GB280495A - Improvements in and relating to hypodermic and like syringes - Google Patents

Abstract

280,495. Wolf, W. Nov. 15, 1926, [Convention date]. Syringes. - Hypodermic and like syringes are provided with a hollow plunger 11 having air passages 11b, 11c at its ends for the escape of air trapped beneath the plunger. The injection is made with the passage llb closed by the finger, the passage being uncovered just before the completion thereof and closed again to eject the remainder of the fluid. The plunger 11 may be provided with several passages such as 11c or may be formed with axial bosses on one or both ends containing the passages 11b, 11c, the barrel 10 of the syringe being recessed to accommodate the lower boss. The hypodermic needle 12 is secured upon a boss 10a. The construction permits the carrying of the syringe is closed position but loaded with injection fluid. For this purpose caps may be provided to close the free ends of the barrel 10 and the plunger 11 respectively. The upper cap may engage the top flange 11d of the plunger, may fit over the boss thereon if provided or may engage the top flange lOb of the barrel thereby holding the plunger in closed position. In the loaded syringe the injection fluid is contained within the piston. When required for use the upper cap is removed and the plunger 11 drawn out to transfer the fluid to the barrel 10; the lower cap is then replaced by the hypodermic needle and the plunger pressed in with the passage 11b closed. Instead of an upper cap a conical lift valve may be provided : this valve is secured within a casing integral with or attached to the plunger and is opened if required during the injection by a pin or the like. Alternatively a valve comprising a pair of relatively rotatable discs secured to the plunger and having eccentric passages therein registering with an eccentric passage in the plunger may be employed. To expel the last traces of fluid from the plunger 11 a rubber ball may be applied to its upper end or a small plunger sliding in a cylinder formed integral with or attached to the plunger 11 may be provided. These appliances act also as closing means for the plunger 11.