Shearwater Petrel 3 User manual

Technical Modes
Operating Instructions

Page 2 Doc. 11301-Tec-RevB (2022-05-25)
Technical Modes
Operating Instructions
Table of Contents
Table of Contents��������������������������������������������������������������� 2
Conventions Used in this Manual����������������������������������������������������� 3
1. Introduction ................................................. 4
1�1� Notes on this manual������������������������������������������������������������������� 5
1�2� Models Covered by this Manual����������������������������������������������� 5
1�3� Modes Covered by this Manual������������������������������������������������ 5
2. Basic Operation ........................................... 6
2�1� Turning On ��������������������������������������������������������������������������������������� 6
2�2� Buttons�����������������������������������������������������������������������������������������������7
2�3� Changing between Modes��������������������������������������������������������� 8
2�4� Dive Mode Differentiation���������������������������������������������������������� 8
3. Dive Interface............................................... 9
3�1� Default Dive Setup������������������������������������������������������������������������ 9
3�2� Main Screen Layout���������������������������������������������������������������������10
3�3� Detailed Descriptions ������������������������������������������������������������������ 11
3�4� Info Screens������������������������������������������������������������������������������������16
3�5� Info Screen Descriptions ����������������������������������������������������������� 17
3�6� Mini Displays ��������������������������������������������������������������������������������� 23
3�7� Notifications���������������������������������������������������������������������������������� 23
3�8� List of primary notifications���������������������������������������������������� 25
3�9� Decompression Stops ��������������������������������������������������������������� 27
4. Decompression and Gradient Factors ... 28
4�1� Decompression Information Accuracy �������������������������������29
5. Example Dives ........................................... 30
5�1� Simple OC Tec Example Dive �������������������������������������������������30
5�2� Complex OC Tec Example Dive��������������������������������������������� 32
5�3� CC Example Dive�������������������������������������������������������������������������34
6. Special Dive Modes ....................................37
6�1� Gauge Mode���������������������������������������������������������������������������������� 37
6�2� Semi-Closed Mode ���������������������������������������������������������������������38
6�3� Bailout Rebreather Mode���������������������������������������������������������38
7. Compass ..................................................... 39
8. Air Integration (AI) ...................................40
8�1� What is AI? ����������������������������������������������������������������������������������� 40
8�2� Basic AI Setup �������������������������������������������������������������������������������41
8�3� AI Displays �������������������������������������������������������������������������������������44
8�4� Sidemount AI��������������������������������������������������������������������������������46
8�5� Using Multiple Transmitters�����������������������������������������������������47
8�6� SAC calculations��������������������������������������������������������������������������48
8�7� GTR calculations��������������������������������������������������������������������������49
8�8� Transmitter Connection Issues�����������������������������������������������50
9. Menus ........................................................... 51
9�1� Menu Structure �����������������������������������������������������������������������������51
9�2� Main Menu Descriptions �����������������������������������������������������������54
9�3� Dive Setup ������������������������������������������������������������������������������������ 60
9�4� Dive Log������������������������������������������������������������������������������������������67
10. System Setup Reference.......................... 68
11. Firmware Update and Log Download ..... 81
11�1� Shearwater Cloud Desktop ������������������������������������������������������ 81
11�2� Shearwater Cloud Mobile���������������������������������������������������������83
12. Changing the Battery ............................... 84
12�1� Behavior on Battery Change ��������������������������������������������������85
13. Storage and Maintenance ........................ 86
14. Servicing..................................................... 86
15. Glossary ...................................................... 86
16. Petrel 3 Specifications ............................. 87
17. Regulatory Information............................ 87
18. Contact ....................................................... 89
. . ...................................................................................
10.2.Deco Setup....................................................................................70
10.3.AI Setup.......................................................................................... 71
10.4.Center Row.................................................................................... 73
10.5.OC Gases (BO Gases) ............................................................... 73
10.6.CC Gases.........................................................................................73
10.7.O2 Setup......................................................................................... 74
10.8.Auto Setpoint Switch ................................................................ 75
10.9.Alerts Setup .................................................................................. 75
10.10.Display Setup .............................................................................. 76
10.11.Compass ......................................................................................... 76
10.12.System Setup............................................................................... 77
10.13.Advanced Config ....................................................................... 78
10 1Mode Setup .69

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Technical Modes
Operating Instructions
Conventions Used in this Manual
These conventions are used to highlight important
information:
INFORMATION
Information boxes contain useful tips for
getting the most out of your Petrel 3�
CAUTION
Caution boxes contain important instructions
for operating your dive computer�
WARNING
Warning boxes contain critical information
that may affect your personal safety�
This computer has bugs. Although we haven’t found them all yet,
they are there. It is certain that there are things that this computer
does that either we didn’t think about, or planned for it to do
something different. Never risk your life on only one source of
information. Use a second computer or tables. If you choose to
make riskier dives, obtain the proper training and work up to them
slowly to gain experience.
This computer will fail. It is not whether it will fail but when it will
fail. Do not depend on it. Always have a plan for how to handle
failures. Automatic systems are no substitute for knowledge and
training.
No technology will keep you alive. Knowledge, skill, and practiced
procedures are your best defense (except for not doing the dive, of
course).
WARNING
This computer is capable of calculating deco stop requirements. These
calculations are at best a guess of real physiological decompression
requirements. Dives requiring staged decompression are substantially
more risky than dives that stay well within no-stop limits.
Diving with rebreathers and/or diving mixed gases and/or performing
staged decompression dives and/or diving in overhead environments
greatly increases the risk associated with scuba diving.
YOU REALLY ARE RISKING YOUR LIFE
WITH THIS ACTIVITY.
DANGER

