7. Dialysate Preparation
• An acid (or acetate) conductivity probe (referred to as the “A”
conductivity probe) which is used to monitor that the acid and
water were mixed correctly. This probe is located in the
supply manifold.
• A bicarbonate conductivity probe (referred to as the “B”
conductivity probe) which is used to monitor that the addition
of bicarbonate concentrate increased the conductivity of the
dialysate by an appropriate amount. This probe is located in
the “B” mix chamber.
The “A” and “B” conductivity probes are used for A & B alarms,
and for proportioning verification. Each of these probes utilizes an
AC signal and local temperature compensation to provide the
required accuracy and confidence.
The acid and bicarbonate conductivity probe signals are amplified,
rectified and buffered on the UF-Proportioning Power board. The
resulting signal is sent to the A/D converter on the UF-
Proportioning Controller board. The microprocessor on the UF-
Proportioning Controller board applies conductivity and
temperature calibration factors to the conductivity and compares
the value to the alarm limits. If the value is outside the alarm limit,
an alarm is passed to the host software on the SBC. The SBC
software generates the system actions (bypass, audio alarm, alarm
lamp etc) if an alarm is generated. The value is also passed to the
host software for display in the conductivity data report. Refer to
Figure 7-8.
157-1278-914 Rev A 7-15
January 2004
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