O₂ Molecules (Paramagnetic)
Non-O₂ Gases (Diamagnetic)
Dumbbell Float
Magnetic Poles (N/S)
O₂ Concentration
0.0
% vol
Deflection Angle
0.0
degrees
Output Signal
4.0
mA
O₂ Concentration 0%
Flow Rate 50%
Magnetic Field Strength 70%
Vibration Level 0%
📊 Live O₂ Concentration vs Output Signal
Response Sensitivity
LOWMEDHIGH
📘 Theory & Principles
🔹 Measurement Principle ▼
Oxygen has two unpaired electrons in its outermost shell, making it strongly paramagnetic. When placed in a non-uniform magnetic field, O₂ molecules are attracted toward the region of highest field intensity. This magnetic attraction creates a measurable mechanical force on the dumbbell system.
🔸 Dumbbell Operation ▼
Two glass spheres filled with nitrogen are suspended on a taut quartz fibre in a non-uniform magnetic field. When oxygen-containing gas enters the chamber, O₂ molecules are attracted to the magnetic poles, displacing the nitrogen spheres. The rotation angle of the dumbbell is directly proportional to O₂ partial pressure.
An optical or electromagnetic feedback system measures this deflection and converts it to a 4–20 mA signal.
✅ Key Features ▼
- High accuracy (±0.1% O₂)
- Fast response (<5 seconds)
- Non-consumable sensor
- Long-term stability
- Suitable for process & safety
- No electrochemical reaction
⚠️ Limitations ▼
- Sensitive to mechanical vibration
- Affected by pressure changes
- Flow rate affects accuracy
- NO and NO₂ also paramagnetic (interference)
- Requires clean, dry sample gas
⚖️ Analyzer Comparison
🧲 Paramagnetic
- Magnetic principle
- No consumables
- 0–25% range
- Room temp op.
- Low maintenance
🔥 Zirconia
- Electrochemical
- Cell wears out
- ppm to %
- 700°C operation
- In-situ possible
🎓 Knowledge Quiz
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