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Technical Modes
Operating Instructions
Features
• High-contrast 2�6” AMOLED display
• Rugged computer construction
• Titanium bezel
• User replaceable battery
• Powerful vibration alerts
• Programmable depth sampling rates
• Depth sensor calibrated to 130 msw
• Depth sensor function past 300 msw
• Crush pressure rating of 290 msw
• 5 customizable gases in technical diving modes
• Any combination of Oxygen, Nitrogen and Helium
(Air, Nitrox,Trimix)
• Full decompression and CCR Support
• External PPO2 monitoring of 1, 2 or 3 oxygen cells
(PO2 Monitor Models Only)
• Bailout rebreather mode (PO2 Monitor Models
Only)
• Bühlmann ZHL-16C with gradient factors standard
• Optional VPM-B and DCIEM decompression
models
• No lockout for violating deco stops
• CNS Tracking
• Gas Density Tracking
• Quick NDL and full decompression planner built in
• Simultaneous wireless pressure monitoring of up
to 4 cylinders
• Sidemount diving features
• Tilt compensated digital compass with multiple
display options
• Bluetooth Dive log uploading to Shearwater Cloud
• Free firmware updates
1. Introduction
The Shearwater Petrel 3 is an advanced technical dive
computer�
Please take the time to read this manual� Your safety
may depend on your ability to read and understand
your dive computer’s displays�
Diving involves risk and education is your best tool for
managing this risk�
Do not use this manual as a substitute for proper dive
training and never dive beyond your training� What you
don’t know can hurt you�

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Technical Modes
Operating Instructions
1.2. Models Covered by this Manual
This manual provides operating instructions for the
following Petrel 3 Models:
• Stand Alone Model SA
• Fischer Connector Model FC
• Analog Cable Gland Model ACG
• DiveCAN Rebreather
Monitor Model
DCM
Some sections of this manual only apply to specific
models of Petrel 3� To help identify which sections are
applicable to your unit, look for the corresponding
model icon throughout this manual� Sections with no
mode icons are applicable to all Petrel 3 models�
1.3. Modes Covered by this Manual
This manual provides operating instructions for the
Petrel 3 in the following technical operating modes:
• Open Circuit Technical (OC Tec)
• Closed Circuit / Bail Out (CC/BO)
• Semi-closed / Bail Out (SC/BO)
• Gauge
• PPO2
Read about Dive Mode Differentiation on page 8�
The Shearwater Petrel 3 also has 3 modes designed
for open circuit recreational diving�
For instructions on operation in recreational modes,
please see the Petrel 3 Recreational Modes Manual.
Some features of the Petrel 3 only apply to certain
dive modes� If not otherwise indicated, features
described are applicable in all dive modes�
Read more about Mode Setup on page 71�
1.1. Notes on this manual
This manual provides operating instructions for the
Petrel 3 dive computer in technical operating modes
only�
This manual contains cross-references between
sections to make it easier to navigate�
Underlined text indicates the presence of a link to
another section�
Do not change any settings on your Petrel 3 without
understanding the consequence of the change. If
you are unsure, consult the appropriate section of the
manual for reference�
This manual is not a substitute for proper training�
Firmware Version: V91
This manual corresponds to firmware version V91�
Feature changes may have been made since this
release and might not be documented here�
Check the release notes on Shearwater.com for a
complete list of changes since the last release.

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Technical Modes
Operating Instructions
2. Basic Operation
2.1. Turning On
To turn the Petrel 3 on, press both buttons together�
Do Not Rely On The Auto-On Feature
This feature is supplied as a backup for
when you forget to turn on your Petrel 3�
Shearwater recommends turning your
computer on manually before each dive
to confirm proper operation and to
double check battery status and setup�
Auto-on
The Petrel 3 will automatically turn-on when
submerged underwater� This is based on pressure
increase and not on the presence of water� When
auto-on is activated, the Petrel 3 will enter the last
configured dive mode�
Auto-on Details
The Petrel 3 turns on automatically and enters dive
mode when the absolute pressure is greater than 1100
millibar (mbar)�
For reference, normal sea level pressure is 1013 mbar
and 1 mbar of pressure corresponds to approximately
1 cm (0�4”) of water� So, when at sea level, the Petrel 3
will automatically turn-on and enter dive mode when
about 0�9 m (3 ft) underwater�
If at higher altitude, then the Petrel 3 auto-on will
occur at a deeper depth� For example, when at 2000
m (6500 ft) altitude the atmospheric pressure is only
about 800 mbar� Therefore, at this altitude the Petrel
3 must be submerged underwater by 300 mbar to
reach an absolute pressure of 1100 mbar� This means
the auto-on occurs at about 3 m (10 ft) underwater
when at an altitude of 2000 m�

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Technical Modes
Operating Instructions
2.2. Buttons
Two titanium piezo-electric buttons are used to
change settings and view menus�
All Petrel 3 operations are simple single button
presses�
MENU (left)
button
Button Hints
When in a menu, button hints indicate the function of
each button:
In the example above, the hints tell us:
• Use MENU to change the brightness value
• Use SELECT to save the current value
Don’t worry about remembering all the button rules
below� Button hints make using the Petrel 3 easy�
SELECT (right)
button
SURFACE
hr
mn
15
Save
Brightness Auto
Change
2
0
DEPTH
TIME
.70
.70
.70
MENU hint SELECT hint
MENU (Left) button
From main screen Brings up menu
In a menu Moves to the next menu item
Editing a setting Changes the setting’s value
SELECT (Left) button
From main screen Steps through info screens
In a menu Performs command or starts
editing
Editing a setting Saves the setting’s value
BOTH BUTTONS
When Petrel 3 is off pressing MENU and SELECT
at the same time will turn the Petrel 3 on� No other
operation requires pressing both buttons at the same
time�

