Self priming inlet for rotary pump - has air connection from pump inlet to top of inverted U=section of suction pipe to prevent reverse siphonage

摘要

A rotary pump (11) draws liquid from a vessel (16), the suction pipe (13) dipping into the liquid and rising to an inverted U (14) above the pump. From this it drops to a U (15) bellow the pump and then enters the pump inlet. Liquid is always trapped between the upper U and the pump to make the pump self priming. A small diameter pipe (18) is taken from the suction inlet of the pump to the top of the upper U. When the pump stops air entering the pump from the discharge side (17) flows through this connection to the top of the U and breaks the liquid column at its highest point. This prevents liquid being siphoned back to the vessel.