Hydrospace HS EXPLORER PPO2 User manual

10/25/06
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HydroSpace Engineering, Inc.
6920 Cypress Lake Court
St. Augustine, FL 32086 USA
Telephone 904-794.7896
Fax 904. 794.1529
http://hs-eng.com
Copyright © 2003-2006, HydroSpace Engineering, Inc.

10/25/06
TABLE OF CONTENTS
i
IF YOU READ NOTHING ELSE IN THIS MANUAL - READ THIS PAGE!......................................................ii
QUICK REFERENCE FIELD SETUP GUIDE -...............................................................................................iii
General........................................................................................................................................................iii
Calibration...................................................................................................................................................iii
INTRODUCTION..............................................................................................................................................5
Acknowledgements......................................................................................................................................5
Thank You....................................................................................................................................................5
GENERAL........................................................................................................................................................6
PREPARING YOUR HS EXPLORER PPO2MONITOR FOR USE.................................................................6
Battery Care and Information......................................................................................................................7
Battery Duration...........................................................................................................................................7
Battery Voltage.............................................................................................................................................7
Inspecting the PPO2Monitor........................................................................................................................7
Oxygen Fuel Cell Setup And Calibration Procedure....................................................................................8
General.................................................................................................... Error! Bookmark not defined.
O2CELL LOAD RESISTORS ......................................................................................................................8
Connecting the O2Cell.............................................................................................................................9
Post Dive....................................................................................................................................................12
Post-Dive Care.......................................................................................................................................12
GENERAL MAINTENANCE...........................................................................................................................12
WARRANTY AND SERVICE.........................................................................................................................13
REPAIR AND UPGRADE POLICY................................................................................................................13
RETURN POLICY..........................................................................................................................................13
Appendix A - Equivalent Depth Tables..........................................................................................................14
Inert Gas Partial Pressure - Imperial..............................................................................................................15
Appendix B - Pressure Conversions..............................................................................................................17
Appendix C - Altitude/Pressure/Depth Correction/Oxygen Concentration Table ..........................................18
References:....................................................................................................................................................19
GLOSSARY ...................................................................................................................................................20
REGISTRATION FORM.................................................................................................................................21

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ii
IF YOU READ NOTHING ELSE IN THIS MANUAL - READ THIS PAGE!
Scuba diving, especially technical diving, can be an extremely hazardous activity. While utilization of tools
such as the HS Explorer PPO2Monitor can mitigate some of the risks associated with technical diving,
misuse of this tool can actually increase or create new risks. Please read this Manual carefully before using
your new HS Explorer PPO2Monitor, especially the warnings contained upon this page. We at
HydroSpace Engineering hope that you will enjoy using your new HS Explorer PPO2Monitor and trust it will
bring you years of service and safe diving.
The warnings contained in this section are designed to prevent harm to two things; you, and your new HS
Explorer PPO2Monitor. Please read them carefully.
WARNING!
IMPROPER USE OF THIS DEVICE CAN RESULT IN SERIOUS INJURY OR DEATH.
Do not dive with a this device until you:
1. Have read the owner's manual
2. Understand fully how operate the device correctly
3. Have received proper training in the use of gas mixtures other than normal air
4. Have received proper training in conducting stage decompression dives.
5. Have received proper training in Open/Closed Circuit SCUBA diving.
Use of this device in any diving activity constitutes agreement by the user that he or she assumes and
accepts full responsibility for all risks.
WARNING!
Insertion of the battery backward (reverse polarity) will ruin the computer and VOID the warranty.
The warranty is null and void if:
•The battery has been inserted backwards (reverse polarity).
•The unit has been dried with compressed air (gas).
•The lens has been removed or the lens screws loosened. The product has been modified in any way.
•The product has been abused.
•The product's limits have been exceeded or the product exposed dry (chamber) exposure.
•The product is not registered within 10 days of purchase.
•The product has been exposed to any material, which causes damage to the case, lens or o-rings.
•The product has been maintained in a manner inconsistent with is usage or standard practices.
REPAIR CHARGES WILL BE ASSESSED ON INVALIDATED UNITS!
•Minimum Charges, when there is no damage to electronics:
•Case Replacement - $400.00, Lens Replacement - $150.00, Battery Cap - $15.00
•Do not remove the lens or loosen the screws. The transducer has been carefully sealed and when the
seal is broken, the transducer calibration is no longer valid. In addition, an internal integrity seal will be
broken if the electronics are opened. You will be assessed $450.00 plus parts and labor to repair any
HS Explorer PPO2Monitor found to have been opened!
•Repair prices are subject to change without notice.
WARNING!
Never use spray lubricants. The chemicals may attack and ruin the housing materials.