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Technical Modes
Operating Instructions
2.4. Dive Mode Differentiation
Each dive mode is designed to best suit a particular
type of diving� Use the correct mode to get the best
experience from the Petrel 3�
Mode Model
Availability
Description
Air SA
FC
ACG
Designed for use during
recreational, air only, no-
decompression diving activities�
• Air (21% oxygen) only, not
switchable underwater
Nitrox SA
FC
ACG
Designed for use during recreational,
Nitrox, no-decompression diving
activities�
• Single Gas Nitrox up to 40%
oxygen
• No gas switching underwater
3GasNx SA
FC
ACG
Designed for introductory technical
diving activities including diving
involving planned decompression�
• Three programmable gases
• Support for gas switching
• Nitrox up to 100%
OC Tec SA
FC
ACG
Open Circuit Technical
Designed for open circuit technical
diving activities including planned
decompression�
• Full Trimix
• No Safety stops
2.3. Changing between Modes
By default the Petrel 3 is set to 3 GasNx Mode�
Recreational focused
modes can be
distinguished by the
large-font layout�
For directions on how
to use the recreational
focused modes on the
Petrel 3, see the Petrel
3 Recreational Modes
Manual.
This manual covers
operation in technical
diving modes� Switch to
one of these modes in
the mode setup menu�
See details on page
71�
Technical modes have
a more dense layout
and are capable
of displaying more
information on the
screen�
The circuit mode is
indicated in the bottom
left of technical dive
mode displays�
300
Air 21
m
.o23°C
10:55am
MAX
.
7
:
:
Mode OC Tec
Salinity EN13319
Next
Edit
Mode Setup
Recreational Modes Layout
Mode Setup Menu
TIME
TTS
OC 21/00 12 3
O2/HE
NDL
PPO2
DEPTH
TIME
STOP
28.0
.80
4
OC Tec Mode

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Technical Modes
Operating Instructions
Mode Model
Availability
Description
CC/BO SA
FC
ACG
DCM
Closed Circuit with Open Circuit
bailout�
Designed for use with a closed
circuit rebreather�
• Fast switching from closed circuit
to open circuit (BO) operating
modes�
• External PPO2 monitoring on
some models�
SC/BO FC
ACG
Semi-Closed Circuit with Open Circuit
bailout�
Designed for use with a semi-closed
circuit rebreather�
• Decompression is calculated
differently in SC mode versus CC,
because the projected PPO2 at
shallower depths is different�
• Only external PPO2 monitoring is
available�
Gauge SA
FC
ACG
A simple depth and time display
with a dedicated layout� See
details on page 38�
• No tissue tracking
• No decompression
information
PPO2 FC
ACG
DCM
Like Gauge but with PPO2 display� No
decompression�
3. Dive Interface
3.1. Default Dive Setup
The Petrel 3 comes pre-configured for recreational
diving� The default dive mode is 3 Gas Nitrox mode (3
GasNx)�
As a quick reference, a diagram of the default diving
display is shown below�
This manual is for technical dive modes only� Many
features of the above default display are shared by
the dive modes covered in this manual�
For directions on how to use Air, Nitrox or 3 GasNx
modes, see the Petrel 3 Recreational Modes Manual.
Default Dive Display -
3 GasNx mode
Ascent Rate
No-Deco
Limit
Dive Time
Active Gas
300
Air 21
m
.o23°C
10:55am
MAX
.
7
:
:
Depth
Safety Stop
Nitrogen
Loading
Temperature
Time

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Technical Modes
Operating Instructions
3.2. Main Screen Layout
The main screen shows the most important
information needed for technical diving�
Open Circuit
TTS
OC 18/45 0 38
O2/HE
NDL
54.0 22
DEPTH
TIME
30
R
T1
107
B
AR
T2
129
B
A
124
%
SurGF
STOP
TIME
1
}Top Row
Depth, Time &
Deco Stops
Center Row
Configurable
Bottom Row
Mode, Gas, NDL
& TTS
}
}
Closed Circuit With Internal Setpoint
All models can be used in CC/BO mode operating
with an “internal”, user defined setpoint� In this mode
left and right positions can be configured, but the
current setpoint is always displayed in the center
position and cannot be removed�
OC Tec mode
TTS
CC 21/00 12 3
O2/HE
NDL
24.0 14
DEPTH
TIME
R
D1
155
B
AR
O2
170
B
A
1.3
STOP
TIME
}Top Row
Depth, Time &
Deco Stops
Center Row
Internal Setpoint,
Configurable
Bottom Row
Mode, Gas, NDL
& TTS
}
}
CC/BO mode, internal PPO2 = 1�3
Closed Circuit with External Setpoint
Models with external sensor monitoring can operate
in CC/BO mode with external PPO2 monitoring� In
this mode the center row prioritizes showing cell
PPO2 values� If operating in 3 cell mode, no space is
available for custom information in the center row�
CC 18/45 0 46
O2/HE
60.6 22
DEPTH
TIME
40
STOP
TIME
1
TTS
1.23 1.25 1.27
NDL
}Top Row
Depth, Time &
Deco Stops
Center Row
Cell PPO2
Bottom Row
Mode, Gas, NDL
& TTS
}
}
CC/BO mode, external PPO2
In every mode the top row contains important depth,
time and decompression information� The bottom row
shows the mode indicator, active gas, no-deco limit
and time to surface�
Pressing the Select (right) button scrolls through
additional data in the bottom row, temporarily
obscuring this information� See the Info Screens
section on page 16 for more information�
In OC Tec mode the entire center row contents can
be configured to display the data that the user feels is
most important�
See page 75 for Center Row configuration options�
FC
ACG

