Xylem PH3110 FIELD PH METER - Manual (Page 19)

pH 3110 Operation
19 ba75791e02 11/2008
4.3 Calibration
Why calibrate? 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.
When do you have to
calibrate?
z After connecting another combination electrode
z When the sensor symbol flashes on the display:
– e.g. after the calibration interval has expired
AutoCal 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:
z Technical buffers (AutoCal TEC)
z DIN buffers (AutoCal DIN)
Calibration points 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:
Note
You can display the slope in the units, mV/pH or %.
You can display the zero point in the units, mV or pH.
ConCal 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.
Stability control
AutoRead
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
.
Determined values Displayed calibration data
1-point ASY z Zero point = ASY
z Slope = Nernst slope
(-59.16 mV/pH at 25 °C)
2-point
3-point ASY
SLO z Zero point = ASY
z Slope = SLO