7 Types of Pressure Sensors: Different Types, Working Principles, and Definitions
What is a pressure sensor?
A pressure sensor is an electronic device that measures the pressure of a gas or liquid and converts it into an electrical signal. This signal may be used for monitoring, control or other purposes.
Pressure sensors are widely used in various industrial processes. Such as filtration plants, chemical raw materials, wastewater industry, etc. In addition to measuring and displaying real-time pressure values. The signal output from the pressure sensor can also be used to indicate the secondary instrument. Such as alarms, loggers and regulators.
Many pressure sensors today are available for a variety of fluids and gases. Of course, fluids with higher viscosity or thicker viscosity may require specially designed sensors. Such as pulp, asphalt, crude oil and certain viscous but mobile foods.
Type of pressure measurement
The main types of pressure measurements are absolute pressure、gauge pressure and differential pressure.
Absolute pressure
Absolute pressure is the actual pressure relative to a given point measured by a complete vacuum (zero pressure), including atmospheric pressure and any additional pressure within the system. Absolute pressure uses units such as PSIA (pound/square inch absolute pressure).
Absolute pressure uses zero or vacuum as the reference point. Its output signal is an absolute pressure value. Absolute pressure measurement is more accurate than gauge pressure. Using absolute pressure measurements is the same wherever you measure. Therefore, more precise pressure measurements can be provided.
Gauge pressure
The gauge pressure is the pressure measured relative to the surrounding atmospheric pressure. It is the difference between the absolute pressure of the system and the atmospheric pressure. Units such as PSI (pounds/square inch) are usually used for gauge pressure.
In industrial production, the gauge pressure can directly read the pressure value. And it can be widely used for remote transmission and recording through additional devices.
Differential pressure
Differential pressure refers to the pressure difference between two points or positions in the system. It is usually used to measure flow, liquid level or pressure drop in a system. Differential pressure is usually in Pascals (Pa) or psi (psi).
Its measuring instrument is usually composed of two measuring units, which measure the pressure values at two positions respectively. The two pressure values are then subtracted to obtain a pressure difference.
Type of pressure sensor and its working principle
Pressure sensors can be designed and classified according to their method for sensing pressure changes. Common types include piezoresistive, capacitive and piezoelectric. Each type uses different principles to measure pressure.
Different types of pressure sensors are listed below:
Strain gauge pressure sensor
The strain gauge pressure sensor has a spring element. Pressure is measured using proportional expansion or contraction of the spring size. Similar to a piezoresistive sensor.
They are the most commonly used sensor types due to their usability and versatility. Strain gauge pressure sensors are commonly used in industrial applications. For example, long-term monitoring and control of hydraulic pressure.
Piezoresistive pressure sensor
Piezoresistive pressure sensors refer to sensors made using the piezoresistive effect of single crystal silicon material and integrated circuit technology.
Piezoresistive pressure sensors are mainly based on piezoresistive effect. Unlike the piezoelectric effect, the piezoresistive effect only produces impedance changes and does not generate charges.
Capacitive pressure sensor
Capacitive pressure sensor is a type of utilizing capacitors as sensitive components. A pressure sensor converts the measured pressure into a pressure sensor with a changing capacitance value.
This type of pressure sensor generally uses a circular metal film or a metal-plated film as an electrode of the capacitor. When the film feels pressure and deforms, the capacitance formed between the film and the fixed electrode changes. Through the measurement circuit, an electrical signal with a certain relationship to the voltage can be output.
Piezoelectric pressure sensor
The working principle of a piezoelectric pressure sensor is to use a piezoelectric effect. Use charge as a response to physical changes in the material. They produce electrical signals proportional to the applied pressure. This enables rapid response.
The small size of the piezoelectric sensor makes it ideal for space-constrained applications. Its only disadvantage is that the output signal is usually reduced when static pressure is applied, and the accuracy of measuring stable pressure is low. And may have high output impedance.
Inductive pressure sensor
The working principle of inductive pressure sensors is due to the difference in magnetic materials and permeability. When the pressure acts on the diaphragm, the air gap size changes. Changes in the air gap affect the changes in the coil inductance, and the processing circuit can convert the changes in the inductance into corresponding signal outputs.
The advantages of inductive pressure sensors are high sensitivity and large measurement range. The disadvantage is that it cannot be applied to high-frequency dynamic environments.
