Cochran Lifeguard 04-150i, Lifeguard 150i User Manual

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LIFEGUARD™

PO2 MONITOR

User Manual

English Language - Imperial Units

Version 150i

USER INFORMATION

For your records, please f ill in the following information.

SERIAL NUMBER OF UNIT:_____________________________ DATE OF PURCHASE: ________________________________ PLACE OF PURCHASE: ________________________________ ADDRESS: ____________________ ___ ___ ___ ___ ___ __ ___ ___ CITY: _______________________________________________ STATE: __________________________ZIP CODE: __________

PHONE NUMBER: ___________________________

________

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 O

Sensor 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

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 PO

Min PO

55 Questions & Answers 56 Care and Maintenance 58

Rinsing and Cleaning 58 O

Sensor 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

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

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 servi ce, 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.

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.

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. DIVEOF-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 Stat ement

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.

Modifications

Changes or modifications not expressly approved by Cochran Consulting, Inc. could void the user’s authority to operate t he equi pme nt.

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

LIFEGUARD Manual

English - Imperial

Version 150i

Introduction

The

LIFEGUARD™

PO2 Monitor 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 (PO

) monitoring in addition to the functionality of a sophisticated dive computer. Userprogrammable 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 (PO

) 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 (PO

) is yet another added feature of this

algorithm. Twelve half-time compartments ranging from 5 minute to 480-minute

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.

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 nodecompression time which is more predominantly seen in the Pre-dive Prediction forecast.

WARNING: While your LIFEGUARD™ will automatically adjust its no decompression algorithm for altitude, you should NOT attempt to dive at altitudes greater than 1,000 feet above sea level without first completing a sanctioned altitude diving course from a recognized training agency for recreational diving. The LIFEGUARD™ should not be used for this type of diving by anyone without this important training.

WATER TEMPERATURE

Diving in cold water can lower a diver's core and skin temperature, affecting the gas exchange rate of the body’s tissues. The LIFEGUARD™ progressively makes its nitrogen algorithms more conservative as the water temperature declines below 75 degrees F. Above this water temperature, there is no temperature compensation. If the diver is wearing an insulated dry suit and is relatively warm even in cold water, this temperature compensation factor may be turned off at the divers discretion using the Analyst

PC software.

MICROBUBBLE

There are several theories regarding the method by which a nitrogen bubble forms from a microbubble which was formed from micronuclei. Currently, the predominant theory states that more rapid ascents accelerate bubble formation. The

LIFEGUARD™

accounts for this by progressively increasing its

compensation as the diver’s ascent rate exceeds 30 feet-per-minute (fpm).

Intelligent Deep-Dive Compensation

Research has established that successive dive profiles in a given dive day should be progressively shallower to minimize susceptibility to decompression sickness (DCS). Avoiding inverted; square or "sawtooth" dive profiles also greatly decreases the risk of DCS symptoms. Intelligent Deep-dive Compensation provides real-time real-condition adjustments to the nitrogen level calculations in all 12 half-time compartments as the LIFEGUARD™ monitors activity during the course of a dive day. Should the dive patterns result in elevated risk of DCS, displayed information on remaining no-decompression (NDC) time (or decompression time) will be adjusted accordingly.

Sea Water/Fresh Wa ter Recognition

(High/Low Conductivity)

There is approximately a three-percent difference in depth readings taken in fresh water versus seawater. Some dive computers are calibrated in feet of fresh water and some are calibrated in feet of salt water. Diving in a medium different from what the dive computer is calibrated will cause apparent depth errors. Only COCHRAN dive computer s, including the LIFEGUARD™, actually determine the type of diving medium and compensate the depth reading accordingly. This is accomplished by measuring the conductivity of the water during a dive. Caution must be taken in interpreting this reading since some apparent fresh water is

actually high in minerals or contaminants and is correctly compensated as salt water (high conductivity). This commonly occurs in some caves, springs and lakes.

THEORY OF OPERATION

The LIFEGUARD™ is designed to constantly monitor and display Partial Pressure of Oxygen (PO

) in addition to the conventional dive computer

information. This PO

value is directly sensed from the breathing loop, and is used for no-decompression/decompression calculations, oxygen toxicity tracking, and other related functions. The diver is able to maintain continual awareness of this essential "raw value" as well as the derived computations.

The LIFEGUARD™ consists of three component parts, the ComputerTransmitter Unit (CTU), the Wrist Unit (WU), and the PO

Sensor. The CTU contains the computer’s electronics, the WU displays the information to the diver, and the PO

Sensor measures the PO2 of the loop gas.

Wrist Unit

The Wrist Unit consists of a Liquid Crystal Display (LCD) screen that Is the primary method of conveying information to the Diver. The information is presented in an easy to read and understand layout. The Wrist Unit is supplied with TACLITE™, the night vision safe red Backlight. Two ENERGIZER

brand NCell Size Alkaline battery power the WU. The WU will receive information from the LIFEGUARD™ CTU from approximately 36 inches; the actual distance will vary depending on the orientation of the WU to the CTU. When the WU is beyond the communications range of the CTU the WU’s display will flash. When the WU is back in communication with the CTU the display will cease flashing.

Computer-Transmitter Unit

The CTU contains the PO2 Sensor connector cable, the Depth/Altitude Sensor, and the computer’s electronics. The CTU performs all of the time-depth calculations and also stores the detailed statistics and profile information. The CTU transmits all information to the WU once per second where it is displayed. Four ENERGIZER

brand AA-cell batteries power the TU; the batteries should be

Alkaline, non-tester.

NOTE: The WU and CTU contain NO USER SERVICABLE PARTS, If the lens is removed from the WU and/or the lid from the CTU it will VOID the limited warranty.

PO2 Sensor

The LIFEGUARD™ is supplied with one of two versions of PO2 Sensors. One version is supplied with a bulkhead connector and sensor. The other version is a "tee" designed to be installed in the inhalation side breathing hose. The "tee" is avaliable in two different diameters.

Equivalent Air Depth

Your LIFEGUARD™ uses Equivalent Air Depth (EAD) in determining the nodecompression limits for each individual dive. A standard NOAA equation is used to determine the EAD based on the oxygen percentage entered. This equation is:

METRIC IMPERIAL

EAD = ( 1 - O

% ) X ( D + 10 ) - 10 EAD = ( 1 - O2 % ) X ( D + 33 ) - 33

.79 .79

Where O

% is entered in decimal form and D is the actual depth in meters/feet.

For example, if you were diving with NOAA II (36% oxygen) to 21 meters / 70 feet, the EAD used for determining your no-decompression would be:

METRIC IMPERIAL

EAD = ( 1 - .36 ) X ( 21 + 10 ) - 10 EAD = ( 1 - .36

) X ( 70 + 33 ) - 33

.79 .79

EAD

= .64 X 31 - 10 = 15.11m

EAD

= .64 X 103 - 33 = 50.44

.79 .79

Therefore, the no-decompression time for this example would be derived from an EAD of 15.1 meters/50.4 feet.

Oxygen Toxicity

While oxygen is, of course, necessary to sustain life, its effects at increased ambient pressures can be quite harmful. It is generally agreed that oxygen toxicity manifests itself in two forms. Of the two, Central Nervous System (CNS) toxicity is the more immediate and potentially dangerous condition. Pulmonary (or "whole-body") toxicity is a longer-term, cumulative effect, which also needs to be monitored. The

LIFEGUARD™

provides audible and visual warnings to alert the diver to buildup of both types of toxicity. Similar to decompression issues, oxygen toxicity is as much theoretical as it is practical, and many varying factors influence the degree and symptomatic presentation of this condition. But research in recent years has led to development of mathematical models, which can generally predict onset of oxygen toxicity in both its main forms before serious harm is done. It is with

these provisions in mind that the following information is presented. The discussion is intended only as a brief overview to the extent necessary for explanation of the LIFEGUARD™ product's functionality. Neither this information nor the product is intended to take the place of extensive training and certification necessary for safe use of rebreathers and enriched air breathing mixtures.

Central Nervous System (CNS) Oxygen Toxicity

Maximum allowable exposure time calculations for a given depth are based on Partial Pressure of Oxygen (PO

). Exceeding a PO2 of 1.6 greatly increases the likelihood of immediate onset of CNS Oxygen Toxicity symptoms. The LIFEGUARD™ calculates CNS toxicity percentages and issues a unique, five double-beep audible alar m once per min ute sho uld the div er reach or exceed 75 percent of the associated max imum lim it. In addition to this audible warning, the WARNING legend will flash on the Wrist Unit (WU) and the TEMPerature digits will be replaced with the current calculated CNS Oxygen Toxicity percentage. This warning status will continue until the calculated toxicity is less than 75 percent.

Maximum exposure time for a given depth is calculated based on the Partial Pressure of Oxygen (PO

). The following formula is used to determine the PO

METRIC IMPERIAL

( D + 10 ) X O

% = PO

(

D + 33 ) X O2% = PO

10 33

For example, if you were diving to 31 Meters/100 Feet with NOAA II (36% O

)

your PO

level would be:

METRIC IMPERIAL

( 31 + 10 ) X .36 = 1.48 ( 100 + 33 ) X .36 = 1.45

10 33

which gives a (rounded up) PO

value of 1.5.

