Abstract: Device for detecting the exceeding of a temperature threshold incorporating a first mobile part (5) in a sealed chamber (4) containing a material melting at the temperature of the threshold and a second mobile part (8) outside the chamber. In the armed position, the two parts exert forces on one another tending to move them apart, but the first part is blocked by the solidified material and the second is immobilized by the combination of shapes (12, 13) in case (9). The melting of the material frees the first part, whose displacement frees the second part, which then operates an alarm system (18). This displacement leads to the return of the first part to the initial position, which permits rearming when the material has resolidified.

Abstract: The device comprises a transparent tube (1) wherein may slide freely a part (4) at the extremities of which are arranged two small magnetic masses (5,6). The tube (1), closed at both ends, forms a sealed tank wherein there is placed a phase changing material (7) which is either in a liquid state or in a solid state, according to the temperature to which it has been brought. At one of the ends of the tube (1) a cap (12) containing a removable magnet (9a) is fitted. A fixed magnet (11) is placed at the other end of the tube (1). The part (4) being initially placed on the side of the cap (12), the material (7) is solidified and the removable magnet (9a) is then removed. In the case of exceeding the melting temperature of the material (7), the part (4) attracted by the magnet (11) moves towards the corresponding end of the tube (1), thus making visible a colored ring (14).