Whether we realize it or not, compressed air is involved in every aspect of our lives, from birthday party balloons to the tires of cars and bicycles. It has likely been used in the manufacturing of the mobile phone, tablet, or computer on which this text is displayed.
As you might guess, the main ingredient of compressed air is air itself, a mixture of numerous gases, primarily nitrogen (78%) and oxygen (21%). Air is thus composed of different molecules, each with a certain kinetic energy.
The temperature of the air is directly proportional to the average kinetic energy of these molecules. This means that the air's temperature is high if the average kinetic energy is large (and the air molecules move faster), and low when the kinetic energy is less.
Compressing air increases the speed at which its molecules move, and consequently its temperature. This phenomenon is called "heat of compression." Compressing air literally means forcing it into a smaller space, thus reducing the distance between the molecules. The energy accumulated during this process is equal to that required to force the air into the smaller space in question. In other words, air stores energy for future use.
Take, for example, a balloon. When it is inflated, the air is forced into a smaller volume. The energy contained in the compressed air inside the balloon is equal to that required to inflate it. When the balloon is opened and the air is released, this energy dissipates, causing it to fly away. This is also the fundamental principle of volumetric compressors.
Compressed air is an excellent means for storing and transferring energy, as it is versatile, flexible, and relatively safe compared to other energy storage methods, such as batteries and steam. Batteries are bulky and the duration of their charge is limited. Steam, on the other hand, is not economically advantageous nor easy to use (due to its extreme temperature). If compressed air is compared with electricity, however, the latter is more advantageous economically. If this is true, why is compressed air used?
Example of Compressed Air Use
If we look at the Earth's surface and the atmosphere, we can consider the latter as a sea of air. The pressure decreases as you go up within this ocean. The lower you remain (closer to sea level), the greater the pressure, because there is more air pushing down. In other words, the air is more compressed at sea level, and below, than at the top of Everest.
Why Use Compressed Air?
One of the main reasons for using air compression instead of electricity is safety. In applications where equipment is subject to overloads, electrical devices pose a safety hazard. They can cause electric shocks or fires, which result in personal injuries or material damage. Compressed air and pneumatic tools can be used in many conditions, such as on wet floors or in areas with high humidity.
Secondly, compressed air is more flexible and easier to use in remote areas such as mines and construction sites. Pneumatic tools cool during use and offer the advantage of variable speeds and torques. If rock drills or similar impact equipment are considered, it would be nearly impossible to develop an equivalent force with electricity, especially in remote areas.
Tools powered by compressed air are also lighter and can be made with materials that make them light and more ergonomic. This allows the cost of air to be offset by the reduction of labor costs due to the lesser fatigue of staff using these lighter tools.
Finally, there is the question of cost. Compressed air has an equivalent cost that can reach 7 or 8 times that of electricity. However, equipment designed to use compressed air is generally less expensive. They use fewer components thanks to the simplicity of their configuration. Usually, pneumatic tools are also robust and have a longer lifespan in production environments.
Not everyone knows that compressed air is considered the fourth utility. Of course, it is likely that we all use the first three in everyday life, namely water, electricity, and gas. Because of its ubiquity, however, compressed air is considered the fourth utility both for small businesses and for large ones.
In addition to electricity, water, and gas, compressed air is fundamental in our world. Perhaps we do not always realize it, but compressed air is everywhere around us. Considering that there are so many uses for compressed air and so much demand, compressors are available in all models and sizes. In this guide, we describe what compressors do, why they are necessary, and the types of options available.
