Thermal Conductivity - Michell Instruments XTP501 User Manual

XTP501 & XTC501 User's Manual
1.1.2

Thermal Conductivity

Thermal conductivity (TC) is a property of all gases. This can be exploited as each
gas has a different TC value and is used to determine the level of one gas in a binary
or pseudo-binary mix. Air is a good example of a pseudo binary mix as it has a fixed
proportion of oxygen and nitrogen (both with very similar thermal conductivities). A
pair of matched thermistors (glass coated) are placed in symmetrical a sensor body
with one in the measuring side and one in the reference side.
accurately measure the difference in the thermal conductivity of the measured gas and
the reference gas.
Advantages of Thermal Conductivity:
• Zero point stability of 0.5% of span per month means less frequent
calibrations
• No moving parts or consumable items
• Stable and accurate measurement from symmetrical cell design
• Cost-effective measurement
• Flexible technology allows many target gas measurements
Michell Instruments
INTRODUCTION
These thermistors
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