Exceeding a PO

of 1.6 will greatly increase the probability of the immediate onset of CNS Oxygen Toxicity. While various training organizations have established maximum PO

limits, the maximum exposure times and their

associated PO

levels used in this dive computer's calculations are shown on the

following table:

PO2 LEVEL Max Bottom Time (minutes)

(Based on CNS Exposure) .5 1304 .6 719 .7 496 .8 379 .9 257

1.1 221

1.2 194

1.3 172

1.4 149

1.5 110

1.6 44

Your dive computer calculates CNS or OTU toxicity percentages and it issues a unique, five double-beep audible alarm once per minute should you reach 75 percent of the associated max imum lim it. In addition to this audible warning, the WARNING legend will appear and flash AND the TEMPerature digits will be replaced with the current calculated CNS Oxygen Toxicity percentage. This warning will continue until the calculated toxicity percentage is less than 75 percent. For example, the maximum bottom time exposure for a PO

level of 1.4

is 149 minutes. Once you reached 112 minutes of bottom time with a PO

of 1.4,

this alarm would be issued since 112 minutes is 75% of 149 minutes. At a PO

of 1.5, this alarm would be issued at 82 minutes, etc.

NOTE: While all other audible alarms of the dive computer consist of five long beeps, the toxicity audible alarm consists of short doublebeeps that sound for five seconds.

Pulmonary (Whole Body) Oxygen Toxicity

Another key function to recognize when breathing mixtures with an O2 content greater than 50 percent is Pulmonary Oxygen Toxicity, also called “Whole Body”

Toxicity. This is a cumulative development, which must also be tracked accurately, and is of particular importance should the diver require recompression therapy or have extended exposure to elevated levels of O

LIFEGUARD™ monitors and computes this longer-term effect as "Oxygen Tolerance Units" ( OTUs ) based on Bill Hamilton’s MODIFIED REPEX method of oxygen exposure management. The following chart illustrates how the OTU function relates to diving activity:

REPEX MAXIMUM DAILY OTU CHART

DAY Daily Dose Period Total

1 850 850 2 700 1400 3 620 1860 4 525 2100 5 460 2300 6 420 2520 7 380 2660 8 350 2800 9 330 2970 10 310 3100 11 300 3300 12 300 3600 13 300 3900 14 300 4200 15 - 30 300 N/A

OTUs are an exponential function of oxygen partial pressure. The timedependent limit varies with the number of days that the diver continues to dive without full recovery. The recovery portion of the whole body effect algorithm is a linear reduction of OTUs over time. The Mission OTU Clock continues running as it tracks cumulative Oxygen exposure. Depending on frequency of dives and other determining factors, as well as between-dive recovery time, this clock may run for several weeks. The clock resets to 0:00 when the OTU level has dropped to 0.

Symptoms of Pulmonary O

Toxicity include burning in the throat and chest,

coughing, and shortness of breath. Should any of these symptoms be experienced, discontinue diving immediately and consult a Doctor.

NOTE: While most other audible alarms of the dive computer consist

of five long beeps, the OTU, PO

, and CNS audible alarm consists of

short double-beeps that sound for five seconds. WARNING: It is possible in certain diving circumstances to reach an

Oxygen Toxicity limit well before reaching a no-decompression limit. For this reason and many others, only a diver who has successfully completed a sanctioned REBREATHER diving course from a recognized training and certifying agency should conduct REBREATHER diving.

Installation

CTU and O2 Sensor

The O2 Sensor should be mounted in the inhalation side of the breathing loop, located where it will not be subjected to water contamination. In most designs the

CTU connects, by means of the watertight bulkhead connector, to the O2 Sensor or by the T adapter which is designed to be placed in line on the breathing hose.

This allows for easy removal of the CTU from the rebreather when necessary.

Note: Press the CTU cable into the bulkhead adapter or "Tee". Finger tighten the ring and press in and finger tighten again. Repeat this process of press and tighten until the connection 'bottoms out'. DO NOT USE TOOLS FOR THIS PROCEDURE

The CTU should be secured in a protected area of the rebreather to prevent snagging and impact with objects, which could damage it. The object is to secure the bulkhead fitting to the outer case with the wires and Molex connector passing through into the counterlung, where the Molex plug attaches to the O

Sensor with the moisture barrier cap (“boot”) pressed down

over the back of the sensor. Bulkhead Mounting Kit Parts List:

1- bulkhead connector assembly consisting of

• three-pin external bulkhead fitting with O-ring on back side

• three-wire harness terminating in 3-hole Molex connector,

with moisture barrier cap (“boot”) 1- retaining nut for bulkhead fitting 1- long cable tie 1- short cable tie

Sensor

1- Sensor OR 1- Tee including Sensor

Wrist Unit (WU)

The Wrist Unit (WU) may be worn on the wrist or attached to the rebreather by its strap or the optional retractor sold by Cochran, as long as it remains within its intended operating range of approximately 3 feet.

Activation

The CTU will automatically activate when it senses an Oxygen level at or above the turn-on set point programmed by the user or by using the power activator area (the “PWR” symbol inside the circular, crosshatched imprint on the left side of the case lid). A sharp rap on this area with the edge of a coin works best. The CTU will issue five "beeps" when it activates using either method.

NOTE: If the CTU is in the Altitude Adaptation Mode, four beeps, rather than five, will be issued.

NOTE: The CTU must be in less than 3 feet of water in order to activate. At depths below three feet the CTU will not turn on manually or by sensing elevated O2 levels. It is strongly recommended that the

Lifeguard

is activated on the surface shortly before beginning the dive, so that its proper operation can be confirmed at the same time other routine equipment checks are performed.

Shut-Off

You cannot manually turn the CTU off. The CTU will turn off:

1. After 30 minutes if no elevated PO

is sensed and no dive is made

2. The Oxygen level drops below the preset activation threshold.

3. All 12 nitrogen half-time compartments are completely "off-gassed" on

repetitive dives.

After a dive the Lifeguard

CTU will remain on for 40 minutes before automatically enter a "sleep" mode to conserve battery life. During this sleep mode, all off-gassing calculations continue to run, but the CTU does not transmit this data. To view current surface interval, time-to-fly, and other data, re-activate the CTU just as would be done when first turning it on. Once “awakened” from its sleep mode, the CTU will remain in active mode for one hour before reentering the sleep mode. This assumes, of course that no repetitive dive is initiated between each wake-up.

NOTE: The LIFEGUARD™ will not enter the Sleep Mode or turn off as long as the PO

sensor is exposed to an oxygen level above the user

programmed turn-on set point.

To activate the WU, perform one of the following for five seconds (or until the display becomes active): (1) rotate your wrist or (2) tap continuously on the lower left corner of the face. Care has been taken to reduce the occurrence of the WU being accidentally activated during transport, the WU may have to be rotated or tapped for a longer period of time. The same rotating or tapping action is used to select the alternate screen. The alternate screen is shown for three seconds before returning to the normal screen. The TACLITE™ active backlighting for the

WU display is also activated whenever the alternate screen is selected. TACLITE™ will remain illuminated for approximately 10 seconds.

Since all diving calculations are made by the TU, it is possible to activate the WU underwater should you mistakenly forget to do so prior to the dive. Once activated, the WU will immediately display the current diving data being calculated by your TU. During the dive, it is not possible to turn the WU off.

Once back on the surface, you can manually turn the WU off. This is recommended as a battery saving measure since all calculations are being performed by the TU. To turn the WU off on the surface, continuously tap the WU, in the same manner as that used to activate the unit, until the display goes blank. With a little practice, you will learn how much tapping is required to turn off the WU.

OPERATING MODES

Self-Diagnostic Mode

At turn-on, both the CTU and WU complete self-diagnostic tests before displaying current information. During these tests, all of the legends and digits on the WU illuminate for approximately 5 seconds. During these tests if an error or malfunction is detected, the unit will turn itself back off. Some of the reasons are:

1. Altitude over 15,000 feet

2. Battery voltage too low

3. Internal diagnostic fault

Upon completion, the LIFEGUARD™ enters Surface Mode.

Fig-1

Self-Diagnostic Mode

Explanation of Page Layouts

The following pages provide a snapshot of the screen displays for each of the computers various functional modes, showing:

1. An illustration of the WU screen

2. The LEGEND displayed

3. The MEANING of that legend

4. The VALUE depicted under that legend

Any

WARNINGS

NOTES

about that mode will be displayed on this page.

Surface Mode

At the completion of Self-Diagnostic Mode (about 10 seconds), the LIFEGUARD™ enters Surface Mode. The Surface Mode has two screens; a Primary Screen and an Alternate Screen. You may switch to the Alternate Screen by rotating the wrist quickly or tapping firmly on the face of the WU. The Primary Screen shows: DIVE number, time-to-FLY, TEMPerature, SURFace time, PO

(times 100), and MAXimum DEPTH (of the last dive). The Alternate

Screen shows the last dive's BOTTOM time, and O

2 percent, then reverts to Main

Display mode after 3 seconds. The following sample displays are of Surface Mode.

