Using compressed air
Air compressors come in a wide range of sizes, from large built-in units that are bolted to the floor, to portable units with a carry handle.
Tools driven by compressed air are called pneumatic tools. They tend to be more efficient and lighter than equivalent tools powered by mains electricity, because they do away with the need for an electric motor inside the tool.
The compressor itself has a pump which compresses air from the atmosphere. The pump is often electrically driven, but for portable compressors it's also common to have petrol or diesel pumps. A receiver, or storage tank, holds the compressed air, and an automatic pressure regulator keeps it at the correct pressure by switching the pump on and off. If the pressure gets too high, air is released through a safety valve.
Air supply
The volume of air that a compressor can supply is called free air delivery, and is generally measured in terms of litres per minute (L/min). This is what determines how many tools can be run at any one time from the compressor and what types of tools it is suitable for.
Another important specification is the operating pressure range. This is measured in kilopascals (kPa) or sometimes pounds per square inch (psi). Different tools operate best at certain pressures, so the operating pressure needs to be checked and re-adjusted if it's found to be incorrect for a particular tool.
It's a good rule to use the minimum pressure required for the tool to operate properly. This will help the compressor to use less power, and there'll be less wear on the tool. If you're using a nail or staple gun, it will also reduce the chance of the fasteners countersinking too far and damaging the timber.
Maintenance and servicing
Depending on the type of air compressor you're using and the tools you're working with, there will be some routine procedures that you need to follow at certain times. Your supervisor will tell you what your specific procedures are, but for a few common examples that apply to most workplaces, select the link below.
Routine maintenance for air compressors
Special safety precautions
Although compressed air is safer than electricity in some respects, it still has dangers. Below are a few safety guidelines you should follow when using compressed air.
1. Always wear safety glasses when blowing out tools or cleaning down work benches with compressed air. The air will cause particles to fly in all directions at high speed.
2. Never point a stream of compressed air directly at anyone's body, particularly bare skin. Many people have suffered ruptured ear drums, eye injuries, skin blisters and burst blood vessels from either cleaning themselves down with compressed air, or playing practical jokes with it.
3. Make sure you secure the loose end of an air hose before turning on the air, to stop it from whipping around when it takes up pressure.
Learning Activity
Some workers know a lot about the air compressor that powers their pneumatic tools, because they are involved with its regular servicing and the adjustments that need to be made to its operating pressure. Other workers, however, don't have much to do with their compressor, especially in large workplaces where there is a central system.
Here are some questions designed to help you gain a better understanding of your compressed air system. You may need to do some research to answer some of these questions, such as looking up the manufacturer's manual, or asking your supervisor or maintenance mechanic. Write down your answers and compare them with the other learners in your group.
- What brand is your air compressor?
- What is the cubic capacity of the receiver?
- Is the pump diesel, petrol or electric?
- How many hoses branch off the compressor?
- What is the free air delivery rating (in litres per minute)?
- What type of air filter does it use?
- What operating pressure is the compressor normally set at?