Accuracy of bimetal thermometers


The working principle of the bimetal thermometer is to use two metals with different temperature expansion coefficients. In order to improve the temperature measurement sensitivity, the metal sheet is usually made into a spiral shape. When the temperature of the multi-layer metal sheet changes, the amount of expansion or contraction of each layer of metal varies so that the spiral rolls up or unwinds. Today, the editor will take you to understand the accuracy of bimetal thermometers.
The temperature compensation range is a typical range smaller than the working temperature range, and the bimetal thermometer working within this range will definitely achieve its due performance indicators. The temperature change affects its output from two aspects, one is the zero drift, and the other is the full-scale output. Such as +/-X%/℃ of full scale, +/-X%/℃ of reading, +/-X% of full scale when out of temperature range, +/-X% of reading when in temperature compensation range, Absence of these parameters leads to uncertainty in use.
Whether the change of transmitter output is caused by pressure change or temperature change. The effect of temperature is the most complex part of understanding how to use a transmitter, how much accuracy a bimetal thermometer needs to be determined by nonlinearity, hysteresis, non-repeatability, temperature, zero offset scale, temperature effects.

The temperature range of the pressure transmitter transmitter is usually a transmitter will calibrate two temperature accurate sections, one of which is the normal working temperature, and the other is the temperature compensation range. The normal working temperature range refers to the working temperature of the transmitter. The temperature range when it is not damaged in the state, and the performance index of its application may not be reached when the temperature compensation range is exceeded.

bimetal thermometer

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