Choosing the right pressure sensor for a specific application requires considering various factors. Here's a detailed guide:
* **Selection Based on the Characteristics of the Measuring Medium:**
* **Corrosive Media:** When measuring the pressure of corrosive media such as acids, alkalis, and salt solutions, choose a pressure sensor made of corrosion-resistant materials, such as 316L stainless steel, or a sensor with a Hastelloy housing and diaphragm.
For example, in monitoring acid-base neutralization reactions in chemical production, sensors made of ordinary materials will quickly corrode and be damaged. Pressure sensors with Hastelloy housings and tantalum diaphragms can operate stably for extended periods.
* **Viscous Media:** For viscous media such as glue, paint, and syrup, choose a diaphragm pressure sensor. This effectively isolates the viscous substance, preventing it from entering the sensor, affecting measurement accuracy, and damaging the sensor.
For example, when measuring the pressure of syrup during food processing, a diaphragm pressure sensor ensures accurate measurement and facilitates cleaning and maintenance.
High-Temperature Media
To measure the pressure of high-temperature media such as furnaces and boilers, high-temperature resistant pressure sensors are required. Their internal sensitive elements, housings, and other components must be able to withstand high temperatures. Generally, pressure sensors with ceramic sensitive elements and stainless steel housings can operate normally at temperatures up to 400℃, meeting the needs of most high-temperature scenarios.
Determining the Measurement Range:
* **Low-Pressure Measurement Scenarios:** In vacuum coating processes, such as those involving microelectromechanical systems (MEMS), extremely low pressure measurements are required. In these cases, a micro differential pressure sensor should be selected, capable of accurately measuring minute pressure changes of a few Pascals or even a fraction of a Pa.
* Medium-Pressure Measurement Range:** In fluid pressure measurements in ordinary industrial pipelines, such as urban water supply systems, the pressure range is typically between 0.1 MPa and 1 MPa. Conventional pressure sensors are sufficient.
* High-Pressure Measurement Applications:** For example, in high-pressure hydraulic systems or deep-sea pressure measurement scenarios, pressures can reach tens or even hundreds of megapascals. Therefore, high-pressure sensors are needed to withstand and accurately measure such high pressures.
Selection Based on Accuracy Requirements:
High Accuracy Requirements: In aerospace flight control systems, pressure measurement accuracy requirements are very high, necessitating the selection of pressure sensors with an accuracy class of 0.1%. Even higher accuracy is required to ensure flight safety and control accuracy.
General Accuracy Requirements: For some common industrial production process control, such as the pressure forming stage in building materials production, the pressure accuracy requirements are relatively low. Pressure sensors with an accuracy class of 0.5% to 1% are usually sufficient for production needs.
Considering Working Environment Conditions:
Harsh Environments: If used in harsh environments with high dust levels, such as mines or construction sites, pressure sensors with a high protection level should be selected, such as IP65, which effectively protects against dust and water.
Additionally, if flammable or explosive gases are present, explosion-proof pressure sensors should be selected, such as basic safety pressure sensors, which can operate safely in hazardous environments.
Vibration and Shock Environments: In vibrating equipment such as automotive engine test benches, pressure sensors with good vibration resistance should be selected. Their internal structure and installation methods can resist a certain degree of vibration and shock, reducing measurement errors.
Based on Signal Output and Compatibility:
Signal Output Type: If subsequent devices or systems can only receive analog signals, such as some traditional industrial control dashboards, a 4-20mA analog current signal from the pressure sensor is required.
For automated control systems connected to digital systems, such as smart factories, pressure sensors that output digital signals, such as SP1 or 12C, can be selected for easy system integration and data transmission.
Compatibility: The pressure sensor should be compatible with other devices and software in the system, including power supplies, communication protocols, and data acquisition devices. In automated production lines, all equipment should work together, and the pressure sensor should have good compatibility with PLCs, industrial control computers, and other equipment to ensure the stable operation of the entire system.