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Technical Modes
Operating Instructions
3.3. Detailed Descriptions
The Top Row
The top row shows depth, dive time, ascent rate,
decompression information and battery status�
Depth
Displayed in feet or meters�
In feet, depth displays with no decimal places� In meters,
depth displays with one decimal place up to 99�9m�
Note: If the depth shows a Flashing Red zero or shows a
depth at the surface, then the depth sensor needs service�
Ascent Rate Display
Shows how fast you are currently ascending�
1 arrow per 3 meters per minute (mpm) or 10 feet per
minute (fpm) of ascent rate�
Decompression calculations assume 10mpm (33fpm)
ascent rate�
GREEN when less than 9 mpm / 30 fpm
(1 to 3 arrows)
YELLOW when greater than 9 mpm /
30 fpm and less than 18 mpm / 60 fpm
(4 or 5 arrows)
FLASHING RED when greater than
18 mpm / 60 fpm (6 arrows)
TIME
67.0 22 39 1
DEPTH
TIME
STOP
in feet in meters
TIME
220 22 130 1
DEPTH
TIME
STOP
69.7
DEPTH
Dive Time
The first “TIME” item, on the left
of the top row, is the length of the
current dive in minutes�
Seconds display as a bar drawn
below the word “Time�” It takes 15
seconds to underline each character
in the word� The seconds bar is not
displayed when not diving�
Decompression Stop Depth and Time
22
TIME
22
TIME
Stop at 27 meters for 2 minutes
TIME
25.2 62 27 2
DEPTH
TIME
STOP
TIME
27.2 62 27 2
DEPTH
TIME
STOP
The third item in the Top row, “Stop”, indicates the
next decompression stop depth in the current units
(feet or meters)� This is the shallowest depth to which
you can ascend� The last item on the right in the top
row, “time”, is how long in minutes to hold the stop�
Decompression Stop Violated
Decompression information will Flash Red if you
ascend shallower than the current stop�
By default the Petrel 3 uses a 3m (10ft) last deco stop
depth� You may perform your last deco stop deeper
if you wish - deco calculations will remain accurate� If
you choose to do this, depending on your breathing
gas, the predicted time-to-surface may be shorter
than the actual TTS since off-gassing may occur
slower than the algorithm expects� There is also an
option to set the last stop to 6m (20ft)�

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Technical Modes
Operating Instructions
BLUE when battery charge is OK
YELLOW when battery needs to
be replaced�
RED when battery must be
replaced immediately�
Surface Interval
When on the surface, decompression stop depth
and time are replaced by a surface interval display
showing the hours and minutes since the end of your
last dive�
SURFACE
TTS
OC 21/00 0 0
O2/HE
NDL
.21
GasPO2
.0
DEPTH
TIME
hm
15
2
CLEAR
TTS
OC 21/00 0 0
O2/HE
NDL
.21
GasPO2
.0
DEPTH
TIME
2:14
2 hour and 15 minute surface interval
Above 4 days, the surface interval is displayed in days�
The surface interval is reset when the decompression
tissues are cleared� See the Decompression Tissue
Loading section on page 87 for more information�
Deco Clear Counter
When deco clears the STOP DEPTH and TIME are
replaced by a counter that begins counting up from 0�
Battery Icon
The default behavior is that the battery icon is shown
on the surface but disappears when diving� If low or
critical then the battery icon will appear while diving�
The Center Row
The Center row layout depends on the current mode�
STOP
TTS
OC 15/40
O2/HE
NDL
DEPTH
TIME
MAX
m
PPO2
61.0
1.15
0
70
TIME
56
22 39 1
.7
SurGF
%
83
All 3 locations configurable in OC Tec mode
In OC Tec mode, center row information is entirely
customizable� There are three configurable locations,
each of which can be populated independently�
A list of data options is given on the next page� Center
Row Setup instructions can be found on page 75 �
The middle location of the center row displays gas
PPO2 by default� It has a smaller selection of data
options because it is slightly narrower than the left
and right slots�
For detailed descriptions of each screen element see
Info Screen Descriptions on page 17
In CC/BO mode, when using an internal PPO2
setpoint, the center slot is not configurable� It always
displays the currently selected rebreather setpoint
with no title text� The right and left slots can still be
customized�
STOP
TTS
OC 15/40
O2/HE
NDL
DEPTH
TIME
DilPO2
61.0
1.3
0
.71
TIME
56
22 39 1
DENSITY
DENSITY
44
g
L
Left and right locations configurable in CC/BO
mode when using internal setpoint�

