Before we describe the various types of air compressors used on Navy ships, let s talk about the composition of air and some of the things air may contain. This discussion should help you to understand why air compressors have special features that prevent water, dirt, and oil vapor from getting into compressed air piping systems. Air is mostly composed of nitrogen and oxygen. The earth s atmosphere, of course, also contains varying amounts of water. Vapor is composed of tiny drops of water that are light enough to stay airborne.
Clouds are an example of the existence of water vapor.
Since air is a gas, it will expand when it is heated. When a given amount of air at a given temperature and pressure is no longer able to soak up water vapor. In other words, one method of drying air out is to cool it until it reaches the dew point. In addition to nitrogen, oxygen, and water vapor, air contains particles of dust and dirt that are so tiny and lightweight that they remain suspended in the air. You may wonder how the composition of air directly affects the work of an air compressor.