It is the principle of opening and closing solenoid valve by thermocouple sensing temperature and generating thermoelectric potential. This kind of flameout protection device is a set of thermocouples and solenoid valves which only control one air passage. It has a high safety factor: if one of them is damaged, it will not affect the normal use of the other furnace head. It is stable and reliable, and generally does not need external power supply.
But it has a certain thermal inertia, so that the output current of the thermocouple can not disappear immediately with the flame extinguishing, and the reaction to accidental extinguishing is slow. Generally, it takes about 5-10 seconds to close the gas valve, but this leakage will not cause any safety problems. Most of the brand manufacturers of cookers are selected in this way.
The second is ion induction.
It is mainly invented by using the principle that the flame contains electric ions and has unidirectional conductivity (the flame is equivalent to a conductor). The advantage of this method is that it cuts off gas quickly.
However, it can only be applied to single air channel, after the protection device, the air channel can not be separated, otherwise it will cause air leakage by misoperation; so if the flameout protection device is damaged, the whole stove can not be used, followed by external power supply, which consumes a large amount of electricity, usually need to replace the battery once in 2-3 months.