Teledyne GFC 7001E Second GAS Sensors, Ethernet + Multidrop OPT 63C, Oxygen Sensor Option 65A

Optional Hardware and Software Model GFC7001E Carbon Dioxide Analyzer

5.7.4.ETHERNET + MULTIDROP (OPT 63C)

This option allows the instrument to communicate on both RS-232 and ETHERNET networks simultaneously. It includes the following:

RS-232 MULTIDROP (OPT 62)

ETHERNET (OPT 63A)

5.8.SECOND GAS SENSORS

5.8.1.OXYGEN SENSOR (OPTION 65A)

5.8.1.1.Theory of Operation - Paramagnetic measurement of O2

The oxygen sensor used in the GFC 7001E/EM Analyzer utilizes the fact that oxygen is attracted into strong magnetic field while most other gases are not, to obtain fast, accurate oxygen measurements.

The sensor’s core is made up of two nitrogen filled glass spheres, which are mounted on a rotating suspension within a magnetic field (see Figure 5-14). A mirror is mounted centrally on the suspension and light is shone onto the mirror that reflects the light onto a pair of photocells. The signal generated by the photocells is passed to a feedback loop, which outputs a current to a wire winding (in effect, a small DC electric motor) mounted on the suspended mirror.

Oxygen from the sample stream is attracted into the magnetic field displacing the nitrogen filled spheres and causing the suspended mirror to rotate. This changes the amount of light reflected onto the photocells and therefore the output levels of the photocells. The feedback loop increases the amount of current fed into the winding in order to move the mirror back into its original position. The more O2 present, the more the mirror moves and the more current is fed into the winding by the feedback control loop.

A sensor measures the amount of current generated by the feedback control loop which is directly proportional to the concentration of oxygen within the sample gas mixture.

Figure 5-14: Oxygen Sensor - Principle of Operation

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