Air assisted severance of viscous fluid stream
Methods and apparatus for dispensing flowable fluids, particularly those which are high viscosity by passing a stream of fluid through an elongate discharge passageway and injecting air into the fluid stream to initiate severing of the stream between an inner portion inward of the injected air and an outer portion outward of the injected air.
1. A method of dispensing a fluid comprising:
passing fluid longitudinally outwardly through an elongate discharge passageway as a continuous fluid stream completely filling the passageway to a discharge outlet of the passageway to thereby dispense the continuous stream completely filling the passageway from the discharge outlet, and
after discharge of the continuous stream completely filling the passageway from the discharge outlet, injecting into the passageway completely filled by the continuous stream an allotment of air proximate the discharge outlet of a volume sufficient to substantially sever an inner stream portion of the fluid stream inward of the injected allotment of air from an outer stream portion of the fluid stream outward of the injected allotment of air.
2. A method as claimed in claim 1 wherein after injecting the allotment of air into the passageway sufficient to substantially sever the inner stream portion from an outer stream portion, drawing the inner stream portion of the fluid stream longitudinally inwardly within the passageway.
3. A method as claimed in claim 2 wherein in the step of injecting the allotment of air into the passageway sufficient to substantially sever the inner stream portion from the outer stream portion displacing with the injected allotment of air the outer stream portion outwardly in the passageway relative the inner stream portion.
4. A method as claimed in claim 3 wherein
fluid moving through the discharge passageway towards the discharge outlet moves downwardly, and
wherein after injecting the allotment of air into the passageway sufficient to substantially sever the inner stream portion from an outer stream portion, drawing the inner stream portion of the fluid stream longitudinally inwardly and upwardly within the passageway to assist in severing the inner stream portion from the outer stream portion.
5. A method as claimed in claim 1 wherein
fluid moving through the discharge passageway towards the discharge outlet moves downwardly, and
wherein after injecting the allotment of air into the passageway sufficient to substantially sever the inner stream portion from an outer stream portion, drawing the inner stream portion of the fluid stream longitudinally inwardly and upwardly within the passageway to assist in severing the inner stream portion from the outer stream portion.
6. A method as claimed in claim 1 wherein the injection of the allotment of air into the passageway is via an air port opening selected from the group of an air port opening disposed annularly about the passageway and an air port opening which opens radially inwardly into the passageway.
7. A method as claimed in claim 6 wherein after injecting the allotment of air into the passageway to substantially sever the inner stream portion from an outer stream portion, drawing back air via the air port from the passageway.
8. A method as claimed in claim 1 wherein a pump assembly is operated to pass the fluid longitudinally outwardly through the elongate discharge passageway as the fluid stream.
9. A method as claimed in claim 1 wherein the injection of the allotment of air forms an air bubble in the passageway, which air bubble extends across a substantial portion of the cross-section of the passageway.
10. A method as claimed in claim 9 wherein the air bubble extends from within the passageway to at least partially outwardly of the discharge outlet.
11. A method as claimed in claim 10 wherein while the air bubble extends at least partially outwardly of the discharge outlet drawing the inner stream portion of the fluid stream longitudinally inwardly within the passageway to assist in breaking of the bubble.
12. A method as claimed in claim 1 wherein the fluid has a viscosity in excess of 400 centipoises.
13. A method as claimed in claim 8 wherein after injecting the allotment of air into the passageway to substantially sever the inner stream portion from the outer stream portion, operating the pump assembly to draw back the inner stream portion of the fluid stream longitudinally inwardly within the passageway.
14. A method as claimed in claim 10 wherein while the air bubble extends at least partially outwardly of the discharge outlet performing at least one procedure selected from the group of procedures of:
drawing air back from the air bubble via the passageway, and
drawing the inner stream portion of the fluid stream longitudinally inwardly within the passageway to assist in breaking of the bubble.
15. A method of dispensing a fluid comprising:
operating a pump assembly to pass fluid longitudinally outwardly through an elongate discharge passageway as a fluid stream to thereby dispense the stream at a discharge outlet of the passageway, and
injecting an allotment of air into the passageway proximate the discharge outlet of a volume sufficient to substantially sever an inner stream portion of the fluid stream inward of the injected allotment of air from an outer stream portion of the fluid stream outward of the injected allotment of air, and
after injecting the allotment of air into the passageway to substantially sever the inner stream portion from the outer stream portion, operating the pump assembly to draw back the inner stream portion of the fluid stream longitudinally inwardly within the passageway.
16. A method as claimed in claim 15 wherein the pump assembly is a piston pump having a piston-forming element reciprocally movable relative a piston chamber-forming body of the assembly to pass fluid longitudinally through the passageway.
17. A method as claimed in claim 15 wherein the injection of the allotment of air forms an air bubble in the passageway, which air bubble extends across a substantial portion of the cross-section of the passageway.
18. A method as claimed in claim 17 wherein the air bubble extends from within the passageway to at least partially outwardly of the discharge outlet; and
wherein while the air bubble extends at least partially outwardly of the discharge outlet performing at least one procedure selected from the group of procedures of:
drawing air back from the air bubble via the passageway, and
drawing the inner stream portion of the fluid stream longitudinally inwardly within the passageway to assist in breaking of the bubble.
19. A method of dispensing a fluid comprising:
passing fluid longitudinally outwardly through an elongate discharge passageway as a fluid stream to thereby dispense the stream at a discharge outlet of the passageway, and
injecting an allotment of air into the passageway proximate the discharge outlet of a volume sufficient to substantially sever an inner stream portion of the fluid stream inward of the injected allotment of air from an outer stream portion of the fluid stream outward of the injected allotment of air,
wherein the injection of the allotment of air forms an air bubble in the passageway, the air bubble extends across a substantial portion of the cross-section of the passageway,
the air bubble extends from within the passageway to at least partially outwardly of the discharge outlet, and
wherein while the air bubble extends at least partially outwardly of the discharge outlet drawing air back from the air bubble via the passageway.
20. A method as claimed in claim 19 wherein prior to injecting an allotment of air into the passageway, the fluid stream is passed longitudinally outwardly through the elongate discharge passageway as a continuous fluid stream completely filling the passageway at the discharge outlet.