A basic overview of different types of compressed air quality
Compressed air is widely used in everyday life, both in the home (e.g. aerosol cans) and for industrial purposes (food processing, electronics, health care, photography, dairy and instrumentation), so much so that consumers often don’t think twice about it. When people sit down to a meal, for instance, the last thing they think about is the quality of the compressed air that was used in the preparation and manufacture of their food. Little do they know that many food manufacturing companies would not be able to function or provide consumers with safe, contaminant-free products without the use of clean compressed air.
From an industrial standpoint, compressed air is often the energy source that powers up pneumatically operated equipment and tools, including those that mix up granular products, aerate liquids and even render meat products. In addition, they are widely used to convey materials and protect equipment or personnel. It is important to note that not all compressed air is the same. The quality of compressed air is actually subject to quality standards, commonly referenced as ISO 8573-1:2010, and determined by measuring three contaminants:
- Oil content
- Water vapour
- Solid particles
According to this measure of quality, there are six different classes or levels of compressed air quality, depending on contaminant level and type.
Contamination levels are obviously influenced by the type of air compressor that is used, along with the related compressed air filtration and compressed air dryer units. Typically, however, compressed air quality is divided into four groups based on usage, which are as follows:
1. Breathing air
The most common applications for breathing air are found in hospitals or medical facilities, as well as for underwater activities. If you have ever been scuba diving, then you definitely understand the importance of having air that is safe to breathe, free of contaminants and that contains a certain amount of water vapour. On the ISO 8573.1 scale, this comes in at class 1 for contaminants or particles (i.e. there should be none of these present) but in classes 4 to 6 for water vapour.
2. Process air
When manufacturing a product that will be consumed by humans or animals, process air is often used in the production process. Not surprisingly, compressed air that meets the standard needs to have zero oil or particle contamination, so food manufacturing companies or even drug companies require their compressed air quality to meet ISO 8573.1 class 1 or 2.
3. Power air
Usually used in pneumatic pumps or equipment such as those used for sand blasting, for instance, the quality of compressed air used for these purposes tend to be a little lower than the first two types of compressed air mentioned above. For power air, oil droplets or water vapour might cause a bit of a nuisance, but it certainly isn’t life threatening. In order to not damage equipment and clog up filters, power air needs to meet class 4 or 5 of the compressed air quality standard.
4. Instrument air
Used for pneumatic instrumentation purposes, the compressed air quality for instrument air needs to be higher than that of power air, and generally meets class 3 or 4 of the compressed air quality standard. This is not only to protect the equipment and instruments that it is being used for, but also to protect the quality of the finished product. Instrument air with a high level of contaminants could affect the quality of the product that it is being used on, such as in paint spraying, for example, or cause untimely instrumentation breakdowns, leading to lost revenue.