Abstract: A multiport flexible diaphragm controlled valve is disclosed. The parts are all interconnected by low dead volume channels. The valve provides extremely fast response times, no moving parts other than the control diaphragm, operability over a wide range of operating conditions including high temperatures and is adaptable to use with all types of chromatography systems. The valve may also be utilized in a double sided configuration enabling two independent flow patterns to coexist simultaneously and be switched totally independent of one another.