Cochran Lifeguard 04-150i User manual

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LIFEGUARD™
PO2MONITOR
User Manual
English Language - Imperial Units
Version 150i
USER INFORMATION
For your records, please fill in the following information.
SERIAL NUMBER OF UNIT:_____________________________
DATE OF PURCHASE: ________________________________
PLACE OF PURCHASE: ________________________________
ADDRESS: ___________________________________________
CITY: _______________________________________________
STATE: __________________________ZIP CODE: __________
PHONE NUMBER: ___________________________________

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TABLE OF CONTENTS
Table of Contents 2
Figures Index 4
Limited Warranty and Liability Statement 5
Product Certifications 7
Patient Information 8
Introduction 9
Overview 9
User & Environmental Adaptation 9
Altitude Acclimatization 10
Water Temperature Compensation 11
Microbubble Compensation 11
Intelligent Deep-Dive Compensation 11
Salt Water/Fresh Water (High/Low Conductivity) 11
Theory of Operation 12
Equivalent Air Depth 13
Oxygen Toxicity 13
CNS 14
Pulmonary Oxygen Toxicity 15
Installation 17
CTU and O2Sensor 17
Activation 18
Shut-Off 18
Operating Modes 20
Self Diagnostic mode 20
Explanation of Page Layouts 20
Surface Mode 21
Predive Prediction Mode 22
CNS/OTU Toxicity Screen Display 24
Battery/Altitude Screen Display 25
Programming Mode 26
Calibration Mode 30
Subsurface Mode 33
Emergency Decompression Mode 35
Gauge Mode 39
Logbook Mode 42
Ascent Rate Bar Graph 44
Post-Dive Interval 45
Sleep Mode 45
Explanation 46
Altitude Diving 46
Ascent Rate 46
Ascent Rate Bar Graph 47

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TABLE OF CONTENTS
(continued)
BATT 47
Bottom 48
Ceiling 48
Depth 48
Dive 49
Max Depth 49
Metric 50
Remain Time NDC 50
Remain Time DEC 50
Surface Time 50
Tank 50
Temp 51
Time-To-Fly 51
Audible & Visual Warnings 52
Maximum Depth 52
Two-Minute 53
Entering Deco 53
60 FT Deco Stop 53
Ceiling Violation 53
Low Battery 53
Ascent Rate 54
Gauge Mode 54
OTU 54
CNS 54
Max PO255
Min PO255
Questions & Answers 56
Care and Maintenance 58
Rinsing and Cleaning 58
O2Sensor Care 59
Battery Type and Replacement 59
Battery Care 60
Technical Specifications 61
Product Assistance & Maintenance 62
Replacement Parts 63
Analyst® Personal Computer Interface 64
Field Programmer 64

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FIGURES INDEX
Figure Page Number
1. Self-Diagnostic Mode 20
2. Surface Mode, Primary Screen, with Nitrogen 21
3. Surface Mode, Alternate Screen, with Nitrogen 22
4. PreDive Prediction Mode, Primary Screen 23
5. CNS/OTU Toxicity Display 24
6. Battery/Altitude Display 25
7. Logbook Mode, Primary Screen 43
8. Logbook Mode, Alternate Screen 43
9. Subsurface Mode, Normal Dive, Primary Screen 33
10. Subsurface Mode, Normal Dive, Alternate Screen 34
11. Subsurface Mode, Emergency Decompression Dive,
Showing STOP Time, Primary Screen 36
12. Subsurface Mode, Emergency Decompression Dive,
Showing TOTAL Time, Primary Screen 37
13. Subsurface Mode, Emergency Decompression Dive,
Alternate Screen 38
14. Subsurface Mode, Gauge Mode, Primary Screen 40
15. CNS/OTU Toxicity Warning Display 42
17. Connecting Field Programming Probe 27
18. Field Programming Mode (Setting Conservatism) 29
19. Field Programming Mode (Setting Depth Alarm) 29
20a. Calibration Mode (Sensor Exposed to Air) 30
20b. Calibration Mode (Sensor Stabilized with 100%) 31
20c. Calibration Mode (Calibrated & Showing 100%) 32
21. Ascent Rate Bar Graph 44

