Chapter 3
3-2 BiPAP Vision Service Manual © Respironics, Inc. 1062788
Theory of Operation
Ventilator settings are saved in case of AC power loss. The ventilator software
revision determines how operation resumes following an AC power loss:
• Software versions 11.0 - 11.11, 12.0 - 12.7, and 13.0 - 13.7: If AC
power is lost for approximately 10 seconds or less and the power switch
remains ON, the ventilator performs a system self test and returns to
normal operation using the same settings that were in effect before the AC
power loss.
If the AC power loss is longer than approximately 10 seconds and the
power switch remains ON, the ventilator performs a system self test,
displays the Exhalation Port Test screen, and does not resume ventilation.
• Software versions 11.12, 12.8, 13.8 and higher: If AC power is lost for
any length of time and the power switch remains ON, the ventilator
resumes operation that was in effect at the time of the AC power loss.
• For all software versions, if the power switch is turned OFF after AC power
is lost, when AC power is restored and the power switch is turned ON: the
ventilator performs the system self test, displays the Exhalation Port Test
screen, and does not automatically resume ventilation.
Table 3-1 summarizes the major BiPAP Vision subsystems.
Table 3-1: BiPAP Vision Subsystems
Subsystem Function
Power supply subsystem
(PSS)
Provides the bulk supply DC voltage to the BiPAP Vision subsystems.
Main control (MC) board Performs all control, data acquisition, and calculations required for user-selected
parameters. The MC board also performs the start-up test and reports all errors.
(Abbreviated as MCS board when referring specifically to older boards in non-
upgraded units built s/n 105999 and below.)
Pressure control (PC) board Controls the blower and valves to generate and regulate system pressure. The PC
board senses outlet pressure and patient pressure and regulates outlet pressure
to the patient circuit. (Abbreviated as PAS board when referring specifically to
older boards in non-upgraded units built s/n 105999 and below.)
Display control (DC) board Evaluates user inputs from the touch pad and passes valid parameters to the MC
board. The DC board receives display data from the MC board. The DC board also
has its own internal functions, whose results are reported to the MC board.
(Abbreviated as DCS board when referring specifically to older boards in non-
upgraded units built s/n 105999 and below.)
Airflow module (AFM) Includes the mass airflow sensor in the airstream, and provides an airflow
measurement interface to the PC board, allowing the PC board to measure total
flow, temperature, and system pressure.
In-line flow restrictor (ILFR) Regulates the total flow from the blower discharge.
Pressure regulation valve
(PRV)
Opens during exhalation to allow patient flow exhaust.
Oxygen module (OM) Regulates the oxygen released into the air from the blower according to the set
oxygen concentration level.