METHODS TO MEASURE THE CONCENTRATION OF A GAS

• The Rayleigh refractometer utilises the refractive index of a gas to calculate its concentration.
• Thermal conductivity is used in katharometers. In these devices, the cooling of a wire causes a change in resistance proportional to gas concentration.
• Solubility is employed in devices such as rubber strips when an increase in length accompanies gas absorption.
• Light emission features in the Raman light scattering measurement device.
• Both infrared and ultraviolet absorption are used in gas concentration measurement.