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LIMITED WARRANTY
To the original purchaser ("OWNER") only, Cochran Undersea Technology, a
division of Cochran Consulting, Inc. ("COCHRAN"), represents this Product to be
free of defects in materials and workmanship under normal SCUBA use for 12
months from the date of shipment to the Authorized Dealer from which it was
purchased. For purposes of establishing warranty eligibility, date of shipment to
Authorized Dealer is noted on the original Product package, or can be
determined by contacting COCHRAN.
Any defective Product, unless cause is specifically excluded in the "Warranty
Conditions and Limitations" section below, will, at the sole discretion of
COCHRAN, be repaired or replaced with a new or refurbished unit of comparable
or better function and condition. COCHRAN is not responsible for any incidental
or secondary damages as a result of Product malfunction
WARRANTY CONDITIONS and LIMITATIONS
Product must have been obtained from a COCHRAN Authorized Dealer.
Verification of Dealer status at the time of the purchase may be obtained by
contacting COCHRAN. This Limited Warranty is not transferable. Warranty
Registration card must be sent to COCHRAN within 15 days of purchase in order
to validate Limited Warranty.
Failure to provide proper care for Product will render this Limited Warranty null
and void. Damages or malfunction resulting from accidental or deliberate abuse,
tampering, battery leakage, exceeding maximum intended operating depth,
extreme heat or cold, or other conditions which COCHRAN may deem to be
outside the intended scope of this Limited Warranty are not covered. Any
modifications or repairs to Product performed by anyone other than a COCHRAN
Authorized Dealer will void this warranty. Plastics, O-rings, oxygen sensors, and
batteries are specifically excluded from this Limited Warranty.
This Limited Warranty will be rendered null and void if an attempt is made to
establish communication with computer with any hardware and/or software other
than the Cochran approved ANALYST®Interface.
OWNER is responsible for shipping this Product to COCHRAN for service, and
paying all associated costs including shipping, insurance and import duties.
OWNER may take Product to an Authorized Dealer to arrange for service under
terms of this Limited Warranty. COCHRAN will return Product to OWNER or
Dealer via a method and carrier of its choosing. Costs for requested expedited
return shipping will be the responsibility of OWNER. Product returned for service
under the terms of this Limited Warranty must be accompanied by a photocopy
of the original sales receipt in order for any warranty repair or replacement to be
performed if Warranty Registration Card is nor on file.

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STATEMENT OF LIMITED LIABILITY
A mathematical model is used by this Product to calculate physiological effects of
SCUBA diving related to use of compressed air or other breathing mixtures while
at depth. Such effects specifically relate to nitrogen absorption into and
elimination from body tissues, as well as effects of oxygen used in Enriched Air
Nitrox breathing mixtures. However, because of the number of variables and the
varying degrees to which they may affect individuals engaged in SCUBA diving,
COCHRAN DOES NOT IN ANY WAY GUARANTEE THAT USE OF THIS
PRODUCT WILL PREVENT DECOMPRESSION SICKNESS OR ANY OTHER
CONDITION OR INJURY INCURRED WHILE USING THIS PRODUCT.
These influencing variables may include but are not limited to dehydration,
obesity, age, old injuries or illnesses, or other physical conditions on the part of
the diver, or environmental extremes of heat, cold, or altitude, or diving practices
which may promote the onset of decompression sickness or other harmful
effects.
This Product is sold and intended to be used only as a guide, providing the
TRAINED and CERTIFIED diver the information needed to make his own
intelligent diving decisions. It is expressly understood that by buying and/or
using this Product the Diver assumes ALL RISK as to its operability, reliability,
quality, performance, accuracy, and suitability for his diving style. Furthermore,
Diver recognizes that this Product is an electronic instrument being used in a
hostile environment and is subject to failure, which may manifest itself in a
number of ways. COCHRAN and its distributors and retailers will not be held
liable for any personal injuries or other damages resulting from its use, even if
COCHRAN has been advised of such occurrences or damages.
These products must be handled with care and properly maintained to assure the
optimum performance. Users must possess the proper training for SCUBA
diving activities and should be fully educated in the operation of this product.
Users are encouraged to possess and utilize a redundant (backup) computer for
their dive planning and execution. Divers are always encouraged to dive with a
buddy at all times.
Cochran strongly supports and agrees with maximum depth limits of 130 feet for
recreational SCUBA diving, as established by recognized training and
certification agencies, and in no way encourages diving beyond these or any
prudent limits as may be necessitated by environmental, diver-specific, or other
conditions.
THE WARRANTY AND REMEDIES SET FORTH ABOVE ARE EXCLUSIVE
AND IN LIEU OF ALL OTHERS, WHETHER ORAL OR WRITTEN, EXPRESSED
OR IMPLIED. COCHRAN UNDERSEA TECHNOLOGY SPECIFICALLY
DISCLAIMS ANY AND ALL IMPLIED WARRANTIES, INCLUDING, WITHOUT
LIMITATION, WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE.

