Thermal resistance can be divided into industrial platinum resistance and sheathed platinum resistance. Industrial platinum resistance thermometers, also called the assembly platinum thermal resistance, that is, platinum resistance temperature sensing element assembly of welding on the lead metal tube closed at one end or ceramic tube, and then install the junction box is made; sheathed platinum resistance is platinum thermal resistance elements, the transition leads, insulated stainless steel tube powder assembled in the mold and then by pulling the overall implementation, with a solid, seismic, and orbit, diameter small, and easy to use installation.