Pressure Transducers – Types, Applications, and How They Work

Pressure transducers play a crucial role in numerous industries, including industrial, automotive, and medical fields. These devices are essential for ensuring safety, efficiency, and optimal performance in systems that rely on precise pressure management. In this comprehensive guide, we'll delve deep into the different types of pressure transducers, their internal components, how they function in practical applications, and much more.

A pressure transducer, sometimes referred to as a pressure sensor or transmitter, is a key device used to measure pressure in gases or liquids. One common application is in heart rate monitors found in medical settings. Pressure transducers convert pressure into an electrical or digital signal, which can then be interpreted by other systems such as controllers, computers, or displays.

Pressure transducers operate continuously, constantly detecting and measuring pressure when connected to a system and powered. If there's a change in pressure within the system, the transducer instantly picks up on the shift. How does it do this? The sensing element inside the transducer reacts to the pressure change, transforming it into an electrical or mechanical signal. This signal is then sent to a display, controller, or data acquisition system, enabling real-time monitoring and control.

To fully grasp how pressure transducers work, it's beneficial to examine their key internal components.

The sensing element is a fundamental part of pressure transducers. It reacts to changes in pressure, facilitating signal transmission within the transducer. Common materials for sensing elements include silicon, metal, and ceramics. Here are the three most widely used types of sensing elements:

• Diaphragm: A thin, flexible membrane that deforms when pressure is applied.
• Strain gauge: A device that changes resistance when deformed by pressure.
• Piezoelectric crystal: A material that generates a voltage when mechanically deformed.

Once the sensing element reacts and deforms, it produces a small signal that requires amplification by the transducer’s signal conditioning circuitry (including amplifiers, filters, and analog-to-digital converters) to generate a usable output signal.

The processed signal from the pressure transducer (typically voltage or current) is sent through the output signal interface, converting it into a format other systems can utilize for monitoring or control purposes.

There are many types of pressure transducers, so going through each one would take considerable time. Instead, we’ll explore them under two main categories: the type of pressure measurement they perform (i.e., pressure measurement) and the technology or mechanism used to measure pressure (i.e., sensing technology).

Pressure transducers use three primary measurement methods: absolute, differential, and gauge.

Absolute Pressure Transducers

These transducers measure pressure relative to a perfect vacuum. The reference point is zero, with one side of the sensor exposed to the medium being measured and the other side sealed to create a vacuum. For instance, absolute pressure transducers are used in aircraft altimeters to measure atmospheric pressure relative to a vacuum. As altitude increases, atmospheric pressure decreases—and by measuring this pressure, the altimeter determines the aircraft's altitude.

Differential Pressure Transducers

A differential pressure sensor measures the difference between two pressures. This difference alters the capacitance, which is then measured. Differential pressure transducers are vital in applications requiring the measurement of pressure differences, such as monitoring filters in water treatment plants or assessing fluid flow rates in industrial processes.

Gauge Pressure Transducers

A gauge pressure transducer measures pressure relative to atmospheric pressure. One side connects to the system, while the other side is open or vented to the atmosphere. Gauge pressure transducers are commonly used in applications where pressure relative to atmospheric pressure is significant, such as tire pressure monitoring and HVAC systems.

Pressure transducers employ various sensing technologies, including capacitive, strain gauge-based, and piezoelectric.

Capacitive Pressure Transducers

Capacitive pressure transducers convert pressure into an electrical signal by measuring changes in capacitance. When pressure is applied, the diaphragm moves, altering the capacitance, which is then measured and converted into a pressure reading. These transducers are often used in industrial equipment with hydraulic systems and high-pressure testing.

Strain Gauge Pressure Transducers

This type of pressure transducer measures the pressure of fluids and gases using strain gauges attached to the diaphragm. The diaphragm deforms when pressure is applied, causing a change in the electrical resistance of the strain gauges, which is then measured and converted into a pressure reading. Strain gauge pressure transducers are also commonly used in hydraulic systems for industrial machinery.

Piezoelectric Pressure Transducers

Piezoelectric pressure transducers use materials like quartz that generate an electrical charge on the surface when pressure is applied. The amount of charge produced is directly proportional to the amount of pressure applied. Therefore, the stronger the pressure, the more electrical charge is generated. Piezoelectric pressure transducers are used to monitor pressure changes caused by vibrations in jet engines, helping assess engine performance and detect potential issues.

Peerless Electronics is an authorized stocking distributor for top manufacturers and suppliers across military, aerospace, industrial, transportation, and medical sectors. We offer high-quality pressure transducers from reputable brands like Danfoss, Inc. and Honeywell AST. Every Peerless purchase includes over 50 Value-Added Services designed to save time, streamline workflows, and reduce costs.