Pressure sensors typically use various transducer elements, such as piezoelectric materials, strain gauges, and capacitors. These elements change in response to applied pressure (such as deformation, resistance change, or capacitance change). These changes are then converted into corresponding electrical signals through a circuit. The design principle of pressure sensors is primarily based on the process of converting pressure into an electrical signal.

Common Types and Principles of Pressure Sensors

1. Piezoelectric Pressure Sensor: 

   This type utilizes the piezoelectric effect. When piezoelectric materials (such as quartz or ceramic) are subjected to pressure, they generate electric charges. These charges are collected by electrodes and converted into a voltage signal output. They are suitable for dynamic pressure measurements, such as vibrations and impacts.

2. Strain Gauge Pressure Sensor: 

   This type utilizes the strain gauge effect. In these sensors, metal or semiconductor strain gauges are attached to a deformable diaphragm. When pressure is applied to the diaphragm, it bends or deforms, causing a change in the resistance of the strain gauge. This change in resistance is converted into an electrical signal output through a Wheatstone bridge circuit.

3. Capacitive Pressure Sensor: 

   This type is based on the principle of capacitance change. Pressure causes the distance between two parallel electrode plates in the sensor to change, thereby changing the capacitance value. The change in capacitance is converted into an electrical signal output through a circuit. These sensors are suitable for low-pressure measurements.

4. Piezoresistive Pressure Sensor: 

   This type is based on the piezoresistive effect and typically uses semiconductor materials (such as silicon). Pressure causes a change in the resistance of the semiconductor material, which is then converted into an electrical signal output through integrated circuits. They are widely used in various pressure measurement scenarios.

These sensors convert pressure changes into changes in electrical signals. Combined with amplifiers, filters, and signal processing circuits, they achieve precise pressure measurement.

How to Select a Pressure Sensor?

When selecting a pressure sensor, it is important to determine the appropriate sensor type and specifications based on the specific application requirements and environmental conditions. The following are key factors to consider when choosing a pressure sensor:

1. Type of Pressure 

   Absolute Pressure: Measurement relative to a vacuum, typically used in high-precision applications and for atmospheric pressure reference. 

   Gauge Pressure (Relative Pressure): Measurement relative to atmospheric pressure, suitable for monitoring pressure changes within containers or pipelines. 

   Differential Pressure: Measures the difference between two pressure points, commonly used for flow measurement and filter pressure drop monitoring.

2. Pressure Range 

   Determine the required pressure measurement range (from minimum to maximum pressure) based on the application scenario. Ensure that the sensor’s measurement range can cover the actual pressure range.

3. Operating Environment 

   Temperature: Consider the sensor's performance stability and accuracy under high or low-temperature conditions. 

   Humidity and Corrosiveness**: Choose a sensor suitable for operating in high humidity or corrosive environments (such as those with stainless steel housing or protective coatings). 

   Vibration and Shock**: Determine if the sensor needs to be designed to withstand vibration or shock, especially in industrial applications.

4. Accuracy and Resolution 

   The required accuracy determines the choice of sensor. High-precision applications (such as scientific experiments and medical devices) require low-error sensors. 

   Resolution refers to the smallest pressure change the sensor can detect.

5. Output Signal Type

   Select the appropriate output signal type according to the system’s signal processing requirements: analog signals (voltage, current) or digital signals (I2C, SPI, UART), etc.

6. Response Time 

   Different applications have different requirements for response time. Fast-response sensors are suitable for dynamic pressure measurements, while sensors with longer response times can be used for slowly changing pressures.

7. Power Requirements 

   Determine the sensor’s operating voltage and current consumption to ensure compatibility with the existing power supply.

8. Structure and Installation Method 

   Consider the sensor’s size, shape, and installation method (threaded, flanged, insertable, etc.) to ensure easy installation and maintenance.

9. Certifications and Standards

   Verify whether the sensor complies with relevant industry standards and certifications (such as CE, RoHS, ATEX, etc.), especially when used in environments with high safety requirements.

10. Cost

   Choose a sensor with the best cost-performance ratio based on the budget, while also considering quality and performance.

By considering these factors, you can select the most suitable pressure sensor to ensure that it meets all the requirements of the actual application and operates stably.

What Are the Precautions for Installing and Using Pressure Sensors?

When installing pressure sensors, proper installation methods and precautions are crucial to ensure measurement accuracy and long-term stability of the sensors. Here are some key aspects to consider when installing pressure sensors:

1. Location Selection 

   Avoid Vibration and Shock: Choose an installation location that is as far away as possible from sources of mechanical vibration and shock, as these factors can affect the accuracy and lifespan of the sensor. 

   Avoid Electromagnetic Interference: Keep the sensor away from high-voltage wires, electric motors, and other equipment that may generate strong electromagnetic interference to prevent interference signals from affecting measurement accuracy. 

   Protect from Environmental Effects: The sensor should not be directly exposed to rain, dust, or corrosive gases. If necessary, use protective covers or shielding.

2. Installation Orientation and Position 

   Vertical Installation: For liquid pressure measurement, it is best to install the sensor vertically to prevent air bubbles from accumulating on the sensor diaphragm. 

   Horizontal Installation: For gas pressure measurement, horizontal installation can prevent condensate from accumulating inside the sensor. 

   Avoid Pulsating Pressure: If there is pulsating pressure or rapid pressure changes in the pipeline, the sensor should be installed in a position that minimizes exposure to these fluctuations.

3. Sealing 

   Prevent Leakage: Ensure that the connection between the sensor and the pipe or container is well-sealed during installation to prevent leakage, which could cause measurement errors. 

   Use Sealing Components: Select appropriate sealing components (such as O-rings or gaskets) according to the application scenario to ensure a good seal.

4. Avoid Overload Pressure 

   Safety Overload Protection: Ensure the sensor's measurement range is higher than the system's maximum operating pressure to prevent accidental overload pressure from damaging the sensor.

5. Electrical Connections 

   Proper Wiring: Follow the electrical connection instructions in the sensor manual to connect the cables correctly, preventing inaccurate signals or equipment damage due to wiring errors. 

   Use Shielded Cables: In environments where electromagnetic interference needs to be prevented, use shielded cables and ensure that the shielding layer is well-grounded.

6. Temperature Control 

   Effect of Temperature Changes: The sensor should be installed away from heat sources and should not be directly exposed to high or low temperatures. Use insulation or cooling measures if necessary.

7. Maintenance and Calibration 

   Ease of Maintenance and Calibration: Consider ease of maintenance and calibration when installing the sensor, ensuring that the sensor is easy to remove and reinstall. 

   Regular Inspection and Calibration: Regularly check the condition of the sensor and the firmness of its connections, and calibrate as needed to ensure measurement accuracy.

8. Installation Accessories 

   Appropriate Installation Accessories**: Select suitable installation accessories (such as T-joints, elbows, extension tubes, etc.) according to the specific installation environment and space requirements.

9. Protection Level 

   Select the Appropriate Protection Level: Choose a sensor with the appropriate protection level (such as IP65, IP67, etc.) based on the installation environment to ensure its dust and water resistance meet the requirements.

10. Pressure Interface Cleanliness 

Interface Cleanliness: Before installation, ensure the cleanliness of the pressure interface to prevent foreign matter from entering the sensor cavity, which could affect measurement accuracy or damage the sensor.

Proper installation and regular maintenance can not only extend the service life of pressure sensors but also ensure the accuracy and stability of measurement data.