8. Ultrafiltration
more information on the speed control of the supply pump, refer to
Section 7, Dialysate Preparation.
8.3.2 Particle Filter ("Post" Supply Pump)
This filter traps particulate matter larger than 150 microns
upstream of the supply pressure regulator. Particulate matter in the
flow equalizer and UF flow meter can cause ultrafiltration errors.
The service life of the particle filters depends on the rate at which
material collects on the filter screens, increasing the filter pressure
drop. Ultimately, the performance of the Instrument may be
affected.
If filter clogging is due to precipitation of dialysate in the fluid
path, the filters must be replaced as part of the fluid path cleaning
process.
Refer to Section 16, Preventive Maintenance, for a recommended
routine maintenance schedule.
8.3.3 Supply Pressure Regulator
The supply pressure regulator controls the peak input pressure to
the "pre" side of the input pressure equalizer. When the flow
equalizer cavity is filled, the pressure in the pressure regulator
increases to its maximum set value (16 psi±1), overcoming the
spring force of the regulator spring allowing the dialysate to
recirculate back to the “B” mix chamber. The Supply Pressure
Regulator is equivalent to an adjustable pressure relief valve.
8.3.4 Input Pressure Equalizer
The Input Pressure Equalizer is located between the outlet of the
supply regulator and the inlet of the Flow Equalizer.
The Input Pressure Equalizer matches the input pressures between
the "pre" and "post" compartments of the flow equalizer.
Matching the pressure across the flow equalizer ensures that the
compartments fill at an even rate.
157-1278-915 Rev A 8-9
January 2004
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