GB850183A - Improvements relating to metering devices - Google Patents

Abstract

850,183. Delivering measured quantities of liquid. ESSO RESEARCH & ENGINEERING CO. May 1, 1957 [May 24, 1956], No. 13924/57. Class 106(5) [Also in Group XXIX]. A method of automatically operating a metering device using a tank 10 having controlled inlet and outlet means 16, 24 adapted to admit and discharge liquid to and from the tank, a chamber 11 positioned on top of the tank and valve means 13 for controlling liquid flow between the tank and the chamber comprises generating a first signal responsive to discharge of liquid from the tank to simultaneously open the inlet means and the valve means and close the outlet means, generating a second signal operatively responsive to the discharge of liquid from the chamber to maintain the inlet means open, the outlet means closed and the valve means open and to cut off the first signal, then bleeding the first and second signals operatively responsive to the rise of liquid in the chamber to simultaneously close the inlet and valve means and open the outlet means to discharge liquid from the tank. As shown in Fig. 1 the valves 13, 16, 24 are all of the spring-biased diaphragm type operated from the pressure source 34, which may be pneumatic, electric, hydraulic, mechanical or a combination of these systems, the valves 13, 16 being spring- biased to the normally-closed position and valve 24 to the normally-open. In operation, after the tank 10 has been discharged, the float 30 of a valve 31 drops and allows a pressure signal from the source 34 to pass through pipes 36, 39, 391, 44, 45, 46 and double check valve 38, and to thereby open both the valves 13, 16 and close the discharge valve 24 almost simultaneously; speed control valves 48, 49 are provided to ensure that the valve 24 is closed slightly before the opening of the valves 13, 16 and viceversa. The fluid in the chamber 11 then drains into the tank 10 and the float 20 of the valve 21 drops and thereby maintains the valves 13, 16, 24 in the same positions by the pressure signal then passing through pipes 35, 37, 44, 45, 46, the check valve 38 having reversed its position. A spring-biased normally-open diaphragm valve 40 positioned in the pipe 39 is now closed by the pressure signal and bleeds the pressure in the pipe 391; an orifice 42 in a by-pass pipe 41 provides a delay in order to ensure that the pressure signal in the pipe 37 has taken over control of the valves 13, 16, 24 before the pressure in the pipe 391 is exhausted. Fluid enters the tank 10 through the pipe 14 until it rises into the chamber 11 so that the float 20 is lifted and thereby actuates the valve 21 to bleed the pipe 37 and so close valves 13, 16 and open valve 24; the liquid then discharges through pipe 33 and the float 30, due to the flooding of the chamber 26, is lifted and thereby bleeds the fluid-pressure communication with the valves 13, 16, 24. When the fluid is completely discharged the float 30 drops and initiates again the cycle of operation. In a modification of the fully-automatic system, the inlet and outlet valves 16, 24 may be replaced by a 3-way diaphragm-type valve, Fig. 4, not shown. A pressure-operated mechanical counter 47 is provided to register each cycle of operation. In an alternative arrangement, the float 20 may be used to close the valves 13, 16 and open the valve 24, the valves then being opened and closed, respectively by hand.