Pippette

Claim 2

Apparatus for use with a fluid storage container for varying air pressure in the container to fill the container with fluid and to discharge fluid therefrom at a slow, controlled rate, the apparatus comprising: bulb means constructed of a resilient material and having means for connecting the bulb means to the container, said connecting means providing an interior gas storage chamber between said bulb means and said container so that the pressure in the chamber can be varied by compressing the bulb means and releasing the compressed bulb means, the gas storage chamber acting as a collector for excess fluid drawn into said container when the compressed bulb means is released, gas flow regulating means between the chamber and the connecting means for limiting the flow rate of gas between the chamber and the connecting means, and means mounting the gas flow regulating means to the bulb means at a point sufficiently remote from the container so that contact between the fluid and the regulating means is prevented when fluid is drawn into the container upon the release of the compressed bulb means.

Claim 3

Apparatus according to claim 1 including a passage between the chamber and the connecting means, and wherein the regulating means is mounted in the passage and includes a plurality of paths extending from one side of the regulating means to the other side thereof, the paths having diameters in the order of between about 0.0001 to about 0.15 millimeters.

Claim 4

Apparatus according to claim 2 wherein the paths have diameters between about 0.0002 to about 0.02 millimeters.

Claim 5

Apparatus according to claim 1 wherein the regulating means comprises a porous plastic disc mounted to the bulb and permitting an air passage of no more than about 120 milliliters per square centimeter of disc area per minute when there exists a pressure differential between the sides of the disc of no more than about 10 pounds per square inch.

Claim 6

Apparatus according to claim 4 wherein the bulb means includes an interior groove having a width and a depth sufficient to firmly secure the disc to the bulb means so that substantially all air passing between the chamber and the connection means passes through the disc.

Claim 7

A flexible, resilient pressure applying apparatus for use on open ended tubular containers and the like to draw relatively small quantities of liquid into and to discharge such liquid from an open ended tubular container at a slow, controlled rate, the apparatus comprising a tubular member having a closed end for substantial air tight connection with an end of the container, the member including a bulb section defining an inner chamber communicating with one of the open ends, the bulb section being constructed of a resiliently deformable material so that upon compression of the bulb section the air pressure in the chamber is increased and air flows from the chamber to and past said one open end and upon release of the compressed bulb section a vacuum is formed in the chamber and air flows from the exterior of the apparatus past said one open end into the chamber, porous means independent of the member, separating the inner chamber from said one open end, spaced from said one open end, and providing the only passage for air from the inner chamber to said one open end of the container, the porous means having a number of pores and the pores having cross sections so that the normal, unobstructed air flow between said one open end and the inner chamber upon a sudden compression of the bulb section and upon the sudden release of the compressed bulb section is extended over a prolonged period of time substantially greater than the time period required by such normal flow, and means for firmly securing the porous means to the member between the chamber and said one open end to prevent dislocations of the porous means during use whereby the controlled, metered filling and emptying of the inner chamber with air substantially independent of the force applied tO the bulb is possible.

Claim 8

A flexible, resilient pressure applying apparatus for use on open ended tubular containers and the like to draw relatively small quantities of liquid into and to discharge such liquid from an open ended tubular container at a slow, controlled rate, the apparatus comprising a tubular member having a closed end for substantial air tight connection with an end of the container, the member including a bulb section defining an inner chamber communicating with one of the open ends, the bulb section being constructed of a resiliently deformable material so that upon compression of the bulb section the air pressure in the chamber is increased and air flows from the chamber to and past said one open end and upon release of the compressed bulb section a vacuum is formed in the chamber and air flows from the exterior of the apparatus past said one open end into the chamber, porous means independent of the member, separating the inner chamber from said one open end, spaced from said one open end, and providing the only passage for air from the inner chamber to said one open end of the container, the porous means having a number of pores and the pores having cross sections so that the normal, unobstructed air flow between said one open end and the inner chamber upon a sudden compression of the bulb section and upon the sudden release of the compressed bulb section is extended over a prolonged period of time substantially greater than the time period required by such normal flow, and means for firmly securing the porous means to the member between the chamber and said one open end to prevent dislocations of the porous means during use whereby the controlled, metered filling and emptying of the inner chamber with air substantially independent of the force applied tO the bulb is possible.

Claim 9

Apparatus according to claim 6 wherein the member comprises a first part defining the chamber and an elongate, tubular second part engageable with the first part and defining the open end, wherein the securing means are defined by adjacent portions of the parts that define an interior groove, and wherein the porous means is disposed in the groove and positioned transversely with respect to the air flow direction between the chamber and the open end.

Claim 10

Apparatus according to claim 6 wherein the porous means has a disc shaped configuration and a periphery engaging an interior surface of the member, and wherein the securing means comprises an annular ring disposed on each side of the disc for positioning of the disc between the rings.

Claim 11

A pippette for metering small quantities of liquid comprising a tube having open ends, a manually operable bulb constructed of a flexible material and having an interior chamber, means for airtightly securing the bulb to the tube to thereby communicate the chamber and an interior of the tube for subjecting the tube interior to an elevated pressure or to a vacuum upon the compression of the bulb or upon the release of the compressed bulb, respectively, and a porous member secured to the bulb and positioned so that contact between the fluid and the member upon the release of the compressed bulb is prevented to thereby prevent a mutual contamination of the member and the fluid, the member having a number of pores and the pores having cross sections so that the normal, unobstructed air flow between the tube interior and the chamber upon a sudden compression of the bulb and upon the sudden release of the compressed bulb is extended over a prolonged period of time substantially greater than the time period required by such normal flow, whereby the controlled, metered filling and emptying of the pippette substantially independent of the force applied to the bulb is possible.

Claim 12

A pippette for metering small quantities of liquid comprising a tube having open ends, a manually operable bulb constructed of a flexible material and having an interior chamber, means for airtightly securing the bulb to the tube to thereby communicate the chamber and an interior of the tube for subjecting the tube interior to an elevated pressure or to a vacuum upon the compression of the bulb or upon the release of the compressed bulb, respectively, and a porous member secured to the bulb and positioned so that contact between the fluid and the member upon the release of the compressed bulb is prevented to thereby prevent a mutual contamination of the member and the fluid, the member having a number of pores and the pores having cross sections so that the normal, unobstructed air flow between the tube interior and the chamber upon a sudden compression of the bulb and upon the sudden release of the compressed bulb is extended over a prolonged period of time substantially greater than the time period required by such normal flow, whereby the controlled, metered filling and emptying of the pippette substantially independent of the force applied to the bulb is possible.

Claim 13

A pippette according to claim 9 wherein the chamber has a volume of between about 1.1 to about 1.7 times the volume of the tube interior to limit the intake of a fluid volume substantially greater than the volume of the tube and to thus prevent contact between the fluid and the porous member mounted to the bulb.

Claim 14

A pippette according to claim 10 wherein the chamber has a volume of between about 1.3 to about 1.5 times the volume of the tube interior.