Respironics BiPAP User manual

BiPAP Focus Ventilator
SERVICE MANUAL

II BiPAP Focus Ventilator Service Manual © Respironics, Inc. REF 1029568 Rev B
Copyright © 2006-2009. Respironics, Inc.
ALL RIGHTS RESERVED.
This work is protected under Title 17 of the United States copyright code and is the sole property of Respironics.
No part of this document may be copied or otherwise reproduced, or stored in any electronic information
retrieval system, except as specifically permitted under United States copyright law, without the prior written
consent of Respironics.
In the U.S. and Canada
Respironics California, Inc.
2271 Cosmos Court
Carlsbad, CA 92011
USA
1-800-345-6443
Authorized European Representative
Respironics Deutschland GmbH
Gewerbestrasse 17
D-82211 Herrsching
Germany
[phone]
For Technical support, contact:
Respironics, Inc. Customer Service
Within the U.S.A. 1-800-345-6443
Outside the U.S.A. 724-387-4000
Facsimile 724-387-5012
[email protected]

REF 1029568 Rev B BiPAP Focus Ventilator Service Manual © Respironics, Inc. III
Table of Contents
1 Introduction and Intended Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.1 Tools and Test Equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
1.2 Where to Go for Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
2 Warnings and Cautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2.1 Warnings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
2.2 Cautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
2.3 Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
3 Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3.1 Pneumatic System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
3.1.1 Air Inlet Filters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
3.1.2 Muffler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
3.1.3 Blower. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
3.1.4 Flow Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
3.1.5 Air Flow Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
3.1.6 Diffuser. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
3.2 Electronic System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
3.2.1 User Interface PCB. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5
3.2.2 Controller PCB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
3.2.3 VGA Interface PCB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
3.2.4 VGA Display. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
3.2.5 External AC/DC Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
3.2.6 Internal Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7
3.3 Back Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8
4 Periodic Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.1 Preliminary Cleaning and Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.2 Cleaning the Reusable Air Inlet Filter. . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
4.3 Replacing Air Inlet Filter(s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
4.4 Battery Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
4.4.1 Battery Operating Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
4.4.2 Battery Charging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4
4.4.3 Battery Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
4.4.4 Fully Depleted Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
4.5 Storing the Ventilator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9

IV BiPAP Focus Ventilator Service Manual © Respironics, Inc. REF 1029568 Rev B
Table of Contents
5 Diagnostic Mode and Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
5.1 Entering Diagnostic Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
5.2 Product Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
5.2.1 Date of Manufacture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
5.3 System Settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
5.4 Preferences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
5.5 Significant Event Log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6
5.6 Sensor Readings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7
5.7 Setting Up the Serial Interface for DRPT . . . . . . . . . . . . . . . . . . . . . . . . . 5-9
5.8 Generating a Diagnostic Report (DRPT) . . . . . . . . . . . . . . . . . . . . . . . . . 5-13
5.9 System Test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-15
5.10 Significant Event Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-16
6 Ventilator Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
6.1 Connecting the Service PC and Ventilator . . . . . . . . . . . . . . . . . . . . . . . . . 6-2
6.2 Loading USB Drivers to the Service PC. . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5
6.3 Installing Operating Software on the Ventilator . . . . . . . . . . . . . . . . . . . . 6-12
6.4 Reprogramming the BiPAP Focus Serial Number. . . . . . . . . . . . . . . . . . . 6-22
7 Testing, Calibration, and Performance Verification . . . . . . . . . . . . . . . . 7-1
7.1 Test Equipment and Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2
7.2 Recommended Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3
7.3 Ventilator Run-in . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4
7.4 Battery Test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5
7.5 Real-time Clock Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6
7.5.1 Downloading Real-Time Clock Calibration Software . . . . . . . . . . . . 7-6
7.5.2 Performing the Real-Time Clock Calibration . . . . . . . . . . . . . . . . . 7-8
7.5.3 If Real-Time Clock Calibration Fails . . . . . . . . . . . . . . . . . . . . . . 7-10
7.6 System Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-11
7.6.1 Downloading System Calibration Software. . . . . . . . . . . . . . . . . . 7-11
7.6.2 Performing the System Calibration . . . . . . . . . . . . . . . . . . . . . . . 7-13
7.7 Electrical Safety Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-24
7.8 Alarm/LED Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-25
7.9 Pressure Accuracy Test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-26
7.10 Performance Verification Data Form. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-27

