GB1030516A - Improvements in or relating to automatic dispensing of liquids - Google Patents

Abstract

1,030,516. Sampling liquids. CKD DUKLA NARODNI PODNIK. June 7, 1963 [July 21, 1962], No. 22851/63. Heading B8N. [Also in Division F1] Specimens of liquid and/or reagents are dispensed from pipettes, e.g. to a photometric analyser, by pressure pulses in a pneumatic circuit operated either hydraulically or by a bellows. In Fig. 1, the specimen liquid from overflow tank 39 flows through nozzle 63 into U-tube 64 having an overflow 68 leading to a reservoir 72 which, when full, is emptied by syphon 73 into reservoir 75. Emptying of reservoir 72 sets up a suction pulse in line 44 to cause pipette 38 to fill with the specimen liquid and pipette 45 to fill with a reagent supplied by a constant level tank 47 floating in a constant level tank 54. A suction pulse is also set up in tube 77 to cause emptying of the chamber 82 of a photometer. As tank 75 fills, a pressure pulse set up in tube 81 cuts off the flow of liquid through overflow 68 into tank 72. Finally, tank 75 is emptied by syphon 79 and when the end of tube 80 is uncovered. the rise in pressure in pipe 44 causes the liquid in pipette 45 to flow into a mixing chamber 50 from which the mixture flows into a second mixer 60 and then into the chamber 82 of the photometer. after which the cycle is repeated. Additional pipettes may dispense other reagents into chamber 56 or chamber 60 and a float in tank 75 may operate a cut-off switch in the photometer while the solution in tank 82 is changing and upon interruption in the inflow of the specimen liquid into the apparatus. In Fig. 2, the pressure pulses for operating the specimen liquid tank 138 and the reagent pipettes 142, 143, are set up by a bellows 147 operated by a cam-actuated lever 148. Additional bellows 155 for emptying the photometric tank 82 is operated by a lever 148, the lever operating cam being on a shaft driven by an electric motor. Bellows 147 is operated to first draw the specimen liquid from chamber 134 into tank 138 and simultaneously fill pipettes 142, 143 with reagents. When all the liquid has been drawn into tank 138, the pipe 146 becomes open to atmosphere whereby pipettes 142, 143 empty into pipe 141 and chamber 139 respectively. The reagent in chamber 139 is sucked into chamber 138 simultaneously with the specimen liquid in chamber 134. Bellows 155 is then operated to initiate a syphon to empty photometer tank 82. A cam 154 on shaft 115 renders the photometer measuring circuit operative while the liquid in tank 82 is charging. In a modification, means are provided to flush the photometer tank 82 with specimen liquid in between measuring cycles. The pipette outlets may be enlarged gradually or in steps and the upper portions of the pipette chambers may be constricted.