Patent ID: 6605059
Filing Date: 2003-08-12
Classification: F42B

Abstract:
A dart for administering an injection fluid to an animal comprising:(a) a tubular member having a front end closed by a penetrable closure; (b) a syringe located within and movable longitudinally along the tubular member, the syringe having: (i) a barrel to receive injection fluid; (ii) a hollow needle extending from one end of the barrel towards the penetrable closure of the front end; (iii) a closure at the other end of the barrel; (iv) a plunger located in the barrel which is in sealing engagement with and movable along the barrel towards or away from the needle; and (v) an aperture or passageway in or extending from the barrel rearward of the plunger in its loaded position communicating between the tubular member and an area in the barrel rearward of the plunger; and (c) sealing means comprising one or more O-rings mounted on the syringe rearward of the aperture or passageway and sealingly engaging the tubular member to seal the syringe within the tubular member, wherein upon impact of the dart, the syringe is caused to move in a forward direction in the tubular member, the pressure in the tubular member between the penetrable closure and the sealing means increases until the needle penetrates through the closure; at the same time the pressure behind the plunger is increasing due to the passage of air through the aperture or passageway so that when the needle penetrates the closure the pressure differential between the area behind the plunger and the area in front of the hollow needle causes the injection fluid to be expelled.