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Technical Modes
Operating Instructions
Home Screen Configuration Options
Option Info Display
PPO2
CNS %
MOD
Gas Density
GF99
Surface GF
Ceiling
@+5
Δ+5
Time To
Surface
Dil� PPO2
FiO2
Mini Display
Option Info Display
CLOCK
Timer
Dive End
Time
RATE
Temperature
Compass
Max Depth
Avg� Depth
Stack Time
Remaining
Tank
Pressure
Surface Air
Consumption
Gas Time
Remaining
Redundant
Time
Remaining
Mini Displays for the left
and right custom slots can
each hold 3 data displays�
See details on page 23�
Mini Displays
TIME
TTS
OC 50/00 0 27
O2/HE
NDL
11
CEIL
13.2 36 12 2
DEPTH
TIME
STOP
GF9937
%
Δ+5 -4
MOD 22m
PO21.09
CNS 21%
SfGF
180
STOP
TTS
OC 15/40
O2/HE
NDL
DEPTH
TIME
Δ
Δ +5
PPO2
61.0
1.15
0
+8
TIME
56
22 39 1
SurGF
%
83
STOP
TTS
OC 15/40
O2/HE
NDL
DEPTH
TIME
@+5
PPO2
61.0
1.15
0
20
TIME
56
22 39 1
SurGF
%
83
STOP
TTS
OC 15/40
O2/HE
NDL
DEPTH
TIME
CEIL
PPO2
61.0
1.15
0
17
TIME
56
22 39 1
SurGF
%
83
TIME
TTS
OC 21/00 0 3
O2/HE
NDL
24.0 22
DEPTH
TIME
STOP
SurGF
44
DENSITY
13
g
L
PPO2
71
%
TIME
TTS
OC 21/00 0 3
O2/HE
NDL
24.0 22
DEPTH
TIME
STOP
GF99
15
DENSITY
13
g
L
PPO2
71
%
TIME
TTS
OC 21/00 0 3
O2/HE
NDL
24.0 22
DEPTH
TIME
STOP
SurGF
44
DENSITY
13
g
L
PPO2
71
%
STOP
TTS
OC 15/40
O2/HE
NDL
DEPTH
TIME
MOD
m
PPO2
61.0
1.15
0
57
TIME
56
22 39 1
.3
SurGF
%
83
STOP
TTS
OC 15/40
O2/HE
NDL
DEPTH
TIME
CNS
PPO2
61.0
1.15
0
11
TIME
56
22 39 1
SurGF
%
83
STOP
TTS
OC 15/40
O2/HE
NDL
DEPTH
TIME
MAX
m
PPO2
61.0
1.15
0
70
TIME
56
22 39 1
.7
SurGF
%
83
STOP
TTS
OC 15/40
O2/HE
NDL
DEPTH
TIME
Δ
TTS
PPO2
61.0
1.15
0
15
TIME
56
22 39 1
SurGF
%
83
STOP
TTS
OC 15/40
O2/HE
NDL
DEPTH
TIME
Δ
DilPO2
PPO2
61.0
1.15
0
.99
TIME
56
22 39 1
SurGF
%
83
STOP
TTS
OC 15/40
O2/HE
NDL
DEPTH
TIME
Δ
FiO2
PPO2
61.0
1.15
0
.32
TIME
56
22 39 1
SurGF
%
83
TIME
TTS
OC 50/00 0 27
O2/HE
NDL
11
CEIL
13.2 36 12 2
DEPTH
TIME
STOP
GF99
37%
Δ+5 -4
MOD 22m
PO21.09
CNS 21%
SfGF
180
TIME
24.0 14
DEPTH
TIME
STOP
R
T1
175
B
A
37
GTR T1 SAC T1
1.5
Bar
min
3:00
57 21 3.13
m
.3
AVG
.7
:
:
MAX
m
AvgATM
.o
3:00
57 21 3.13
m
.3
AVG
.7
:
:
MAX
m
AvgATM
.o
3:00
319

.7
:
:
DATE
18C
TEMP
43
RATE
ft
min
STOP
TTS
OC 15/40
O2/HE
NDL
DEPTH
TIME
Δ
DET
PPO2
61.0
1.15
0
TIME
56
22 39 1
SurGF
%
831:31
STOP
TTS
OC 15/40
O2/HE
NDL
DEPTH
TIME
Δ
TIMER
PPO2
61.0
1.15
0
0:58
TIME
56
22 39 1
SurGF
%
83
STOP
TTS
OC 15/40
O2/HE
NDL
DEPTH
TIME
Δ
CLOCK
PPO2
61.0
1.15
0
12:58
TIME
56
22 39 1
SurGF
%
83
TIME
24.0 14
DEPTH
TIME
STOP
R
T1
175
B
A
37
GTR T1 SAC T1
1.5
Bar
min
TIME
24.0 14
DEPTH
TIME
STOP
R
T1
175
B
A
37
GTR T1 SAC T1
1.5
Bar
min
TIME
24.0 14
DEPTH
TIME
STOP
R
T1
175
B
A
16
RTR T1 SAC T1
1.5
Bar
min
In CC mode, PPO2 displays in Flashing Red
when less than 0�40 or greater than 1�6�
In OC Tech mode, PPO2 displays in Flashing Red
when less than 0�19 or greater than 1�65�
The above limits can be adjusted in the Adv�
Config 2 menu� See details on page 81
Default PPO2 Limits
In CC/BO mode, when using external PPO2
monitoring, the Cell PPO2 values occupy the center
row�
CC 18/45 0 46
O2/HE
60.6 22
DEPTH
TIME
40
STOP
TIME
1
TTS
1.23 1.25 1.27
NDL
All center row positions show PPO2 information
in CC/BO 3 sensor external PPO2 mode
In addition to the normal three cell mode, the dive
computer can also be operated in single or dual cell
mode� The unused location(s) can be customized in
these operating modes� See details on page 57�
Switch between internal PPO2 setpoint and external
PPO2 monitoring mode at the surface in the Mode
Setup Menu (page 71�) or in the dive setup menu
(page 61)�
When using external sensors and you have bailed
out to OC, the center row continues to display the
external measured PPO2�
Note all PPO2 units are absolute atmospheres�
(1ata=1013mbar)�
TIME
24.0 14
DEPTH
TIME
STOP
R
T1
175
B
A
2:55
Stack SAC T1
1.5
Bar
min

