Glossary of Pneumatic Terms

Glossary of Pneumatics Terms

Pneumatics play a crucial role in modern industry, utilising compressed air to transmit and control energy. Pneumatic systems are everywhere, from factory floors to the automation of mechanical processes. At the heart of these systems are principles of air compression and gas laws, enabling machines to lift, push, pull, and move loads with precision and reliability.

Fluid-Air Components Ltd, with its extensive expertise and product range, stands at the forefront of supplying pneumatic solutions. Catering to a vast array of industries, we provide everything from pneumatic fittings to sophisticated control valves, ensuring that every application runs smoothly and efficiently.

As we delve into the key pneumatic concepts, we’ll explore the building blocks of pneumatic systems, highlighting how components like actuators and compressors come together to create powerful and versatile systems. This journey through pneumatics will not only define essential terms but also shed light on the products and services offered by Fluid-Air Components Ltd, tailored to meet the needs of any factory or industrial company relying on pneumatics.

Next, we’ll begin our deep dive into the A-Z of pneumatic terms, starting with the actuator, a fundamental component in translating compressed air into mechanical action.

Key Pneumatic Concepts

A-V of Pneumatic Terms (including major terms under each letter)


An actuator is a device that converts the energy stored in compressed air into mechanical motion. This motion can be linear, as in the case of pneumatic cylinders, or rotary, for applications requiring rotation. 

Air, Compressed

Compressed air is air that is kept under a pressure greater than atmospheric pressure, serving as the energy source for pneumatic systems. It powers actuators, drives pneumatic tools, and operates machinery, making it a versatile and clean energy source. 

Boyle’s Law

Boyle’s Law is a fundamental principle of gas behaviour that describes the inverse relationship between the pressure and volume of a gas at constant temperature. In pneumatics, understanding Boyle’s Law is essential for predicting how compressed air will behave under different conditions, influencing system design and efficiency.

Cylinder, Types of

Pneumatic cylinders are actuation devices that utilise compressed air to produce linear motion and force. They come in various types, including single-acting (where air pressure is applied to one side of the piston only) and double-acting (where air pressure can be applied to both sides). 


The durometer measures the hardness of elastomers and polymers, which is critical in pneumatic systems for selecting seals, hoses, and other components that can withstand the pressures and wear associated with compressed air. 

Flow Rate

Flow rate in pneumatics refers to the volume of air passing through a point in the system within a given time, usually measured in cubic feet per minute (CFM) or litres per minute (L/min). Optimising flow rate is crucial for efficient system performance, affecting the speed and force of pneumatic devices.

Gauge, Pressure

Pressure gauges in pneumatic systems measure the pressure of the compressed air, essential for monitoring and adjusting system performance. 


A lubricator adds controlled amounts of oil into a pneumatic system to reduce friction and wear on moving parts, prolonging equipment life. It’s a critical component in maintaining system efficiency and reliability, especially in systems with extensive mechanical motion.


A manifold in pneumatics is a component that distributes air or fluid to various parts of a system from a single input source. It simplifies the system design and reduces the need for multiple hoses and connections, enhancing system reliability and ease of maintenance.


Pneumatics refers to the technology that uses compressed air as a means of transmitting and controlling power. It’s the foundation of countless industrial applications, offering a clean, efficient, and safe alternative to electric or hydraulic systems.

Pressure, Various Types

Pressure in pneumatics can be classified into several types, including absolute, gauge, atmospheric, and differential. Understanding these differences is vital for system design, selection of components, and troubleshooting.

Valve, Types of

Valves in pneumatic systems control the flow and direction of air, essential for regulating system operations. Types include solenoid valves, manual valves, and control valves, each serving a specific function within pneumatic circuits. 

Next, we will explore additional terms and components that, while not foundational, are nonetheless crucial for a comprehensive understanding of pneumatics and its applications. This includes materials like acetal plastic, concepts such as fluid logic, and devices like quick disconnect couplings.

Also of Interest:

Acetal Plastic

Acetal plastic is a high-strength, low-friction engineering plastic widely used in pneumatic fittings and valves for its durability, resistance to moisture and chemicals. Its properties ensure reliable, leak-proof connections in pneumatic systems.

Active Device

An active device in pneumatics is a component that requires an external power source to operate, typically used for controlling or modifying the system’s operation, such as solenoid valves which direct airflow when electrically actuated.

Air Motor

An air motor is a type of motor powered by compressed air rather than electricity. These motors are used for various applications requiring safe, non-electric power sources, particularly in volatile environments. They offer high power-to-weight ratios and can be easily controlled for speed and torque.

Circuit, Types of

Pneumatic circuits control the flow and pressure of air within a system, and there are several types, including sequential, parallel, and cascade circuits. Each type is designed to meet specific operational requirements, ensuring efficient control and automation of pneumatic systems.

Compression Set

Compression set refers to the permanent deformation of a material after it has been compressed. In pneumatics, it’s a critical measure of a material’s ability to maintain an effective seal under pressure, affecting the longevity and reliability of pneumatic seals and o-rings.