Fig-2

Primary Screen, With Residual Nitrogen

• DIVE of the day number 2 (2nd dive of day)

• current time-to-Fly 15 hours

• present air TEMPerature 73 deg. F

• current SURFace time 0:20 minutes

• TANK indicating current PO

times 100 .51 ata

• Maximum Depth (of previous dive) 118 feet

Surface Mode (continued)

Fig-3

Alternate Screen, with residual Nitrogen

• BOTTOM time of last dive 1:26 (1 hr. 26 min)

• BP indicating percent O

2 in current mix .51 (51%)

PreDive Prediction Mode

After 1 minute of Surface Mode, the

LIFEGUARD™

enters its PreDive Prediction Mode. The PreDive depths start at 30 feet and increase in 10-foot increments. The PreDive Predictions will terminate when the No-Decompression (NDC) time prediction is at least 2 minutes or when the set maximum PreDive Prediction depth is reached, or when the user-set MAX PO

Alarm is computed. The

LIFEGUARD™ calculates the PreDive Prediction times based on either the PO

or FO2 of the gas in the loop. Whether PO2 or FO2 is used in the predictions is selected via the ANALYST

. If FO2 is selected the fractional percentage of oxygen in the breathing gas in the loop will be used only for PreDive Prediction. The no-decompression (NDC) times that a r e computed during a dive are calculated on the PO

of the loop gas regardless of the PreDive Prediction selection. There is only a Primary Screen in this mode. The WU shows DEPTH, current system PO

/ FO2 and NDC (no-decompression time). The Predive Information mode is repeated once each minute after being turned on. It continues this cycle until either a dive is initiated or the time out limit is reached.

Predive Predictio n M o de (continued)

Fig-4

Primary Screen

• REMAINing TIME NDC 2:09 (2 hrs. 9 min.)

• TANK indicting system PO

times 100 .37 ata

• Or in FO2 mode

• TANK indicting system FO

in percent 37 %

• predicted DEPTH 60 (feet)

CNS/OTU Toxicity Display

At the conclusion of each Predive Prediction Mode cycle, the LIFEGUARD™ enters Predive Information Mode, and first displays current Central Nervous System (CNS) Toxicity and Oxygen Tolerance Unit (OTU) Toxicity levels. These values are shown as percentages. This screen will be displayed for three seconds. There is only a Primary Screen for this mode.

Fig-5

Primary Display

• REMAINing TIME NDC 2:00 Indicates CNS/OTU

• TANK indicating CNS toxicity percentage 27%

• DEPTH indicating OTU toxicity percentage 8%

Battery/Altitude Display

At the conclusion of the CNS/OTU Toxicity display, current CTU battery voltage and altitude are shown for 3 seconds. The two digits under the DEPTH legend indicate the current CTU battery voltage as a factor of 10. For example, if the CTU's battery voltage were 5.8 volts, the two digits under the DEPTH legend would read 58.

The numbers under the TANK legend display altitude in 1000-foot increments. For example, a 2 under the TANK legend would indicate an altitude of 2000 feet above sea level.

After this 3-second display, the unit returns to Surface Mode. There is only a Main Display for Predive Information Battery/Altitude mode.

Fig-10

Primary Screen

• REMAINing TIME NDC 0:00 indicates Battery/Altitude

• TANK indicting Altitude value 2000 feet above sea level

• DEPTH indicting Battery voltage 5.8 volts

WARNING: While the LIFEGUARD™ will automatically adjust its nodecompression algorithm for altitude, do NOT attempt to dive at altitudes greater than 1,000 feet above sea level without first completing a sanctioned altitude diving course from a recognized training agency. A LIFEGUARD™ should not be used at altitude without this essential training.

Programming Mode

By using the Field Programmer the following functions may be programmed directly into the LIFEGUARD™ with out the necessity of a P.C.

• Added Conservatism factor

• Depth Alarm preset

• O2 Calibration

NOTE: It is essential that the LIFEGUARD™ be calibrated before its first use and prior to the beginning of each diving day. Additional calibration checks may also be advisable on an extended dive day.

The P rogramming Mode is entered from normal Surface Mode. If Pre-Dive Predict scrolling is taking place, wait until the cycle is completed before proceeding.

Characters and digits in the upper left corner of the WU display indicate the function being programmed. Digits in the lower center of the display indicate the values being set for each programming element. For purposes of Programming and Calibration modes, disregard the figures on the lower left and lower right corners of the display. These are CNS and OTU oxygen toxicity values as explained later in this manual.

All programming sequences use the same routine of pressing the “

SELECT

” button to bring up the desired programming element and

the “

INCREMENT

” button to change the values within the selected element. It is necessary to hold the button down for approximately 1 second to cause the selected value to change. You may also hold the buttons down for continuous scrolling through each button’s sequence of available values. Each change of the SELECT or INCREMENT value will cause the Computer-Transmitter Unit (CTU) to issue a single beep and the letter (SELECT) or numeral (INCREMENT) to change as they are stepped through. If a value requires three digits to be programmed, a -3, -2, and -1 will be displayed in the upper left hand corner in that order. The -3 identifies the most significant (farthest left) digit, of the value being displayed. The -2 identifies the next most significant (center) digit, and the -1 identifies the least significant (farthest right) digit.

To begin the programming sequence:

1. Insure that the O2 sensing unit is properly attached to the CTU by means of

the waterproof cable and fittings.

Programming Mode (continued)

2. Turn the CTU on. This is done either by exposing the sensing unit to a higher concentration of O2 or by using the power activator area (the “PWR” symbol inside the circular, crosshatched imprint on the left side of the case lid). A sharp rap on this area with the edge of a coin works best. The CTU will issue five "beeps" when it activates using either method.

3. Turn on the WU by continuously "drumming" your fingertips on its face for about 5 to 10 seconds, or until the display activates. When the WU powers up, it will go through a self-diagnostic display with all segments and legends coming on briefly, followed by the WU serial number across the bottom of the screen. (This serial number appears as a single digit followed by a space and four more digits).

4. Attach the Field Programmer to the CTU by snapping the probe into the three clips on the back of the CTU. The cable of the Field Programmer probe should be at the same end as the O2 sensor cable. Snapping the probe into place may cause the CTU to enter Programming Mode and “

C-2

” to appear in the upper left corner. If not, tap the PWR circle sharply a single time to invoke Programming Mode.

Fig-17

Connecting Field Programmer Probe

Programming Mode (continued)

5. Use the SELECT and INCREMENT buttons on the Field Programmer to change any desired functions, referring to the following chart.

6. Once all desired changes have been made, hold the SELECT button down to scroll through the remaining Programming functions and lock in the changes made. At the conclusion of the cycle the CTU will revert to its normal Surface Mode, as confirmed by the WU readout.

Element Identifier Function C-2

(1)

Added Conservatism, 10s place

C-1 Added Conservatism, 1s place A-3 Depth Alarm, 100s place A-2 Depth Alarm, 10s place A-1

Depth Alarm, 1s place.

P-3

(2,3)

O2 Calibration (See “Calibration Mode” section, next.)

P-2

(2,3)

O2 Calibration

P-1

(2,3)

O2 Calibration

(1)

NOTE: The Computer will accept input values up to 99 for the Added Conservatism function, but the highest value actually used is 50%. Any number greater than 50 will be treated as 50%.

(2)

NOTE: The P- functions are not used in Programming

Mode. They are for use in Calibration Mode onl y.

(3)

WARNING: Do not press the INCREMENT button while P-3, P-2, or P-1 is showing. This w ill cause the CTU to leave Programming Mode and lock in a potentially incorrect O2 value. See the next section on the Calibration Mode for furthe r information.

Programming Mode (continued)

Fig-18

Field Programming (Setting Conservatism)

• Programming the 10's digit of added Conservatism

• OTU exposure calculated at 6%

• CNS exposure calculated at 12%

Fig-19

Field Programming (Setting Depth Alarm)

• Programming the 100's digit of Depth Alarm

• OTU exposure calculated at 6%

• CNS exposure calculated at 12%

Calibration Mode

CAUTION: TO CALIBRATE THE LIFEGUARD™ YOU MUST USE 100% OXYGEN.

The LIFEGUARD™ uses a two-point calibration. The First point is and

must be

21% while the Second point is and

must be

100 %. Calibrate the

LIFEGUARD™ as follows:

1. Attach sensor and cable to your LIFEGUARD™. If you are calibrating a new O

sensor allow the sensor to stabilize in air for approximately 24 hrs after

removal from the package.

2. Have a source of pure (100%) O

at hand for use in Step 6, below.

3. Expose the sensor to

atmospheric air (21%)

and allow its readings to

stabilize (see Figure 20a).

Fig-20a

Calibration Mode (Sensor exposed to 21% - AIR)

4. Attach the Field Programmer probe to the CTU and verify the WU display changes to show “

C-2

” in the upper left corner (see figure 18, page 29) to indicate start of PROGRAMMING/CALIBRATION Mode. If not, tap the PWR circle a single time and confirm PROGRAMMING/CALIBRATION Mode (by noting presence of the “

C-2

”).

5. Press the SELECT button as described in the Programming Section, stepping through each of the follow ing:

• C-2

• C-1

• A-3

• A-2

Calibration Mode (continued)

• A-1

• P-3

STOP HERE.

6. Expose the sensor to 100% O

(this must be 100%). This can be

accomplished by placing the sensor in a plastic bag and flowing O

into the

bag (make sure not to seal the bag so as to produce pressure build up which would cause a false reading) or using a continuous flow device.

