Limit sensing indicator

摘要

A limit sensing device for permanently indicating when a predetermined temperature limit has been reached in a fluid conduit, includes a housing mounted on the conduit in heat transmitting relation with the fluid and an indicator movable in the housing between a retracted position and an activated, non-resettable, extended position to provide a visual indication that the predetermined temperature limit has been reached. The indicator is biased outwardly towards the activated position and a retainer in the form of a separate and discrete annulus formed of fusible material normally secures the indicator in the retracted position within the housing against the force of a biasing spring until the predetermined temperature has been reached causing the retainer to melt or fuse and thereby release the indicator to move outwardly to the extended position providing a visual indication signaling that an overtemperature condition has been reached in the fluid conduit.