Table of Contents
REF 1029568 Rev B BiPAP Focus Ventilator Service Manual © Respironics, Inc. V
8 Component Removal/Installation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1
8.1 Disconnecting Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2
8.2 Top Cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3
8.3 Display Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-6
8.4 User Interface PCB. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-9
8.5 Controller PCB. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-10
8.6 Flow Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-12
8.7 Blower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-13
8.8 Backup Alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-15
8.9 Primary Alarm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-16
8.10 Bottom Cover and Muffler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-17
8.11 Interconnect Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-18
9 BiPAP Focus Replacement Parts List. . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1
9.1 Complete Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1
9.2 Exterior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4
9.3 Front Panel/User Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-6
9.4 Ventilator Interior. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-7
9.5 Communications Cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-9
9.6 Electronic Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-10
10 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1
10.1 Ventilator Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1
10.2 Patient Circuit Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-6
10.3 Maximum Pressure Drop for Disconnect . . . . . . . . . . . . . . . . . . . . . . . . . 10-7
10.4 Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-7
10.5 Date of Manufacture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-8
10.6 Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-9
10.7 Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-13

VI BiPAP Focus Ventilator Service Manual © Respironics, Inc. REF 1029568 Rev B
Table of Contents

REF 1029568 Rev B BiPAP Focus Ventilator Service Manual © Respironics, Inc. 1-1
Chapter 1. Introduction and Intended Use
The BiPAP Focus Ventilator System provides noninvasive ventilation for adult
(over 30 kg or 66 lbs.) patients for the treatment of respiratory insufficiency
and distress, and obstructive sleep apnea. The BiPAP Focus is appropriate for
acute, sub-acute, and intra-hospital transport settings.
The BiPAP Focus is intended for use with nasal and full face masks, and is not
intended to be a life-support device.
The BiPAP Focus ventilator meets all applicable safety requirements,
consensus guidelines, US regulatory statutes, and international regulatory
standards for life support/mechanical ventilation devices.
Read this manual thoroughly before performing service or maintenance on the
ventilator. This manual contains advanced troubleshooting, calibration, and
maintenance instructions. All service is to be performed by qualified service
personnel.
Review the BiPAP Focus Operator’s Manual thoroughly before running tests,
checking operational readiness, or initiating patient use. The operator’s
manual includes important information about ventilator safety, operation, and
applicable warnings and cautions.
Read the appropriate instructions before connecting accessories or related
equipment such as humidifiers and remote alarm systems to the BiPAP Focus.

Chapter 1
1-2 BiPAP Focus Ventilator Service Manual © Respironics, Inc. REF 1029568 Rev B
Introduction and Intended Use
1.1 Tools and Test
Equipment
Table 1-1 lists the tools, test equipment, and materials required to service and
maintain the BiPAP Focus ventilator.
Table 1-1: Test Equipment, Tools, and Materials
Description Manufacturer and Model
Test Equipment
Digital multimeter (DMM) accurate to three decimal
places
Local supplier
Electrical safety analyzer Dale LT 5440 or equivalent
Flow source capable of providing up to 120 LPM of air
PC or laptop with:
• Windows XP or compatible operating system
• 9-pin serial communication port COM1 (or USB to
serial adapter assignable to COM1)
•USBport
• CD-ROM drive
• Internet connection
Local supplier
Pneumatic calibration analyzer capable of measuring
low pressure (cmH2O), flow rate (LPM), volume (liters
BTPS), and respiratory rate (/min).
Respironics P/N 1040310 or equivalent
Respironics utility software (required for calibrating
and testing BiPAP Focus ventilator)
Log on to
http:// my.respironics.com
to download utility software to a PC.
Ventilator Accessories
Connector, 22-mm (quantity 2) Respironics P/N 1002505 or equivalent
Coupling, silicone (qty. 2) P/N 500-1000-43
Flow control valve Respironics P/N 1006120
Inspiratory bacteria filter, 22-mm M/F (qty. 1) Respironics P/N 1014047
Oxygen enrichment adapter Respironics P/N 312710
Oxygen safety valve Respironics P/N 302418
Patient tubing, reusable, 18-in. (qty. 1) Respironics P/N 1003649
Patient tubing, reusable, 42-in. (qty. 1) Respironics P/N 1003643
Silicone cork Respironics P/N 1001735
Test orifice, BiPAP, 0.25-in. (qty. 1) Respironics P/N 332353
Hand Tools and Materials
Antistatic workstation 3M Model 725 or equivalent
Cable kit, BiPAP Focus, communications (USB and
serial cables)
Respironics P/N 1039800
Cable, BiPAP Focus, battery charging (NiMH to 9V
alkaline)
Respironics P/N 1040421
Cleaning cloth Local supplier
Isopropyl alcohol Local supplier
Mild detergent or antiseptic wipes Local supplier

