A detector (3) is provided that is independent of outside energy, for a release device, for which detector no battery and no external power supply is provided, and that generates a signal at a defined temperature, a thermal release element (3.2), at least one piezo element (3.1) and a coupling element (11) being arranged such in a bracket/housing (3.3) that as a result of a change in state of the thermal release element (3.2) by the coupling element (11) exerts a mechanical pressure on the piezo element (3.1) so that an electric signal is generated. A valve for a release device is also provided.