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4.2 Fluidic Module
4.2.1 Standard A
Standard A is drawn to the electrode module by vacuum provided by the peristaltic
pump. When Standard A is to be aspirated into the electrode module, solenoid
valve A is opened and solenoid valves B, V and R are closed. Standard A is then
drawn from the ISE SnapPak
TM
, to the fill port, through the sample needle and is
sensed by the sample sensor. At this point, solenoid valve V is opened and sole-
noid valve A is closed as the peristaltic pump continues to pump Standard A into
the electrode module. As the trailing edge of the Standard A sample is sensed by
the sample sensor, the peristaltic pump stops. During the time Standard A is
aspirated into the electrode module, the reference housing is pressurized due to the
peristaltic pump providing pressure to the reference solution line and solenoid valve
R being closed. An amount of reference solution is forced out through the reference
junction to provide contact to the sample.
4.2.2 Standard B/C
The process for Standard B/C is identical to that of Standard A with the exception
of the operation of solenoid valves B and C. These solenoid valves are operated in
reverse order of Standard A aspiration.
4.2.3 Reference Solution
The reference housing is filled automatically using the second winding of the
peristaltic pump and solenoid valve R. The reference solution connector allows for
the reference housing tubing to be plugged into the reference solution circuit. As the
peristaltic pump aspirates reference solution, solenoid valve R is opened to allow
excess solution to be pumped into the reference return line of the
ISE SnapPak
TM
.
4.2.4 Waste Liquids
Calibration standard and sample waste are pumped out of the left side of the
electrode module (green-banded tubing) through the peristaltic pump to the waste
line of the
ISE SnapPak
TM
. An internal one-way valve is incorporated into the
waste line of each
ISE SnapPak
TM
to prevent any waste products from leaking
out of the
ISE SnapPak
TM
.