How a combustible catalytic sensor works

The sensor is the core component inside a Combustible Gas Alarm that allows the user to detect and analyze any nearby concentrations of combustible gases. The two most common combustible gas sensing technologies are catalytic and infrared.

A catalytic sensor uses temperature changes caused by a combustible gas reacting with oxygen to measure gas levels.

They consist of a very small sensing element sometimes called a ‘bead’. They are made of an electrically heated platinum wire coil. when a combustible gas/air mixture passes over the hot catalyst surface, combustion occurs and the heat evolved increases the temperature of the ‘bead’. This in turn alters the resistance of the platinum coil and can be measured by using the coil as a temperature thermometer in a standard electrical bridge circuit. The resistance change is then directly related to the gas concentration in the surrounding atmosphere and can be displayed on a meter or some similar indicating device.

Catalytic sensors are less susceptible to interference from dust and dirt, can detect most hydrocarbons and hydrogen, and humidity, condensation, pressure, or temperature do not affect them.

Combustible gas can be produced at home and in recreational vehicles, and is found in two typical forms: Natural Gas (primarily methane) and Liquefied Petroleum Gas (LPG). Both of these can be extremely dangerous if the gas is able to reach a concentration high enough to become explosive, so it is vital that there are combustible gas alarms to detect their presence.

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