GB880405A - Improvements in flow control valves - Google Patents

Abstract

880,405. Fluid-actuated valves. TECALEMIT Ltd. Jan. 10, 1958 [Jan. 25, 1957], No. 2809/57. Class 135. A fluid control valve assembly 1, Fig. 1, for controlling the flow of variable-pressure fluid so that it will be in a desired relationship to a selected pressure drop across a manually-adjustable throttle valve 10, comprises vertical and horizontal pressure chambers 4, 16 divided respectively by a diaphragm 5 or equivalent into upper and lower compartments 6, 7 and by a diaphragm 22 or equivalent into left-hand and right-hand compartments 23, 24. The diaphragm 22 is subjected to the variable-pressure (P 1 ) upstream of the throttle valve 10 transmitted through a conduit 9, the compartment 6 and a passage 17 against the action of a spring 25 to position a cam member 18 co-operable with a piston 20 to adjust the loading of a spring 21 acting on the diaphragm 5. The diaphragm 5 besides being loaded by the spring 21 is also urged downwardly by the pressure P 1 against the loading of a spring 15 and pressure (P 2 ) downstream of throttle 10 to position a valve member 12 controlling an outlet 14 from the assembly. The shape of the cam member 18 will determine the relationship between the value of the pressure P 1 and the pressure drop across the throttle valve 10. Since flow through the valve 10 is proportional to the square root of the pressure drop across it, by suitably selecting the dimensions of the components and the shape of the cam any desired relationship between the pressure P 1 and flow through the valve 12 may be obtained. In a modification, an impeller 45, Fig. 2, is fitted between the inlet 41 to the assembly and the upstream side of a manually adjustable throttle valve 49. The diaphragm 36 in the horizontal pressure chamber in this case is subjected on one side to impeller outlet pressure and on its other side to impeller inlet pressure (inlet pressure) and the loading of a spring 40 to position a cam member 39 adjusting the loading of a spring 33 acting on the diaphragm 27 in the vertical pressure chamber. The pressure drop across the throttle valve 49 and therefore the flow through the valve 30 controlling the outlet 31 is determined in a desired relationship to the pressure difference generated by the impeller 45 and therefore to the speed of the impeller.