VALVE FOR WITHDRAWAL OF A SUBSTANCE FROM A CONTAINER

摘要

A valve has a housing defining a bore. Two bottom ports and two side ports in the housing communicate with the bore. Two annular grooves are in the outer surface of a spool received in the bore. A bypass extends within the spool from an annular groove to a bypass port. In one embodiment, the bore extends only partially through the housing and the bypass port is at an end of the spool. In another embodiment, the bypass port is on the outer cylindrical surface of the spool at a location substantially devoid of annular grooves therein. An actuator permits selective movement of the spool within the bore between a first position in which the first bottom port communicates with the first side port and the second bottom port communicates with the second side port and a second position, in which the first and second bottom ports communicate with each other and the first and second side ports communicate with each other. The valve has reduced dead space, making it desirable for use with aggressive chemical products.