Patent GB-637155-A (GB)
Title: Improvements in liquid or gas dispensing and measuring apparatus
IPC: G01F15/07
Filed: 1945-04-26
Abstract: 637,155. Dispensing liquid fuel &c. S.A.T.A.M. SOC. ANON. POUR TOUS APPAREILLAGES MECANIQUES. April 26, 1945, No. 10483. Convention date, Feb. 4, 1942. [Class 116] [Also in Group XXIX] In apparatus for dispensing fluid of the type in which partial throttling of the delivery by means of a manually controlled valve (nozzle) on the delivery pipe causes a main valve upstream of the nozzle to close whereupon final cut-off of the delivery is controlled by an indicating device driven from a meter, a by-pass is provided to the main valve having a pilot valve therein which can close only when the indicating device is in zero position, and a leakage path is also provided round the main valve through which delivery commences when the nozzle is opened causing movement of the indicating device which opens the pilot valve in the bye-pass, the subsequent flow through which opens the main valve hydraulically to give full delivery. Means for temporarily closing the leakage path during closing of the bye-pass valve at the end of delivery are provided to ensure complete cut-off. In the apparatus of Fig. 2, petrol is pumped via a meter to the inlet port 23 of a valve housing 20, and on opening the nozzle at the end of a hose pipe connected to the outlet port 24 petrol flows through a leak passage formed by the orifice 51 in a diaphragm 50, passage 60, orifice 73, chamber 25, orifice 62 and pipe 61. This slight flow registering on the indicator causes the cam 80 to rotate and displace the lever 90 lifting the valve 70 and permitting an increased flow through the byepass formed by the orifice 51, passage 60, valve 70, chamber 25, orifice 62 and pipe 61. The difference in pressure on the two sides of the diaphragm 50 resulting from the increased flow through the orifice 51 is sufficient to raise the diaphragm against the spring 11 and open the valve 10 establishing normal flow until the operator throttles the delivery at the nozzle. This reduces the pressure difference across the diaphragm 50 and allows the spring 11 to close the valve 10, flow continuing through the bye-pass until the valve 70 is closed under the action of the current when the slot in the cam 80 comes opposite the end of the arm 90 at a point corresponding to a whole number of units dispensed. During previous passages of the cam 80 through this position the valve 70 was held open by the end of the pipe 61 raised by the diaphragm 50. The opening of valve 70 at the beginning of delivery raised a spring-loaded dash pot 40 from which depends a stem carrying at its end a ball 41. This ball blocks the bore in the stem of valve 70 leading to orifice 73, when the valve closes, thus sealing the leak path for a short time thereafter to ensure complete cut-off. Whiie the dash pot 40 is returning to reopen the leak path the operator can close the nozzle. In the apparatus of Fig. 3, shown in the full delivery position, the leak passage is formed by the orifices 51, 84, 85 and the channel 25, and the bye-pass by orifices 51, 14 and pipes 60, 61. On opening the nozzle the bye-pass valve 70 is opened by the lever 90, the member 50 rises opening the main valve 10, and the dash pot 13 rises, cutting off the leak passage. On the indicator passing through the zero position, the valve 70 is no longer positively kept open, but remains open due to the flow of liquid through it maintained by the pressure difference on the two sides of the valve ensured by forming the outlet pipe 24 as a Venturi. When the nozzle is throttled, the valve 10 is closed as before, the valve 70 is closed by its spring 71 on the indicator reading its zero position, and the flow is completely stopped until the leak passage is ultimately re-opened by the spring of the dash pot 13 restoring it to its lower position. Specification 637,156, [Group XXIX], is referred to. The Specification as open to inspection under Sect. 91, shows, Fig. 3 (Cancelled), similar apparatus, the leak passage being formed by the orifice 52 in a sleeve 17 on the diaphragm 50 surrounding the main valve stem 15 and an orifice in the side of the hollow valve stem 15 which are aligned when the main valve 10 is closed and the diaphragm is in its lowest position. Flow through this path causes the meter to turn the indicator and open the valve 70 in the main valve bye-pass 60, the resulting flow through the orifice 51 causing sufficient pressure difference on the two sides of the diaphragm to raise it against the spring 53, closing the leak passage and opening the main valve. Raising of the diaphragm 50 also raises a dash pot piston 13 against the spring 11, the piston 13 being integral with the valve stem 15. The valve 70 closes during each passage of the indicating device through zero but closure of the main valve is prevented during this short time by the dash pot 13, the valve 10 moving only a short distance towards its closed position. On throttling of the delivery at the nozzle the main valve closes under the influence of springs 11 and 53 but the flow is still sufficient to keep the diaphragm 50 up against the shoulder 18 on the valve stem 15 so that the diaphragm does not descend to reopen the leak path until the flow has been finally cut off by the closure of the pilot valve 70. This subject-matter does not appear in the Specification as accepted.