• 工业温度计热回差怎么样估计
  • 本站编辑:杭州博阳仪器仪表有限公司发布日期:2019.11.22

Estimating the effect of thermal resistance thermometer and thermal stress on platinum requires very careful testing. If a thermometer is suspected to have a return of heat, the heating process of the thermometer must be controlled during the test. The meaningful return test is the calibration of the thermometer over the entire temperature range by comparing it with the standard platinum resistance thermometer at many temperature points in the direction of warming and cooling, respectively. The use of the same standard platinum resistance thermometer and the same resistance measuring instrument throughout the test is important to avoid the effects of instrumentation errors. Whether it is heating up or cooling down, it is necessary to ensure that the temperature of the test is smoothly transferred from one test temperature to another, so that the thermal process can be controlled and the values of the heating and cooling resistances at the same temperature point can be averaged The average R T curve is obtained. The interpolation used in this experiment is the same as that used in the standard resistance thermometer. In the temperature range from-196 °C to + 196 °C, four dividing points are generally required. Convert the difference between the resistance value of each temperature test point and the average resistance value of the thermometer into temperature. There are some problems in the practical work of this test method. If a liquid tank is used as a dividing device, each liquid has a limited temperature range, which may be as narrow as 100 °C. This means that the thermometer may be moved very quickly from one slot to another in order to maintain the thermal process of the thermometer. This transfer process also produces small but measurable changes in resistance due to mechanical shock during operation. Extensive experiments have been carried out with the above methods on many different types of thermometer elements with different span. According to this and other tests on different types of resistance thermometer, the magnitude of the backlash is proportional to the temperature span, with the large difference occurring at the midpoint of the temperature span. It is also found that the thermal recovery error has good reproducibility, the same temperature cycle mode and the same hysteresis loop.
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