Metering pump based on U tube - has hole in immersed part, and air is forced through tube for liquid delivery

摘要

The metering pump for liquids comprises a tube bent into a U, V or S shape which, at the end submerged in the supply of liquid, is provided with an orifice through which the tube fills up to the level in the supply vessel. By admitting pressurised gas into one end of the tube, liquid it contains is delivered from the other end. Operation may be optimised by selection of the ratio of cross-sectional areas of tube and orifice. The flow resistance through the orifice may be increased by capillary tube or nonreturn valve.