A mechanical device which uses a metal pointer on a circular scale to indicate the temperature measurements and which is also called as differential absorption lidar thermometer is known as dial thermometer. Dial thermometer has two primary components which are metal pointer or needle and a temperature sensor and also these sensors may be bi -metal or bimetallic, liquid or gas filled and also which is vapor tension based. The type of bimetal dial thermometer is also known as bimetallic strip thermometer that makes use of coil spring technology and this sensing device is made of two different metals which are welded or fastened together like that of steel and copper or steel or brass as one of these metals have low heat sensitivity while the other metals have high heat sensitivity. The bimetal sensor is attached to the metal which is pointed or has the needle on the face of the thermometer.A bimetal technology has been used in these dial thermometers which operate on the principle of expansion and contraction. A liquid or gas based dial thermometer is very much accurate at low temperatures than compared to that of bimetal and this type is very commonly found in hvac systems, refrigeration plants, refrigerated trucks and photo processing equipment. Dial thermometer is usually made of metal and stainless steel with glass or plastic crystal covering which has a circular face. A less expensive choice of dial thermometer has been equipped with vapor tension base device as these types of thermometer is filled with permanent gas and are often used in refrigerators, drying ovens, chemical processing and solar heating etc. These dial thermometer are very much used for measuring the temperature of soil, bitumen and any other hot material when is inserted in ordinary glass thermometer there is much of risk from breakage point of view.
These dial thermometers are used for common industrial purpose and are very much equipped with metal dials with wide dimensions. Dial thermometers are known for their accuracy and high functionality with which these are very much appreciated by the people.
