8. Ultrafiltration
Mode. This value remains during the Rinse Mode and is cleared
upon the entry of the Self Test Mode.
In Rinse Mode, the UF removal rate is 3.6 L/h and the screen
indicates no UF volume accumulated. During the Self Test Mode,
no UF removal occurs except for during specific self tests
performed by the Instrument (no UF volume is accumulated). In
the Prime Mode, the UF removal rate is set by the operator and is
no greater than the service technician-set maximum UF rate (no
UF volume is accumulated). During the Dialyze Mode and while
the blood pump is running, the UF removal rate is set by the
operator and is limited to the range between the lower (0.00 to 1.00
L/h) and upper (1.00 to 4.00 L/h) limits set by the service
technician.
For UF removal to occur in the Dialyze Mode the following
conditions must be met:
A target UF volume and a UF rate have been entered (or
treatment time and target UF volume have been entered and
a UF rate calculated by the Instrument is used).
The blood pump is pumping.
The target UF volume has not been reached (or a manual
UF rate is set, or the minimum UF is greater than the
calculated UF).
The UF–Proportioning Power board is used to drive the UF
removal valves.
8.3 DESCRIPTION
The primary hydraulic components of the UF system are the Flow
Equalizer and the UF flow meter.
The Flow Equalizer controls the ultrafiltration to zero by balancing
the flow to and from the dialyzer, making sure that fresh and spent
dialysate are introduced and removed in equal volumes from the
dialyzer.
Ultrafiltration is controlled by the UF flow meter, using a
diaphragm chamber to displace the ultrafiltrate volume. The only
place the ultrafiltrate can come from is across the dialyzer
membrane.
Refer to Figures 8-3, 8-4 and 8-5 for the location of the
components in the Instrument and a simplified hydraulics diagram.
157-1278-915 Rev A 8-5
January 2004
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