What is a pressure transducer?
A pressure transducer, also known as a pressure sensor or pressure transmitter, is a device that converts pressure into an electrical signal. The device is used to measure and monitor the pressure of air, gas, or liquid flowing through an industrial system. It then converts it into a readable output, such as voltage or current, that can be used by a computer or other monitoring system. Pressure transducers are commonly used in industries such as vehicles, medical, off-road equipment, and automation.
How does a pressure transducer work？
The working principle of a pressure transducer is to convert the physical pressure applied to a sensitive element (such as a diaphragm) into an electrical signal. The sensor usually consists of a sensing element and an electronic circuit. When pressure is applied to the sensor, it causes physical deformation, which is then converted into a measurable electrical output, so that pressure changes in the system can be monitored.
The core component is a pressure sensitive element, usually a flexible diaphragm, which deforms when pressure is applied. This mechanical deformation generates an electrical signal, usually a voltage or current. This is then amplified and converted into a numerical value by the associated electronic circuit.
Applications of pressure transducers
Pressure transducers are widely used in many fields. The following are their main application areas:
- Automotive:
Pressure sensors are used to monitor the pressure of the intake and exhaust manifolds to control fuel injection and emissions.
- Medical:
Medical equipment often needs to measure the pressure of the human body to evaluate the condition.
- Environmental monitoring:
Measure atmospheric pressure and water pressure, and monitor pressure changes in oceans, lakes and rivers.
- Industrial manufacturing:
Measure and monitor pressure changes during cargo transportation, as well as hydraulic and air pressure in various mechanical equipment.
- HVAC systems:
Monitor pipeline airflow and control pressure regulation in heating, ventilation, and air conditioning systems.
- Energy production and transmission:
Monitor pressure in pipelines and other equipment to ensure safe and efficient production and transmission.
- Pharmaceutical and food processing:
Measure and monitor pressure changes in the process to ensure product quality and safety.
Types of pressure transducers
The main types of pressure transducers include the following:
1. Strain gauge pressure transducer
The working principle is that the metal strain gauge deforms under the action of external force to cause the resistance value to change. The advantages are simple structure and low price, but low sensitivity and hysteresis effect.
2. Capacitive pressure transducer
The pressure is measured by the change of the capacitance value caused by the change of the position of the capacitor plate. With the development of technology, its volume can be very small, but the input and output are usually nonlinear and need to be linearized.
3. Inductive pressure transducer
The pressure value is calculated by measuring the displacement change using the differential transformer principle. It is suitable for gauge pressure and differential pressure measurement, but the dynamic response performance is poor and is easily affected by acceleration and vibration.
4. Piezoelectric pressure transducer
The piezoelectric effect of piezoelectric materials is used to measure pressure. It has fast response speed and high sensitivity. It is often used for high-frequency pressure signal measurement.
5. Piezoresistive pressure transducer
The piezoresistive effect of semiconductor materials is used to measure pressure. It has high sensitivity and accuracy and is suitable for occasions requiring high-precision measurement.
Electrical output of pressure transducers
Pressure transducers typically output an electrical signal in the form of a voltage, usually in the range of 0-5V or 0-10V DC, and some models also provide current outputs, such as 4-20mA, depending on the specific design and application.
Pressure transducers generally have three types of electrical outputs: millivolts, amplified voltage, and 4-20mA.
Millivolt (mV):
Considered the most economical choice, but produces a very low voltage output (approximately 30mV) that is proportional to the excitation voltage supplied to the sensor. The power supply can be either constant current or constant voltage. Accuracy is somewhat limited by the simple passive compensation circuits that are often used.
Amplified Voltage (V):
Provides a higher voltage output than millivolts, can provide a variety of amplified signals, typically in the range of 0-5V or 0-10V, and is less susceptible to noise due to internal signal conditioning.
Current (4-20mA):
Has excellent noise immunity, requires only two wires, and has the advantage that the signal is not degraded by very long wiring runs. Preferred for long cable runs in industrial environments, the current output remains relatively stable even if there is resistance in the wiring.
What is the difference between a pressure gauge and a pressure transducer?
A pressure gauge is a stand-alone indicator that converts the sensed process pressure into the mechanical movement of a pointer. A pressure transducer can combine the sensor element and power supply of the instrument together.
Essentially, a pressure gauge is used for simple local pressure readings, while a pressure transducer is used in complex monitoring and control systems. The main differences are:
| Difference | Pressure Gauge | Pressure Transducer |
| Output | Pressure gauges display pressure directly on a dial | Pressure transducers output an electrical signal |
| Accuracy | Pressure gauges typically provide less precise visual readings and lower accuracy | Pressure transducers provide greater accuracy and the ability to measure pressure in greater detail |
| Applications | Suitable for basic monitoring where visual readings are required | Pressure transducers are used in automated systems that require precise pressure data and integration with control systems. |
Is a pressure transducer the same as a pressure switch?
No, pressure transducers are not the same as pressure switches. Although they are both used to measure pressure, pressure transducers provide a continuous analog output signal representing the pressure level, while pressure switches simply activate or deactivate a circuit when the pressure reaches a specific set point.
Key Differences:
| Differences | Pressure Transducer | Pressure Switch |
| Output | Pressure transducers give a continuous electrical signal proportional to pressure | Pressure switches only give a binary signal (on or off). |
| Applications | Pressure transducers are used to monitor and control systems | Pressure switches are used to trigger actions, such as activating an alarm or shutting down a system when pressure reaches a critical level |
| Complexity | Pressure transducers are generally more complex than pressure switches | Pressure switches are generally simpler than pressure sensors |
Pressure transducers are essential to industrial development and are used in many control and monitoring applications to monitor and control pressure in systems such as pipelines, hydraulics, and medical equipment. However, when the sensor is used in critical applications and harsh environments, the pressure sensor may require more frequent calibration.
If you have any questions about pressure transducers, or which pressure transducer is best for your testing needs, please feel free to contact an engineer at Sino-Inst. Understanding the working principle and choosing a good sensor will achieve good results.