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No Cochran Undersea Technology dealer, agent, or employee is authorized to
make any modification, extension, or addition to this warranty.
CAUTION!!! ACCIDENTAL OR INTENTIONAL LOSS OF BATTERY POWER
WILL CAUSE ALL PREVIOUS DIVE NITROGEN LOADING TO BE LOST. THIS
MAY AFFECT NITROGEN CALCULATIONS ON NEAR-FUTURE DIVES.
AFTER A BATTERY CHANGE, CONFIRM THAT NO-DECOMPRESSION TIME
DATA IS REASONABLE DURING THE PRE-DIVE PREDICTION MODE. DIVE-
OF-DAY NUMBER GOING TO ZERO IMMEDIATELY AFTER CHANGING
BATTERIES IS ANOTHER INDICATION OF A LOSS OF NITROGEN LOADING.
IF LOSS OF NITROGEN LOADING OCCURS, COCHRAN STRONGLY
RECOMMENDS THAT A PERIOD OF 24 HOURS ELAPSES BEFORE MAKING
ANY SUBSEQUENT DIVES.
FCC Label
FCC ID: LYP744556-01
This device complies with Part 15 of the FCC Rules. Operation is subject to the
following two conditions: (1) this device may not cause harmful interference, and
(2) this device must accept any interference received, including interference that
may cause undesired operation.
Interference Statement
NOTE: This equipment has been tested and found to comply with both the limits
for a Class B digital device and an intentional radiator, pursuant to Part 15,
Subpart B/C of the FCC Rules. This equipment generates, uses, and radiates
radio frequency energy. If not installed and used in accordance with the
instructions, it may cause interference to radio communications. The limits are
designed to provide reasonable protection against such interference in a
residential situation. However, there is no guarantee that interference will not
occur in a particular installation. If this equipment does cause interference to
radio or television reception, which can be determined by turning the equipment
on and off, the user is encouraged to try to correct the interference by one or
more of the following measures:
•Reorient or relocate the receiving antenna of the affected radio or
television.
•Increase the separation between the equipment and the affected
receiver.
•Connect the equipment and the affected receiver to power outlets on
separate circuits.
•Consult the dealer or an experienced radio/TV technician for help.

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Modifications
Changes or modifications not expressly approved by Cochran Consulting, Inc.
could void the user’s authority to operate the equipment.
Shielded Cables
To maintain compliance with FCC Regulations, this product is designed only for
use with the ANALYST®interface cable (RS-232).
Patent Information
Protected under one or more Foreign or US patents. Other patents pending.
All specifications subject to change without prior notice. LIFEGUARD and
Analyst are registered trademarks of Cochran Consulting, Inc. Copyright 1999
Cochran Consulting, Inc.
(C) 1999 Cochran Undersea Technology
LIFEGUARD Manual
English - Imperial
Version 150i

