Process Engineering Division – Instrumentation and Automation Section – Daily Question – Question from 2020-07-20
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Process Engineering Division – Instrumentation and Automation Section – Daily Question – Question from 2020-07-20: Discussion question: 182. How does a bimetallic thermometer work? (Working principle)
A bimetallic thermometer uses a thermally responsive bimetallic strip wound in a spiral shape as the temperature sensing element, which is placed inside a protective casing. One end of this strip is fixed, known as the fixed end, while the other end is connected to a thin shaft, referred to as the free end. A pointer is mounted on the free-end spool. When the temperature changes, the free end of the temperature-sensitive device rotates, causing the pointer on the thin shaft to change angle and indicating the corresponding temperature on the dial.
When the temperature changes, due to different expansion coefficients, the bimetallic strip undergoes angular displacement, which drives the pointer to indicate the corresponding temperature. This is the working principle of a bimetallic thermometer.
It consists of two pieces of metal with different coefficients of expansion that are firmly bonded together; one end is fixed, while the other end is connected to a pointer through a transmission mechanism. When the temperature changes, due to different expansion coefficients, the bimetallic strip undergoes angular displacement, which causes the pointer to indicate the corresponding temperature.
Different metals have different coefficients of thermal expansion. When two metals with significant differences in their coefficients of thermal expansion are bonded together, heating causes the bonded metals to bend due to these differences, which in turn moves a mechanism that causes the pointer to deflect, thereby indicating the temperature.
Different metals have different coefficients of thermal expansion. When two metals with significant differences in their coefficients of thermal expansion are bonded together, heating causes the bonded metals to bend due to these differences, which in turn moves a mechanism that causes the pointer to deflect, thereby indicating the temperature.
A bimetallic thermometer uses a heat-sensitive bimetallic strip wound in a spiral shape as the temperature sensing element, which is placed inside a protective sleeve. One end of this strip is fixed, known as the fixed end, while the other end is connected to a thin shaft, referred to as the free end. A pointer is mounted on the free-end spool. When the temperature changes, the free end of the temperature-sensitive device rotates, causing the pointer on the thin shaft to change angle and indicating the corresponding temperature on the dial.
When two metals with different coefficients of expansion are stacked together, upon heating and expanding, the difference in these coefficients causes the two metals to bend to the left or right, which in turn drives the pointer to move
Working principle of bimetallic thermometer: It uses a heat-sensitive bimetallic strip wound in a spiral shape as the temperature sensing element, which is placed inside a protective casing. One end of this strip is fixed, while the other end (the free end) is connected to a thin shaft, at the end of which a pointer is mounted. When the temperature changes, the free end of the temperature-sensitive element rotates accordingly; this causes the thin shaft to move the pointer through an angular displacement, thereby indicating the change in temperature on the dial.
It consists of two metal elements with different coefficients of expansion; one end is fixed while the other end deforms in response to temperature changes, thereby causing the pointer to rotate and indicate the corresponding temperature.
Two metals with different coefficients of expansion are combined together