Injection syringe with liquid held between two pistons has stops inside barrel to hold forward piston in initial position

摘要

A syringe (10), comprising a tubular barrel (11) with a plunger (20) and two pistons (24, 26) forming a chamber (29) holding the substance (28) to be injected, has stops (30) in the form of ridges inside the barrel to hold the forward piston (26) in its initial position prior to use. A syringe (10), comprising a tubular barrel (11) with a plunger (20) and two pistons (24, 26) forming a chamber (29) holding the substance (28) to be injected, has stops (30) in the form of ridges inside the barrel to hold the forward piston (26) in its initial position prior to use. When the injection is given the forward piston is moved towards the end wall (12) of the barrel by the pressure of the plunger and liquid and is pierced by a pointed projection (16B) on the inner end of the needle (16), allowing the liquid to pass through the needle.