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iii
QUICK REFERENCE FIELD SETUP GUIDE -
First read the previous page: THEN IF YOU READ NOTHING ELSE IN THIS MANUAL - READ THIS
PAGE! Note
The HS Explorer PPO2Monitor is supplied with the display unit and
O2cell connection cable. It is up to the user to furnish the O2 cell and
cell adapter (holder). The user is also responsible for the cable/cell
holder installation.
General
1. Press and Release the LEFT Button (A) to activate the Explorer PPO2Monitor.
2. If calibration is lost, the left most display will alternate ‘`’ then ‘^’ for calibration alert.
3. Press Left Button (A ) for a 9count to activate the Setup Function.
4. General Setup information: The LEFT button (A) increments the Function. The LEFT button (A) is
used to EXIT the calibration mode.
5. To exit the calibration mode, Press and hold Button A and B until active mode to exit the calibration
mode. An ‘b’ (Exit) will be displayed
Calibration
1. Place the O2fuel cell in the calibration gas and allow time for it to stabilize.
2. Press LEFT Button or place a coin over the middle and left water contact for 3 seconds.
3. The letter ‘`’ will appear on the left side of the screen and the oxygen percentage of the calibration gas
will appear to the right.
4. Press Button A will decrease the calibration gas percentage.
5. Press Button B to increase the calibration gas percentage.
6. When the calibration gas percentage is showing in the window, simultaneously press Buttons A and B
for 3 seconds (no count number is displayed). An ‘b’ for (Exit) will appear on the left side indicating that
both buttons are pressed. At the end of the 3 seconds, unit will shift into the operations mode.
7. The display will now start counting. When the count is complete, the unit will go into the standby mode.
The HS Explorer PPO2Monitor contains a water activation circuit and will activate on immersion.
The HS Explorer PPO2 Monitor is now setup and ready to use.


10/25/06
INTRODUCTION
Figure 1 – HS Explorer PPO2 Monitor with Cable and O2 Cell
The purpose of this manual is to acquaint the new user with the procedures and techniques for using the HS
Explorer PPO2Monitor. It applies to both the 1 Cell and 3 Cell models. The calibration procedure is the
same for both units. The PPO23 Monitor cycles between each cell every 2 second which will require 6
second to view all 3 readings,
Please read this manual fully prior to using the HS Explorer PPO2. It is not uncommon for new users to
spend several hours reading these instructions, and working with their new HS Explorer PPO2Monitor prior
to understanding the functions sufficiently to utilize them during the dive.
Technical diving is an activity that involves many objective hazards and risks. While the HS Explorer PPO2
Monitor can be used to mitigate some of those risks, if the PPO2Monitor is used improperly it can actually
lead to a greater degree of risk associated with inert gas decompression sickness.
Use of the HS Explorer PPO2Monitor will not eliminate the chance of experiencing decompression sickness.
Regardless of the decompression model that the diver uses, or how cautiously a diver dives, there's always
risk of decompression sickness. This risk will be increased if the gas mixes are improperly set. Please take
the time to read these directions, to insure that you know and understand the proper way of configuring your
new HS Explorer PPO2Monitor.
HydroSpace Engineering appreciates comments or suggestions you have for future upgrades to its HS
Explorer PPO2Monitor or the simulation software. Please address suggestions to support@hs-eng.com.
MANUAL CHANGES/UPDATES - Changes from the previous version are in light blue color. When the
manual is updated, previous changes will be set to dark blue from light blue and any previous dark blue
changes will be reset to the normal color (usually black) for that section/type of text.
Acknowledgements
The authors wish to thank the following individuals for there help and comments in preparing this manual:
Jeff Bozanic, Patrick Duffy, Bob Hicks, Mark Johnson, Tom Mount, Joe Radomski, Peter Steggle, Forrest
Wilson.
Thank You
A special "Thank You" to all of you who have offered comments and suggestions that have enabled us to
improve the HS Explorer to a friendlier and easier to use PPO2Monitor. A sincere apology to anyone whose
name was omitted. Any omission was unintentional.