A compressor is a machine that increases the pressure of air by reducing its volume, serving as the heart of any pneumatic system. Compressors are essential for supplying the compressed air needed to power pneumatic tools, machinery, and actuation systems.


A pneumatic filter removes contaminants from compressed air, such as dust, particles, and moisture, ensuring the air is clean and dry to protect pneumatic equipment from wear and damage, thus extending its lifespan and maintaining efficiency.


Pneumatic fittings are used to connect tubes, hoses, and other components in a pneumatic system, ensuring secure and leak-proof connections. Available in various sizes and materials, fittings are crucial for the assembly and maintenance of efficient pneumatic systems.

Fluid Logic

Fluid logic involves the use of fluids to perform analogue or digital operations similar to electronic logic circuits. In pneumatics, fluid logic can control the flow and pressure of air to automate processes and machinery without the need for electricity.

Pascal’s Law

Pascal’s Law states that pressure applied to a confined fluid is transmitted undiminished in every direction. This principle underpins the operation of pneumatic systems, where applied pressure can cause movement or exert force, demonstrating the foundational role of physics in pneumatics.

Quick Disconnect Coupling

Quick disconnect couplings are fittings that allow for the quick and easy connection or disconnection of fluid lines without the use of tools. They are essential for maintaining flexibility and efficiency in pneumatic systems, facilitating maintenance and system configuration changes.

Seal, Types of

Seals in pneumatic systems prevent leakage of compressed air and ensure that components maintain pressure as needed. Types of seals include o-rings, piston seals, and rod seals, each designed to meet specific sealing requirements and operational conditions.

Continuing our exploration of pneumatics, we will next delve into technical definitions, focusing on devices and principles that further enhance the understanding of pneumatic systems and their components.

Technical Definitions

AND Device

An AND device in pneumatics is a logic element that outputs air pressure (signals) only when all its inputs receive pressure. This device is essential for safety and control circuits, ensuring actions occur only when multiple conditions are simultaneously met. For e.g. Port 1 AND Port 2 must be engaged for an output to occur.

Circuit, Metered-In/Metered-Out

Metered-in and metered-out circuits control the speed of pneumatic cylinders. Metered-in regulates air entering a cylinder, while metered-out controls air exiting. These circuits ensure precise control over cylinder speed and movement.

Cylinder Capacity, Extending

Cylinder capacity, extending, refers to the volume of compressed air required to fully extend a pneumatic cylinder. It’s a crucial factor in selecting the appropriate compressor size and storage capacity to match the system’s demands.

Detented (Maintained)

A detented, or maintained, valve position remains in its last state until acted upon by an external force. This feature is useful in applications requiring the valve to stay in an open or closed position without continuous control input.

Normally Closed/Open (Electrical & Fluid Power)

Normally Closed (NC) devices block the flow of air until activated, ensuring safety and energy efficiency in pneumatic systems.

Normally Open (NO) devices allow air flow in their default state, providing continuous operation until deactivated.

Pressure, Differential (Pressure Drop)

Differential pressure, or pressure drop, refers to the decrease in air pressure as it moves through a pneumatic system. Understanding and minimising pressure drop is crucial for maintaining system efficiency and performance.

Valve, Directional Control

Directional control valves dictate the path of airflow within a system, determining the movement of actuators and other components. These valves are critical for directing, stopping, and starting flow, enabling precise control over pneumatic operations.

These technical definitions enhance our understanding of how individual components and principles contribute to the overall functionality of pneumatic systems. Each element plays a specific role, ensuring efficient and reliable operation, which Fluid-Air Components Ltd expertly supports through its comprehensive range of pneumatic products and solutions.


The exploration of pneumatic terms and concepts, from the foundational principles like Boyle’s Law and Pascal’s Law to the intricacies of components such as actuators, valves, and cylinders, underscores the complexity and versatility of pneumatic systems. Through this glossary, we’ve delved into the mechanics that drive pneumatic technology, highlighting the critical role of each component in ensuring efficient, reliable operations across various industrial applications.

Fluid-Air Components Ltd, with its comprehensive range of pneumatic products and deep technical expertise, stands as a pivotal partner for industries seeking to harness the power of pneumatics. Our dedication to quality, combined with the ability to offer tailored solutions, ensures that we meet the specific needs of our customers, helping to drive their success in an ever-evolving industrial landscape.

As we conclude our glossary, remember that the world of pneumatics is continually advancing, with new technologies and innovations expanding the boundaries of what’s possible and this is only a very brief guide of some common terms and phrases you will come across. Fluid-Air Components Ltd remains committed to staying at the forefront of these developments, offering the latest products and insights to help our customers achieve their operational goals.

This glossary is not just a list of terms but a gateway to understanding the pneumatic systems that power the modern world. As we look forward, Fluid-Air Components Ltd is excited to continue providing the components, knowledge, and support needed to explore the potential of pneumatics together.

Next steps in pneumatics will inevitably lead to advancements in efficiency, sustainability, and capabilities, promising an exciting future for industries worldwide.