Chapter 1
Introduction and Intended Use
REF 1029568 Rev B BiPAP Focus Ventilator Service Manual © Respironics, Inc. 1-3
1.2 Where to Go for
Help
For customer service and product support contact:
Respironics, Inc.
USA telephone: [phone]
Fax: [phone]
International telephone: [phone]
International fax: [phone]
[email protected].
[e-mail].
www.respironics.com.
Pliers Local supplier
Pliers, needle nose Local supplier
Screwdriver, flat, #2 Local supplier
Screwdriver, flat, pen size Local supplier
Screwdriver, Phillips, #1 Local supplier
Screwdriver, Phillips, #2 Local supplier
Screwdriver, Phillips, pen size Local supplier
Torque driver (1 to 25 in.-lbs) Local supplier
Tubing, silicone, 3/16-in. ID x 6.5 ft. Local supplier
Table 1-2: Measurement Accuracy Requirements
Unit of
Measure Range Accuracy
Pressure -25 to 150 cmH20
0-100 psi
+/- 1% of reading or +/- 0.20 cmH20 (whichever is
greater).
Flow (standard) 0-300 SLPM +/- 2% of reading +/- 0.20 SLPM (whichever is greater)
Torque 5 to 25 in-lbs. +/- 1 in-lbs. of reading
Voltage DC: +/- 5 to 50V
AC: 2 to 300 V
+/- 2% of reading
Table 1-1: Test Equipment, Tools, and Materials (Continued)
Description Manufacturer and Model

Chapter 1
1-4 BiPAP Focus Ventilator Service Manual © Respironics, Inc. REF 1029568 Rev B
Introduction and Intended Use
(This page is intentionally blank.)

REF 1029568 Rev B BiPAP Focus Ventilator Service Manual © Respironics, Inc. 2-1
Chapter 2. Warnings and Cautions
Warnings, Cautions, and Notes are used throughout this manual to identify
possible safety hazards, conditions that may result in equipment or property
damage, and important information that must be considered when performing
service procedures on the BiPAP Focus.
2.1 Warnings • To ensure personal safety and ventilator performance, service is to
be performed only by qualified service personnel.
• To avoid injury to the patient airway, DO NOT use the BiPAP Focus
where ambient room temperature is above 95 °F (35 °C) because
outlet gas temperature may exceed 106° F (41°C).
• Use only Respironics repair/service parts. Using non-Respironics
parts can alter ventilator reliability or result in damage, and
affects the ventilator warranty. Contact Customer Service.
• High voltages are present in the AC/DC power supply, power cord,
and VGA interface PCB. To avoid electrical shock, disconnect
power before cleaning or repairing the ventilator.
• DO NOT immerse this device in liquid or allow liquid to enter the
cabinet or the filter intake.
• To avoid personal injury, always disconnect external AC and DC
power sources from the ventilator before servicing or cleaning.
• To avoid personal injury or the possibility of damage to the
ventilator, regularly inspect the power cord to ensure it is free from
defects and any obvious wear, and is properly grounded.
• Never troubleshoot while a patient is connected to the ventilator,
since normal operation is suspended.
• If the ventilator has been operating, the internal parts may be hot.
Use caution when accessing.
WARNING: A condition that could cause injury to a patient, operator or technician if
the instructions in this manual are not followed correctly.
CAUTION: A condition that could cause damage to, or shorten the service life of,
the device.
NOTE: Important information concerning the construction or operation of the
device.

Chapter 2
2-2 BiPAP Focus Ventilator Service Manual © Respironics, Inc. REF 1029568 Rev B
Warnings and Cautions
• To prevent disease transmission, use personal protective
equipment when handling contaminated bacteria filters or other
patient accessories. Follow manufacturers' labeling and
institutional guidelines for disposal of contaminated accessories.
• To avoid introducing foreign matter into the ventilator, inspect and
replace the air inlet filters at the recommended intervals
• To avoid cross-contamination between the test equipment and
ventilator, always install a bacteria filter between the main outlet
and test device.
• Explosion hazard. Do not operate the ventilator in the presence of
flammable anesthetic agents.
• To avoid the risk of fire, use only Respironics-approved batteries.
All battery connectors are keyed to ensure proper connection. Do
not attempt to connect a battery incorrectly.
• When running on battery, the high flows that occur during a
patient disconnect can deplete the battery in 2 minutes. Connect
AC power immediately if the Battery Depleted alarm occurs to
avoid total loss of power.
• Use only Respironics-supplied cables with the nurse call station/
serial communications connector.
• To avoid personal injury or the possibility of damage to the
ventilator, DO NOT operate this device if it has failed any
diagnostic tests.

