GB809651A - Fluid flow control apparatus - Google Patents

Abstract

809,651. Valves. KEELAVITE CO. Ltd. Dec. 8, 1955 [Dec. 22, 1954], No. 37095/54. Class 35. When fluid enters the valve 14 through pipe 11 it experiences a pressure drop across the adjustable metering orifice 13 whilst the input pressure is transmitted to a chamber 25 via a conduit 47 leading from the pipe 11 at a point upstream of the orifice 13 and embodying a constriction 48; the lower end of a piston 23 engages a cup-shaped member 33 and its movement is opposed by an associated adjustable spring 31; the upward movement of the member 33 is limited by flanges 37, 38. When a pressure increase occurs, the lower pressure, downstream of the orifice 13, is transmitted to the fluid in an inlet chamber 18 and thence to a lower chamber 26 by way of a T-shaped passage 44 in the piston 23 where it opposes the pressure in the upper chamber 25 urging the piston down; the resultant force moves the piston 23 downwards to restrict the flow through the port 20 to the outlet 16 until the equilibrium is reached so reducing to a minimum fluctuation in the rate of flow. In a similar manner if the direction of fluid flow through the valve is reversed any inlet pressure increase will result in the piston 23 being subject to a resultant force which moves it against an upper adjustable spring 30 and causing the lower end of the piston to restrict the port 20 and reduce the flow rate since the lower pressure, downstream of the orifice 13, now acts on the upper end of the piston. Irrespective of the direction of flow the orifice and valve are in series and any change in the rate of flow produces a pressure drop across the orifice which causes a movement of the piston in a direction tending to restore the flow rate to its original value. In a modification, the orifice is of fixed crosssection and is formed in a plate threaded in the passage 15 adjacent the chamber 18; a plug 50 in a passage 49 is thus removed and the pipe connection 46 replaced by a plug so that the passage 49 will place the side of the orifice remote from the valve in communication with the chamber 25, via the passage 45.