Patent ID: 7255126

Claim:
A liquid pressure sanitary control valve comprising: a liquid housing defining a liquid flow passage having a plurality of liquid-contacting surfaces comprising a first flow passage, a second flow passage, and an orifice means intermediate between and providing communication between the first flow passage and the second flow passage, the orifice means having an opening; wherein the liquid-contacting surfaces of the liquid housing are free from dead-legs or pockets, thereby enabling complete draining of liquid from the first and second flow passages after use and during cleaning, a diaphragm assembly comprising a diaphragm having a liquid side forming a portion of the first flow passage, and an opposed control side, the diaphragm being moveable along a central axis; a control housing comprising a control means for applying a control force to the control side of the diaphragm; a valve plug positioned proximate the opening of the orifice means, and having a first side affixed to the liquid side of the diaphragm, for movement of the valve plug along the central axis with the moveable diaphragm, to a position relative to the orifice means opening, whereby an orifice is formed between the orifice means opening and the valve plug, the orifice having a variable effective area as a function of the position of the valve plug, the valve plug having an opposed second side having a second surface in liquid communication with the second flow passage, where against a liquid in the second flow passage can exert a differential force against the diaphragm; a pressure receiving means in liquid communication with the second flow passage, upon which a liquid in the second flow passage can exert a balancing force; and a means for communicating the balancing force to the diaphragm opposing the differential force.