Fresenius Medical Care 5008, Service Manual

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Chapter 11: Functional Description
11-18 Fresenius Medical Care 5008 SM 1/08.04
Reduction of the weight is solely determined by the UF pump (P04). The
UF pump removes a predefined volume (UF goal) from the closed
system which it pumps to the drain 2, bypassing the balancing
chambers. This volume is removed from the patient's blood as
ultrafiltrate and is replaced by an equal volume flowing through the
dialyzer membrane.
Dialysate circuit Via the valves (V11, V13) fresh dialysate is fed in cycles by the
balancing chambers via the filter (F04) and the dialyzer valve (V24) to
the dialyzer.
The flow pump (P03) ensures that the dialysate discharged by the
dialyzer is fed to the balancing chambers via the secondary air
separator (H18).
If the level sensor (S09) detects air, the air separation valve (V29s)
starts its activity. The air is discharged by the negative pressure in the
degassing path and can therefore not enter the balancing chambers.
After the balancing process the dialysate is passed via the outlet valve
(V30), the heat exchanger (H04) and the drain valve (V19) to the drain
2.
Correct mixing and the temperature of the fresh dialysate are monitored
by the conductivity cells (CD3, CD4, CD7) and the temperature sensor
(PT7). If the values are outside the predefined limits, the system will
alert the operator and will switch to the bypass mode. The dialyzer valve
(V24) closes, the bypass valve (V26) opens, which prevents the
improper dialysate from being fed to the dialyzer.
The pressure transducer (S07) and the blood leak detector (S08) are
further safety elements.