Temperature cycle counter

Abstract

An apparatus for counting the number of times a temperature cycle occurs includes an indicator having sequential indicia and a temperature responsive member for indicating a next one of the indicia. Mechanical, fluid mechanical and electronic versions of the invention are disclosed. In the mechanical version, the indicator can be a ratchet member having teeth, a pawl and a display surface containing indicia. A temperature responsive element such as a bimetallic member engages the teeth of the ratchet and advances the ratchet each time the apparatus is subjected to a preset temperature cycle. A housing with a window masks the display to indicate one of the indicia as advanced by the temperature responsive element. Preferred embodiments of the mechanical version include a ring-like ratchet member with interior teeth and an exterior display surface. The number of teeth is preferably one or more less than the number of indicia so that upon advancing the ratchet member to the last indicia, it can be advanced no further. The bimetallic element is mounted inside the ring and the housing covers the outer surface of the ring. A removable locking pin is provided to prevent movement of the ratchet member until activated.