Thermal conductivity gas analyzers exploit the physical property that different gases have different thermal conductivities for concentration analysis.
Measurement Principle
Gas thermal conductivity differences form the basis of this analysis. For example, hydrogen's thermal conductivity is approximately 7 times that of air, while carbon dioxide's is only 0.6 times. By measuring temperature changes in thermistor elements within a Wheatstone bridge circuit (determined by gas thermal conductivity), target gas concentration is precisely calculated.
Key Design Considerations
Thermistor elements typically use platinum wire or thermistors; the measurement cell requires precise temperature control; the reference gas must be stable and reliable; cross-interference from other gas components must be compensated.
Typical Applications
Hydrogen purity analysis in hydrogen production plants, H₂/N₂ ratio control in ammonia synthesis, CO₂ and SO₂ analysis in flue gas, argon purity testing, and heat treatment furnace atmosphere control.