb at all times. Any variation introduced by the user to the supplied equipment may degrade the instrument's EMC performance. To avoid electrical shock, do not use this instrument when voltages at the measurement surface exceed 24 Vac or 60 Vdc. To avoid damages or burns, do not perform any measurement in microwave ovens. WARRANTY HI 98127 and HI 98128 are warranted for one year against defects in workmanship and materials when used for their intended purpose and maintained according to instructions. [. . . ] · If measurements are taken in different samples successively, rinse the probe thoroughly to eliminate cross-contamination; and after cleaning, rinse the probe with some of the sample to be measured. ±0. 1 pH (HI 98127) ±0. 05 pH (HI 98128) ±0. 5°C / ±1°F ±0. 1 pH (HI 98127) ±0. 02 pH (HI 98128) ±0. 3°C / ±0. 6°F Automatic CALIBRATION For better accuracy, frequent calibration of the instrument is recommended. In addition, the instrument must be recalibrated whenever: a) The pH electrode is replaced. Calibration procedure From normal measuring mode, press and hold the /MODE button until OFF on the secondary LCD is replaced by CAL. The LCD enters the calibration mode displaying "pH 7. 01 USE" (or "pH 6. 86 USE" if the NIST buffer set was selected). After 1 second the meter activates the automatic buffer recognition feature. If a valid buffer is detected then its value is shown on the primary display and REC appears on the secondary LCD. If no valid buffer is detected, the meter keeps the USE indication active for 12 seconds, and then it replaces it with WRNG, indicating the sample being measured is not a valid buffer. For a single-point calibration with buffers pH 4. 01, 9. 18 or 10. 01, the meter automatically accepts the calibration when the reading is stable; the meter displays the accepted buffer, with the message "OK 1". After 1 second the meter automatically returns to the normal measuring mode. If a single-point calibration with buffer pH 7. 01 (or pH 6. 86) is desired, then after the calibration point has been accepted the /MODE button must be pressed in order to return to normal mode. After the button is pressed, the meter shows "7. 01" (or "6. 86") - "OK 1" and, after 1 second, it automatically returns to the normal measuring mode. Note: It is always recommended to carry out a twopoint calibration for better accuracy. For a two-point calibration, place the electrode in pH 7. 01 (or pH 6. 86) buffer. After the first calibration point has been accepted, the "pH 4. 01 USE" message appears. The message is held for 12 seconds, unless a valid buffer is recognized. If no valid buffer is recognized, then the WRNG message is shown. If a valid buffer (pH 4. 01, pH 10. 01, or pH 9. 18) is detected, then the meter completes the calibration procedure. When the buffer is accepted, the LCD shows the accepted value with the "OK 2" message, and then the meter returns to the normal measuring mode. Note: When the calibration procedure is completed, the CAL tag is turned on. To quit calibration and to reset to the default values · After entering the calibration mode and before the first point is accepted, it is possible to quit the procedure and return to the last calibration data by pressing the /MODE button. The secondary LCD displays "ESC" for 1 second and the meter returns to the normal measuring mode. · To reset to the default values and clear a previous calibration, press the SET/HOLD button after entering the calibration mode and before the first point is accepted. The secondary LCD displays "CLR" for 1 second, the meter resets to the default calibration and the CAL tag on the LCD disappears. · The pH electrode can be easily replaced by using the supplied tool (HI 73128). [. . . ] Release the button. BATTERY REPLACEMENT The meter displays the remaining battery percentage every time it is switched on. When the battery level is below 5%, the symbol on the bottom left of the LCD lights up to indicate a low battery condition. If the battery level is low enough to cause erroneous readings, the meter shows "0%" and the Battery Error Prevention System (BEPS) will automatically turn the meter off. To change the batteries, remove the 4 screws located on the top of the meter. pH ELECTRODE MAINTENANCE · When not in use, rinse the electrode with water to minimize contamination and store it with a few drops of HI 70300 storage solution in the protective cap. [. . . ]