Abstract: Sensitive control of the rate of flow of a fluid under pressure over a wide range of pressures and over a wide range of pressure differentials is effected by a valve comprising a pair of telescoping piston and regulator elements movable relative to each other against the biasing action of a spring when the fluid pressure upon the valve exceeds a predetermined level, the relative motion of the two elements (the upstream piston element and the downstream regulator element) resulting in a degree of closure of ports in the downstream regulator element which depends on the degree to which the pressure differential across the valve differs in magnitude from a pre-selected pressure differential. A critical relationship of the areas of piston ports, regulator ports and fixed-area exit orifice is defined which gives novel and unexpected flow-rate control over wide pressure differentials across the valve.

Abstract: An improved hydraulic flow-control valve with critical dimensional characteristics which assure laminar flow rather than turbulent flow through the valve thus reducing or eliminating valve "hunting" or chattering and increasing sensitivity of the valve to pressure changes and assuring accurate and totally predictable fluid flow control over a wide range of differential pressures across the valve.