Pressure Transducers – Types, Applications, and How They Work

Pressure transducers are essential components used in a variety of industries, including industrial, automotive, and medical fields. They play a crucial role in ensuring the safety, efficiency, and performance of systems that depend on precise pressure management. In this article, we’ll take an in-depth look at the different types of pressure transducers, their key components, how they function in various applications, and much more.

A pressure transducer is a critical device that measures pressure in gases or liquids to provide accurate and reliable pressure readings in applications. A common example of an application that relies on pressure transducers is the blood pressure monitors used in healthcare facilities. Pressure transducers (sometimes referred to as a sensor pressure transducer, a pressure sensor transducer, or a pressure transmitter) convert pressure into an electrical or digital signal that is transmitted and read by other devices, such as controllers, computers, or displays.

A pressure transducer typically operates in a continuous mode, meaning it is always sensing or measuring pressure when connected to a system and powered. Therefore, if the pressure changes in a system or application, the pressure transducer immediately detects the change. How does it sense the change? The pressure transducer sensor (i.e., the sensing element) translates the pressure into an electrical or mechanical signal, which is sent to a display, controller, or data acquisition system. This process allows for real-time monitoring and control.

To fully understand how it works, it’s helpful to identify the key components of a pressure transducer.

The sensing element is a core component of pressure transducers. It reacts to pressure changes, facilitating signal transmission within the pressure transducer. Sensing elements are typically made of silicon, metal, or ceramics. The following are the three most common types of sensing elements used.

• 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.

When the sensing element reacts and is deformed, it produces a small signal that needs to be amplified by the pressure transducer’s signal conditioning circuitry (i.e., amplifiers, filters, and analog-to-digital converters) to produce a usable output signal.

The pressure transducer’s processed signal (typically voltage, current, etc.) is sent through the output signal interface, translating it into a format that other systems can use for monitoring or control.

There are numerous types of pressure transducers, making it time-consuming to explore each. Therefore, this section will detail types of pressure transducers using two main categories: the type of pressure measurement they make (i.e., pressure measurement) and the technology or mechanism the transducer uses to measure pressure (i.e., sensing technology).

Pressure transducers use three main measurement modes: absolute, differential, and gauge.

Absolute Pressure Transducers

These pressure transducers measure pressure relative to a perfect vacuum. Therefore, the reference point is zero (i.e., a vacuum), with one side of the sensor exposed to the medium to be measured and the other sealed to create a vacuum. For example, absolute pressure transducers are used in aircraft altimeters to measure atmospheric pressure relative to a vacuum. As altitude increases, the atmospheric pressure decreases—and by measuring this pressure, the altimeter calculates the aircraft's altitude.

Differential Pressure Transducers

A differential pressure sensor measures the difference between two pressures. Thus, the pressure difference causes a change in the capacitance, which is measured. Differential pressure transducers are essential in applications that require the measurement of pressure differences, like monitoring filters in water treatment plants or measuring fluid flow rates in industrial processes.

Gauge Pressure Transducers

A gauge sensor pressure transducer measures pressure relative to atmospheric pressure. Therefore, one side connects to the system, and the other opens or vents to the atmosphere. Gauge pressure transducers are common in applications where pressure relative to atmospheric pressure is important, like tire pressure monitoring and HVAC systems.

Pressure transducers use 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. Therefore, when pressure is applied, the diaphragm moves and changes the capacitance, which is measured and converted into a pressure reading. These types of pressure transducers are common in industrial equipment using 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

These pressure transducers use piezoelectric materials, like quartz, that generate an electrical charge on the surface when pressure is applied. The amount of charge it produces 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, which helps assess engine performance and detect potential issues.

Peerless Electronics is an authorized stocking distributor for many leading manufacturers and suppliers within the military, aerospace, industrial, transportation, and medical sectors. We stock high-quality pressure transducers from respected manufacturers like Danfoss, Inc. and Honeywell AST. Every Peerless purchase includes over 50 Value-Added Services designed to save time, maintain workflow, and lower costs.