User manual HANNA INSTRUMENTS HI 207

[. . . ] 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. If under warranty, report the model number, date of purchase, serial number and the nature of the problem. If the repair is not covered by the warranty, you will be notified of the charges incurred. [. . . ] To turn the meter OFF While in normal measurement mode, press the ON/OFF/MODE key. Note: The instrument is provided with an acoustic signal feature, which is heard every time a key is pressed. Note: When the instrument detects the absence of the probe, the "ATC" tag turns off and the secondary display shows a default temperature value of 25 °C (77 °F) blinking. When the probe is connected, the instrument automatically returns to the Automatic Temperature Compensation mode, the "ATC" tag turns on, and the measured temperature is shown on the secondary display. pH MEASUREMENT & CALIBRATION · Make sure the instrument has been calibrated before use. · If the probe is dry, soak it in HI 70300 storage solution for one hour to reactivate it. · Make sure that the stirrer LED is off or press the STIR ON/OFF key to stop the stirrer (HI 208 only). · Place the beaker with the solution to be tested into the beaker holder and attach the electrode holder. · Insert the probe in the electrode holder and use the supplied rubber O-ring for probe in order to immerse the probe tip approximately 4 cm (1½") into the sample to be measured. · Press STIR ON/OFF to start the stirrer (HI 208 only) and wait until the stability indicator turns off. · The LCD shows the pH value automatically compensated for temperature variations 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 For better accuracy, frequent calibration of the instrument is recommended. In addition, the instrument must be recalibrated whenever: a) The pH electrode is replaced. · From normal mode press and hold the ON/OFF/ MODE key until "OFF" message 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) and "CAL" tag blinking. After 1 second the instrument activates the automatic buffer recognition feature. If a valid buffer is detected, then its value is shown on the primary display, and "REC" message appears on the secondary display. If no valid buffer is detected, the instrument keeps the "USE" message active for 12 seconds, and then replaces it with "WRNG", to indicate an invalid buffer. · For a single-point calibration with pH 4. 01, 9. 18 or 10. 01 buffer, the meter automatically accepts the calibration when the reading is stable; the meter will show the accepted buffer, with the "OK 1" message, and an audible signal is produced. After 1 second the meter automatically returns to normal measurement mode. [. . . ] The secondary display shows "ESC" message for 1 second and the instrument returns to normal mode. · To reset to the default values and clear a previous calibration, press the HOLD/SET key after entering calibration mode and before the first point is accepted. The secondary display shows "CLR" message for 1 second, the instrument resets to the default calibration and the "CAL" tag turns off. INSTRUMENT SETUP The SETUP mode allows the selection of the temperature unit and the pH buffer set. To enter SETUP mode, press and hold the ON/ OFF/MODE key until "CAL" message on the secondary display is replaced by "TEMP" and the current temperature unit (e. g. [. . . ]