7. Watch the WU readout as its digits climb. Depending on how much

adjustment the CTU needs to make, a minute or so may be necessary for the reading to stabilize. It is not unusual for the readout to go past 100 or stop slightly short of that reading when it stabilizes (This confirms that the calibration was necessary).

NOTE: This reading must stabilize prior to proceeding to the next step.

Fig-20b

Calibration Mode (Sensor stabilized with 100% Oxygen)

8. When 15 seconds have passed with no change in the readout, press the

INCREMENT

button to lock in the calibration.

9. With the sensor still exposed to 100% O

, observe the WU reading for this

value. If the reading was higher or lower than 100, you will see it gradually re-adjust to 100, +/- 1.

Calibration Mode (continued)

Fig-20c

Calibration Mode (Unit Calibrated and showing 100%)

10. Remove the sensor from the 100% O2 and expose it to normal (21% O2) air. The reading should decrease until it reaches 21, confirming that it is now

properly calibrated. If this reading is not 21 +/- 1, re-initiate the Calibration sequence and follow steps 2-9.

NOTE: All program settings are locked in when the INCREMENT button is pressed in Step 9. If it is necessary to change any of these settings, re-enter “Programming” and proceed as outlined in the instructions for that mode.

Subsurface Mode

Whether in the Surface Mode, PreDive Prediction Mode, Field Programming Mode, or the Logbook Mode, the

LIFEGUARD™

will automatically enter the Subsurface Mode when the unit senses a depth greater than 5 feet and is exited when the unit senses a depth less than three 3 feet.

The Subsurface Mode has a Primary and an Alternate screen. The Primary screen shows the REMAINing TIME for NDC, ASCENT rate, CEILING (if required), BOTTOM time for this dive, current PO

, and current DEPTH.

The Alternate screen shows: REMAINing TIME NDC (as a system check); TEMPerature, BP (current O2 %), and MAXimum DEPTH of this dive.

When accessed the Alternate screen is seen for three seconds.

Fig-9

Primary Screen

• REMAINing TIME by NDC 0:22 (22 minutes)

• Current ASCENT rate 20-29 feet per minute

• Required CEILing 0 feet (none)

• Current BOTTOM time 0:38 (38 minutes)

• TANK indicating current PO

1.04 ata

• current DEPTH 60 (feet)

Surface Mode (continued)

Fig-10

Alternate Screen

• REMAINing TIME NDC indicating System check 9:59 (confirmation)

• Current TEMPerature 75 deg. F

• BP indicating current O2 % 37 %

• MAXimum DEPTH 87 feet

Emergency Decompression Mode

WARNING: Your LIFEGUARD™ should not be used for deliberate decompression diving, but merely as an aid to assist you during ascent should you mistakenly overstay your no-decompression limit. Cochran Undersea Technology in no way encourages deliberate decompression diving.

Should you exceed your NDC time limit, your LIFEGUARD™ will enter Decompression Mode. Five audible warning chirps will sound and the DEC legend will appear on your WU. In this Mode, the CEILing digits will display the depth at which the diver must stop and not ascend above during his final ascent. The WU will display the first ceiling at 10 feet and continue in 10-foot increments to a maximum of 90 feet. To alert the diver to an even more hazardous situation, the WARNING legend will illuminate when a ceiling of 70 feet is calculated. In the case of a ceiling greater than 90 feet the computer will issue a five chirp audible warning once per minute to alert the diver to this situation, this alarm will continue until the calculated ceiling is less than 90 feet.

WARNING: You should IMMEDIATELY begin your ascent to the proper CEILing depth upon hearing these warnings.

The LIFEGUARD™ is configured at the factory to alternate between total decompression time for three seconds and time at current stop for three seconds. Via the Analyst, you can select to have only total decompression time or only stop time di splayed if so desired.

CEILING is the depth to which you must ascend, BUT NOT EXCEED, for your first decompression stop. The WU display will indicate the various ceiling stop depths as follows:

Ceiling Calculated Ceiling Displayed

10 foot 10 20 foot 20 30 foot 30 40 foot 40 50 foot 50 60 foot 60 70 foot 7 80 foot 8 90 foot 9

Emergency Decompression Mode

(continued)

NOTE: When completing decompression stops, minor changes in your depth may occur due to swells at the surface. For this reason, it is recommended that you make your stop slightly deeper than the CEILing depth. The LIFEGUARD™ will continue to give decompression credit when this precaution is taken.

Time spent above a CEILing depth will not be credited to the required decompression obligation. Instead, a 1.5-second penalty will be added to that time for each second spent above the CEILing.

CAUTION: Ascending above the CEILing depth will cause your LIFEGUARD™ to issue a warning chirp. The current depth digits and the WARNING legend will flash. Both the audible alarm and the flashing display will continue until you descend below the CEILing depth.

Your BOTTOM time, TANK (PO

), ASCENT rate, and DEPTH gauge will

continue to operate normally as if you were in the Subsurface Mode.

Fig-11

Primary Screen, Showing STOP Time

• REMAINing TIME DECompression at CEILing* 0:05 ( 5 minutes)

• current ASCENT rate less than 10 fpm

• depth of CEILing 20 feet

• current BOTTOM time 1:56 (1 hr. 56 min.)

• TANK indicating current PO

1.09 ata

• current DEPTH 25 feet

Emergency Decompression Mode

(continued)

Fig-12

Primary Screen, Showing Total Decompression Time

• REMAINing TIME DECompression total* 0:15 (15 minutes)

• current ASCENT rate less than 10 fpm

• depth of current CEILing 20 feet

• current BOTTOM time 1:56 (1 hr. 56 min.)

• TANK indicating current PO

1.09 ata

• current DEPTH 25 feet

* This value is dependent upon how the dive computer is configured. If BOTH is selected, this value alternates between total decompression obligation, the greater time and stop time, the lesser time. At a 10-foot stop, Total and Stop times may be the same and therefore appear not to alternate. See section regarding REMAIN TIME DEC for more information.

Emergency Decompression Mode

(continued)

Fig-13

Alternate Screen

• REMAINing TIME NDC indicating System check 9:59

• current water temperature 68 deg. F

• BP indicating O

% 62 %

• MAXimum DEPTH 122 feet

Gauge Mode

Violating certain conditions will cause the LIFEGUARD™ to stop calculating nitrogen absorption/elimination and cease providing remaining time information. When this occurs, your LIFEGUARD™ has entered its Gauge Mode. Once in

this mode, 24 hours of surface time MUST elapse without a dive being made before the system will resume its normal operation.

Any one of the following conditions will cause the LIFEGUARD™ to immediately enter Gauge Mode

• More than five minutes elapsed at a depth less than the CEILing.

• A ceiling depth greater than 90 feet is calculated.

• The maximum functional operating depth of 327 feet is exceeded.

Exceeding the Calculated Ceiling Depth: At any depth shallower than the displayed Ceiling depth when in Decompression Mode, the dive computer will continuously issue its “chirp” alarm, and flash the WARNING legend and the DEPTH digits once a second until you descend back below the CEILing. After 5 minutes, if this violation is not corrected, the LIFEGUARD™ enters Gauge Mode.

Exceeding a 90-foot Ceiling Stop: If the LIFEGUARD™ calculates a Ceiling of greater than 60 feet, it will immediately issue its 5-second chirp alarm. If a ceiling stop greater than 90 feet is calculated, the LIFEGUARD™ will issue five audible warning "chirps" and immediately enters Gauge Mode.

Exceeding the Maximum Functional Operating Depth:

Descent below 100 meters/ 327 feet will cause the LIFEGUARD™ to issue its 5-second chirp alarm and immediately enter Gauge Mode. Depths greater than 100 meters/327 feet exceed the design capabilities of the LIFEGUARD™.

NOTE: Exceeding the Maximum Operating Depth of the LIFEGUARD™ will void the Limited Warranty.

In Gauge Mode, the

LIFEGUARD™

will continue to display DEPTH (if it is 100 meters/ 327 feet or less), TEMPerature, BOTTOM time, ASCENT rate, and TANK (PO

WARNING: It is strongly advised that you wait a minimum of 24 hours before flying or making another dive if your LIFEGUARD™ has entered Gauge Mode. Failing to do so will greatly increase your risk of Decompression Sickness.

Gauge Mode only has a Primary Screen.

Gauge Mode (continued)

Fig-14

Primary Screen

• current water TEMPerature 55 degrees F

• current ASCENT rate 31-40 feet per minute

• current BOTTOM time* 3:36 ( 3 hrs 36 mins)

• current SURFace time*

• TANK indicating current PO

1.00 ata

• current DEPTH 22 feet

* NOTE: Either BOTTOM or SURFace time will show, depending on whether the unit is in or out of the water. Once it has entered Gauge Mode, a period of 24 hours must elapse before the LIFEGUARD™ will revert to normal operation.

CNS / OTU Toxicity Warning Display

The LIFEGUARD™ has the ability to track Oxygen Toxicity levels for the Central Nervous System (CNS) as well as the Mission Oxygen Tolerance Units Dose (OTU). In addition, a maximum Partial Pressure of Oxygen (PO2) warning alarm can also be set. While most other audible alarms of the dive computer consist of five long beeps, the CNS, OTU, and PO

have a distinctive audible alarm that consists of short double-beeps that sound once per second for five seconds. As long as one or more of these three parameters is outside its limits, the WARNING legend will illuminate and flash and the audible alarm will be repeated once per minute.

