What safety device is used in many ignition systems to prevent ignition during incorrect operation?

The thermocouple is a critical component in many ignition systems, specifically designed to enhance safety during the operation of heating appliances. It serves as a temperature-sensing device that generates a small voltage when heated. In typical applications, the thermocouple monitors the presence of a flame. If the flame goes out or is not present when it is supposed to be, the thermocouple will stop producing voltage. This loss of voltage signals the gas valve to close, effectively preventing the release of gas and eliminating the risk of an explosion or fire caused by unignited gas.

The role of the thermocouple in ensuring that gas is only supplied when there is a combustion source—such as a pilot flame—makes it an essential safety device in ignition systems. This mechanism prevents ignition during incorrect operations, such as the pilot light going out, thus maintaining safe conditions in the heating system.