Why Filter Compressed Air?

Oil, dust, dirt and water contaminate compressed air systems. Contaminants can plug orifices of sensitive pneumatic instruments, wear out seals, erode system components, reduce the efficiency of air-operated tools, damage finished products and otherwise contribute to product rejects, lost production hours and rising maintenance costs. The best defense against oil and dirt is effective compressed air filters.

Compressed air filters are used to remove water, oil, oil vapor, dirt, and other contaminants from a compressed air supply. This product area includes water separators, centrifugal separators, oil separators, air oil separators, and demisters. Filter size rating, maximum air volume, maximum inlet pressure, and operating temperature are the most important performance specifications to consider when selecting compressed air filters. As a rule, filter size rating is the low end of the size-range that is filtered or blocked. Bowl size, bowl drain, and bowl material are also important parameters for compressed air filters. Bowls for a compressed air filter feature a manual or automatic drain and are made of aluminum, polycarbonate, steel, stainless steel, or zinc.  

There are several basic types of compressed air filters. All are designed to remove contaminants, but some have specific features that make them better-suited for particular applications. General-purpose compressed air filters can remove liquid and solid contaminants of various sizes. Coalescing oil removal filters are able to remove oil and other contaminants at the sub-micron level. These filters are used in situations where general-purpose compressed air filters would leave too many contaminants in the system. Adsorbent oil vapor removal filters are designed to maintain a very pure airflow.  They use adsorbent materials such as charcoal as a filter media to reduce vapor to less than 1 ppm.  These devices are often used in conjunction with instrumentation, fiber optics and other components that are highly susceptible to damage and misreading due to contamination.  Multi-stage compressed air filters that are capable of two or more of the above ratings are also available.

Compressed air filters carry port specifications that indicate the thread type and measurement. Thread types include national pipe thread (NPT), British standard pipe thread, and metric pipe thread. There are many choices for NPT compressed air filters. Examples include: #10-32, 1/8-in, 1/4-in, 3/8-in, 1/2-in, 3/4-in, 1-in, 1 1/2-in, and 2-in NPT. In terms of features, some compressed air filters include a service life indicator, pressure gauge, or integral lubricator. Others are rated for caustic or corrosive media. Service life indicators may read the pressure drop across the compressed air filter, or use more advanced techniques. A pressure gauge for a compressed air filter provides a direct measurement of operating pressure or pressure drop.

Source : GLOBALSPEC | The Engineering Search Engine