Page 14 Doc. 11301-Tec-RevB (2022-05-25)
Technical Modes
Operating Instructions
Current Circuit Mode
The active breathing mode configuration is displayed
on the far left of the bottom row� The options are:
The Bottom Row
The bottom row of technical dive modes displays the
current circuit mode, active gas, No Decompression
Limit (NDL), and Time To Surface(TTS)�
No Decompression Limit (NDL)
The time remaining, in minutes, at the
current depth until decompression
stops will be necessary� Displays in
Yellow when the NDL is less than the
low NDL limit (Default 5 minutes)�
NDL Replacement Options
Once NDL reaches 0 (i�e� deco stops needed), the
NDL display can be replaced by a small selection of
custom options to best utilize this space� See details
on page 78� The Mini option is described in more
detail on page 15�
NDL replacement options:
• Ceiling
• @+5
• Delta+5
• GF99
• SurGF
• Mini
Time To Surface (TTS)
The time-to-surface in minutes� This is
the current time to ascend to the surface
including the ascent plus all required
deco stops�
TTS
OC 15/40 0 56
O2/HE
NDL
CC
OC
BO
OC = Open circuit
CC = Closed circuit
BO = Bailout
(displays in Yellow to indicate bailout condition)
Active Gas
The current active gas shown as a percentage of
Oxygen and Helium� The remainder is assumed to be
Nitrogen�
20
NDL
5
NDL
Important!
All decompression information including
Deco Stops, NDL, and Time to surface are
predictions that assume:
• Ascent rate of 10mpm / 33fpm
• Decompression stops will be followed
• All programmed gases will be used as
appropriate
See the Decompression Information
Accuracy section on page 30 for more
information�
35
TTS
In open circuit mode, this is the breathing gas fraction�
In closed circuit mode, this is the active diluent gas�
The active gas displays in yellow when there is a
better gas available� Only turn on gases you plan to
use on your dive�
21/00
O2/HE
10/50
O2/HE
21/00
O2/HE
Air:
21% O2
79% N2
Trimix:
10% O2
50% He
79% N2
A better
deco gas is
available

Page 15 Doc. 11301-Tec-RevB (2022-05-25)
Technical Modes
Operating Instructions
Additional Information
The bottom row is also used to show additional
information�
Only the bottom row changes during a dive, so critical
information contained on the Top and Center Rows is
always available�
Additional information that can be displayed on the
bottom row includes:
Info Screens:
Shows additional dive
information�
Press SELECT (right
button) to step through
info screens�
Menus:
Allows changing
settings�
Press MENU (left button)
to enter menus�
Warnings:
Provide important alerts�
Press any button to clear
a warning�
TIME
AvgATM
TIME
Save
Brightness Med
Change
67.0 22 39 1
DEPTH
TIME
STOP
TIME
MISSED DECO STOP
Error CONFIRM
18.8 38
21 2
DEPTH
TIME
STOP
Sample Info Screen
Sample Menu
Sample Warning
m
.7
MAX
AVG
57
PPO2
1.15
PPO2
1.42
PPO2
1.15
67.0 22 39 1
DEPTH
TIME
STOP
m
.9
71 6.76
Mini NDL Replacement Display
The Mini NDL replacement
display option reconfigures
the right side of the bottom
row to allow two additional
pieces of custom information
to be displayed�
The Mini NDL replacement
display can be configured
from System Setup > Deco
Setup described on page
72�
When the mini option is
selected the chosen custom
information is displayed at all
times� This is unlike the other
NDL replacement display
options which only appear
while the NDL is zero�
When in use, TTS is always
the first row option of this
mini display and cannot
be changed� The NDL is
relocated to the deco stop
and time information section
of the top row while there is
no decompression obligation�
CC 21/00
O2/HE
29.2 5
DEPTH
TIME
15
NDL
1.23 1.25 1.27
DEN 5.2
TTS 3
SfGF
21%
Top
Center
TTS
DENSITY
Change Save
Mini Setup
Bottom Surf GF
DEN 1.1
TTS 0
SfGF
0%
NDL Replacement Mini
appearance
NDL Replacement Mini
setup menu�

Page 16 Doc. 11301-Tec-RevB (2022-05-25)
Technical Modes
Operating Instructions
3.4. Info Screens
Info screens provide more information than is
available on the main screen�
From the main screen, the SELECT (right) button
steps through info screens�
When all info screens have been viewed, pressing
SELECT again will return to the main screen�
Info screens also automatically time-out after 10
seconds, returning to the home screen� This prevents
active gas information from being hidden for an
extended period�
Note that the Compass, Tissues and AI Info screens do
not automatically time out when active�
Pressing the MENU (left) button will return to the
home screen at any time�
Although these screens are generally representative
of the Petrel 3 display, info screen content varies for
each mode� For example, decompression related info
screens are not available in gauge mode�
The next section gives detailed descriptions of the
data elements shown on the info screens�
3:00
12 52 -20/ 2
Δ+5
.7
:
:
DET @+5/TTS
:
Press the right (FUNC)
button, to step through
Info Screens
Return to Main Screen by:
•Pressing the left (MENU) button
•Stepping past last screen
•Waiting 10 Seconds (most screens)
3:00
Air 21
m
.o23°C
10:55am
MAX
.7
:
:
3:00
57 21 3.13
m
.3
AVG
.7
:
:
MAX
m
AvgATM
.o
3:00
20 12
GF
.7
:
:
TEMP
°C
CNS
30/70
3:00
15 62 0
SurGF
.7
:
:
GF99
%
CEIL
%
3:00
.7
:
:
TISSUES
3:00
4 . 12V
1.5V
.7
:
:
Alka
BATTERY
3:00
1020 1021
.7
:
:
PRESSURE mBar
SURF NOW
3:00
03-Mar-20 6 42
.7
:
:
DATE CLOCK
:
3:00
9F1F0432 20080BC
.7
:
:
SERIAL NO VERSION
SAFETY STOP
SURFACE
h
NDL
00
LAST DIVE
0
ft
N2
m
01
37
#1234
MAX m 0 h 52 m 38 s
.6
TIME
TTS
OC 21/00
O2/HE
NDL
PPO2
DEPTH
TIME
STOP
16.4
.55
33
240
9
4
TIME
NE
N
24
1.30
22.1 3
DEPTH
TIME
STOP
TIME
24.0 14
DEPTH
TIME
STOP
R
T2
163
B
A
R
T1
175
B
A
GTR 45
SM
SAC 1.5

