AEC FSS Series 1.5- 10 HP Fountain Solution Systems - Manual (Page 47)

Page 46 FSS Series Fountain Solution Systems
IAE-600
39) Put the sensor in a cup of pH 7.00 (Make sure the threads on
the sensor are fully submerged)
40) Let the temperature equalize for about 30 minutes or until the
pH reading is stable. If the reading on the operator screen is
7.00 +/- 0.1 @ 75 degrees F, this will confirm calibration is
correct.
* If the slope is higher than 62 or lower than 54, the sensor has aged or
become dirty and its slope decreases. When the slope is less than 54
mV/pH, clean the sensor to improve its performance. If you are using a
GLI Differential sensor and the slope remains low, replace the salt bridge
and standard cell solution (see sensor operating manual for details).