CNS / OTU Toxicity Warning Display

(continued)

PARTIAL PRESSURE OF OXYGEN (PO

): High levels of PO

can cause severe

Oxygen poisoning. Widely different levels of PO

can affect individual diver s.

The user via the Analyst

can set the PO2 alarm to any level between 0.50 ATA

and 1.60 ATA. Should the PO

be above the alarm set point, the warning legend will illuminate and the audible alarm will sound. As shipped from the factory, this is set to 1.60 ATA.

CENTRAL NERVOUS SYSTEM (CNS) TOXICITY: Should the CNS Toxicity reach 75% of the maximum allowable, the warning legend will illuminate and the audible alarm will sound and the TEMPerature digits will be replaced with the current calculated two digit CNS percentage. These digits on the display will be flashing along with the WARNING legend (see Figure 15 which shows a diver that has reached 92% of the allowable maximum bottom time for any PO

). During the Surface Interval, this percentage will decrease as the CNS declines toward zero. Once this has dropped below 75%, the TEMPerature reading will return.

NOTE: By the accepted definition of CNS toxicity. If a PO

value

greater than 1.6 ATA be measured, the CNS Toxicity will be 100%.

OXYGEN TOLERANCE UNITS (OTU):

An issue with long term breathing of higher partial pressures of Oxygen above 0.5 ATA is Pulmonary Oxygen Toxicity or sometimes called WHOLE BODY, which must be tracked properly.

The

LIFEGUARD™ will track the OTUs based on Dr. Bill Hamilton’s ‘REPEX’ method of oxygen exposure management. The OTU Dose is an exponential function of oxygen partial pressure and time.

The time-dependent limit varies wi th length of time (days) that the diver continues to dive without full recovery to zero OTU. The Mission OTU Clock tracks the OTU, which is a running clock that tracks long-term Oxygen exposure. This clock may run for several weeks if frequent dives are made using high levels of PO

The current Mission Clock, CNS, and OTU levels can be viewed via Analyst

The recovery portion of the OTU algorithm is a linear reduction of OTU over time. The Mission OTU clock is reset to 0:00 when the OTU Dose reaches zero.

Should the OTU Dose reach 75% of the maximum allowable, the audible alarm will sound and the TEMPerature digits will be replaced with the current calculated two-digit OTU Dose percentage. These digits and the WARNING legend will be flashing. Symptoms of Pulmonary Oxygen Toxicity include burning in the throat and chest, coughing, and shortness of breath. Discontinue diving and consult a Physician should any of these, or other, symptoms appear.

CNS / OTU Toxicity Warning Display

(continued)

Whatever the current CNS/OTU Toxicity level, it can also be viewed during the PreDive Prediction scrolling or in the Field Programming Mode (see figure 18, page 29)

• WARNING immediate attention required (Flashing)

• TEMPerature 92 % CNS exposure

• BP indicating O

% 26 % O

•

MAXimum DEPTH 98 (feet)

Logbook Mode

The

LIFEGUARD™

can recall and display stored data from its last 300 dives, beginning with the most recent dive. This Logbook Mode is accessed from Surface Mode. To view key data from previously stored dives, tap the "PWR" actuator area on the CTU one time. Data from the most recent stored dive will appear on the screen. Each successive tap on the PWR actuator will bring up the next preceding stored dive, in reverse chronological order. Wait for the new data to be displayed on the WU each time before tapping again to go to the next prior dive. Access the WU's Alternate Screen for any of the dives being viewed by tapping the WU once. The data will appear for 3 seconds, and then the display will revert to the Primary screen. LIFEGUARD™ will return to Surface Mode thirty seconds after the last desired data log has been displayed.

Logbook Mode (continued)

Fig-7

Primary Screen

• DIVE of the day number 2 (2nd dive)

• time to FLY 15 hours

• maximum ASCENT rate during the dive 31-40 feet / minute*

• average water TEMPerature of the dive 63 deg. F

• BOTTOM time of the dive 1:46 (1 hour 46 minutes)

• TANK indicting PO

1.41 ata

• MAXimum DEPTH of the dive 63 feet

Fig-8

Alternate Screen

• minimum REMAINing TIME by NDC 0:23 (23 minutes)

• maximum CEILing required 0 feet

• BP indicting average O

% 36 %

• Average DEPTH of the dive 43 feet

ASCENT RATE BAR GRAPH

The Ascent Rate bar graph and alarms are active in both the Subsurface Mode and Decompression Mode when the depth is below ten feet. The five-segment bar graph is used to display the diver's rate of ascent. The factory default for maximum ascent rate is 60 feet per minute. With this setting, no bars will illuminate if a diver is ascending at a rate less than 10 feet per minute. If the diver has an ascent rate of more than 60 feet per minute, the entire Ascent Rate Bar Graph will flash, and audible alarm will sound once per second, and the WARNING legend will illuminate. Each segment indicates an additional 10 feet per minute of Ascent Rate.

Via the Analyst

P.C. Interface, the maximum Ascent Rates alarms can be

selected from 20 to 60 feet per minute in one-foot increments. Another Analyst

selection pertains to the bar graph itself. The two selections given are either FIXED or PROPORTIONAL.

With FIXED, each of the five bars indi cates an additional 10 feet per minute of Ascent Rate regardless of the maximum Ascent Rate selected. With PROPORTIONAL, each of the five bars indicate 20% (one-fifth) of the selected maximum Ascent Rate.

A third option that is accessible via the Analyst

P.C. Interface is a VARIABLE Ascent Rate. With this option, the Ascent Rate Alarm is determined by depth. As the diver ascends to shallow depths, the maximum Ascent Rate is lowered. The maximum Ascent Rates and their associated depth are:

60 feet or deeper 60 feet per minute 59 to 30 feet feet per minute equal to the depth Less than 30 feet 30 feet per minute

Fig-21

ASCENT RATE BAR GRAPH

(Fixed at 60 feet-per-minute)

The ascent rate footage ranges are for reference only. They do not appear

on the

WU.

ASCENT RATE BAR GRAPH

(continued)

NOTE: Customizing the Ascent Rate and Ascent Rate Bar Graph are just

two of the many additional programmable features available when using the Analyst

P.C. Interface. See an Authorized Team Cochran

Dealer for a complete demonstration. Some available features are described in the section “USER CONFIGURABLE OPTIONS”.

NOTE: Regardless of the Ascent Rate Bar Graph's settings the Ascent Rate

legend will only appear when the programmed ascent rate causes the first bar of the Ascent Rate Bar Graph to appear, for a 60 fpm ascent rate this will occur at 10 fpm.

The sensitivity or responsiveness of the Ascent Rate may be selected. Via the

Analyst

, eight different levels of sensitivity are available

POST-DIVE INTERVAL

During the first ten minutes after a dive the LIFEGUARD™ is in the Post-Dive Interval. The flashing "SURF" legend and a Surface Time of less than ten minutes indicate this. Should another dive be commenced before the completion of the Post-Dive Interval the dive will be considered as a continuation of the pervious dive. In this case, bottom time will NOT include the time spent on the surface in this Post-Dive Interval Mode. However, when reviewing the profile with the Analyst

the time spent on the surface in this mode will be shown. After

the Post-Dive interval has expired the information on the dive is stored in the

LIFEGUARD™'s

electronics. The

LIFEGUARD™ will not communicate through

the Analyst

while in the Post-Dive Interval.

SLEEP (PSEUDO-OFF) MODE

Thirty minutes after the

LIFEGUARD™ has concluded the Post-Dive Interval the

LIFEGUARD™

will enter into a Sleep Mode. In the Sleep mode the LIFEGUARD™'s computer continues to perform out-gassing calculations and keep track of the Surfac e time, and Time To Fly but ceases all other activities. When the

LIFEGUARD™

enters the Sleep Mode, the Wrist Unit’s display will flash. The LIFEGUARD™'s Wrist Unit will turn its elf off fifteen minutes after the Tank Unit goes to Sleep. To Wake-up the unit, turn on the

LIFEGUARD™

WU and CTU. The LIFEGUARD™ will display current information on the Surface Mode Screen.

NOTE: The LIFEGUARD™ CTU will not enter the sleep mode or turn off as

long as the PO

sensor is being exposed to elevated leve l of oxygen.

EXPLANATIONS

Altitude Diving

The LIFEGUARD™ senses the barometric pressure for altitudes up to 15,000 feet above sea level. Barometric pressure at a given altitude can change due to high and low-pressure weather systems as well as temperature.

When compared with most analog gauges at altitude, the LIFEGUARD™ will display a greater depth. This is due to the reduced atmospheric pressure at the surface so that true depth can be derived from ambient pressure.

WARNING: Diving at altitude requires completion of a sanctioned altitude diving course from a recognized recreational dive-training agency. Greater care should be taken when diving at altitude to avoid extending no-decompression times to their maximum limits. Your LIFEGUARD™ will continue to display your rate of ascent as usual, but rates slower than 60 feet per minute should be used in altitude diving, as recommended by your certifying agency

Ascent Rate

Subsurface Mode, Decompression Mode, or Gauge Mode

Ascent rate is averaged over a running 4-second period. For purposes of explanation, references in this manual to ascent rate are with the understanding that this is a 4 second averaged ascent rate and not an instantaneous rate.