Chapter 2
Warnings and Cautions
REF 1029568 Rev B BiPAP Focus Ventilator Service Manual © Respironics, Inc. 2-3
2.2 Cautions • Federal law (US) restricts this device to sale by, or on the order of,
a physician.
• Failure to replace a dirty filter may cause the device to operate at
higher than normal temperatures and damage the device.
• Use only Respironics-approved filters.
• Use only Respironics-approved batteries.
• The gray reusable air inlet filter must be completely dry before
use. Never place a wet filter into the device.
• Never install more than one gray reusable air inlet filter into the
ventilator. The ventilator is designed to accommodate one gray
reusable air inlet filter and one white disposable ultra-fine filter.
• During battery charging, disconnecting AC mains power before
charging completes may result in a Battery Depleted or Missing
alarm. If a Battery Depleted or Missing alarm occurs, connect AC
power immediately to avoid total loss of power.
• To prevent the premature depletion and reduced life expectancy of
the battery, store the ventilator with AC power connected and the
ON/OFF switch in the ON (I) position. When the ventilator is
stored disconnected from AC power with the power ON/OFF switch
ON ( I ) and in standby, the battery may become depleted within
two weeks. When the ventilator is stored with the ON/OFF switch
in the OFF (O) position, the battery typically becomes depleted in
three months.
If a 343 error code is displayed, remove the battery and charge it
using the BiPAP Focus battery charging cable (P/N 1040421).
This cable provides the initial charge required so that the
ventilator can recharge a depleted battery. Refer to the battery
charge instructions supplied with the cable.
• Replace any filter that is damaged.
• Do not attempt to clean or reuse disposable air inlet filters.
• Electronic components used in this device are subject to damage
from static electricity. Perform repairs only in an antistatic,
electrostatic discharge (ESD)-protected environment.
• Avoid exposing the ventilator to extreme environmental conditions.
Allow the ventilator to return to room temperature before
operation.
• Never place liquids on or near the BiPAP Focus.
• The information in this manual is provided for service personnel
reference.
• Do not pull or crimp cables, tubes, or wires.

Chapter 2
2-4 BiPAP Focus Ventilator Service Manual © Respironics, Inc. REF 1029568 Rev B
Warnings and Cautions
2.3 Notes • Refer to the BiPAP Focus Operator’s Manual for product use,
additional warnings, cautions, and notes.
• Service calibration procedures require a printer to be assigned to
the service PC: this can be an internal print location (for example,
using Adobe PDF) or a printer connected to the PC. If a print error
occurs at the end of the calibration, the calibration table is
cleared and the calibration must be repeated.

REF 1029568 Rev B BiPAP Focus Ventilator Service Manual © Respironics, Inc. 3-1
Chapter 3. Theory of Operation
The BiPAP Focus ventilator provides noninvasive breathing support for adult
patients weighing 30 kg (66 lbs.) or more.
The BiPAP Focus offers two ventilation modes:
• Continuous positive airway pressure (CPAP), which provides a single
level of positive pressure to the patient.
• Spontaneous/timed (S/T), which provides two levels of positive
pressure (one during inspiration and one during exhalation), and
delivers timed breaths if the patient does not initiate a breath.
Ventilator alarms occur when high or low pressure, apnea, patient disconnect,
low power, or loss of AC power conditions occur. The system displays a real-
time estimated delivered pressure bar graph.
The BiPAP Focus includes alarm silence and alarm pre-silence features. A fully
charged backup battery provides a minimum of 45 minutes of backup power at
default settings in case AC power is not available (for example, during
transport within the hospital).
The BiPAP Focus features Digital Auto-Trak, which the ventilator to detect and
compensate for unintentional leaks, and adjust its trigger and cycle algorithms
to maintain optimum performance.

Chapter 3
3-2 BiPAP Focus Ventilator Service Manual © Respironics, Inc. REF 1029568 Rev B
Theory of Operation
3.1 Pneumatic
System
Figure 3-1 shows a pneumatic diagram of the BiPAP Focus ventilator.
Figure 3-1: BiPAP Focus Pneumatic Diagram
3.1.1 Air Inlet Filters
Air inlet filters:
• The gray reusable filter removes coarse particulate from ambient air
entrained by the blower.
• The white disposable filter is optional, and is recommended for
enhanced particulate filtration.
3.1.2 Muffler
The muffler reduces the noise of air flow into the blower. This is done by
channeling the air through a baffled system lined with sound absorbing
material. The channel also provides a path for air recirculation.
BiPAP Focus ventilator
Air inlet
filter(s)
Muffler
Air inlet
port
Blower
(motor) Flow valve
Diffuser
Bacteria filter
(mandatory)
Oxygen enrichment
adapter (if using oxygen)
Tubing (elbow)
Pressure sensor
Patient circuit (to
mask outlet)
Oxygen safety valve
(if using oxygen)
Outlet port and
pressure sensor
Flow sensor
Reusable
particulate filter
(gray)
Disposable particulate
filter (white)
Muffler