Page 17 Doc. 11301-Tec-RevB (2022-05-25)
Technical Modes
Operating Instructions
3.5. Info Screen Descriptions
This section contains detailed descriptions of all info
screen and custom screen elements�
Last Dive Info
Maximum depth and dive time from the last dive� Only
available at the surface�
Air Integration
Only available if AI feature is turned on� The contents
of the AI info line will automatically adapt to the
current setup� Some examples include:
More information on AI features, limitations, and
displays can be found in the Air Integration (AI)
section on page 41�
SAFETY STOP
SURFACE
h
NDL
00
LAST DIVE
0
ft
N
2
m
01
37
#1234
MAX m 0 h 52 m 38 s
.6
T1 Only
T1 & GTR/SAC
T1 & T2
T1, T2 &
GTR/SAC
Compass
T1, T2, T3,
& T4
TIME
24.0 14
DEPTH
TIME
STOP
R
T1
175
B
A
TIME
24.0 14
DEPTH
TIME
STOP
R
T1
175
B
A
37
GTR T1 SAC T1
1.5
Bar
min
TIME
24.0 14
DEPTH
TIME
STOP
R
T2
163
B
A
R
T1
175
B
A
TIME
24.0 14
DEPTH
TIME
STOP
R
T2
163
B
A
R
T1
175
B
A
GTR 45
SM
SAC 1.5
TIME
24.0 14
DEPTH
TIME
STOP
R
T2
163
B
A
R
T1
175
B
A
T3 197
T4 203
54.0 22
DEPTH
TIME
30
R
T1
107
B
AR
129
B
A
124
%
SurGF
STOP
TIME
1
T2
SAFETY STOP
SURFACE
h
NDL
00
MILLIVOLTS
0
ft
N
2
m
01
10.7 11.010.5
Marked headings appear in green while reciprocal
headings are shown in red� Green arrows point in the
direction of your mark when off course by 5˚ or more�
Compass info row will not time out and is only
available when compass feature is turned on�
See the Compass section on page 40 for more
information�
Millivolts
Shows the raw millivolt outputs of external PPO2 cells�
This is important information used to understand the
O2 cell output behavior over time�
FC ACG

Page 18 Doc. 11301-Tec-RevB (2022-05-25)
Technical Modes
Operating Instructions
Maximum Depth
The maximum depth of the current
dive� When not diving, displays the
maximum depth of the last dive
Average Depth
Displays the average depth of the
current dive, updated once per
second� When not diving, displays
the average depth of the last dive�
Average Atmospheres
The average depth of the current
dive, measured in absolute
atmospheres (i�e� a value of 1�0 at
sea level)� When not diving, shows
the average of the last dive�
Temperature
The current temperature in degrees
Fahrenheit or degrees Celsius as
configured in Display Setup)
Maximum Operating Depth (MOD)
Only available as a custom display�
In OC mode MOD is the maximum
allowable depth of the current
breathing gas as determined by
PPO2 limits�
In CC mode, MOD is the maximum depth of the
diluent�
Displays in Flashing Red when exceeded�
Read more about PPO2 Limits on page 81
3:00
57 21 3.13
m
.3
AVG
.7
:
:
MAX
m
AvgATM
.o
3:00
57 21 3.13
m
.3
AVG
.7
:
:
MAX
m
AvgATM
.o
3:00
57 21 3.13
m
.3
AVG
.7
:
:
MAX
m
AvgATM
.o
18C
TEMP
STOP
TTS
OC 15/40
O2/HE
NDL
DEPTH
TIME
MOD
m
PPO2
61.0
1.15
0
57
TIME
56
22 39 1
.3
SurGF
%
83
Partial Pressure of Oxygen (PPO2)
In CC mode, displays in Flashing
Red when less than 0�40 or greater
than 1�6 by default�
In OC mode, displays in Flashing
Red when less than 0�19 or greater
than 1�65 by default�
Diluent PPO2
Only displayed in CC mode�
Displays in Flashing Red when the
partial pressure of the diluent is less
than 0�19 or greater than 1�65�
When performing a manual diluent
flush, you can check this value to
see what the expected PPO2 will be
at the current depth�
Fraction of Inspired O2 (FiO2)
Only displayed in CC mode�
The fraction of the breathing gas
composed of O2�
This value is independent of
pressure�
.36
PPO2
.16
PPO2
STOP
TTS
OC 15/40
O2/HE
NDL
DEPTH
TIME
Δ
DilPO2
PPO2
61.0
1.15
0
.99
TIME
56
22 39 1
SurGF
%
83
.42
FiO2
1.77
DilPO2

Page 19 Doc. 11301-Tec-RevB (2022-05-25)
Technical Modes
Operating Instructions
CNS Toxicity Percentage
Central Nervous System oxygen
toxicity loading percentage� Turns
Yellow when greater than 90%�
Turns Red when greater than 150%�
The CNS percentage is calculated
continuously, even when on the
surface and turned off� When deco
tissues are reset, the CNS will also
be reset�
The CNS value (short for Central Nervous System
Oxygen Toxicity) is a measure of how long you have
been exposed to elevated partial pressures of oxygen
(PPO2) as a percentage of a maximum allowable
exposure� As PPO2 goes up, the maximum allowable
exposure time goes down� The table we use is from
the NOAA Diving Manual (Fourth Edition)� The
computer linearly interpolates between these points
and extrapolates beyond them when necessary�
Above a PPO2 of 1�65 ATA, the CNS rate increases at a
fixed rate of 1% every 4 seconds�
During a dive the CNS never decreases� When back at
the surface, a half-life of elimination of 90 minutes is
used� So for example, if at the end of the dive the CNS
was 80%, then 90 minutes later it will be 40%� In 90
more minutes it will be 20%, etc� Typically after about
6 half-life times (9 hours), everything is back close to
equilibrium (0%)�
Rate
Numerical rate of ascent or descent�
Same colour rules as ascent indicator�
Available as a custom display only�
Mini Compass
A small compass that can be
displayed at all times� The red arrow
always points toward north�
Only available as a custom display
11
CNS
100
CNS
3:00
319

