HCEN12630 Revision 07.2015
Program version 1.xx
AK 98™ Dialysis Machine - Technical description 89
Degassing chamber
The chamber has four connectors, inlet, outlet, air outlet and rinse valve (RIVA). A
floater is placed inside the chamber. The top of the float consist of a needle which
seals against a very small o-ring inside the air outlet connector. The gas escapes the
top of chamber since there is suction here from the Suction pump. As a result, the
floater jumps up again and seals the outlet, until more gas forces the fluid level down.
UF measuring cell
The UF cell – is based on the electromagnetic flow measurement principle (Faraday’s
Law of Induction):
The voltage V, is proportional to the velocity of the fluid, the area of the measuring
channel and the magnetic field. From this follows that if the field is kept constant the
voltage will be proportional to the flow only.
For this to happen the field, the tube, and the electrodes shall be aligned 90° to one
another and the fluid shall contain free ions. In practice, independence of conductivity
is achieved when conductivity is higher than 0.1–0.2 mS/cm.
Another practical consideration is that the magnetic field must alternate. Otherwise the
presences of free ions would lead to electrochemical deposits on the measuring
electrodes.
UF protective flow meters
The UF protective system is based on two flow meters. The UF protective system rely
on the same electromagnetic measurement principle as the UF cell.
Ultrafilter (option)
An ultrafilter (U 9000) is inserted in the fluid path in the front of the dialyzer and acts as
a bacteria and endotoxin filter.
Deaerating chamber
Plastic chamber containing a magnetic floater which slides on a pin with two reed
relays inside. The floater can have tree positions: high, low and middle (not high and
not low).
Blood leak detector
The transducer is a LED.
The receiver is a photo transistor.
Pressure transducers
The pressure transducers are so called Gauge transducers which means that the
pressure transducer uses the atmospheric pressure as reference. The transducers are
connected to the main electronic via data buses.
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