Measurement Principle Of Transmitter; Co, No And Nh 3 Transmitter; Transmitter - Dräger VarioGard Gebrauchsanweisung

Measurement principle of transmitter

Measurement principle of transmitter
CO, NO, NO and NH
2
The VarioGard CO, NO, NO
measuring transducers for measuring the partial pressure of the respective
gas under atmospheric conditions.
1 measured gas
2 dustfilter or selective filter
3 membrane
4 sensing electrode
5 electrolyte
6 reference electrode
7 counter electrode
The ambient air being monitored diffuses through a membrane into the liquid
electrolyte in the sensor. The electrolyte contains a sensing electrode, a
counter electrode and a reference electrode. An electronic potentiostat-
circuit ensures a constant electrical voltage between sensing electrode and
reference electrode. Voltage, electrolyte and electrode material are selected
to suit the gas being monitored so that it is transformed electrochemically on
the sensing electrode. The flow of electrons generated by the reaction is a
measure of the gas concentration.
At the same time, oxygen from the ambient air reacts electrochemically at the
counter electrode.
O

transmitter

2
The VarioGard O transmitter is an electrochemical measuring transducer for
2
measuring the O concentration in ambient air.
2
1 measured gas
2 dustfilter
3 capillary
4 sensing electrode
5 electrolyte
6 reference electrode
7 counter electrode
The ambient air to be measured diffuses through a capillary to the measuring
electrode. At the electrode, the oxygen is converted by electrochemical
reaction. An external potentiometer-type regulator maintains a constant
voltage for this reaction between the measuring electrode and an additional
reference electrode. The flow of electrons generated by the reaction is a
measure of the oxygen concentration.
The reverse reaction takes place at the counter electrode.
80
transmitter
3
and NH transmitters are electrochemical
2 3
4
2
4
1
2
3
5
6 7
1
3
5
6 7