GB1432741A - Metering apparatus - Google Patents

Abstract

1432741 Dispensing measured volumes of liquid ALFA LAVAL AB 18 Feb 1974 [19 Feb 1973] 7358/74 Heading B8N [Also in Division B1] Metering apparatus comprises a pair of metering chambers 3, 4 in which a piston 2 is reciprocable between two end positions, each of the chambers 3, 4 having a fluid inlet 5, 7 and a fluid outlet 6, 8 controlled by respective shut off valves 13, 14, 15, 16, sensing means 24, 25 for sensing when the piston is adjacent each of its end positions and for initiating adjustment of the valves to return the piston to its opposite end position, and delay means 27, 28 connected to the sensing means for delaying the adjustment of the valves for a predetermined period of time commencing with the sensing of the piston by one of the sensing means. As described the piston carries a magnet 26 which causes a movable member, e.g. 30, in the sensing means to contact a fixed member 29 when the piston approaches and thus to complete an electrical circuit. The circuit includes a delay device, e.g. 27, comprising an electronic tiner 33 and an AND circuit 34, and connects with a valve control unit 21. In operation with valves 13, 16 open and valves 14, 15 closed fluid is delivered by centrifugal pump 11 via conduits 9 and 5 to the chamber 1 and fluid is ejected by the piston from chamber 4 via conduit 8 and outlet 12. When the means 25 senses the piston the electrical circuit is closed, and after a predetermined delay controlled by the device 28 a signal reaches the control unit 21 causing it to close valves 13 and 16. A short time later valves 14, 15 are opened and chamber 4 fills as chamber 3 is emptied. In a second embodiment two pairs of measuring chambers are provided for different liquids and of different lengths. The corresponding sensing means of the measuring chambers are connected in series with a common delay means so that accurately measured volumes of the liquids can be delivered to a common outlet where they mix together.