Bimetallic Strip - What is it?

Bimetallic strip

  • A thin strip that is joined together by two distinct metals is known as a bimetallic strip.
  • The metals used to make the strip have various coefficients of thermal expansion, which means that when heated or cooled, they will expand or contract at various rates.
  • When exposed to temperature variations, the strip bends as a result. Thermostats, thermometers, and switches are just a few of the devices that make use of bimetallic strips.
  • For instance, the strip of a thermostat is used to regulate temperature by bending when the temperature changes and either opening or closing a circuit. Some mechanical clocks also use bimetallic strips to control the timing of the movement.

Construction of Bimetallic Strip

  • The composite strip is constructed into a coil, in which heating the device causes the coil to unwind and cooling causes the coil to contract.
  • The coil has a dial attached to it that rotates relative to a scale as the coil winds and unwinds. The dial measures the system’s temperature.
  • Working Principle of Bimetallic Strip.
  • When the temperature changes, metals expand or contract, changing their size. The rate of expansion or contraction depends on the metal’s temperature coefficient of expansion.
  • Different metals have a different temperature coefficient
  • As a result, deflections are caused by difference in thermal expansion rates and are proportional to temperature changes. A strip of two different metals fastened together constitutes the temperature sensitive element.
  • One material has a high thermal expansion coefficient, while another has a low one. As the device is heated, one material will attempt to expand more than the other since the metals have clearly different thermal expansion coefficients. This will result in a deformation from the reference position.

How is temperature measured using bimetallic strip?

  • By utilizing their special qualities, bimetallic strips can be utilized to gauge temperature.
  • A bimetallic strip is affixed to a thermometer or dial in order to measure temperature. The strip bends and the gauge or dial moves, showing the temperature as it changes.
  • In industrial and lab settings, bimetallic thermometers are frequently used to monitor temperatures.
  • They are reasonably priced, simple to use, and can measure both high and low temperatures.
  • It’s vital to remember that variables like the length and thickness of the strip, the materials utilized, and the mounting position might have an impact on the accuracy of bimetallic thermometers.
  • Other types of thermometers can be required to measure temperatures with greater accuracy