Adjustable valve for pipette gun
AssigneeDrummond Scientific Company
InventorJames W. Kenney
Life of this patent
Estimating the term…
Abstract
A valve for use in a pipette gun for selectively providing different ranges of flow rates through a pipette cooperating with the pipette gun. The valve has a predetermined number of discrete settings, each of which provides a range of fluid flow rates between zero and a different maximum flow rate. The operator controls the flow rate by depressing the gun trigger a selected distance. To change the flow rate setting, the operator simply rotates the gun trigger to a desired setting. The present valve also eliminates the "piston effect" of prior art valve elements by isolating the pipette chamber while the valve element operably slides in and out of engagement with a port thereby connecting the pipette with a fluid source either under pressure or at a vacuum.
Claims20
A valve for use in a pipette gun for variably controlling the flow of liquid samples into and out of a pipette, comprising:
- a housing;
- a first conduit located in said housing constructed and arranged to be connected to a fluid pressure source;
- a second conduit located in said housing constructed and arranged to be connected to a pipette and to contain a volume of fluid;
- an elongated valve chamber within said housing having a length, an inner diameter, a longitudinal axis, and a peripheral surface, said chamber having one opening connecting said first conduit with said chamber, and port means extending inwardly from the peripheral surface connecting said second conduit with said chamber;
- an elongated valve element having a length, an outer surface, and an outer dimension constructed and arranged to slide along said longitudinal axis within said chamber with said outer surface in confronting sealing engagement with said port means, said valve element having an axial, longitudinal groove in the outer surface shorter than the length of said valve element and operable to register with said port means;
- an operator connected to said valve element at one end for moving said groove of said valve element into and out of registry with said port means, said groove providing a fluid passage through said sealing engagement of said outer surface with said port means connecting said first and second conduits when said groove is in registry with said port means, and said valve element isolating said second conduit when said groove is out of registry with said port means,
- whereby the port means separates the second conduit from the chamber so that the volume of fluid in said second conduit remains substantially unchanged while said groove is moving into and out of registry with said port means.
A valve for use in a pipette gun for variably controlling the flow of liquid samples into and out of a pipette, comprising:
- an elongated valve chamber within a housing having a longitudinal axis, a peripheral surface, first flow means connectable with the pipette providing fluid flow between the pipette and said chamber, and second flow means connecting a source of pressure fluid with said chamber, one of said flow means comprising a port extending inwardly from said peripheral surface;
- an elongated valve element having a longitudinal action section in said chamber with an outer surface constructed and arranged to slide along said longitudinal axis within said chamber with said outer surface in engagement with said port, in at least one position said outer surface being in confronting sealing engagement with said port, said valve element having an axial, longitudinally-tapered groove in the outer surface and operable to register with said port;
- and
- means for slidably displacing said element longitudinally to move said groove of said valve element into and out of registry with said port, said groove providing a fluid passage through sealing engagement of said outer surface with said port connecting said source and said pipette when said groove is in registry with said port, and closing said passage when said groove is out of registry with said port.
Dependencies are inferred from the claim text.