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6
GENERAL
WARNING!
IMPROPER USE OF THIS DEVICE CAN RESULT IN SERIOUS INJURY OR DEATH. Do
not dive with this device until you (1) have read the owner's manual, and (2)
understand fully how to operate the device correctly, and (3) have received proper
training in the use of gas mixtures other than normal air, (4) have received proper
training in conducting staged decompression dive's and (5) have received proper
training in the equipment you are using. Use of this device in any diving activity
constitutes agreement by the user that s/he assumes and accepts full responsibility
for all risks.
The HS Explorer PPO2Monitor was designed to be a simple, easy to use monitor for PPO2levels when
diving with Closed Circuit and Semi-Closed Circuit SCUBA equipment. Calibration requires that the O2fuel
cell be placed in the appropriate calibration gas. The difference between the two models PPO21 and PPO2
3 is the number of O2 cells each will read. The PPO21 reads one O2cell and the PPO23 reads 3 cells.
Button Terminology - The Left Button is 'Button A' and the Right Button is 'Button B'.
PREPARING YOUR HS EXPLORER PPO2MONITOR FOR USE
Battery installation
The HS Explorer PPO2Monitor is shipped with the battery installed. In the even the battery needs to be
replaced, complete the following steps. Warning: Removing the battery invalidates the O2cell(s)
calibration.
1. Unscrew the knob covering the battery compartment by turning it counterclockwise. Ensure that the
brass tab rotates freely. If the brass tab does not rotate freely, unscrew the screw that holds that to the
cap by one quarter turn. Confirm that the brass tab will now rotate freely. If it still does not do so,
continue to unscrew the screw by one-eighth turn until it rotates freely.
2. Inspect the two O-rings on the sealing cap. Utilizing a suitable silicone lubricant, lightly lubricate the O-
rings. Confirm that the O-rings are intact and clean.
3. Confirm that the flat end of the battery (the negative side) is the end being lowered into the battery
compartment first. Insert the battery into the computer's battery compartment . With the brass tang
positioned to the right (3 o'clock) (6 and 9 o'clock are secondary positions), slide the tang into the battery
compartment between the battery and the brass sleeve (positive contact) . The tang should slide
smoothly in place. If you encounter any resistance, STOP inserting and pull the tang back, inspect for a
damaged tang and/or sleeve. If no damage is visible, retry the tang insertion. Failure to insert the
battery properly will cause irreversible damage to the computer, and will void your warranty!
Note: The fit of the battery with the brass tang while being lowered in the battery compartment is snug.
This is to insure that a positive contact is made for the battery electrodes to the rest of the computer. If
you have trouble inserting the battery, do not force the battery into place. It may be that the tab has not
slipped fully into place inside the brass sleeve inside the battery compartment. Forcing the battery and
cap into place may damage the brass tab! Such damage may necessitate a return of the battery and HS
Explorer PPO2Monitor to the factory for repair or replacement.
4. Once the tang has been inserted in the compartment, begin to screw the battery housing cap closed, by
rotating the cap clockwise. At some point after the first O-ring has made a seal, but prior to the second
O-ring making a seal, it is likely that the computer will turn itself on. This is normal. Continue to screw
the battery compartment plug again until the second O-ring just provides a seal. If the computer has not
turned on by this point, you may turn on the computer by depressing switch A. Do not tighten the battery
compartment plug any further. Over tightening the battery compartment plug may cause permanent
damage to the battery or crack the bottom of the battery compartment case. It may also result in over
tightening of the retaining screw for the brass tab. This may lead to further damage of the brass tang
and battery cap! The battery is now installed properly in your HS Explorer PPO2Monitor.

