Pellistor
From Wikipedia, the free encyclopedia
A pellistor is a solid-state device[1] used to detect gases which are either combustible or which have a significant difference in thermal conductivity to that of air. The word "pellistor" is a combination of pellet and resistor.
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[edit] Principle
The detecting element consist of small "pellets" of catalyst loaded ceramic whose resistance changes in the presence of gas.
[edit] History
The pellistor was developed in the early 1960's for use in mining operations as the successor of the flame safety lamp and the canary.
[edit] Types
[edit] Catalytic
The catalytic pellistor as used in the catalytic bead sensor works by burning the target gas; the heat generated producing a change in the resistance of the detecting element of the sensor proportional to the gas concentration.
[edit] Thermal Conductivity
The thermal conductivity (TC) pellistor works by measuring the change in heat loss (and hence temperature/resistance) of the detecting element in the presence of the target gas.
