General Tools and Instruments DPHC2001 - Manual (Page 10)

4) PH 7 calibration
Connect the PH ELECTRODE with the " BNC socket "
( 3-10, Fig. 1 ) and immerse the electrode in the PH7
buffer solution.
Press the " CAL Button " ( 3-8, Fig. 1 ) then the upper
display shows texts of " CAL " and the lower display
shows the default calibration value.
CAL
7.00
* The texts " CAL " will flash for around 5 seconds.
After that, the meter calibrates itself automatically.
The upper display will show the calibrated value,
the lower display will show the temperature value.
7.00
25.0
5) PH 4 or PH 10 calibration
Rinse the electrode with distilled water.
Immerse the electrode in the PH4 buffer solution ( or PH10
buffer solution ).
Press the " CAL Button " ( 3-8, Fig. 1 ) then the upper
display shows texts of " CAL " and the lower display
shows the default calibration value.
8