Automatic fluid injector

In apparatus for repetitively accurately measuring and injecting preselected quantities of fluid specimens into a media such as an inlet to an analytical instrument, the combination comprising

• a housing, which can be mounted adjacent an inlet leading into the analytical instrument,
• a tubular member mounted within the housing, said tubular member including a pair of communicated openings therethrough, a first axial opening of the pair extending through the tubular member and housing, and a second opening adjacent to and communicated with said first axial opening which can be aligned upon the inlet leading into the analytical instrument,
• a needle syringe mounted upon the piston of a piston reciprocating unit, the needle of which is aligned upon said second opening through the tubular member within and through which the needle can be reciprocated by movement of the piston, said syringe including a barrel within which is mounted a plunger, said plunger constituting an integral portion of the piston reciprocating unit by virtue of which said plunger can be reciprocated within the chamber of said barrel,
• an injector feed assembly including a hollow probe provided with communicating upper and lower openings mounted on the piston of a piston reciprocating unit, said probe being aligned upon the said first axial opening through the tubular member within and through which the probe can be reciprocated by movement of the piston, and extended through the said first axial opening,
• means for transporting a fluid specimen contained in a vial, with a resilient, puncturable closure, below the said first axial opening and into the path of the hollow probe for penetration of said closure by the probe,
• means for pressurizing the fluid contents of the vial so that the fluid specimen contained within the vial can be transferred via the lower and upper side openings of the probe into the opening of the needle and into the barrel of the syringe,
• the improvement comprising
• a valved side inlet located within the barrel of the syringe forward of the point reached by the forward face of the plunger on movement to its maximum forward position within the syringe barrel, the valved side inlet providing, when the valve is in open position, a channel for flow of fluid from the dispensing end of the needle through the forward portion of the barrel, and rearward movement of the plunger to fill the barrel with a fluid specimen in predetermined quantity, and on subsequent forward thrust of the needle of the syringe into the inlet of the analytical instrument, with the valve in closed position the fluid specimen can be readily injected through the dispensing end of the needle by forward movement of the plunger.