Thermal resistance sensor WZP-130 WZP-330 WZP-430 WZP-630 WZP-120 WZP-220 WZC-130 WZC-230 WZC-330 is the most commonly used temperature detector in the mid-low temperature zone. Thermistor temperature measurement is based on the fact that the resistance value of a metal conductor increases as the temperature increases. Its main features are high measurement accuracy and stable performance. Among them, platinum thermal resistance has the highest measurement accuracy, and it is not only widely used in industrial temperature measurement, but also made into a standard reference instrument. Most of the thermal resistances are made of pure metal materials. Currently, platinum and copper are the most widely used. In addition, thermal resistances such as nickel, manganese and tantalum have been used. Metal thermal resistors commonly use a variety of temperature sensing materials, the most commonly used is platinum wire. In addition to platinum wire, metal thermal resistance materials for industrial measurement include copper, nickel, iron, iron-nickel, and the like.
The temperature measurement principle of the thermal resistance is based on the characteristic that the resistance value of the conductor or the semiconductor changes with temperature to measure the temperature and the temperature-related parameters. Most of the thermal resistors are made of pure metal materials. Platinum and copper are the most widely used. Now, thermal resistance is made of materials such as nickel, manganese and tantalum. Thermal resistance usually requires the resistance signal to be transmitted through a lead to a computer control device or other secondary instrument.
For the installation of the thermal resistance, attention should be paid to the accuracy of temperature measurement, safety and reliability, and convenient maintenance, and does not affect the operation and production operation of the equipment. To meet the above requirements, pay attention to the following points when selecting the mounting location and insertion depth of the RTD:
1. In order to ensure sufficient heat exchange between the measuring end of the thermal resistance and the measured medium, the position of the measuring point should be reasonably selected to avoid installing thermal resistance near the dead angle of the valve, elbow and pipeline and equipment.
2. The thermal resistance of the protective sleeve has heat transfer and heat loss. In order to reduce the measurement error, the thermocouple and the thermal resistance should have sufficient insertion depth:
1) For the thermal resistance of the fluid temperature in the center of the pipe, the measuring end should normally be inserted into the center of the pipe (vertically or tilted). If the diameter of the pipe of the fluid to be tested is 200 mm, the insertion depth of the RTD should be 100 mm;
2) For the temperature measurement of high temperature and high pressure and high speed fluid (such as main steam temperature), in order to reduce the resistance of the protective sleeve to the fluid and prevent the protective sleeve from breaking under the action of the fluid, the protection tube may be inserted in a shallow insertion manner or a hot sleeve type. Thermal resistance. The shallow insertion type thermal resistance protection sleeve shall be inserted into the main steam pipe to a depth of not less than 75 mm; the thermal insertion type thermal resistance shall have a standard insertion depth of 100 mm.
3) If it is necessary to measure the temperature of the flue gas in the flue, even though the flue diameter is 4 m, the thermal resistance insertion depth is 1 m.
4) When the measurement original insertion depth exceeds 1m, it should be installed as vertical as possible, or the support frame and protective sleeve should be installed.