Measuring Principle Of The Analyzer; Principle Of Measurement; Fig. 2: Paramagnetic Measuring Cell - M&C GENTWO PMA1000 Instruction Manual

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Measuring principle of the analyzer

5.1 Principle of measurement

All gases are diamagnetic but just a few gases have a paramagnetic behavior. Oxygen is a
paramagnetic gas, which means that oxygen molecules are attracted into a strong mag-
netic field. This paramagnetic susceptibility distinguishes oxygen from most other gases.
The M&C PMA gas is working according to the magneto-mechanical principle: The PMC
uses this paramagnetic characteristic to measure the concentration of oxygen in a gas
mixture.
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Fig. 2: Paramagnetic measuring cell

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dumbbell
3
mirror
The PMC used in this oxygen analyzer represents the so called 'dumbbell'-type. It consists
of two nitrogen-filled spheres suspended on a fine platinum wire in an inhomogeneous
magnetic field. Around the dumbbell is a single turn of platinum wire which is connected
to the rest of the electronics through the platinum suspension. Before the measurement,
the spheres are kept in balance in the inhomogeneous magnetic field. When the gas mix-
ture with the oxygen concentration flows through the paramagnetic cell, the dumbbell
starts moving.
PMA1000/PMA1000L | 1.00.00
2 3
2
suspension wire
4
magnetic poles
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