Speak of the old thermometer will be thinking of you mercury thermometer that is commonly used in daily life, in the development of recent years considering the user's usage in the thermometer industry also implements the comprehensive development, nowadays the thermometer with kerosene thermometer, alcohol thermometer, mercury thermometer, universal type double metal thermometer, gas thermometer, resistance thermometer, etc. Universal type bimetallic thermometer is a kind of measurement in the field of low temperature test instrument. Can be directly measured in the process of various production - 80℃- Liquid + 500 ℃ range steam and gas medium temperature. Its working principle is one with two or more pieces of metal laminate composed of multilayer metal together, using two different metal working in the principle of expansion degree of different temperature changes. Is based on the ring around made of bent bimetallic strip. End is heated expands, turns the pointer, the instrument will show thermoelectric potential should value. Universal type bimetallic thermometer is one of the structure form of bimetallic thermometer, behind the use of the spring piece, can rotate 180 °, convenient operators readings.