Compressed air dryers 

They are special types of filter systems that are specifically designed to remove the water that is inherent in compressed air. The process of compressing air raises its temperature and concentrates atmospheric contaminants, primarily water vapor. Consequently, the compressed air is generally at an elevated temperature and 100% relative humidity. As the compressed air cools, water vapor condenses into the tank(s), pipes, hoses and tools that are downstream from the compressor. Water vapor is removed from compressed air to prevent condensation from occurring and to prevent moisture from interfering in sensitive industrial processes.

Excessive liquid and condensing water in the air stream can be extremely damaging to equipment, tools and processes that rely on compressed air. The water can cause corrosion in the tank(s) and piping, wash out lubricating oils from pneumatic tools, emulsify with the grease used in cylinders, clump blasting media and fog painted surfaces. Therefore, it is desirable to remove condensing moisture from the air stream to prevent damage to equipment, air tools and processes. The function of removing this unwanted water is the purview of the compressed air dryer.

There are various types of compressed air dryers. These dryers generally fall into two different categories: primary, which includes coalescing, refrigerated, and deliquescent; and secondary, which includes desiccant, absorption, and membrane. Their performance characteristics are typically defined by flow rate in Standard Cubic Feet per Minute (SCFM) and dew pointexpressed as a temperature, (sometimes referred to as Pressure Dew Point.)