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7
Battery Care and Information
Your HS Explorer PPO2Monitor utilizes a 3.6V lithium AA battery. To replace it, utilize a Tadiran® TL-2100,
Saft LS 14500 or equivalent battery. CAUTION!
The Saft battery is slightly longer than the Tadiran. Do not over-tighten the
battery cap as it may cause the bottom of the battery compartment to crack.
They may be purchased directly from HydroSpace Engineering, Inc. utilizing the order form from the back of
this manual, or may be available from many electronics stores, photographic stores, or pharmacies.
Improper use of these batteries may result in explosion, fire, or severe burns! Proper battery care includes
the following:
•Do not recharge these batteries. They are not rechargeable.
•Do not heat above 40oC (104oF). Do not expose to fire or high heat.
•Do not expose to water.
•Do not short the contacts.
Battery Duration
The length of time that the HS Explorer PPO2Monitor will run on a battery is dependent on usage.
Whenever the battery is in the computer, there is always some power drain from the battery. Even when the
computer is turned off, there is a continuous low-level power drain from the battery. The following table
provides average battery life. Actual results may vary based on water temperature, frequency and duration
of use.
Mode Battery Life (hours)
Standby ~10 years (battery limit)
On (diving) 2,000+ hours
Your HS Explorer PPO2Monitor has an “Auto-Off” feature. On the surface, this places the HS Explorer PPO2
Monitor in the sleep mode after 30 seconds. This state does minimize battery power consumption.
Battery Voltage
A fresh battery starts at 3.6 volts. As the battery is utilized, voltage drops until it reaches a level incapable of
powering the computer properly. If battery voltage drops too low, the HS Explorer PPO2Monitor may
spontaneously reboot, or cease operation. It is recommended that the battery be replaces after 8years of
usage.
Guidelines for maximizing battery life:
•Keep the HS Explorer PPO2Monitor warm before and between dives. Air temperatures below 50oF
(10oC) will reduce battery current capacity (shorten apparent capacity).
•Never leave the computer in Setup or manual programming mode, as the battery will operate the
computer until it is completely drained (This will take about 2 years).
•Always keep a spare battery on hand, and bring extra batteries when traveling to remote locations or on
extended dive vacations.
•Prevent crushing or impact to battery when not in use.
•Store batteries in a cool environment when not in use.
•Allow batteries to warm to ambient temperature prior to installation.
Inspecting the PPO2Monitor
It is important to visually inspect your HydroSpace Engineering PPO2Monitor prior to using it in open water.
Pay special attention to the following points:
1. Inspect the clear faceplate to insure that there are no cracks. Pay particular attention to the area around
the screws that fasten the faceplate to the computer. Also look for any signs of moisture or water under the
faceplate. If any cracks or moisture is observed, do not dive with the computer! Return the computer as
quickly as possible to HydroSpace Engineering, Inc., at the address listed of the warranty service page at the
back of this manual.

10/25/06
8
3. Inspect the two wrist wraps for cracks, tears, or other weak points. If any damage is found in the straps,
replace the strap prior to diving.
Your HS Explorer PPO2Monitor is now ready to dive. Continue reading for programming instructions prior to
beginning the dive. WARNING!
Never use spray lubricants on the housing or wrist straps. The chemicals may attack
and ruin the housing materials, seals and/or straps.
Oxygen Fuel Cell Setup And Calibration Procedure
Caution!
Calibration of the O2cells is required prior to each use.
Oxygen Cells are chemical batteries and therefore have a limited life span. While O2Cells can last longer
than 12 months, HydroSpace Engineering, Inc. recommends replacement of the O2cell(s) on an annual
basis. This will help insure the reliability and accuracy of the O2Cell's usage. An aged cell may calibrate
successfully with 100% Oxygen at sea level but fail to provide adequate output at the higher PPO2's
encountered while diving.
The HS Explorer has been tested with the Teledyne R-22D Oxygen Cell. While other O2Cells may perform
satisfactory, their use has not been tested. It is the responsibility of the user to verify the accuracy and
response of the O2Cell in use. The use of O2Cells other than the R-22D and the results obtained are the
sole responsibility of the end user. Specifications and information on the R-22D may be found on the
Teledyne web site: http://www.teledyne-ai.com/oem/diving.html
Inaccurate or false Oxygen sensor readings can be caused by many factors. Some of the preventable
factors include: water on membrane, touching the sensor face, contaminants, CO2exposure, heat,
temperature extremes and impact damage. Oxygen fuel cells are delicate devices. Treat them accordingly.
The Explorer only displays the PPO2in units, tenths and hundredths. For Example: A PPO2display of NKPM
will include 1.295 to 1.314.
The activation and calibration of the O2Cell is a three-step process.
1. Connect the O2Cell to the Explorer.
2. Activate the HS Explorer PPO2Monitor calibration mode.
3. Calibrate the O2Cell output.
O2CELL LOAD RESISTORS
The PPO2-1 Monitor has a 10K Ohm balance resistor installed. The PPO2-3 Monitor is intended to be used
in conjunction with another device connected to the O2cell which provides the correct balance resistor for the
O2cell in use. The HS Explorer PPO2Monitors were tested with Teledyne R22-D oxygen fuel cells. The
monitor should work with other cells but it has not been tested with other O2cells. The R22-D requires a 10K
Ohm load to balance the internal temperature compensating network. The HS Explorer PPO2-3 when
shipped with a setpoint controller has 220K Ohm resistors across the O2 Cell input. The HS
Explorer PPO2-3 when shipped alone has 10K Ohm resistors across the O2 Cell input. When
connected in parallel with another 10K Ohm load resistor the resultant load is about 9.5K Ohms. This could
result in a 5% change in the O2cell output temperature compensation over the temperature range. If the
PPO2-3 Monitor is used by itself a 10.5K Ohm resistor placed across each O2cell will provide the 10K Ohm
load recommended by Teledyne.
21 2*1 RR RR
Rt +
=22000010000 220000*10000
+
=Rt Ω
=
KRt 565.9
WARNING
It is YOUR responsibility to install the proper load resistors for the O2cell in use.

