A filtering unit for use in a fluid pressure system having an inlet port for admitting fluid flowing under pressure through a filter and a desiccant bed to a distributing chamber. During the system's compression cycle, a portion of the fluid under pressure flows from the distributing chamber through...http://www.google.es/patents/US4071337?utm_source=gb-gplus-sharePatente US4071337 - Filter unit having a constant rate purging cycle
