Ceragel CPS71D and CPS71

2

Endress+Hauser

Function and system design

Measuring principle

pH measurement

The pH value is used as a unit of measurement for the acidity or alkalinity of a liquid medium. The

membrane glass of the electrode supplies an electrochemical potential which is dependent upon the

pH value of the medium. This potential is generated by the selective penetration of H+ ions through

the outer layer of the membrane. An electrochemical boundary layer with an electric potential forms

at this point. An integrated Ag/AgCl reference system serves as the required reference electrode.

The transmitter converts the measured voltage into the corresponding pH value using the Nernst

equation.

Measuring system

A complete measuring system consists of the following components at least:

• pH electrode CPS71D or CPS71

• Transmitter, e.g. Liquiline CM42, CM44x/R, Mycom S CPM153, Liquisys M CPM2x3

• Memosens data cable CYK10 for Memosens sensors or CPK9 for analog sensors

• Immersion, flow or retractable assembly, e.g. Cleanfit CPA871/875

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4

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Example of a measuring system for pH measurement

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Retractable assembly Cleanfit CPA871

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pH electrode CPS71D

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Memosens data cable CYK10

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Liquiline M CM42 two-wire transmitter for hazardous area