H87.0.0X.6C-01
Operating manual G 7500 Series
page 26 of 34
7.2.3 buffer
The buffers are auto detected. When the buffer is not recognized (no PHL or DIN
buffer, very bad electrode, extreme temperature or contaminated buffer solution) the
device will ask for manual input of pH value and temperature.
On manual input and using oft he listed standard buffers, please check the electrode
quality after calibration. If in doubt prepare new buffer solutions and clean or replace
the electrode. At extreme temperatures, try to bring them to room temperature (20..25
°C).
7.2.3.1 PHL standard
For calibration the standard buffers for the GMH handheld instruments are used.
These are pH 4 (red), pH 7 (green) und pH 10 (blue).
7.2.3.2 DIN standard
For calibration DIN standard buffers are used.
pH 1,680
pH 3,557
pH 3,776
pH 4,001
pH 6,881
pH 7,429
pH 9,225
pH 10,062
7.2.3.3 No detection
Device will ask for manual buffer input after detecting a stable value within the valid
temperature range.
7.2.4 calibration mode
This setting has strong influence about the accuracy and duration of the calibration
process.
7.2.4.1 standard
allowed deviance 0,075 mV between last 45 measurements
7.2.4.2 strict
allowed deviance 0,075 mV between 45 measurements and allowed deviance 0,01
mV between last 10 measurements
7.2.4.3 fast
allowed deviance 0,23 mV between last 10 measurements
