This analyzer makes use of two principles:
- Oxygen is strongly paramagnetic - it is attracted by a magnetic field
- Nitrogen is diamagnetic - it is repelled by a magnetic field.
Two small spheres are arranged, dumbbell fashion about a pivot and between two pairs of pole pieces. The spheres are each filled with nitrogen which is repelled by the magnets, applies a torque to the dumbbell. The gas to be analyzed is passed between the pole pieces, the magnetic field concentrates the oxygen from the gas and a small force, proportional to the oxygen concentration exerts a further torque on the dumbbell arrangement. A mirror attached to the dumbbell reflects light from a lamp onto a photocell where it is converted into an electric input for an amplifier. The amplifier output is arranged to pass through a small coil which is positioned around the dumbbell and generates a torque which is in opposition to that applied due to the paramagnetic effect. A measure of the current flow required to provide the balancing torque is proportional to the oxygen concentration.