.7
:
:
DATE
43
RATE
ft
min
Gradient Factor
The deco conservatism value when
the deco model is set to GF� The low
and high gradient factors control
the conservatism of the Bühlmann
GF algorithm� See “Clearing up the
Confusion About Deep Stops” by
Erik Baker for more information�
VPM-B (and VPM-BG)
The deco conservatism value when
the deco model is set to VPM-B�
If the deco model is VPM-B/GFS,
also displays the gradient factor for
surfacing�
GF99
The current gradient factor as a
percentage (i�e� super-saturation
percent gradient)
0% means the leading tissue super-saturation is equal
to ambient pressure� Displays “On Gas” when tissue
tension is less than the inspired inert gas pressure�
100% means the leading tissue super-saturation is
equal to the original M-Value limit in the Bühlmann
ZHL-16C model�
GF99 is displayed in Yellow when the current gradient
factor modified M-Value (GF High) is exceeded�
GF99 is displayed in Red when 100% (un-modified
M-Value) is exceeded�
3:00
15 62 0
SurGF
.7
:
:
GF99
%
CEIL
%
3:00
20 12
GF
.7
:
:
TEMP
°C
CNS
30/70
+3
VPM-B
+3/90
VPM-BG

Page 20 Doc. 11301-Tec-RevB (2022-05-25)
Technical Modes
Operating Instructions
SurfGF
The surfacing gradient
factor expected if the diver
instantaneously surfaced�
SurfGF colour is based on the current GF (GF99)� If
the current GF is greater than GF High, SurfGF will be
displayed in Yellow� If the current gradient factor is
greater than 100%, SurfGF will be displayed in Red.
Ceiling
The current decompression ceiling
not rounded to the next deeper
stop increment� (i�e� not a multiple
of 10ft or 3m)
@+5
“At plus 5” is the TTS if remaining
at the current depth for 5 more
minutes� This can be used as a
measure of how fast you are on-
gassing or off-gassing�
Δ+5
The predicted change in TTS if you
were to stay at the current depth
for 5 more minutes�
A positive “Delta plus 5” indicates that you are on-
gassing the leading tissue while a negative number
indicates that you are off-gassing the leading tissue�
Battery
The Petrel 3’s battery voltage�
Displays in Yellow when the battery
is low and needs replacement�
Displays in Flashing Red when the
battery is critically low and must be
replaced as soon as possible� Also
shows battery type�
3:00
15 62 0
SurGF
.7
:
:
GF99
%
CEIL
%
STOP
TTS
OC 15/40
O2/HE
NDL
DEPTH
TIME
CEIL
PPO2
61.0
1.15
0
17
TIME
56
22 39 1
SurGF
%
83
STOP
TTS
OC 15/40
O2/HE
NDL
DEPTH
TIME
@+5
PPO2
61.0
1.15
0
20
TIME
56
22 39 1
SurGF
%
83
STOP
TTS
OC 15/40
O2/HE
NDL
DEPTH
TIME
Δ
Δ +5
PPO2
61.0
1.15
0
+8
TIME
56
22 39 1
SurGF
%
83
3.99V
BATTERY
3.7V
LiIon
Gas Density Display
The Gas Density display is only
available as a customizable display
and is not available in the info row�
For open circuit diving, the gas
density display turns yellow at 6�3
grams per liter� No other warnings
are generated�
For closed circuit diving, the gas
density display turns yellow at 5�2
grams per liter and red at 6�3 grams
per liter� No other warnings are
generated�
Gas density is an approximation based on the diluent
gas and loop PPO2�
You may be surprised at how shallow gas density
warning colors appear�
Read more about why we chose these levels starting
on page 66 here (recommendations on page 73):
Anthony, T.G and Mitchell, S.J. Respiratory physiology
of rebreatherdiving. In: Pollock NW, Sellers SH,
Godfrey JM, eds. Rebreathers and Scientific Diving.
Proceedings of NPS/NOAA/DAN/AAUS June 16-19,
2015 Workshop. Durham, NC; 2016.
Dive End Time (DET)
This is similar to TTS but is
expressed as a time of day�
The time of day at which you
can expect to surface if you
depart immediately, ascend at
10mpm or 33fpm, change gases
when prompted, and perform all
decompression stops as directed�
TIME
TTS
OC 21/00 0 3
O2/HE
NDL
24.0 22
DEPTH
TIME
STOP
SurGF
44
DENSITY
13
g
L
PPO2
71
%
TIME
TTS
OC 21/00 0 3
O2/HE
NDL
24.0 22
DEPTH
TIME
STOP
SurGF
44
DENSITY
53
g
L
PPO2
71
%
TIME
TTS
OC 21/00 0 3
O2/HE
NDL
24.0 22
DEPTH
TIME
STOP
SurGF
44
DENSITY
64
g
L
PPO2
71
%
STOP
TTS
OC 15/40
O2/HE
NDL
DEPTH
TIME
Δ
DET
PPO2
61.0
1.15
0
TIME
56
22 39 1
SurGF
%
831:31