10/25/06
9
Connecting the O2Cell
The bulkhead receptacle on the HS Explorer and the corresponding cell connector are self aligning.
WARNING
Never force the connector and do not use tools on the connector. The
connector/receptacle may be damaged or loosened on the housing causing a leak.
WARNING
The connector is NOT designed to be connected/disconnected under water. Never
connect/disconnect the connector under water.
•Inspect the connector and receptacle for cleanliness. Remove any dust, dirt, salt crystals or other debris.
Be careful not to damage the sealing O-ring at the bottom of the receptacle.
•Place a light coat of silicon grease on the outer portion of the connector shell where it goes into the
receptacle.
•Align the pins with the receptacle contacts, gently insert the connector into the receptacle, screw in the
connector. The connector is IP-68 rated only when fully connected.
Figure 2 – Connecting O2Cell Cable
•Press the left button on the HS Explorer PPO2Monitor for a ‘V’ count. The HS Explorer PPO2Monitor is
in the O2cell calibration mode.
Figure 3 - Calibration
•The screen will be cleared, "`" will be displayed on the left and the calibration gas percentage on the
right. For example, “21” is 21% Oxygen (Air). The value used for calibration is 20.9.

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10
Figure 4 – Calibration Oxygen Percentage
•Set the calibration gas percentage of oxygen. Please see the appendix for setting the correct
percentage at altitude.
•To change the calibration gas percentage, press the LEFT button to decrease the percentage and press
the right button to increase the percentage.
•When the O2cell is in equilibrium in the calibration gas, the exit the calibration mode
•If you are not changing the O2calibration percentage, press and hold both buttons to set the calibration
and exit the calibration mode. An “b” will be displayed on the left during the exit procedure. The display
will not count but will change to the Active mode “^” momentarily. Then display “M” (On) and the PPO2
value “MKON”.
Figure 5 – Normal PPO2Display

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11
In the event calibration is lost and the unit is active, an “A” will be displayed on the center segment. This
requires calibration to clear. Removing the battery is the currently known method for loss of calibration.
Figure 6 below shows the monitor in the active mode with a calibration alarm.
Figure 6 – Going Active with Calibration Error Figure 7 – Active with Loss of Calibration (Alarm)
The left most display will alternate ‘`’ then ‘^’ for calibration alert when the monitor is activated on the
surface.
Figure 8 – “A” changing to “C” at 29 seconds

