Commonly used industrial temperature instrument - Bimetallic thermometer

The working principle of bimetallic thermometer bimetallic thermometer working principle is to use two different temperature expansion coefficient of metal, in order to improve the temperature measuring sensitivity, is usually made of metal spiral coil shape, when multi-layer metal temperature change, the layers of metal expansion or shrinkage, makes the spiral coil rolled up or let go. As a result of the spiral coil end fixed and the other end connected to a free rotating pointer, therefore, when the bimetallic strip feel the temperature change, Pointers can be on a circular dividing scale to indicate the temperature. The instrument of temperature measurement range in - Between 80 ℃ ~ + 500 ℃, the permissible error are the scale range of 1. About 5%. Second, the classification of the bimetallic thermometer ordinary double metal thermometer, seismic bimetallic thermometer, electric contact bimetallic thermometer. The bimetallic thermometer pointer plate with the direction of protecting tube connection bimetallic thermometer can be divided into axial, radial and 135 & deg; To type and universal type four. (1) the axial type bimetallic thermometer: pointer vertical connection tube plate and protection. (2) the radial type bimetallic thermometer: pointer GuanPing line connection plate and protection. ③ 135° The bimetallic thermometer: pointer tube plate and protection into 135 & deg; The connection. (4) universal type bimetallic thermometer: pointer plate connected to the protecting tube Angle can be arbitrary adjustment. In selecting three, selection and use of bimetallic temperature time, we must give full consideration to the practical application environment and requirements, such as the dial diameter, precision grade, fixed installation way, risk categories and measured medium environment, etc. In addition, also attaches great importance to the performance and maintenance workload and other factors. In addition, the bimetallic thermometer in use process should pay attention to the following: A, bimetallic thermometer protecting tube immersed in the measured medium length must be greater than the length of the thermal components, immersed in length is more than 100 mm, 0 50 ℃ range into greater than 150 mm in length, so as to ensure the accuracy of measurement. B, all kinds of bimetallic thermometer should not be used to measure open containers within the medium temperature, electric contact thermometer should not be at work used in the control circuit of larger vibration occasions. C, bimetallic thermometer in custody, use the installation and transportation, should avoid collision protection tube, do not make the protection tube bending variant and the table when the spanner is used. D, thermometer in the case of normal use shall be regular inspection. Is every six months. Electric contact thermometer is not allowed to work under strong shock, so as not to affect the reliability of the contact. E, the temperature of the instrument often work better in the scale range of 1/3 to 2/3.