6. Temperature Control
set temperature by more than 0.05°C, then the control
temperature threshold sent to the UF–Proportioning
controller is updated, changing the temperature control so
that the “B” conductivity probe temperature will equal the
user-set temperature. Using this correction routine, the
dialysate temperature at the “B” conductivity probe is
adjusted so that flow rate, ambient temperature, concentrate
type, and temperature effects on the “B” conductivity probe
temperature (and the primary temperature, displayed on the
video screen) will be compensated. This control
temperature adjustment is performed a maximum of every
5 minutes.
6. The UF-Proportioning Controller board, using the
information (step 2) from the SBC and the heater control
temperature probe, controls the heater duty cycle through
the UF Power board to increase or decrease the temperature
as required by enabling a solid state relay which provides
the power to the heater with a 5 Hz pulse-width modulated
digital signal (heater enable signal).
7. The UF-Proportioning Controller generates a backup high
temperature alarm when the “B” probe temperature is
higher than the host-initialized high temperature alarm
limit (maximum limit of 41ºC ), and no primary dialysate
temperature alarm exists.
8. The UF-Proportioning Controller directly deactivates the
bypass valve (removing flow to the dialyzer) during a
backup temperature alarm.
9. The SBC reads the the measured temperature (from the I/O
Controller), the set temperature, and alarm indication from
the UF-Proportioning Controller, and displays them on the
LCD. BACKUP is displayed above the temperature
window if the“B” probe back up high temperature alarm is
triggered.
10. There is a resettable safety thermostat in the heater
assembly that will remove power to the heater at 107ºC
(225 ºF).
157-1278-913 Rev A 6-5
November 2003
To Next Page
Loading...