You can select between a Fixed and Variable Ascent Rate with the optional Analyst Personal Computer Interface.

FIXED ASCENT RATE: In the fixed mode, the ascent rate will be fixed throughout the entire dive profile regardless of depth. The fixed rate set at the factory is 60 feet per minute. With this default setting, your computer will alarm if you exceed an ascent rate of 60 feet per minute.

The diver may select fixed rates from 20 to 60 feet per minute.

VARIABLE ASCENT RATE

: This feature utilizes several different ascent rates that are depth-dependent. At depths greater than 60 feet, the maximum allowable ascent rate is set to 60 feet per minute. At depths less than 30 feet, the maximum allowable ascent rate is set to 30 feet per minute. From depths between 30 and 60 feet, the maximum allowable ascent rate will be the same as the current depth. For example, at 43 feet of depth, the maximum allowable ascent rate is 43 feet per minute.

Logbook Mode: The maximum speed of ascent recorded on the dive is

displayed.

NOTE: Ascent rate is only computed and displayed at depths greater than 10 feet.

Ascent Rate Bar Graph

The Ascent Rate Bar Graph is comprised of a vertical five-segment bar. With the optional Analyst Personal Computer Interface, you can select this bar graph to either represent the speed of your ascent or a percentage of the selected maximum ascent rate.

FIXED: With this option, each bar of the graph represents an additional 10 feet

per minute of speed. For example, if you were ascending between 11 and 20 feet per minute, one bar segment would illuminate. If you were ascending between 21 and 30 feet per minute, two bar segments would illuminate, and so on with all five bar segments appearing when ascending between 51 and 60 feet per minute. The performance of this option remains the same regardless of the type or the maximum ascent rate selected.

PERCENTAGE

: With this option, each bar of the graph represents an additional 20% of the maximum ascent rate selected. For example, if you had selected a fixed ascent rate limit of 30 feet per minute, each bar segment would represent an additional ascent rate of 6 feet per minute. (6 is 20% of 30) This option is especially useful if a variable ascent rate is selected. Regardless of the depth and associated maximum ascent rate, you will quickly be able to identify if you are approaching 100% maximum limit.

The Ascent Rate Bar Graph is set at the factory to display SPEED.

Batt

This legend is illuminated when the battery in either the CTU or WU is low. If this legend is flashing, then the battery in the CTU is low. If the legend is on continuously, then the battery in the WU is low.

NOTE: If both batteries are low, then the BATT legend will flash. Upon replacement of the CTU’s batteries, the BATT legend will then be on continuously indicating that the WU’s batteries do need to be replaced.

Bottom

This is the total bottom time ( displayed in hours and minutes ) calculated for a particular dive. Should a diver ascend to the surface, remain on the surface for less than 10 minutes and then commence another dive, the bottom time will continue to increment as though there was no time spent on the surface. No offgassing Credit will be given.

Surface Mode: The bottom time of your last dive is provided to you on the

Alternate Display in hours and minutes. At the start of a new dive day, the bottom time will be 0:00.

Logbook Mode: The bottom time for the profile viewed is displayed on the Main

display.

Gauge Mode or Decompression Mode or Subsurface Mode: Your dive

computer begins to count your bottom time when you have descended below approximately five feet. Bottom time continues to be counted until you have ascended above three feet. This time is expressed in hours and minutes.

Ceiling

Subsurface Mode: When making a no-decompression dive, the CEILing should

read 0 indicating that you may make a direct ascent to the surface without completing any decompression stops. Should you enter into a decompression situation, the CEILing will indicate, in feet or meters, the depth to which you must ascend and complete a Decompression Stop.

Decompression Mode: The depth above which you must not ascend when in

the Decompression Mode.

Logbook Mode: This will show whether the dive profile viewed was a no-

decompression dive. If you entered Decompression Mode on that particular dive, the CEILing would display the deepest stop that was required.

Depth

Battery/Altitude Display: On this display the number under the DEPTH legend

will indicate the CTU’s current battery voltage as a factor of ten. For example, if the CTU’s battery voltage were a 5.8 volts, the two digits under the DEPTH legend would display 58. If the battery voltage were a 5.3 volts, the two digits under the DEPTH legend would be 53.

Predive Prediction Mode: The numbers under the DEPTH legend indi cate the

depth associated with the displayed NDC prediction.

Subsurface Mode: The numbers under the DEPTH legend display the current

depth. Your dive computer can distinguish between fresh and seawater, thereby providing you with the actual depth for the type of water in which yo u are diving.

Decompression Mode: The numbers under the DEPTH legend are used to

display the current depth.

Gauge Mode: The numbers under the DEPTH legend are used to display the

current depth.

Logbook Mode: The numbers under the DEPTH legend are used to display the

average depth of the dive.

CNS/OTU Toxicity Display: On this display, the numbers under the DEPTH

legend are used to display the OTU Toxicity percentage.

Dive

Surface Mode: The dive number counts the number of dives made in a single

“dive day”. This counter begins with 0 and continues through 9, resetting back to 0 each time the CTU is powered on if no Residual Nitrogen remains in your system.

Logbook Mode: The dive number in the Logbook Mode will identify which dive of

that particular “dive day” you are viewing. For example, if you had just made your third dive of the day, the dive number would display 3 for the first profile viewed. The next would display 2, and the next would display 1. The next would display the last dive’s DIVE number from the previous day. If you only made two dives on that previous day, the DIVE number would display 2 and so on.

NOTE: A "dive day" is defined as the period of time starting when the CTU first enters the Subsurface Mode and lasting until all twelve halftime compartments return to normal levels. For this reason you may have more than one "dive day" within a single 24-hour period or a "dive day" may last for more than 24 hours.

Max Depth

Surface Mode: The maximum depth reached on the dive just concluded would

be displayed up to the maximum gauge depth of 327 feet.

Subsurface Mode: This is the maximum depth recorded during the dive. Logbook Mode: The maximum depth recorded on the profile viewed is

displayed.

Metric

This legend indicates that the dive computer is set to calculate and display altitude and depth values in the METRIC mode. Altitude and Depth will be calculated in meters. You may select the metric display via the optional Analyst Personal Computer Interface.

NOTE: The PO

displayed in the Metric mode will show a period in the

display. If your PO2 display showed 12.8 it would be showing a PO2 of

1.28 ata.

Remain Time NDC

Predive Prediction Mode: This prediction is based on PO

/ FO2 % in your

breathing loop and computed using the decompression algorithm. All Pre Dive predictions will be made using only no-decompression times.

NOTE: If the no-decompression limit for a given depth is less than two minutes, your dive computer will not make a PreDive prediction for that depth.

Battery/Altitude Display: The number 0:00 under the REMAIN TIME legend is

used to indicate the Battery/Altitude Display.

Subsurface Mode: This is the amount of no-dec ompression time remaining

displayed in hours and minutes.

Logbook Mode: If during the profile being displayed, the minimum remaining

time data was determined by no-decompression time, the Alternate Display will show this data under the REMAIN TIME legend.

CNS/OTU Toxicity Display: The number 2:00 under the REMAIN TIME legend

is used to indicate the CNS/OTU Toxicity Display.

Remain Time DEC

Decompression Mode: The time displayed will be dependent upon how the dive

computer has been setup. The information displayed will be either:

• Total time to complete all required decompression, or

• Time Remaining at each individual stop, or

• Alternating between total and stop time

If the alternating option is selected, each time is displayed for three seconds. Logbook Mode: If you are viewing a Decompress ion dive, the total required

decompression time would be displayed followed by the DEC legend.

Surface Time

Surface Mode or Gauge Mode: Surface time is displayed in hours and minutes

from the time the CTU is turned on or at the end of a dive when ascending above three feet. Surface times from 0:00 to 17:03 will be displayed.

Tank

Surface Mode: This is the current PO

that the sensor is exposed to.

Predive Prediction Mode: The numbers under the TANK legend indicate the

current PO2 that the sensor is exposed to or the current FO2 that the sensor is exposed to. The PreDive predicted NDC times are based on these values.

Subsurface Mode: This is the current PO

of the loop.

Logbook Mode: This is the average PO

of the loop for the viewed profile.

Temp

Surface Mode: This is the current ambient temperature. Subsurface Mode: This is the current ambient temperature. Logbook Mode: This is the average water temperature recorded for the viewed

profile.

Time-To-Fly

Surface Mode: If you plan to fly after diving, you must first allow time for your

body to eliminate all of the residual nitrogen it has absorbed from diving. Your dive computer calculates this for you and displays the hours you must wait before safely flying or traveling to altitude after divi ng. The time calculated includes an additional 12-hour surface time for added safety. For example, if it would take your body three hours to eliminate all residual nitrogen, the time-to-FLY would display 15 hours (three hours plus the 12 hour added safety margin).

Logbook Mode: In the Logbook Mode, the time-to-FLY calculated at the end of

that particular dive profile is displayed.

CAUTION: It is always recommended that you wait at least 24 hours after

diving before flying.

AUDIBLE & VISUAL WARNINGS

In this section you will learn to recognize the audible and visual warnings that your dive computer may issue to alert you of potentially hazardous conditions.