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Introduction
The LIFEGUARD™ PO2Monitor from Cochran Undersea Technology is an
independent monitoring device designed to be integrated with the breathing loop
of most commercially available rebreathers. It provides oxygen level (PO2)
monitoring in addition to the functionality of a sophisticated dive computer. User-
programmable options accommodate a broad range of personal preferences and
diving conditions, yet the LIFEGUARD™ remains very simple to use. All
essential information is continually updated and presented on an informative and
easy to comprehend display, with minimal distraction. Audible alerts advise of
conditions, which require immediate attention. Throughout the course of each
dive vital data is stored internally for later retrieval and study via the ANALYST™
PC Interface System.
This manual is organized to provide the basic operating information first, followed
by more technical and detailed sections for reference. The LIFEGUARD™ user
is strongly encouraged to read this document thoroughly before attempting
any operation of the device.
We wish to thank Dr. Bill Hamilton for working with us and sharing his
considerable knowledge in the areas of decompression theory and oxygen
toxicity.
The LIFEGUARD™: Overview
USER & ENVIROMENTAL ADAPTATION
The LIFEGUARD™ is designed and intended for use with rebreather devices,
where a combination of factors drives the need for monitoring oxygen levels
(PO2) in the breathing mixture. Additionally, the LIFEGUARD™ is one of the
new breed of Dive Computers that adapts its algorithm to the user’s diving
environment and style as originally pioneered by COCHRAN. All of COCHRAN’s
newer dive computers incorporate this capability. The factors used for this
‘Adaptation’ in the LIFEGUARD™ are:
Altitude Acclimatization Water Temperature
Salt/Fresh Water Compensation Microbubble
User Conservatism Previous Dive Profile
Intelligent Deep-Dive Compensation
However, the LIFEGUARD™ allows the diver, via the optional Analyst®PC
Interface, to disable the Temperature compensation should the diver deem a
particular diving situation would so warrant. Calculation of Central Nervous
System Oxygen Toxicity (CNS), Mission Oxygen Tolerance Units (OTU's), and
the Partial Pressure of Oxygen (PO2) is yet another added feature of this
algorithm. Twelve half-time compartments ranging from 5 minute to 480-minute

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theoretical tissue groups are used. You will find that this unit is extremely user
friendly and can be customized to your individual diving conditions and practices.
Factors that influence the decompression algorithm of your LIFEGUARD™ are
detailed as follows.
Altitude Acclimatization
Driving or flying to a dive site significantly higher in altitude requires special
modifications to the "sea level" algorithm. The LIFEGUARD™ regularly samples
the ambient barometric pressure to determine these changes in altitude.
Accordingly, the decompression algorithm is changed to reflect these barometric
pressure changes. Note that temperature and weather systems also affect
barometric pressure and hence, apparent altitude. Using the Time To Fly digits,
the number of hours required to adapt to the new altitude is immediately known
to the diver. If a significant altitude change occurs, a minimum of one hour
should pass before diving to allow the unit to adapt to this new altitude. Rapid
changes in altitude should be avoided. The dive computer may interpret a rapid
change from a high altitude to a lower altitude as a dive. Should this occur,
removing the batteries for ten minutes would reset the computer, however, all
tissue nitrogen loading will also be lost.
Should it be desired to initiate a dive PRIOR to completing the adaptation time,
the LIFEGUARD™ will treat this dive as a repetitive dive in its algorithm, taking
into account the "residual" nitrogen present due to travel to altitude. There are
two methods of compensating for altitude. Via the Analyst®Personal Computer
Interface, ZONE or SEAMLESS compensation for altitude may be selected.
In ZONE, all altitudes less than 2,000 feet above sea level use the sea-level
algorithm. At altitudes greater than this, altitude compensation is seamless;
literally, every small fraction of gained altitude is considered in adjusting the
algorithm. ZONE will reduce the occurrences of obtaining slightly different
altitude readings and corresponding no-decompression (NDC) limits when diving
within a given area. ZONE reduces the accuracy of altitude compensation for the
first 2,000 feet above sea level, treating altitudes below 2,000 feet as sea level.
The advantage in ZONE is that changes in apparent altitude (due to temperature
or weather changes at sea level) will not affect NDC computations.
In SEAMLESS, the algorithm is adjusted for extremely small changes in altitude.
A difference in altitude may be seen from day-to-day at a given dive site due to
temperature or weather systems and their effect on barometric pressures.
SEAMLESS will provide the most accurate altitude compensation algorithm, but
normal variations in atmospheric barometric pressure may affect the no-
decompression time which is more predominantly seen in the Pre-dive Prediction
forecast.