VOLTCRAFT PHT-200 Bedienungsanleitung Seite 31

For 2-point calibration, proceed as follows:
Neutral point calibration pH 7
• Connect the pH electrode to the measuring device and turn it on. Pay attention to the measuring function "PH".
• Remove the moisture container from the electrode and rinse the electrode thoroughly with distilled water.
• Immerse the electrode in the buffer solution pH7. Stir the electrode gently in the buffer solution until the reading
stabilizes. This flows around the electrode and speeds up the process.
• Press the "CAL." key (6). The upper line of the display shows "CAL" and the lower line shows the preset calibration
value. (e.g., CAL 07.00)
• The display flashes for approximately 5 seconds. During this time, the measuring device calibrates automatically.
• The display returns to the normal measuring screen. The calibrated value appears in the upper line and the tem-
perature value is displayed in the lower line.
The automatic calibration only works if there is a measurement error of less than ± 1 pH. If the display
difference is greater, it must be adjusted manually. Open the side socket cover (16). Use a small flat-head
screwdriver on the adjustment dial "CAL. PH7" (13) to adjust the display value to approximately 7.00. Close
the cover and perform a neutral point calibration as described above. After that, the reading should fit.
• Rinse the electrode thoroughly with distilled water.
Calibration pH 4 or pH 10
• Immerse the electrode in the appropriate buffer solution (pH 4 or pH 10). Stir the electrode gently in the buffer solu-
tion until the reading stabilizes. This flows around the electrode and speeds up the process.
• Press the "CAL." key (6). The upper line of the display shows "CAL" and the lower line shows the preset calibration
value. (e.g., CAL 04.00 or CAL 10.00)
• The display flashes for approximately 5 seconds. During this time, the measuring device calibrates automatically.
• The display returns to the normal measuring screen. The calibrated value appears in the upper line and the tem-
perature value is displayed in the lower line.
The automatic calibration only works if there is a measurement error of less than ± 1 pH. If the display
difference is greater, it must be adjusted manually. Open the side socket cover (16). Adjust the display
value to approximately the setpoint (for example 4.00 or 10.00) using a small flat-head screwdriver on the
adjustment knob "SLOPE PH4 PH10" (15). Close the cover and perform another pH 4/pH 10 calibration as
described above. After that, the reading should fit.
• Rinse the electrode thoroughly with distilled water.
• To get a stable result, repeat calibration 1 - 2 times.
• The measuring device is ready for the following measurements.
For 1-point calibration, proceed as follows:
• If no pH 4 and pH 10 buffer solution is available, single point calibration (pH 7) can be performed. However, for more
accurate readings and linearity, a two-point calibration is always recommended.
• To do this, carry out the calibration procedure as described above up to the neutral point calibration pH 7.
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