User Defined Maximum Depth

Via Field Programming you have the ability to define a maximum depth to which you wish to dive. The depth may be set from 0 to 320 feet in 1-foot increments. Refer to the Field Programming section of this manual. You may also set this depth via the ANALYST

Personal Computer Interface. Should you descend to a depth deeper than your selected maximum depth, the DEPTH digits will flash and once every minute, the five-chirp audible alarm will sound. The factory setting for this warning is 320 feet.

NOTE: The Depth Alarm is disabled during the Decompression Mode.

Two-Minute Warning

Should you have less than two minutes of remaining no-decompression time, your dive computer will:

• Issue a one time, five-chirp audible warning, and

• Flash the WARNING legend on the WU.

Entering Decompression Mode

Should you enter Decompression Mode, the CTU will issue a one time five-chirp audible alarm.

60 Foot Decompression Stop Warning

Should you require a decompression stop greater than 60 feet, the unit will issue a one time five-chirp audible warning.

Ceiling Violation

When in the Decompression Mode, ascending to a depth shallower than the Ceiling depth will cause your dive computer to:

• Flash the WARNING legend and the depth digits and

• Continuously sound its audible chirp alarm.

This is not a settable alarm.

NOTE: If you remain in a CEILing violation condition for more than five minutes, your dive computer will enter its Gauge Mode.

Low Battery Voltage

Standard, user-replaceable batteries power both the CTU and WU. The CTU is powered by four, size-AA alkaline batteries and the WU by two size-N alkaline batteries. Should the WU’s battery voltage become low, the BATT legend on the WU will illuminate. When the CTU’s batteries become low, the BATT legend on the WU will flash and the CTU will issue a one time five-chirp audible warning. The batteries should be replaced as soon as possible after the low battery indicator appears.

NOTE: Properly replacing the batteries from the CTU will not cause your dive computer to lose current nitrogen absorption and elimination data for the most recent dive or dive series. See the section regarding BATTERY REPLACEMENT in this manual.

Ascent Rate Alarm

Your dive computer allows the user to select either fixed or variable Ascent Rate warnings. See the description of Ascent Rate under the EXPLANATION OF FUNCTIONS section for a description of fixed and variable ascent rates. Exceeding the maximum ascent rate will cause the dive computer to:

• Flash the WARNING legend and

• Sound its audible alarm once every second.

The sound of this audible alarm is unique. Rather than a low-to-high "sweep", the Ascent Rate Alarm sound is a high-to-low "sweep".

Gauge Mode Alarm

The dive computer will sound its five-chirp alarm just prior to entering Gauge Mode. It will re-issue this five-chirp alarm if the CTU is powered up within 24 hours after entering Gauge Mode. The computer will enter the Gauge Mode if:

• More than five minutes has elapsed with the depth less than the ceiling, or

• A ceiling depth of greater than 90 feet is required, or

• The maximum functional operating depth of 327 feet is exceeded.

Oxygen Tolerance Units (OTU) Dose Warning

Should you reach 75 percent of the allowable Mission OTU dosage, your dive computer will issue a one-time audible warning consisting of short, double-beeps that sound for five seconds. The WARNING legend will appear and flash and the TEMPerature digits will be replaced with the current calculated OTU toxicity percentage. This visual warning will continue until the calculated toxicity percentage is less than 75 percent.

Central Nervous System (CNS) Oxygen Toxicity Warning

Should you reach 75 percent of the associated maximum limit, your dive computer will issue a one-time audible warning consisting of short, double-beeps that sound for five seconds. The WARNING legend will appear and flash and the TEMPerature digits will be replaced with the current calculated CNS Oxygen Toxicity percentage. This visual warning will continue until the calculated toxicity percentage is less than 75 percent.

NOTE: If both CNS and OTU levels are greater than 75 percent, the more critical of the two percentages will be displayed.

Maximum PO

Alarm

This alarm, settable via the Analyst interface, allows you to set a desired maximum level from 0.5 to 1.6 ATA. Should you exceed this setting, the TU will issue the double chirp toxicity alarm once per minute. The factory setting for this alarm is 1.6 ATA.

Minimum PO

Alarm

This alarm, settable via the Analyst interface, allows you to set a desired minimum level from 0.2 to .40 ATA. Should you exceed this setting, the TU will issue the double chirp alarm once per minute. The factory setting for this alarm is .2 ATA.

USERS NOTES

QUESTIONS AND ANSWERS

What c auses m y PO2 reading to fluctuate when exposed to air?

Two major reasons you may see the PO

fluctuate while exposed to air. FIRST: If your connection is not tight or has been allowed a build up of oxidation/corrosion on the contacts. You may clean the contacts wi th electronics cleaner or WD40. SECOND: If you did not properly calibrate your unit.

Q. Must I use 100% Oxygen for calibration. A. Yes!

The computer uses 2 reference points for calibration. One being

21% while the other is 100%.

Q. Should I turn my WU off when it is not in use? A. Yes. While your WU is powered by two alkaline ‘N’ batteries that will

provide a long battery life, you still should turn the WU off when you are going to be away from the CTU for an extended time.

Q. Shouldn’t I take the batteries out of the CTU when it is not going to be

used for several months?

A. No! Inside your CTU is a small lithium " COIN CELL " that provides

power for long-term data storage. Removing the main batteries, or leaving fully discharged batteries in the CTU, will cause this coin cell to gradually lose its power. Also, the time stamp clock does not operate when the main batteries are removed.

Q. Is this coin cell replaceable? A. The coin cell can only be replaced by Cochran Undersea Technology

since it requires the opening of the CTU. By keeping charged batteries in the CTU, the life of this coin cell is expected to be over ten years.

Q. When I change the batteries in my CTU, will my unit retain data for the

current dive?

Yes, providing you follow the instructions on battery replacement.

Q. When I tapped the CTU on, it did not issue the five confirmation beeps? A. The CTU may already be on. Turn your WU on to see if the CTU is

transmitting data. If it is not, check the batteries to see if their voltage is low. In a noisy environment, such as on the boat when it is underway, it may be difficult to hear the confirmation beeps.

Q. At what battery voltage will my CTU cease to operate? A.

Fully charged, the four AA alkaline batteries provide six volts. When they discharge to below 4.8 volts, your CTU will not turn on.

Can I turn the CTU on underwater?

A. No. The CTU will not turn on if you are underwater. Should you enter

the water and begin a descent without turning the CTU on, slowly surface, turn the CTU or wait for the O2 sens or to read a higher O

You must wait for it to complete its Self-Diagnostic Mode, and then begin your descent once again.

Q. Is the transmitting range affected by the positioning of the CTU and

WU?

Yes. However, in normal diving situations there is sufficient operating range regardless of orientation.

Q. What is the proper way to tighten the CTU and WU battery caps? A. The caps should be tightened using the enclosed battery removal tool.

The O-rings should not be visible when the caps are properly tightened, but be careful not to over tighten the caps. Once the O-rings are seated, simply hand-snug each cap.

Q. What happens if the battery compartments flood? A. The electronics of both the CTU and WU are completely

environmentally sealed. The construc tion of the battery compartments will not allow water to enter the electronics. If you have flooded the battery compartments, first rinse the compartments as soon as possible with fresh water. Then fill each compartment with alcohol and shake the alcohol to ensure complete rinsing. Drain the alcohol and allow the compartment to air-dry 12 hours with the battery caps off. Discard the batteries. Finally, examine the battery cap, replace and lubricate the Orings, install new batteries and reinstall the battery caps. You may also need to use a clean eraser or a burnishing cloth to completely clean the contacts.

Can I transport my dive computer in a watertight container while traveling at altitude?

A. No! Your dive computer continuously monitors the altitude to perform

nitrogen in-gassing and out-gassing. These nitrogen levels are then used when you arrive at the dive site and intelligently applied to your dive.

What should I do if I have additional questions?

A. Call us! For your convenience, we are available Monday through

Friday, 8:00 a.m. to 5:00 p.m. Central Time. Our staff of certified divers will be glad to assist you by answering any of your questions. Our telephone number is 972.644.6284. You may also FAX questions to

972.644.6286 or E-MAIL your questions to service@divecochran.com.

Most problems can be resolved without returning the unit. The unit may also be returned to the place of purchase and request the dealer to contact us. If this is not possible or is inconvenient due to change in location, contact us for the name of the nearest Team Cochran Authorized Dealer.

CARE AND MAINTENANCE

The Computer-Transmitter Unit and Wrist Unit contain NO user serviceable components. DO not remove the lid from the ComputerTransmitter Unit or the Lens from the Wrist Unit, doing so WILL VOID the Limited Warranty.

Rinsing and Cleaning

Your dive computer is designed to require minimum care and maintenance. Both the CTU and WU are molded from fiberglass-reinforced resins that are extremely resistant to salt, ch lorine, and exposure to ultraviolet light. However, both the CTU and WU contain sophisticated electronic components, and therefore, require reasonable care and treatment.

• Avoid sharp impacts to the CTU and WU.

• Do not expose units to extreme heat or cold.

• Replace batteries when they become discharged, or every 6 months,

whichever should occur first.

• Rinse both units wi th fresh water and allow them to air-dry after each use. Take special care when rinsing the opening on the CTU that is between the battery caps. NEVER attempt to clean this area with a pointed object or with blasts of compressed air or high-pressure water. Doing so will cause severe damage to your CTU, rendering it inoperable and voiding the Warranty. Avoid getting the O

sensor or inside of the

connector to the sensor or bulkhead conne ctor w et.

