Endress+Hauser CPS31D Specifications

TI00030C/07/EN/13.13
71201979

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Technical Information

Memosens CPS31D and
Ceratex CPS31

pH electrodes, analog and digital with Memosens
technology
For drinking water and swimming pool water

Gel-filled reference system with ceramic diaphragm

Application

•Drinking water

• Swimming pool water

• pH compensation for measuring free chlorine

Your benefits

• One or three ceramic diaphragms

• Optional salt ring for extended operating life

• Very low level of ion depletion in electrolyte

• Gel filling, no electrolyte refill required

• Can be used up to 4 bar (60 psi) absolute pressure

• Can be used up to 80˚C (176 °F)

• Shaft length 120 mm

• Memosens plug-in head

•ESA or GSA plug-in head

Further benefits offered by Memosens technology

• Maximum process safety thanks to non-contact, inductive signal transmission

• Digital data transmission ensures data security

• Very easy to use as sensor-specific data are stored in the sensor

• Recording of sensor load data in the sensor enables predictive maintenance

Function and system design

Measuring principle pH measurement

The pH value is a measure of the acid or base character of a medium. Depending on the pH value of the
medium, the electrode's membrane glass provides an electrochemical potential. This is the result of H
ions selectively penetrating the outer layer of the membrane. As a result, an electrochemical boundary
layer forms here with an electric potential. An integrated Ag/AgCl reference system forms the required
reference electrode.
The transmitter converts the measured voltage into the corresponding pH value according to the
Nernst equation.

General characteristics Durability

Depending on the version, the electrode can withstand pressures up to 4 bar (60 psi) and temperatures
up to 80 ˚C (176 ˚F).

CPS31D/CPS31

+

Communication and data processing with CPS31D

Measuring system data which digital sensors can save in the sensor include:

• Manufacturer data
– Serial number
–Order code
–Date of manufacture

• Calibration data
– Date of calibration
– Calibrated slope at 25 ˚C (77 ˚F)
– Calibrated zero point

at 25 ˚C (77 ˚F)
– Temperature offset
– Number of calibrations
– Serial number of the transmitter used to perform the last calibration

• Operating data
– Temperature application range
– pH application range
– Date of initial commissioning
– Maximum temperature value
– Operating hours at temperatures above 80 ˚C / 100 ˚C (176 ˚F / 212 ˚F)
– Operating hours for very low and very high pH values

(Nernst voltage below –300 mV, above +300 mV)
– Number of sterilizations
– Glass membrane impedance

The data listed above can be displayed using the Mycom S CPM153, Liquiline M CM42 and Liquiline
CM44x transmitters.

Dependability with CPS31D Reliability

Memosens technology digitizes the measured values in the sensor and transmits them to the
transmitter via a non-contact connection in a way that is free from any potential interference. The
result:

• Automatic error message generation if the sensor fails or the connection between sensor and
transmitter is interrupted

• Immediate error detection increases measuring point availability

2 Endress+Hauser

CPS31D/CPS31

Maintainability

Sensors with Memosens technology have integrated electronics that save calibration data and other
information, such as total hours of operation and operating hours under extreme measuring conditions
etc. Once the sensor has been connected, the sensor data are automatically sent to the transmitter and
used to calculate the current measured value.
Saving the calibration data makes it possible to calibrate and adjust the sensor irrespective of the
measuring point. The result:

• Convenient calibration in the measuring lab under optimum external conditions improves the
quality of the calibration.

• Measuring point availability is dramatically increased by the quick and easy replacement of
precalibrated sensors.

• The availability of the sensor data makes it possible to accurately determine the maintenance
intervals of the measuring point and enables predictive maintenance.

• The sensor history can be documented using external storage media and evaluation programs. The
sensor's field of application can be determined based on its previous history.

Integrity

With its inductive transmission of the measured value via a non-contact plug-in connection,
Memosens guarantees maximum process safety and offers the following advantages:

• All problems caused by moisture are eliminated:
– The plug-in connection is free from corrosion
– Moisture cannot corrupt the measured value
– Plug-in system can even be connected under water

• The transmitter is galvanically decoupled from the medium.

• EMC safety is guaranteed by screening measures in the digital measured value transmission.

Measuring system A complete measuring system comprises:

• pH electrode CPS31D or CPS31

• Transmitter, e.g. Liquiline CM44x (for CPS31D with Memosens technology)

• Measuring cable, e.g. CYK10 for CPS31D

• Immersion, flow or retractable assembly, e.g. Flowfit CCA250

Example of a measuring system: pH compensation for chlorine measurement

1 Cable CYK10
2 Liquiline CM44x transmitter
3 Chlorine sensor CCS142D
4 Flowfit assembly CCA250
5 pH electrode CPS31D

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