Air filters, pressure reducing valves and oil mist lubricators are together known as the pneumatic triad. The three components are connected without tubes and are called triple components. The three components are indispensable air source devices in most pneumatic systems, installed near the pneumatic equipment, is the final guarantee of compressed air quality. The installation order of the three components in accordance with the direction of air intake for the air filter, pressure reducing valve and oil mist lubricator respectively. Depending on the actual requirements, one or two of these components can be used, or all three components can be utilized together.