Abstract: A safety and warning apparatus for detecting gas leakages in private and work premises, is disclosed, in which the improvement consists in providing an explosion chamber in which a miniature deflagration is caused to occur in a chamber in which ambient air is supplemented with a specific gas rate of flow. The miniature explosion chamber is connected to an overlying pilot flame chamber so that as soon as the miniature blowup occurs, the pilot flame is blown out and a temperature sensing means is capable of commanding the gas cutoff, the energization of an alarm signal, or both.