Zero dead volume valve

A zero dead volume valve for controlling the flow of a fluid including a valve block having at least one substantially flat valving site on a surface thereof, said valve block defining a plurality of linear passages therein communicating with the valving site through openings, said passages being free of intersections within said valve block, at least two of said passages intersecting at the surface of said valve block at said valve site, at least one other of said passages terminating at the surface of said valve block at a point on said valve site which is spaced apart from where said two passages intersect, a resilient diaphragm covering said valving site and forming a fluid tight seal with said valve block along the periphery of the valving site, and a closure element having a substantially flat closure surface, said closure element being actuable between an open condition wherein said closure surface is retracted a preselected distance from said valving site and diaphragm, and a closed condition wherein said closure surface forces said diaphragm against the valving site;

• whereby the diaphragm can be urged away from the valving site by fluid pressure in the passages when the closure element is in the open condition, establishing a valve chamber above the valving site for fluid flow between the passages, and is forced against the valving site when the closure element is in the closed condition, eliminating the valve chamber and expelling any fluid therein and, when said closure is in the open condition, there is fluid communication between all passages at said valve site and, when said closure is in the closed condition, there is fluid communication only between said intersecting passages.