Search Results

The introduction of the ‘pressure swing’ desiccant air dryer had a significant impact on how commercial vehicle brake systems are kept dry and free from moisture. With the drive towards cleaner systems and improved reliability, the role of the air dryer has been brought back into focus. At present, almost all commercial vehicle brake systems are operated at above atmospheric pressure, normally in the region of 8bar to 13bar depending on system requirements and application. A reciprocating compressor is commonly used to generate the system pressure. A reciprocating compressor uses oil for lubrication, but some amount of oil will pass into the brake system and contaminate it. Oil can cause damage to elastomeric materials such as valves and reduce the efficiency of desiccant used in the air dryer. This paper outlines a design of an improved air dryer cartridge that gives greater protection from oil contamination emitted from the compressor.

The measurement of pressure dew point is a well-known method of describing air quality, however this value seldom assists commercial vehicle OEM’s and operators in establishing specific air drying requirements for their vehicles. This paper describes the method and examines the results of using the dryer capacity method specified in SAE document J2384, section 5.2, for determining air dryer performance, and compares the results of various air-drying techniques and the impact on vehicle system design to give the most efficient solution. The paper further goes on to discuss how the drying capacity can also be influenced by the design of the air dryer to meet a wide range of vehicle applications both in Europe and North America. Since J2384 excludes continuous flow air dryers from the scope of the document, they will likewise be excluded from discussion here.