Patent ID: 7415939

Claim:
Temperature sensitive indicator comprising: a tube that comprises a first open end and a second closed end; an axially movable slidable piston to be assembled inside the tube forming a first compartment comprised between the piston and the closed end and a second compartment comprised between the piston and the open end; compressible means to be located inside the first compartment inside the tube; a freezable fluid to be located in a the second compartment inside the tube; a releasable cap to cover the first open end of the tube and to be responsible to hold the freezable fluid; wherein the temperature sensitive indicator is activated when the releasable cap released by the frost action of the freezable fluid inside the second compartment and the temperature sensitive indicator reveals the occurrence of the temperature increase in the environment in which the indicator is immersed, by the irreversible motion of the piston in a single direction inside the tube when the freezable fluid inside the second compartment thaws and flows out of the tube.