User manual

VITEK
®
2 Instrument Instrument Hardware Components
VITEK
®
2 Instrument User Manual 4-13
510731-10EN1
Note: The displacement pump is not normally visible as it is located directly behind
the interface screen and keypad.
Displacement Pump Operation
The displacement pump is part of a larger assembly that performs the
pipetting and transfer of the suspension when VITEK
®
2 is in the Automatic
dilution mode. Here is how it works:
1) The container drops a pipette tip into position.
2) The displacement pump assembly extends a hollow metal tube into the
container, attaches a pipette tip to the tube, and withdraws the pipette tip
from the container. The instrument checks to ensure that a pipette tip is
attached.
3) The pump assembly rotates so the pipette tip is over the ID suspension
test tube. The pipette tip is then lowered into the suspension. The
instrument checks to make sure there is fluid in the ID test tube.
4) The pump draws the preprogrammed amount of suspension and
withdraws the pipette tip from the test tube.
5) The cassette moves so that the susceptibility test tube is now under the
pipette tip.
6) The pipette tip is lowered into the test tube and the pump dispenses the
suspension into the tube where it mixes with the saline from the
Dispenser.
7) The pipette tip is removed from its attachment and left in the sample tube
for disposal.
Filler Station
At the Filler Station, all of the test cards in a cassette are inoculated with the
suspension contained in their corresponding test tubes.
The Filler Station uses a vacuum chamber and pump. When the boat carrying
a cassette reaches this station, the top of the vacuum chamber lowers onto
the boat, so the boat serves as the base of the vacuum chamber.
1) The pump evacuates the air from the chamber. This forces the air inside
each test card to escape via the transfer tube and bubble up through the
suspension. The channels and wells inside of each test card are now at a
vacuum.
2) After a short period, the vacuum is slowly released. The increasing air
pressure inside the chamber forces the suspension in each test tube
through the transfer tube and into the channels and wells of the test card.