Xylem MULTI 3400 MULTI-PARAMETER METERS Manual de usuario descargar pdf (Pagina 20)

Operation Multi 3400i

4.2.4 pH calibration

Why calibrate? pH electrodes age. This changes the asymmetry (zero point) and slope

of the pH electrode. As a result, an inexact measured value is dis-

played. Calibration determines the current values of the asymmetry

and slope of the electrode and stores them in the measuring instru-

ment. Thus, you should calibrate at regular intervals.

When to calibrate? z After connecting another electrode

z When the sensor symbol flashes:

– after the calibration interval has expired

– after a voltage interruption, e. g. after changing the batteries

AutoCal TEC is specially matched to the WTW technical buffer solutions as a fully au-

tomatic two-point calibration. The buffer solutions are automatically

recognized by the measuring instrument. Depending on the instrument

setting (see section 4.8 C

ONFIGURATION), the instrument displays the

relevant buffer nominal value or the current electrode voltage in mV.

The calibration can be terminated after the first buffer solution. This cor-

responds to a single-point calibration. To do this, the instrument uses

the Nernst slope (-59.2 mV/pH at 25 °C) and determines the asymme-

try of the electrode.

AutoRead The calibration procedure automatically activates the AutoRead func-

tion.

The current AutoRead measurement can be terminated at any time

(accepting the current value) by pressing <RUN/ENTER>.

Displaying the calibra-

tion data

You can view the data of the last calibration on the display. The pro-

ceeding is described on page 48.

Printing the

calibration protocol

The calibration record contains the calibration data of the current cali-

bration. You can transmit the calibration protocol to a printer via the se-

rial interface (see O

UTPUTTING THE CALIBRATION PROTOCOL ON THE

INTERFACE, page 51).

Note

You can automatically print a calibration record after the calibration. To

do so, connect a printer to the interface according to section 4.7.2 be-

fore calibrating. After a valid calibration, the record is printed.

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Xylem MULTI 3400 MULTI-PARAMETER METERS Manual de usuario Pagina 20