GB1469174A - Sample injection system - Google Patents

Abstract

1469174 Syringes VARIAN ASSOCIATES 4 March 1974 [5 March 1973] 9569/74 Heading F1R A syringe is purged by a method comprising (a) providing a syringe comprising a tubular barrel 90 defining an internal passageway 93 having an axial end opening and a side opening 466 and a plunger 92 supported in said chamber for axial movement relative to the barrel, the imaginary solid intersection of the internal passageway and an extension of the perimeter of the side opening defining a space within the internal passageway; (b) positioning the plunger in the barrel with a plunger end portion disposed adjacent to the side opening 466 such that the plunger end portion intersects the space defined by the imaginary solid intersection, and (c) directing purging fluid into the passageway through one of the openings to impinge on the projecting plunger end portion to scrub material from the plunger and discharging the fluid from the passageway through the other of the openings to purge the passageway. The syringe shown is mounted on carriage assembly 32 slidable on parallel ways 50 for reciprocation by means of single acting pneumatic ram type actuator 34 and a return spring to and from analysis apparatus 12a into which sample liquid is to be injected, the plunger 92 having actuating mechanism comprising radially projecting plunger end portion 92a, plunger drive mechanism 130 operated by a double actuating pneumatic ram assembly 132 and adjustable dosage stops (134), 136 each of which has a solenoid operated pin 168 which in its extended position engages cross bar 140 to prevent forward movement of the plunger. With the drive mechanism as shown in Fig. 3, plunger 92 is in its fully retracted position, the inner tip of the plunger is as shown in Fig. 5 and purge fluid can be directed through side-arm 96 and out through needle 94. After purging, one of the dosage stops (134), 136 is energized and actuator assembly 132 advances the plunger until cross bar 140 abuts the projecting pin 168 of the dosage stop, so leaving a predetermined quantity of liquid in the syringe for injection into the analysis apparatus. Purge liquid, which as described may be solvent or the next sample, is passed by means of syringe needle 94 into a septum-covered waste receiver 200 which is itself mounted on a pivotable support arm 210 and is retracted from its purge liquid receiving position under solenoid control to allow needle 94 to advance to analysis apparatus 12a. Purge liquid passes from receiver 200 through flexible conduit 204 to tank 202.