Abstract: A drain valve has an inlet (36) for liquids and small solids, an accumulation chamber (37) and an outlet (17). The outlet has a seal (13) which is connected to an air-activated piston (12). The piston is in turn connected to a positive air pressure inlet (18) via an air communication path (19) and a closure (22). The closure (22) is opened by a closure activation means (29), causing positive air pressure to flow to the piston (12), which briefly causes the outlet seal (13) to be opened, allowing liquids and small solids from the accumulation chamber to be expelled. Upon de-activation by the closure activation means (29), the closure (22) recloses, blocking the supply of positive air pressure to the piston (12).

Abstract: An air filter includes an inlet for compressed air, a prefiltration chamber into which air from the inlet passes, a porous filter through which air from the prefiltration chamber passes to strain particular matter from the air, a plurality of venturis through which air from the porous filter passes, an expansion chamber in which air from the venturis expands and cools so that droplets of oil and water precipitate and accumulate at the bottom of the expansion chamber, and an outlet for air from the expansion chamber.