Patent ID: 7624758
Filing Date: 2009-12-01
Classification: G05D,Y10T

Abstract:
1. A fluid flow controller comprising a variable aperture flow control valve, an inlet of said flow control valve adapted to receive fluid from a supply source and an outlet of said flow control valve to deliver fluid along a conduit, wherein a back-pressure regulator is located downstream of said flow control valve, said regulator, in turn, being adapted to deliver fluid to an outlet, while a permanently open orifice is connected to said conduit upstream of said back-pressure regulator and provided with an exhaust outlet, with characteristics of said flow control valve, of said back-pressure regulator and of said orifice being so selected that upon a slight opening of said flow control valve said back-pressure regulator maintains a closed condition, while further opening of said flow control valve raises the fluid pressure at said back-pressure regulator which commences opening, to provide a continuous exhaust flow at said exhaust outlet, to extend the operating range of said flow control valve down to relatively low flow rates.