Pressure type thermometer is the use of heat pump type system of measuring temperature instrument. So-called heat pump type system, by inductive charging temperature, medium temperature, capillary and pressure sensitive elastic element consisting of all metal components. Pressure type thermometer is according to in closed containers of liquid, gas or low boiling point liquid saturated steam heated volume expansion and pressure change this principle and production, and pressure gauge to measure the pressure change. When the temperature changes, the temperature of working medium pressure changes caused by expansion, the pressure changes in the capillary to the elastic element ( Such as spring tube) , make the deformation of elastic element, the transmission mechanism make the pointer along the scale deflection, indicates the corresponding temperature value, thus the measured temperature. As capillary pressure type thermometer can be up to dozens of meters, and has simple structure, low price, is widely used in the production process of the distance of corrosive liquid or gas temperature measurement. We often use is circular gauge steam, gas, pressure type thermometer.