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12
Post Dive
Post-Dive Care
Proper post-dive care will extend the life of your HS Explorer PPO2Monitor, and will minimize maintenance
problems. Follow these simple guidelines after diving:
1. Rinse your HS Explorer PPO2Monitor immediately with fresh water after diving in salt water.
2. Soak your HS Explorer PPO2Monitor in fresh water for 15 minutes after a day’s diving activities.
3. NEVER blow the computer dry with compressed air. This will force water past the o-rings, and
ruin the electronics. It may also embolize the transducer protective gel. If you do this, your warranty
is no longer valid and you will be charged for repairs.
4. Dry the water activation contacts with soft towel. These contacts are connected to the "wake-up"
circuit. Any residual water will be sensed and the unit may not stay in the sleep mode, thus
shortening battery life.
5. After drying, store your HS Explorer PPO2Monitor in a secure location, with the polycarbonate
faceplate padded and protected from abrasion or impacts that might scratch the plastic cover.
6. Always, before reinstalling the battery cap, clean and remove any sand, grit, or other debris from the
threads and O-ring. Lightly lubricate the O-ring with an appropriate silicone grease prior to
installation. WARNING!
Never use spray lubricants on the housing or wrist straps. The chemicals may attack
and ruin the housing materials and or straps.
WARNING!
Under no circumstances should you open the monitor. If the internal tamper seal is
broken (indicating the computer has been opened), there is a minimum $450 service
charge to service the computer.
GENERAL MAINTENANCE
While your HS Explorer PPO2Monitor is a robust and durable piece of diving equipment, it is also a
sophisticated electronic tool with many sensitive parts and components. Many of these may be damaged if
your HS Explorer PPO2Monitor is improperly treated. Abusive treatment or improper care of your HS
Explorer PPO2Monitor will invalidate the warranty. Follow these guidelines to maintain your HS Explorer
PPO2Monitor:
•Follow the Post-Dive Care guidelines provided in the previous section.
•Do not expose your HS Explorer PPO2Monitor to high temperatures.
•Always insert the battery properly with reference to the polarity.
•Use only approved 3.6V lithium batteries.
•Prevent abrasion or impacts to the polycarbonate faceplate.
•Never remove or tighten the screws connecting the polycarbonate faceplate to the computer.
•Do not over-tighten the battery cap when installing the battery.
•If any signs of water in the housing are noted, return the unit to HydroSpace Engineering, Inc. for
inspection/repair as soon as possible.
•Do not expose your HS Explorer PPO2 Meter to cleansers or other harsh chemicals.
•Never insert anything other than the battery into the battery compartment.
•Store your HS Explorer PPO2Monitor out of direct sunlight.
•Clean sand, grit, or other debris from battery cap threads prior to installing battery cap.
•Remove battery prior to long-term storage of your HS Explorer PPO2Monitor.
•Always install the battery cap prior to immersion in water.
•Do not immerse or dive with a computer if it shows signs of flooding or other damage, or if it seems to be
operating improperly.
•Do not expose your HS Explorer PPO2Monitor to organic solvents, as they will damage the housing,
polycarbonate faceplate, and O-rings.
•Insure the brass tab or tang in the battery compartment is capable of rotating freely at all times.

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13
WARRANTY AND SERVICE
HydroSpace Engineering, Inc. remains committed to producing only the finest PPO2Monitors, and stands
behind their product 100 percent. Should experience difficulties with your HS Explorer PPO2Monitor, follow
the instructions below.
return merchandise authorization (RMA) number.
2. Return the HS Explorer PPO2Monitor to Repair Department , HydroSpace Engineering Inc., freight
prepaid, at 6920 Cypress Lake Court, St. Augustine, Fla. 3206, USA.
3. Enclose a written explanation of the problems experienced with the unit. Be as specific as possible,
explaining exactly what you were doing when the problem arose. Specify whether the problem occurred
above or below the surface, and whether it occurred prior, during, or after a scuba dive.
4. Enclosed a sheet with the address to return the repaired HS Explorer PPO2Monitor to. Also enclose your
daytime telephone number, and your e-mail address if available. Specify the best time for one of our
technicians to contact you if we have further questions about the problem you experienced with your HS
Explorer computer.
5. If your HS Explorer PPO2Monitor is being repaired under warranty, it will be repaired or replaced at no
charge to you. To activate your warranty, you must have returned the HS Explorer product registration form
sent to you with your HS Explorer Computer within 10 days of purchase. Please enclose a copy of that
product registration form, along with a receipt from the vendor showing the date of purchase that you
acquired the HS Explorer computer.
6. If your HS Explorer Computer is not being repaired under warranty, there is a minimum repair/evaluation
charge of $75. An estimate will be provided to you for the total cost of repair or replacement after our
technicians have had an opportunity to evaluate your computer. If additional charges are indicated, the
repair will not be completed until you have provided authorization, with prepayment of the repair charges.
7. The return merchandise authorization (RMA) number must be included inside your shipment container,
and must also be written on the address label to HydroSpace Engineering, Inc.
HydroSpace Engineering reserves the right to determine if the user has invalidated the warranty by misuse
of the HS Explorer PPO2Monitor, or by improper treatment or maintenance protocols.
REPAIR AND UPGRADE POLICY
1. Contact HydroSpace Engineering, Inc. for a Return Authorization Number. Write this number on the
outside of the package. Be sure to include your name and address on the inside.
2. All units are to be returned freight prepaid.
3. Units requiring repair may be repaired or replaced as required by the circumstances.
4. Any return prepaid shipping will be per direction.
5. There is a $10.00 (U.S.A.) and $20.00 (International) shipping and handling charge assessed for
firmware upgrades on units older than 30 days. Additional charges may apply to special courier.
RETURN POLICY
1. The HS Explorer may be returned unused within 30 days for a refund. A 20% restocking fee will be
assessed.
2. After 30 days, no refunds will be given.

