wtw pH 3300i, Operating Manual

Page: 14 / 69

Operation pH 3300i/3400i
14 ba75682e02 03/2008
4.2 Measuring
4.2.1 General information
You can measure the following variables:
z
pH value
z
ORP voltage
Preparatory
activities
Perform the following preparatory activities when you want to measure:
Warning
When connecting an earthed PC/printer, measurements cannot be per-
formed in earthed media as incorrect values would result. The RS 232 inter-
face is not galvanically isolated.
Note
Incorrect calibration of pH electrodes leads to incorrect measured values.
Calibrate regularly before measuring.
Temperature
sensor
You can measure with or without a temperature sensor. If a temperature sen-
sor is connected, it is indicated on the display by
TP .
Note
The measuring instrument automatically recognizes the type of the tempera-
ture sensor used. Therefore, you can connect temperature sensors of the
NTC30 or Pt1000 type.
The temperature measurement is absolutely essential for a reproducible pH
measurement. If the measurement is made without a temperature sensor,
proceed as follows:
1 Connect the electrode to the measuring instrument.
2 Adjust the temperature of the buffer solutions or test solutions, or
measure the current temperature, if you measure without a tempera-
ture sensor.
3 In conjunction with the electrode, check or calibrate the measuring in-
stument. How to calibrate is described in section 4.3.
4 Select the measuring mode with <M> .
1 Measure the current temperature of the test sample using a ther-
mometer.
2 Enter the temperature on the instrument: Set the temperature value
of the test sample using
<
▲
> <
▼
> .