Measuring and testing – Measuring vessel
Patent
1977-03-15
1978-10-17
Swisher, S. Clement
Measuring and testing
Measuring vessel
222309, G01N 114
Patent
active
041202023
ABSTRACT:
A variable volume, positive displacement pump apparatus for withdrawing samples of liquid from a reservoir and discharging them into a sample analyzer. In the preferred form of pump, two syringe assemblies are provided, each one having a movable plunger assembly and a valve unit associated therewith. The plunger assemblies are reciprocated by engagement thereof by a motor driven, reciprocable carriage assembly which includes a cross member for pushing selected metering rods upwardly against the plungers. The carriage also includes a pair of yokes to engage the plungers and pull them downwardly to aspirate the specimens. Valve movement is achieved by a gear drive which moves the valve between one position which enables the syringe to be filled and another position enabling the syringe contents to be discharged. The volume displaced with each stroke is determined by the length of the metering rod inserted between the carriage and the syringe plunger. Selection of a desired length of metering rod is achieved by rotating a turntable containing plural rods so as to index a given rod of selected length into a position of engagement between the carriage and the plunger. This enables rapid and highly accurate digital selection of pump volume to be made and provides the pump with outstanding accuracy. Appropriate lost motion is provided in the mechanism so that, although the carriage operates continuously, the syringes are not moved during the time the valves are being positioned and vice versa.
REFERENCES:
patent: 3495742 (1970-02-01), Hdamik
patent: 3572130 (1971-03-01), Goldsmith
Range Richard J.
Soodak Charles I.
Baxter Travenol Laboratories Inc.
Collins Henry W.
Fitzgibbon James T.
Kinney Richard G.
Swisher S. Clement
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