The Fundamentals of Pneumatics
Part III - Filters, Regulators, and Lubricators

This is the third in a series of articles covering the principles of pneumatics. In this article, filters, regulators, and lubricators will be discussed.

Filters, regulators, and lubricators are generally used together on each machine to condition the air properly. When used together they are referred to as FRL's, see Figure 1. In the pneumatic system, the air flows through the filter first, the regulator second, and, if needed, the lubricator third.

Filters

Filters are usually used in conjunction with a separator bowl, see Figure 2. The air enters the bowl where it will swirl around the filter, forcing contaminates and water to accumulate in the bottom of the bowl. The air then passes through the filter and exits through the output port. Filter separators are stamped with an arrow indicating which direction the air must flow through them, aiding in proper installation.

Filters serve an important function by removing dirt and contaminants from air that can prematurely wear moving parts. Therefore, filters must be constantly maintained to avoid clogging. A clogged filter can restrict the air flow, causing a machine to work sluggishly. Reusable filters should be periodically cleaned. Disposable filters should be replaced when dirty, and the separator bowl should be washed out with a mild detergent.  Caution should be used when using cleaning solvents to avoid weakening or destroying polycarbonate bowls.

The frequency of maintenance depends on the condition of your air.

Figure 3A shows a filter separator with a manual drain. Depressing the small button at the bottom allows excess water to drain. Figure 3B shows a filter separator with an automatic drain. When the water level reaches a certain point, a float will rise and allow water to drain until the float is no longer supported and drops back into place. The automatic drain has the advantage of less maintenance, but care should be taken to see that the filter is properly serviced.

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