Gambro AK 95 S, Service Manual

Page: 33 / 247

Technical Description
AK 95 / AK 95 S Service Manual
HCEN 9134 Rev. 10.2005
2:12
For example, if there is a blockage somewhere in
the tubes, the HPG generates an alarm and the
AK 95 S enters the bypass mode.
T
reg
after the heater is used together with the
temperature transducer on conductivity cell B,
to control the heater.
The bypass unit includes two valves:
The direct valve,
DIVA , is normally open during
treatment (if the temperature, pressure, conduc-
tivity etc. are within the predefined limits).
The direct valve is closed and the bypass valve,
BYVA , is opened when the dialysis fluid is
bypassed from the dialyzer. The dialysis fluid is
led past the dialyzer directly to the drain.
The dialysis fluid is forwarded to the dialyzer
via the output tube.
From the dialyzer the dialysis fluid (mixed with
waste products) is returned to the fluid unit via
the input tube. The input tube nipple is fitted
with a filter.
The Dialysis fluid pressure transducer, PD,
after the dialyzer measures the dialysis fluid
pressure. This pressure transducer is the most
important pressure transducer in the system.
PD is used for calculation of the transmembrane
pressure,
TMP .
TMP is calculated by the system and presented
on the operators panel. If the TMP is not within
the predefined limits, an alarm is issued.
The dialysis fluid is fed to a deairating cham-
ber , which is used to separate air from the fluid.
For example, a leakage may occur in the dialyzer
connection. It is important that the air bubbles
are separated from the dialysis fluid, otherwise
the UF measuring could be affected. When the
fluid level in the deairating chamber reaches the
minimum level, i.e. when there is too much air
in the deairating chamber, the evacuation valve,
EVVA , is opened and the air is released. When
the fluid level reaches over the minimum level,
the evacuation valve is closed and so on. The
“degassed” fluid is taken out in the bottom of the
deairating chamber.
The taration valve,
TAVA , is normally open
during treatment. During calibration of the UF
measuring unit, the taration valve is closed.
TAVA is also closed when the protective system
demands a minimum of UF.
The dialysis fluid is led through channel 2 of the
UF measuring cell to the
blood leak detector .
The blood leak detector detects any blood in the
fluid. In the event of leak between the blood side
and dialysis fluid side of the dialyzer, an alarm
will be activated and the machine enters the
bypass mode.
Most of the dialysis fluid (90 to 95%) is taken out
at the top of the blood leak detector. The rest is
let out via a
drain restrictor . The reason for
this is that the blood leak detector has to be
completely emptied during drain phase.
Finally, the dialysis fluid is led to the drain, via
the
suction pump , the outlet restrictor and
the drain-tube .