Gas safety valve sensitive to temperature and method for the construction of such a safety valve

A gas safety valve comprising:

• a valve body which defines an inlet, an outlet and a flow pipe connecting said inlet to said outlet;
• a shutter located in said flow pipe and movable between an open position, in which said shutter allows the flow of an operating gas through said flow pipe, to a closed position, in which said shutter prevents said flow;
• first thrust means configured to push said shutter into said closed position;
• a retaining mechanism movably mounted in said valve body, said retaining mechanism being movable between a first position suited to maintain said shutter in said open position and a second position where said shutter is released so that said shutter can move to said closed position;
• a control element movably mounted in said valve body, said control element being movable between a locking position that holds said retaining mechanism in said first position and a released position, said retaining mechanism being urged to the second position when said control element is in said released position;
• a first actuator device suited to force said control element into said released position,
• said first actuator device comprising:
• an actuator body equipped with a first end, said actuator body being movable between a rest position in which it allows said control element to maintain said locking position and a working position in which said first end forces said control element into said released position;
• a retaining spring configured to force said actuator body into said rest position;
• a shape memory spring configured to overcome the force of said retaining spring on said actuator body so as to force said actuator body into said working position when the temperature of said shape memory spring is within a predetermined temperature range;
• said valve body comprising a through hole facing said control element, said first actuator device comprising a casing that houses said retaining spring and said shape memory spring and equipped with a hole in which said actuator body is slidably mounted so that said first end protrudes outside said casing, said casing being removably connected to said valve body so that said first end is arranged through said through hole, said first actuator device comprising a locking button slidably inserted in a through hole of said casing, configured to be able to act on said actuator body and equipped with a first end positioned outside of said casing and a second end associated with said actuator body in such a way that a movement of said locking button toward said actuator body causes a corresponding displacement of said actuator body into said working position.