You can extend the service life of your dive computer by simply rinsing it with fresh water. When using a garden hose to rinse your unit, keep the water pressure very low. No chemicals of any type should be used on your dive computer. The WU’s rubber strap may be conditioned with silicone spray designated for use with SCUBA equipment. You will find this type of silicone spray at your local dive shop. Care should also be taken to prevent your WU’s lens from becoming scratched or damaged. Minor scratches will become invisible underwater. However, severe gouges or cracks in the lens would require that it be replaced. The installation of the optional WU lens protector available through your Cochran Dealer will prevent this type of WU lens damage.

O2 Sensor Care

Care should be taken to prevent shock or immersion in liquids. The life of the sensor will also be reduced by exposure to high % of O

. For maximum life and to

avoid voiding your warranty use only sensors sold by Cochran.

Battery Type and Replacement

Your dive computer operates on two different sizes of user-replaceable batteries. The CTU requires four alkaline ‘AA’ batteries while the WU requires 2 alkaline ‘N’ batteries. We recommend using only high quality alkaline batteries for both the CTU and the WU. Avoid self-testing batteries as they can cause loss of

power by going into the self-test mode while in the CTU. Other types of batteries (such as Lithium and Nickel Cadmium) may permanently damage the Computer Transmitter Unit or Wrist Unit and void the warranty. Use of

old, off-brand, incorrect and/or visibly corroded batteries will also affect performance, damage the units, and void the warranty.

There are factors, which can significantly vary battery-operating life. These include:

• Original quality of battery as manufactured.

• Age of battery prior to installation.

• Length of time batteries have been installed.

• Frequency and cumulative number of WARNINGS issued by the

computer.

• Temperature of the battery in operation. Fresh ENERGIZER

brand batteries installed in the CTU will read about 6 volts. At 5.4 volts the low battery indicator is shown on the WU. At 4.8 volts, your CTU will not turn on. Battery life in the WU will be affected by the number of times you activate the TACLITE. On a new, fresh set of ENERGIZER

brand N-type

batteries in the Wrist Unit, you should get approximately 10,000 TACLITE cycles. To replace batteries on CTU:

a) Prepare four new ENERGIZER® brand AA alkaline batteries (NO Lithium)

Coat both ends of each battery with a light coat of silicone or Vaseline to reduce oxidation buildup.

b) Double check the orientation of batteries with the picture on the bottom of

the battery tubes

c) Remove one battery cap; replace batteries, re-install battery cap carefully

making sure not to cross-thread the batte ry cap d) Wait one minute e) Remove the other battery cap, replace batteries, and reinstall battery cap

making sure not to cross-thread the batte ry cap.

NOTE: The one-minute delay allows the circuit, which maintains power to the CTU during a battery change time to recharge.

To replace the WU batteries:

a) Prepare two new ENERGIZER® brand alkaline 'N-cell' batteries b) Double check the orientation of batteries with the picture at the

bottom on the back of the WU case

c) Using the supplied battery replacement tool, remove the battery

cap; replace the batteries, re-install the battery cap carefully making sure not to cross-thread the battery cap

Battery Care

Two separate, sealed battery compartments isolate the alkaline batteries from the main computer. Gases given off by the chemical reaction that produces electricity within batteries react with the metal contacts of the batteries, causing corrosion. Over time, this coating ac cumulates and lowers the amount of power the battery can deliver. Even though batteries that have been in the dive computer for a period of time may indicate ample voltage, the corrosion interferes with delivery of power from the battery to the dive computer. Preventive maintenance in the form of the periodic burnishing of the battery's contacts and applying a thin film of silicone grease to the battery terminals will greatly minimize this corrosion from forming.

NOTE: It is always advi sable to replace older or questionable CTU batteries with new, fresh batteries before a long series of dives, especially if your dive computer has been inactive for an extended time.

NOTE: Remember, your CTU cannot be manually turned off; and since the CTU computes all of the diving data, turning your WU off will not affect your decompression information. Residual nitrogen elimination, as well as time-to-FLY can be viewed by turning the WU back on.

CAUTION!!! DO NOT ALLOW THE LIFEGUARD™ TO HAVE LOW OR NO

BATTERIES FOR ANY EXTENDED PERIOD OF TIME! 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 L OADING. IF LOSS OF NITROGEN LOADING OCCURS, COCHRAN STRONGL Y RECOMMENDS THAT A PERIOD OF 24 HOURS ELAPSES BEFORE MAKING ANY SUBSEQUENT DIVES.

TECHNICAL SPECIFICATIONS

(Subject to change without notice)

No-Decompression Model

Algorithm: Modified Haldanean Number of Half Time Compartments: 12

Decompression Ceilings

Ceiling Depths: 10, 20, 30, 40, 50, 60, 70, 80, 90 feet

3, 6, 9, 12, 15, 18, 21, 23, 27 meters

Altitude Diving Model

Procedure: Altitude adjust is seamless from sea level to 15,000 feet (4600 meters) above sea level.

FUNCTIONAL

RANGE INCREMENT Altitude 15,000 feet / 4,600 meters Seamless Dive Number 0 - 9 dives 1 Dive Depth 0 - 327 feet 1 Foot

0 - 99.9 meters 0.1 meter Temperature 0 - 99 deg F. 1 degree

0 - 37 deg C 1 degree Surface Time 0 - 17 hours 03 minutes 1 minute Maximum Depth 0 - 327 feet 1 foot

0 - 99.9 meters 0.1 meter High PO

Alarm .50 - 1.6 ATA

Low PO2 Alarm .20 - .40 ATA

OPERATIONAL

Altitude 15,000 feet / 4,600 meters Depth/Max Depth 327 feet / 99.9 meters Depth Gauge Range 327 feet / 99.9 meters Clock Timer 17 hours 03 minutes Logbook 300 dives Dive Of The Day Counter 9 dives Second-by-second Profiles13.6 hours

HARDWARE

Casing Fiberglass reinforced ABS Plastic Lens Material Polycarbonate

POWER

CTU UNIT WRIST UNIT Battery 4 ‘AA’ 2 ‘N’ Battery type Alkaline Alkaline

TURN-ON

CTU WU

Activation Sonic / O2 % Inertial Switch

ACCURACY

Altitude +/- 1,000 feet Temperature +/- 1.5% full scale Depth Gauge +/- 1.0% full scale Bottom/Surface Time +/- 1.0 sec. /24 hours

NOTE: Specifications are an additional +/- one least significant digit due to rounding. Specifications subject to change without notice.

PRODUCT ASSISTANCE, REPAIR & MAINTENANCE

If you suspect that your

LIFEGUARD™ is not operating correctly, please contact our Customer Support Department in the USA for assistance at 972.644.6284 or FAX details to 972.644.6286 or E-mail details to service@divecochran.com. Most problems can be resolved without returning the unit. The unit may also be returned to the place of purchase and request the dealer to contact us. If this is not possible or is inconvenient due to a change in loc atio n, cont act us for the name of the nearest Team Cochran Authorized Dealer.

• NEVER TEST OR SUBJECT THE PRODUCT TO PRESSURIZED AIR!

• NEVER REMOVE THE LENS FROM THE WRIST UNIT!

• NEVER REMOVE THE LID FROM THE COMPUTER TRANSMITTER

UNIT!

•

ONLY PRESSURE POT TEST DIVE THE UNIT IN WATER!

• ONLY USE FRESH WATER TO CLEAN THE UNIT! NEVER USE

SOLVENTS!

• DO NOT USE A SCREWDRIVER TO REMOVE THE BATTERY CAPS!

• ALWAYS KEEP FRESH ENERGIZER

BRAND

BATTERIES INSTALLED!

•

ALWAYS USE 1.5 VOLT BATTERIES!

• LUBRICATE BATTERY ENDS WITH A THIN FILM OF SILICONE

GREASE!

REPLACEMENT PARTS

Tank Unit Battery Cap O-ring 19915 Tank Unit Battery Caps w/O-rings 19911 Wrist Unit Battery Cap O-ring 19930 Wrist Unit Battery Cap w/O-rings 19934 Mounting Clips, TU, Pkg. of Three 19914 Strap, Replacement Set, Gray 19950 Pins (2), replacement 19949 Wrist Unit Lens Protector 15401 Large Retractor 15925 Large Retractor w/compass 15935 O2 Sensor 12814 Bulkhead Connector 12850 Large (1" id) O

"Tee" 12860

Small (3/4" id) O2 "Tee" 12861

ANALYST® PERSONAL COMPUTER INTERFACE

The Analyst® Personal Computer Interface Is a complete hardware/software systems that uploads data from the

LIFEGUARD™ dive computer to an IBM or

compatible Personal Computer with a Windows

95/98/NT operating system.

The Analyst

Personal Computer Interface allows the diver to retrieve dive data, customize the dive computer and to also enter and store additional information for each dive in a logbook database.

To install your ANALYST® follow the instructions supplied with the CD.

Field Programmer

The Field Programmer is designed for use with the LIFEGUARD™ PO2 Monitor. This device allows the user to program into the unit an added degree of conservatism, a maximum depth alarm, and to calibrate the PO

sensor.

NOTE: The Field Programmer is NOT waterproof.

Cochran Lifeguard 04-150i, Lifeguard 150i User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual