The application of heat resistance principle

Thermal resistance is commonly used in the low temperature zone of a temperature test apparatus. Its unique place is largely survey precision is high, performance reliable. There is platinum thermal resistance of survey accuracy is enormous, which not only widely used in industrial temperature measurement, and is made into standard benchmark instrument. The thermometry principle and material thermal resistance, heat resistance temperature measurement is based on the metal conductor resistance value increases with the increase of temperature the special properties to temperature survey. Thermal resistance are mostly made of bare metal materials, applications so far more platinum and copper, the outside, starting right now and use the survey, nickel, manganese and rhodium materials such as thermal resistance. Second, the structure of the thermal resistance ( 1) Have a clear knowledge of thermal resistance industry commonly used thermal resistance temperature components ( http://www。 wuxiyibiao。 com/） The structure and unique place - see table 2 1 - 11. In temperature measuring principle of thermal resistance, the temperature change is being tested directly through the thermal resistance of resistance to the change of, because of this, the thermal resistance of lead wire and other wire resistance change will affect the temperature survey. To eliminate the influence of the lead resistance with a right to use three wire or four wire system, the specific internal substantial meaning see this chapter 3 section 1. ( 2) Armored thermal resistance armored thermal resistance is by thermal components ( The resistor body) , wire, insulation materials, stainless steel casing combination solid body, as shown in figure 2-3 1 - 7, its diameter is usually from 2 ~ 8 mm, xiaoke phi mm. And type of thermal resistance in usually, it has the following lists advantages: (1) large and small, no air gap and thermal inertia, reconnaissance behind small; (2) good mechanical properties, resistance to vibration and shock. (3) to buckling, is easy to install (4) use fixed number of year to live long. ( 3) Face the end resistance heat resistance temperature sensing element by a special deal with the resistance of the wire winding, close to the face in the thermometer, its structure as shown in figure 2 1 - 8. It and usually by the axial thermal resistance, can be more nice and quickly reflect the actual temperature of end face, suitable for use in surveying bushing and other parts of the end surface temperature. ( 4) Flameproof thermal resistance flameproof thermal resistance through the special structure of the junction box, put inside the shell in explosive gas mixture in sparks or electric arc impact and explosion limit within the junction box, that wouldn't make production field explosion. Flameproof thermal resistance can be used in the Bla ~ B3c zone with the temperature of the explosive dangerous location survey. Three, thermal resistance temperature measurement system composed of thermal resistance temperature measurement system unify and countersigned by the thermal resistor, lead and expose instrument, etc. It is important to note the following two points: one, heat resistance and appear instrument index number must be exactly the same as 2, in order to eliminate the influence of wire resistance change period, be sure to use right and three-wire system connection. In resistance of the circuit repair set to change varies wire resistance and impact resistance, resistance change for this new body is good, if see fit and use welding repair, to check up to the standard after welding ability after use.