Fluid handling apparatus having a fluid metering volume therein

Claim 1

A fluid handling apparatus comprising: a stator having a planar surface, a first and a second fluid conduction passage, a fluid transfer passage and a fluid metering volume therein, one end of each of the conduction passages and of the transfer passage opening at the planar surface, the other end of the transfer passage communicating with the metering volume, the stator having a slotted arm thereon; a piston disposed in a close fitting sliding relationship within the fluid metering volume; a seal member having a slot formed therein, the seal being rotatably disposed with respect to the planar surface of the stator, the slot being sized to permit communication between the transfer passage and one of the conduction passages; means connected to the seal for rotating the seal member from a first position in which the transfer passage communicates through the slot with the first of the conduction passages to a second position in which the transfer passage communicates through the slot with the second of the conduction passages, the seal rotating means having a positioning pin therein; and an actuator connected to the piston for moving the piston in a first, suction, direction when the seal is in the first position to draw fluid through the first conduction passage, the slot and the transfer passage into the metering volume and for moving the piston in a second, pumping, direction when the seal is in the second position to urge fluid from the metering volume, through the transfer passage, the slot into the second conduction passage, the rotating means being movable in a first direction wherein the positioning pin is engaged within the slotted arm to secure the rotating means to the stator and movable in a second direction wherein the positioning pin is disengaged from the slotted arm to permit removal of the rotating means from the stator.