Calibration - wtw pH 3110 Operating Manual

pH 3110
Why calibrate?
When do you have to
calibrate?
AutoCal
Calibration points
ConCal
Stability control
AutoRead
ba75791e02 11/2008
4.3

Calibration

pH combination electrodes age. This changes the zero point
(asymmetry) and slope of the pH combination electrode. As a result, an
inexact measured value is displayed. Calibration determines the
current values of the zero point and slope of the combination electrode
and stores them in the measuring instrument. Thus, you should
calibrate at regular intervals.
After connecting another combination electrode
When the sensor symbol flashes on the display:
– e.g. after the calibration interval has expired
is adapted to the permanently programmed buffer solutions as a fully
automatic single-point, two-point or three-point calibration. The buffer
solutions are automatically recognized by the meter.
The following buffer sets are suitable:
Technical buffers (AutoCal TEC)
DIN buffers (AutoCal DIN)
Calibration can be performed using one, two or three buffer solutions in
any order (single-point, two-point or three-point calibration). The meter
determines the following values and calculates the calibration line as
follows:
Determined values
1-point ASY
2-point ASY
3-point SLO
Note
You can display the slope in the units, mV/pH or %.
You can display the zero point in the units, mV or pH.
This function is a conventional two-point calibration using two buffer
solutions (pH 7.0 ± 0.5 and any other buffer solution) or a single-point
calibration using any buffer solution and is used as a high-speed
method.
The calibration procedure automatically activates the stability control
function. The current measurement with stability control can be
terminated at any time (accepting the current value) by pressing
<ENTER>.
Displayed calibration data
Zero point = ASY
Slope = Nernst slope
(-59.16 mV/pH at 25 °C)
Zero point = ASY
Slope = SLO
Operation
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