Chapter 3
Theory of Operation
REF 1029568 Rev B BiPAP Focus Ventilator Service Manual © Respironics, Inc. 3-3
3.1.3 Blower
The blower consists of a speed-controlled DC motor coupled to a single stage
impeller. The motor speed is monitored and adjusted by the controller PCB
based on patient settings. A pressure tap at the blower outlet enables
monitoring and comparison with the proximal (patient) pressure.
3.1.4 Flow Valve
The flow valve is a mechanical sliding assembly driven by an electromagnetic
coil. Valve commands from the controller PCB control current (-125 to
675 mA) to the coil. Flow valve movement is proportional to the current
through the coil. The flow valve operates as a closed-loop system, using
feedback from the flow sensor and pressure transducers.
3.1.5 Air Flow Sensor
The air flow sensor measures flow from the flow valve. The ventilator uses this
measurement to provide closed loop control of the flow valve to interpret
patient demand and calculated leak rate.
3.1.6 Diffuser
The diffuser is located on the output of the flow valve and is designed to
provide a reduction of air turbulence.
Blower
Flow
valve
Air flow
sensor
Diffuser

Chapter 3
3-4 BiPAP Focus Ventilator Service Manual © Respironics, Inc. REF 1029568 Rev B
Theory of Operation
3.2 Electronic System The BiPAP Focus electronic system controls, monitors, and displays patient
and ventilator data. Two microcontrollers (on the user interface and controller
PCBs) interpret user and sensor inputs while controlling inspiratory and
expiratory pressures according to the selected ventilator settings. Figure 3-2
shows an interconnect block diagram of the BiPAP Focus ventilator.
Figure 3-2: BiPAP Focus Block Diagram
Communication between the microcontrollers allows each to check the
function of the other, ensures proper transition between AC and DC power
sources, and allows internal battery maintenance.
Exter
nal
AC/
DC Motorola 68332 microcontroller,
A/D, primary alarm, temperature
monitor, primary alarm driver,
voltage monitoring,

Chapter 3
Theory of Operation
REF 1029568 Rev B BiPAP Focus Ventilator Service Manual © Respironics, Inc. 3-5
3.2.1 User Interface PCB
The user interface PCB (Figure 3-3) includes:
• Motorola 68332 microcontroller
• Inter-processor communication with controller PCB
• VGA display, keyboard, and front panel LED interface
• Primary alarm driver
• Remote alarm relay
• USB and RS-232 serial communication
• Power supply input, monitoring, and distribution
• 18 VDC input voltage/primary working voltage
• 12 VDC-relay control and 3.3 and 5.5 supply sources
• 5 VDC - USB drivers, LCD display, CCFL inverter
• 3.3 VDC - kernel circuits, digital circuits
Figure 3-3: BiPAP Focus User Interface PCB
J1-interprocessor
communications
cable
Connects to J1
and J10 of the
controller PCB
S1
ON/OFF
switch
J10
interconnect
power cable
18 VDC to
controller PCB
J13
switch control
cable
J8
battery cable
J12
primary alarm
connector
J9
VGA/UI
ribbon
cable
J3
serial
port
J4
USB
port
J6
power supply
connection

Chapter 3
3-6 BiPAP Focus Ventilator Service Manual © Respironics, Inc. REF 1029568 Rev B
Theory of Operation
3.2.2 Controller PCB
The controller PCB (Figure 3-4) includes:
• Blower on/off/closed-loop speed control
• Air flow valve controller
• Pressure measurement
• RS-232 communication
• Inter-processor communication with user interface PCB
• Backup alarm driver
• Flow sensor measurement and calibration
• Real-time clock with battery backup
• Microprocessor watchdog
Figure 3-4: BiPAP Focus Controller PCB
Interprocessor
communications
cable J1
Connects to user
interface PCB (J1)
Backup alarm
cable
Blower
connection J5
Switch control
cable
MT2 -P1 connects to air
flow sensor nipple
(closest to patient outlet)
MT2 -P2 connects to air
flow sensor nipple (away
from patient outlet)
Flow valve assembly J9
Interprocessor
communications
cable J10
Connects to user
interface PCB (J1)
MT3 blower sensor port MT4 patient
outlet port