4. Hydraulic Theory
While in Rinse Mode, the Instrument will automatically go into
Bypass Mode periodically.
There is also a manual Bypass Mode that permits the operator to
put the Instrument in bypass when a dialyzer is connected or
sequential ultrafiltration therapy is performed. This manual
Bypass Mode is activated via the Bypass switch located on the
Membrane Switch Panel.
4.2.14.2 Bypass Valve Flow Sensor
A temperature-dependent flow sensor connected (see Figure 4-11)
to the dialysate monitoring manifold after the bypass valve is used
to monitor dialysate flow. When the Instrument is in bypass, the
bypass valve diverts the dialysate flow away from the dialyzer;
therefore this sensor verifies the correct functioning of the bypass
valve by detecting that no flow is going through the sensor. The
Instrument generates a shutdown alarm in the event of a bypass
valve failure.
The signal from the Flow Sensor is also used to indicate dialysate
flow or bypass on the touchscreen display. Refer to Section 4.2.12
for more information on the sensor assembly.
4.2.15 Rinse Block
When the Instrument is not being used for a patient treatment and a
dialyzer is not in use, the dialysate lines are attached to a rinse
block. The rinse block has proximity sensors that are used to
determine the placement of the dialyzer connectors and are used as
interlocks for mode changes.
4.2.16 Dialysate Sample Ports
The sample ports (pre- and postdialyzer) are provided as an
opening for the operator to obtain a sample of the dialysate to test
for conductivity or residual disinfectant.
4.3 ULTRAFILTRATION SYSTEM
The ultrafiltration (UF) system allows the operator to remove a
precise amount of fluid from a patient in a controlled manner. By
controlling exactly how much dialysate is going to and returning
from the dialyzer, accurate fluid removal is achieved.
The main components of the UF system are (as they appear in the
flow path):
Supply Pump
150µ Particle Filter
157-1278-893 4-17
January 2004
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