The matching of the measuring range of the pressure transmitter and the working pressure is the key to ensure the accuracy of the measurement and the long-term stable operation of the equipment.
The measuring range of the pressure transmitter refers to the interval between the maximum and minimum pressure values that it can accurately measure, which is usually determined by the physical characteristics and design of the equipment. The working pressure refers to the pressure value generated by the measured medium during the actual working process. In order to ensure the accuracy of the measurement, the measured pressure should be within the appropriate range of the pressure transmitter.
When selecting a pressure transmitter, the appropriate measuring range should be selected according to the actual working pressure range. It is generally recommended to set the range to 1/3 to 2/3 of the pressure transmitter range to ensure accuracy. This is because within this range, the sensor characteristics of the pressure transmitter are usually linear and the error of the signal processing circuit is relatively small. For example, if the working pressure is between 0-50 Pa, a transmitter with a range of 0-100 Pa can be selected to ensure measurement accuracy.
In addition to the normal pressure range, possible extreme situations should also be considered. For example, in a hydraulic system, the normal working pressure may be 5-15 MPa, but at the moment of system start or stop, pressure shock may occur, and the pressure peak may reach 20 MPa. To ensure that the pressure transmitter is not damaged and can measure accurately in this case, the range should be selected to cover these extreme values.
Different industries have different standards and specifications for pressure measurement. When selecting a pressure transmitter, you should refer to the relevant industry standards to ensure that the measurement range of the selected device meets the application requirements. For example, in the food and beverage industry, for liquid pressure measurement in pipelines, the range is usually determined by the design pressure level of the pipeline. According to ASME B31.3 (American Society of Mechanical Engineers Process Piping Standard), if it is a low-pressure pipeline system (design pressure less than 1.03 MPa), the pressure transmitter range can be selected from 0-1.6 MPa.
The physical and chemical properties of the medium (such as temperature, viscosity, density, humidity, corrosiveness, etc.) and environmental conditions (such as temperature, humidity, vibration, corrosion, dust and explosion-proof requirements) will also affect the selection of the measurement range. The appropriate diaphragm material and sensor material should be selected according to the characteristics of the medium, and the appropriate protection level should be selected according to the environmental conditions. For corrosive media or high-temperature media, it may be necessary to use a diaphragm with a special alloy or coating and use an isolation fluid to protect the sensor.
In actual applications, the measuring range can be further optimized by adjusting the zero and span settings of the pressure transmitter according to the actual pressure conditions on site. This helps to ensure measurement accuracy and long-term stability of the device.
Matching the measuring range of a pressure transmitter to the operating pressure requires a combination of factors, including understanding the concepts of measuring range and operating pressure, selecting the appropriate measuring range, considering extreme situations, following industry standards and specifications, considering media characteristics and environmental conditions, and adjustments and optimizations in actual applications. Through scientific and reasonable matching, the accuracy of pressure measurement and the long-term stable operation of the equipment can be ensured.
