3201 Lecture Notes - Lecture 2: Gas Thermometer, Diode, Boiling Point
Document Summary
Change-of-state temperature sensors calculate just that a change in the state of a substance caused by a temperature change, such as the transition from ice to water and then to steam. This type of device is commercially available in the form of stickers, pellets, crayons, or lacquers. Temperature measurements in degrees fahrenheit and degrees celsius are shown on change- of-state labels. The white dot on these devices turns black when the temperature shown is exceeded, and it is a nonreversible sensor that stays black until it changes color. Temperature marks are useful when you need proof that a temperature did not reach a certain amount during shipping, such as for engineering or legal reasons. Change-of-state devices, including the bimetallic strip, have an advantage in many applications since they are nonelectrical. Some members of this group of sensors (lacquer, crayons) do not change color; the traces they leave simply fade away. the pellet version becomes visually deformed or fully melts away.
