Reduced sputtering syringe
Syringe for dispensing medical foam having a substantially cylindrical barrel with a nozzle at its forward end and a plunger with a substantially cylindrical shaft disposed within the barrel. A flexible annular flange is provided on the inner surface of the barrel which extends toward the nozzle to contact the shaft and form a seal between the barrel and the plunger.
1. A syringe for dispensing medical foam comprising:
a substantially cylindrical barrel comprising a nozzle at its forward end;
a plunger comprising a substantially cylindrical shaft disposed within the barrel; and
a flexible, annular flange provided on the inner surface of the barrel, the flange including a base affixed to the inner surface of the barrel and an inwardly extending portion extending from the base in an inward direction away from the inner surface to an end opposite the base, the end opposite the base and the inwardly extending portion being free of direct attachment to the inner surface of the barrel and an entirety of the inwardly extending portion being angled toward the nozzle to contact the shaft, wherein at least a portion of the flange is movable toward the shaft in response to pressure of fluid in the barrel to thereby form a seal between the barrel and the plunger.
2. The syringe according to claim 1 wherein the flange is mechanically fixed to the inner surface of the barrel.
3. The syringe according to claim 1 wherein the flange is flexible over its entire surface area.
4. The syringe according to claim 1 wherein the flange is tapered from a thicker base to have reduced thickness at a point at which it contacts the shaft.
5. The syringe according to claim 1 wherein the flange extends generally forwards and generally inwards and contacts the shaft at an angle which is less than 90°.
6. The syringe according to claim 1 wherein the flange has a generally frustoconical shape.
7. The syringe according to claim 1 wherein the flange extends to an annular edge having a circumference that is equal to or less than the outer circumference of the shaft.
8. The syringe according to claim 1 wherein the flange extends to an annular edge having a circumference that is greater than the outer circumference of the shaft such that foam within the barrel deforms the flange to contact the shaft, and such that the flange forms a seal between the barrel and the plunger.
9. A syringe for dispensing medical foam comprising:
a substantially cylindrical barrel comprising a nozzle at its forward end;
a plunger comprising a substantially cylindrical shaft disposed within the barrel; and
a flexible, annular flange provided on the inner surface of the barrel, the flange including a thicker base portion affixed on the inner surface of the barrel, and a thinner inwardly extending portion extending from the base in an inward direction away from the inner surface to an end opposite the base, the end opposite the base and the thinner inwardly extending portion being free of attachment to the barrel and an entirety of the thinner inwardly extending portion being angled toward the nozzle to contact the shaft, wherein at least a portion of the flange is movable toward the shaft in response to pressure of fluid in the barrel to thereby form a seal between the barrel and the plunger;
wherein the flexible annular flange is tapered from the thicker base to have reduced thickness at a point at which it contacts the shaft.