Principle of Measurement
The physical property distinguishing oxygen from other gases is its paramagnetism which is significantly greater than that of other common gases. Consequently, the molecules of oxygen are attracted by strong magnetic fields, a phenomena which can be used for detection purposes. A paramagnetic sensor consists of two spheres arranged in the form of a dumbbell suspended in a symmetrical, non-uniform magnetic field.
When the surrounding gas contains oxygen, the dumbbell spheres rotate out of the magnetic field by the relatively strong attraction of oxygen. A light beam focused on a mirror attached to the dumbbell reflects asymmetrically onto two photo diodes resulting in a voltage shift. The voltage difference produces a current used to drive the dumbbells back to the original position. The current flow required to maintain the null position is directly proportional to the oxygen concentration and is shown linearly in volume percent oxygen in the display. Properly maintained paramagnetic sensors last for years with little or no upkeep.
Advantages
Stability Built-in
Paramagnetic sensors, operating under suppressed, high-purity conditions, are natively subject to swings in their output based on changes in the surrounding barometric pressure. To properly compensate for such atmospheric pressure changes, Teledyne has incorporated an absolute pressure sensor in our system design.
In addition, to ensure an enhanced, stable performance, Teledyne maintains the paramagnetic sensor in its own isolated, heated compartment. A PID controller is used to properly control and maintain the temperature within the sensor compartment to optimize the analysis. The analysis section is mounted directly beside the 3010MA control unit allowing for a panel-saving, single 19" rack mount configuration.
Flexibility
The 3010MA offers three dynamic, user-configurable ranges plus auto-ranging. The instrument is linear on all three ranges, eliminating the need to recalibrate while switching between ranges. The analyzer comes standard with an isolated 4-20 mADC output for oxygen concentration and range identification (optional). Additionally, a bi-directional RS-232C serial communication interface provides for remote monitoring and control of span and zero functions. Teledyne provides auto-calibration capabilities as a standard feature in the 3000 series platform.
Additional Advantages
- Linearity of analysis across three user-selectable ranges
- Temperature controlled/isolated sensor for long term stability
- Atmospheric Pressure Compensation for high-end, accurate performance
- Auto-ranging to follow process upsets
- Auto-calibration electronics standard
- Exceptional value at a favorable price
