Paramagnetism
The physical property distinguishing oxygen from other gases is its paramagnetism, which is significantly greater than other common gases. Consequently, the molecules of oxygen are attracted by strong magnetic fields which can be used in detection. The 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 spheres rotate out of the magnetic field by the relatively strong attraction of oxygen. A light beam focused on a mirror attached reflects asymmetrically onto two photo diodes resulting in a voltage shift. The difference of this 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 sensors last for years with little or no attention making them ideal for critical measurements in the low percent range.
Flexibility
This unit offers three dynamic, user-configurable ranges plus auto ranging and can be calibrated in any range. It is linear on all three ranges, eliminating the need to recalibrate while switching between ranges. This analyzer comes standard with an isolated 4-20 mADC output for oxygen concentration and range identification. Additionally, a bi-directional RS-232C serial communication interface provides for remote monitoring and control of span and zero functions.
Additional Advantages
- Linearity of analysis across three user-selectable ranges
- Auto-ranging to follow process upsets
- Auto-calibration electronics standard
- No purge gas requirements
Sample Gas Conditioning Requirements
- Sample Inlet Pressure: 5 to 20 psig (regulate to fixed inlet pressure)
- Sample Flow: 1 to 2 SCFH
- Sample Dewpoint: Non-condensing at ambient temperature
- Sample Temperature: 32° to 122°F (0° to 50°C)
- Detector Wetted Parts: Glass, steel, gold, Viton, acrylic glass and epoxy resin
