Delta OHM HD2205.2, Manual

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pH measurement
The HD2205.2 and HD2256.2 instruments work with pH/temperature probes complete with
SICRAM module, pH measurement electrodes, redox potential measurement electrodes (ORP), and
specific ion electrodes. The pH measurement is generally accompanied by the temperature meas-
urement. The SICRAM combined pH/temperature probes are fitted with Pt100 temperature sensor:
The instruments measure also the temperature using probes fitted with 4 wire Pt100, or 2 wire
Pt1000 sensors, or using probes complete with SICRAM module. The temperature is used for the
automatic compensation of the Nernst coefficient with the pH electrode.
If a temperature only probe is connected (connector
5
), it has priority on the temperature supplied
by any combined probe: Please see the chapter dedicated to temperature measurement on page 36.
Probes with SICRAM and without SICRAM
The SICRAM pH probe is formed by a pH electrode, a Pt100 temperature sensor and an electronic
module. The module has a memory circuit that enables the instrument to recognize the type of
probe connected. It stores also the serial number, the factory calibration of the Pt100 sensor, the
manufacturing date and the parameters of the last two pH calibration performed by the user.
The instrument stores the last eight pH calibrations performed by the user: The last two calibration
are stored also in the probe’s SICRAM memory. Upon power on, the instrument reads the two cali-
brations in the probe and, if the probe was calibrated on the same instrument, they are added to the
ones already stored in the instrument in order to make up the history calibration of the SICRAM pH
probe. If the SICRAM pH probe is connected to a different instrument, only the parameters in the
probe memory will make up the calibration history.
If a SICRAM pH probe is connected to the instrument, the relevant BNC direct input is dis-
abled
: The SICRAM pH probe has priority on the electrode connected directly to the BNC input.
Module pH SICRAM KP47
The KP47 module is a SICRAM type interface for pH electrodes with BNC connector. By using
this module you can add all of the advantages of a SICRAM probe to a pH electrode: For example,
you can move the module linked to the electrode from an input to another (for the HD2205.2) or
from an instrument pH SICRAM input to a second instrument, without performing a new calibra-
tion.
The module is automatically recognized by the instrument when you turn it on, and the serial num-
ber and parameters described above are read.
You just need to connect the electrode to the module female BNC connector, connect the module to
the pH SICRAM inputs (
3
and
4
), and turn on the instrument. Perform a first calibration on two
or more points. One must be in the neutral band (e.g. 6.86pH). The module is now ready for use.
Of course, once the calibration is performed, the electrode linked to the module should not be
changed: As the electrode calibration information are saved in the module, this will generate meas-
urement errors. When you replace the electrode you should do a new calibration.