Gas Flow Diagram Of The Analyzer Pma 30; Figure 3 Figure - M&C PMA Series Instruction Manual

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Figure 3
The measuring cell consists of two nitrogen-filled spheres  which are arranged in the form of a dumbbell.
In the dumbbell's central point of rotation, a small mirror  is placed. The dumbbell is surrounded by a wire
coil needed for the compensation procedure. The described system is fixed rotationally symmetrical inside a
glass tube via a tightening strap out of platinum  and is screwed with two pole pieces .
Two permanent magnets are producing an inhomogeneous magnetic field. When oxygen is flowing in, the
molecules of the oxygen are drawn into the magnetic field. In consequence, the lines of electric flux on the
cuneiform pole pieces  are compressed. The nitrogen-filled diamagnetic spheres are pushed out of the
magnetic field. This causes a rotation of the dumbbell. The rotation is detected via an optical system consist-
ing of mirror , projection LED  and photoelectric cell .
In case the dumbbell is pushed out of the magnetic field, the tension of the photoelectric cell is immediately
changed. The measuring amplifiers  and  are producing a respective current which develops via the wire
coil on the dumbbell an electro-magnetic load moment. The load moment is resetting the dumbbell into its
zero position.
Every change of the oxygen concentration produces a linear proportional change of the compensation cur-
rent and can be read directly in % O
Due to its very small stagnant volume (2 cm
fast response time (T -time) of 1 second for a high gas flow can be realized.
90
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GAS FLOW DIAGRAM OF THE ANALYZER PMA 30


Fine filter

Flow meter with needle valve
Figure 4
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Scheme of the measuring cell and optical signal processing
as oxygen value on the display .
2
3
) and the direct flow of the M&C measuring cell, an extremely
Gas flow diagram PMA 30
PMA30 | 1.01.03
7 8

Measuring cell

Flow alarm sensor
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