Filters are necessary to reduce particulate contaminants and separate moisture from the compressed air - both for the entire plant and at the machine level. Filters are available in a wide range of sizes, with inlet and outlet port sizes ranging (typically) from 1/8 NPT to 1 NPT. NITRA brand filters use replaceable filter elements, which are available in different grades: standard filters remove particles down to 40 µm, while fine filters are available to remove particulates down to 5 µm or less.
All pneumatic components can benefit from filtration, but keep in mind that a filter that is too fine for the application can quickly become blocked. While a 40 µm filter works well to protect valves and cylinders, process instrumentation or high speed pneumatic tools may require fine particle filtration. Special, finer filters may also be needed for food, pharmaceutical and paint shop applications. Specify a coalescing filter if oil vapors or aerosols need to be removed from the air stream (Automation Direct does not currently sell coalescing filters).
As noted above filtering is generally provided at the plant level AND at the machine level. Consider using additional filters when individual actuators or small subsystems are widely spread throughout a facility (think conveyor systems) especially if they are plumbed with metal pipes. Particulates from flaking, rust, and corrosion are much more prevalent in metallic piping than is generally seen with tubing and hoses.
Filters usually incorporate a bowl to trap and collect liquids as they are separated from the air. These bowls are removable to facilitate cleaning and to allow easy replacement of the filter elements contained within. The bowls are also equipped with either manual, semi-automatic or automatic drains to purge the trapped liquid that has been separated from the air.
HELPFUL HINT: Specify FRL components with the same fitting sizes for ease of connection and mounting.
Combination filter/regulator air prep units are also available. These units have all the capabilities of the separate filters and regulators combined into a single unit. This design can reduce cost, and save significant space if it is appropriate for the application.