ES Magazine Issue 38 Korea Special | Page 20

TECHNOLOGY FOCUS

PARAMAGNETIC SENSING – FOR RELIABLE PERCENTAGE OXYGEN MEASUREMENT

Magnetic field
Servomex ’ s ground-breaking magnetodynamic Paramagnetic technology provides fast , accurate and sensitive measurements of percentage levels of oxygen ( O 2 ), and is ideal for measurements in flammable or corrosive gas mixtures .
The Paramagnetic cell consists of two nitrogen-filled glass spheres , mounted within a magnetic field , on a rotating suspension , with a centrally-placed mirror .
N 2 filled spheres
N 2 filled spheres
Taut band Band
Mirror
Light shines on the mirror and is reflected onto a pair of photocells . O 2 is naturally Paramagnetic , so is attracted to the magnetic field , displacing the glass spheres and causing suspension rotation , which is detected by the photocells .
Current is applied through a feedback coil present in the magnetic field to provide sufficient torque to return the suspension to its original position .
Paramagnetic magnet
Rotation
Light Source
Light source
The magnitude of this current is directly proportional to the O 2 present in the sample gas mixture .
Unlike electrochemical sensing technologies and other types of paramagnetic implementation , a Servomex Paramagnetic cell is non-depleting , so it never needs changing and its performance never deteriorates over time , and no reference gas is required . This reduces ongoing maintenance requirements and delivers a long operational life .
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