User manual HANNA INSTRUMENTS HI 991003

[. . . ] The probes are warranted for a period of six months. This warranty is limited to repair or replacement free of charge. Damage due to accidents, misuse, tampering or lack of prescribed maintenance are not covered. If service is required, contact the dealer from whom you purchased the instrument. [. . . ] Note: When the meter detects the absence of a temperature probe at its input, the Automatic Temperature Compensation is turned off, and the meter uses a default value of 25°C (77°F) for the temperature measurement and compensation. In this condition, the secondary LCD shows 25. 0°C (77. 0°F) blinking. When a probe is connected, the meter automatically returns to the ATC mode, the ATC tag is turned on, and the temperature is shown on the secondary display. pH MEASUREMENT & CALIBRATION · Make sure the meter has been calibrated before use. · If the probe is dry, soak it in HI 70300 storage solution for one hour to reactivate it. · Place the probe into the sample to be tested. · Stir briefly and wait until the symbol on the top left of the LCD is turned off. · The LCD shows the pH value (automatically compensated for temperature) and the temperature of the solution. · If measurements are taken in different samples successively, rinse the probe tip thoroughly to eliminate cross-contamination. After cleaning, rinse the probe tip with some of the sample to be measured. pH calibration · Press and hold the ON/OFF/MODE button until OFF on the secondary display 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 display. If no valid buffer is detected, the meter keeps the USE indication active for 12 seconds, and then it replaces it with WRNG, indicating that 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 measurement is stable; the meter will show on the primary display the accepted buffer, with the message "OK 1" on the secondary display, and an audible signal is produced. After 1 second, the meter automatically returns to the normal mode. If a single-point calibration with buffers pH 7. 01 or 6. 86 is desired, then after the calibration point has been accepted the ON/OFF/MODE button must be pressed in order to return to the normal measuring mode. After the button is pressed, the meter shows "7. 01" (or "6. 86") "OK 1", and an audible signal is produced. After 1 second, the meter automatically returns to the normal measuring mode. · For a two-point calibration, place the probe in pH 7. 01 (or pH 6. 86) buffer. After the 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 this reading is outside the range ±40 mV, the electrode is considered "poor" and it is recommended to replace it with a new one. The slope value of the electrode is the difference between readings in pH7 and in pH4 buffers. For a new electrode this is about 174 mV (@25°C/ 77°F). When it reaches the value of about 150 mV, the electrode is considered "poor", and it is recommended to replace it with a new one. [. . . ]