AMAZON multi-meters discounts AMAZON oscilloscope discounts
Several types of non-electrical temperature sensors use a variety of bimetal strips and filled-bulb temperature sensors. The bimetal temperature sensors work on the principle that two different types of metal are bonded (joined) together so that when they are heated one will expand faster than the other. This causes the bimetal strip to curl one direction when it's heated and the other direction when it's cooled. The bimetal effect can be amplified by shaping the sensor in the shape of a coil or helix. When the two types of metal begin to expand as they are heated. the end of the coil will move farther than a single piece of bimetal material. ill. 1 shows an example of the bimetal strip when it's heated and when it's cooled and a bimetal strip in the shape of a coil. A different version of the bimetal sensor is the filled-bulb sensor. The bulb on this type of sensor is filled with alcohol or refrigerant that will change pressure when it's heated. When the fluid changes pressure, it will exert pressure on a Bourdon tube or helix and cause it to move or change shape. This movement can be used to activated a switch, so these types of devices can be used as thermostats or alarm switches.
Above: ill. 1 (a) A bimetal strip that is warped upward when it's
heated. (b) A bimetal strip that is warped downward when it's cooled.
(c) A bimetal strip in the shape of a coil to amplify the movement caused
when the coil is heated.
