What is compressed air?

You may use compressed air more often than you realize. Ever blown up a balloon or pumped up a bike tyre? Both of these activities involve compressed air! But what exactly is compressed air, and how is it produced in an industrial or manufacturing setting? Strap in, as we take a closer look at the fascinating world of compressed air.

Basically, compressed air is atmospheric air or normal air that surrounds us that has been pressurised to a level higher than normal atmospheric pressure. The compression is done by forcing the air into a smaller volume, which increases both the density and the pressure. Once the air has been compressed, it can be stored and used later for a variety of applications, including powering tools, inflating tyres, and even as an energy source. During the compression process, heat is generated, which is known as the heat of compression.

Compressed Air: Pressure

Pressure refers to the force exerted over a specific area. Think of it as how hard compressed air is pushing against the walls of the container, pipe, or balloon it’s stored in. The higher the pressure, the harder the air is pushing to escape. Typically, we measure pressure in kilopascals (kPa) or megapascals (MPa):

• 1 kPa = 1,000 Pa
• 1 MPa = 1,000,000 Pa or 1,000 kPa

Understanding pressure requirements is essential for choosing the right compressed air technology for the task at hand. Not every application requires the same level of pressure. Different applications require different pressures, from lower pressure applications for small jobs to high-pressure or big volumes of compressed air for industrial applications.

Compressed Air: Quantity

To ensure that a system using compressed air operates smoothly, it must always have access to the right amount of compressed air. This is typically specified as a minimum flow rate, for example:

• 25 m³/h
• 250 l/s

The flow rate indicates how long it takes for a specific volume of air to pass a given point. The volume of air is usually measured in cubic metres (m³) or litres (l), while time is expressed in hours (h) or seconds (s). Maintaining an adequate flow rate is critical for the efficient performance of pneumatic systems and to prevent costly downtime.

Compressed Air: Quality

What are some of the quality standards regarding compressed air? There are many different levels of quality when it comes to compressed air, referring to contaminants such as dust, moisture, or oil that might be present. These types of impurities can significantly impact the effectiveness of compressed air and how it can be used. Industries such as food manufacturing, pharmaceuticals, and healthcare require pure, clean, contaminant-free air.

The international standard ISO 8573-1 classifies compressed air into different quality levels based on its intended use. These classes help determine what type of air treatment equipment you need to achieve the required air quality for your application. High-quality compressed air is often necessary to avoid equipment damage, maintain product quality, and ensure safety in sensitive environments.

Uses of Compressed Air

Compressed air is a versatile utility that plays an important role in many industries and applications, often referred to as the "fourth utility" after electricity, gas, and water. Below are some common uses of compressed air:

• Pneumatic Tools: Powering air hammers, drills, and wrenches.
• HVAC Systems: Used in control systems to manage heating, ventilation, and air conditioning.
• Spray Painting: Atomizing paint for an even and smooth application in automotive and industrial painting.
• Automotive Applications: Inflating tyres, brake systems, and air suspension.
• Manufacturing: Powering assembly line machinery, robotics, and material handling systems.
• Medical and Breathing Air: Providing clean, pressurized air for respiratory purposes in medical facilities and underwater diving.

Compressed air's versatility allows it to be used in situations where other energy sources might not be feasible, such as in remote locations or hazardous environments.