Hall Pressure Sensor
Hall pressure sensors are made based on the Hall effect of certain semiconductor materials. The Hall effect refers to when a solid conductor is placed in a magnetic field. When an electric current passes, the charge carrier in the conductor is subjected to Lorentz force and is biased to one side. Then the phenomenon of electricity (Hall voltage) is generated.
Most of the materials used for Hall components are semiconductors. Including N-type silicon (Si), indium antimonide (InSb), indium arsenide (InAs), and multi-layer semiconductor structural materials.
Eddy current pressure sensor
The eddy current pressure sensor is based on the pressure sensor of the eddy current effect. The eddy current effect is caused by a moving magnetic field intersecting a metal conductor. Or it is generated by the vertical intersection of moving metal conductors and magnetic fields.
The eddy current effect is caused by the electromagnetic induction effect. This action generates a current circulating within the conductor. The eddy current characteristic makes the eddy current detection have characteristics such as zero frequency response.
The type of pressure transmitter and its working principle
Of course, most of our users do not need to consider the principle of pressure transmitters when purchasing pressure transmitters. We can start directly from the actual requirements of measurement. We need to measure the differential pressure, so we choose the differential pressure transmitter.
Therefore, what we more commonly divide pressure transmitters into the following categories:
Differential pressure transmitter
A differential pressure transmitter is used to measure the difference between two pressures. A diaphragm or sensor deformed under pressure changes is usually used to convert this deformation into an electrical signal proportional to the pressure difference. These devices are often used to monitor various industrial processes.
Absolute pressure transmitter
The absolute pressure transmitter measures the pressure relative to the complete vacuum (absolute zero). These transmitters convert mechanical pressure into electrical signals. Then it is used to display pressure readings. Used in places where gas or liquid pressure is isolated from atmospheric pressure changes.
Gauge pressure transmitter
The gauge pressure transmitter measures the pressure relative to atmospheric pressure. The gauge pressure transmitter uses a diaphragm or sensing element to measure pressure. It is then converted into an electrical signal. Usually 4-20mA current or voltage.
Multivariate pressure transmitter
The multivariate pressure transmitter measures three process parameters and calculates the flow rate. Multiple process parameters (such as differential pressure, static pressure, and temperature) can be measured and calculated in a single device. Usually used for flow measurement. And it has advantages such as reducing installation complexity and cost.
The difference between pressure sensor and transmitter
| Main differences | Pressure sensor | Pressure transmitter |
| Output | The signal output by the pressure sensor is usually not standardized | The pressure transmitter outputs a standardized signal |
| Uses | Pressure sensor for local measurement | Pressure transmitter for remote measurement and control |
| Signal strength | The pressure sensor detects pressure and outputs signals (such as voltage or current) | Pressure transmitters are designed to transmit signals to longer distances without distortion |
Precautions for purchasing pressure sensors
When determining which type of pressure sensor is best for your needs. You should consider the following points to make sure it meets the specific needs of your application:
Sensor Type: This is the main consideration when choosing a pressure sensor that suits your application needs
- Pressure range: Determine the minimum and maximum pressure values that the sensor needs to accurately measure.
- Pressure type: Consider whether you need to measure absolute pressure, gauge pressure or differential pressure.
- Accuracy and accuracy: the degree to which the sensor’s reading matches the actual pressure value. Consistency of sensor readings under the same conditions.
- Output type: The analog signal provides continuous voltage or current signals. Digital output signals provide digital signals.
- Output level: the voltage or current range of the sensor output.
- Temperature range: Ensure that the sensor can withstand the expected temperature changes.
- Calibration: Regular calibration helps maintain accuracy and reliability.
- Response time: Consider how quickly the sensor needs to respond to pressure changes.
- Application details: Some applications require faster response times than others
- Pressure medium: Consider the possibility of pressure medium or environmental pollution.
- Measuring pressure and using this measurement to monitor and control processes is a critical need for many manufacturing and service industries. Pressure transmitters are very important in industrial control systems. Widely used in various process control and monitoring scenarios. Such as oil and gas, chemicals, electricity, and other industries.
Choosing the right pressure sensor requires careful consideration of various factors. Including media compatibility, operating environment… Our industrial pressure transmitters have more than 50 types and are widely exported to various countries. Including the United States, the United Kingdom, India, South Africa, etc.
Whether it is absolute pressure, gauge pressure or differential pressure. Sino-Inst can provide the right measurement solutions. If you have any questions about the pressure sensor, or which pressure sensor is best for your testing needs, please feel free to contact us.