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14
Appendix A - Equivalent Depth Tables
PPO2Setpoint
Depth 0.21 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8
30 36 32 28 24 20 16 11 7 3 -1 -5 -9 -14 -18 -22 -26 -30
40 49 45 41 37 32 28 24 20 16 12 7 3 -1 -5 -9 -14 -18
50 61 58 53 49 45 41 37 33 28 24 20 16 12 7 3 -1 -5
60 76 72 68 64 60 55 51 47 43 39 35 30 26 22 18 14 10
70 87 83 79 75 70 66 62 58 54 49 45 41 37 33 29 24 20
80 99 96 91 87 83 79 75 71 66 62 58 54 50 45 41 37 33
90 112 108 104 100 96 92 87 83 79 75 71 66 62 58 54 50 46
100 125 121 117 113 108 104 100 96 92 87 83 79 75 71 67 62 58
110 137 134 129 125 121 117 113 108 104 100 96 92 88 83 79 75 71
120 150 146 142 138 134 129 125 121 117 113 109 104 100 96 92 88 84
130 163 159 155 151 146 142 138 134 130 125 121 117 113 109 105 100 96
140 175 172 167 163 159 155 151 146 142 138 134 130 126 121 117 113 109
150 188 184 180 176 172 167 163 159 155 151 147 142 138 134 130 126 122
160 201 197 193 188 184 180 176 172 168 163 159 155 151 147 143 138 134
170 213 209 205 201 197 193 189 184 180 176 172 168 164 159 155 151 147
180 226 222 218 214 210 205 201 197 193 189 185 180 176 172 168 164 159
190 239 235 231 226 222 218 214 210 206 201 197 193 189 185 181 176 172
200 251 247 243 239 235 231 227 222 218 214 210 206 202 197 193 189 185
210 264 260 256 252 248 243 239 235 231 227 223 218 214 210 206 202 197
220 277 273 269 264 260 256 252 248 244 239 235 231 227 223 218 214 210
230 289 285 281 277 273 269 265 260 256 252 248 244 239 235 231 227 223
240 302 298 294 290 286 281 277 273 269 265 261 256 252 248 244 240 235
250 315 311 307 302 298 294 290 286 282 277 273 269 265 261 256 252 248
260 327 323 319 315 311 307 303 298 294 290 286 282 277 273 269 265 261
270 340 336 332 328 324 319 315 311 307 303 298 294 290 286 282 278 273
280 352 349 345 340 336 332 328 324 319 315 311 307 303 299 294 290 286
290 365 361 357 353 349 345 341 336 332 328 324 320 315 311 307 303 299
300 378 374 370 366 362 357 353 349 345 341 336 332 328 324 320 316 311
Equivalent Depth in Feet
Inspired gas pressure compensated for water vapor pressure

10/25/06
15
Appendix A (continued)
PPO2Setpoint
Depth 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8
30 1.65 1.56 1.46 1.36 1.26 1.16 1.06 0.96 0.86 0.76 0.66 0.56 0.46 0.36 0.26 0.16 0.06
40 1.96 1.87 1.77 1.67 1.57 1.47 1.37 1.27 1.17 1.07 0.97 0.87 0.77 0.67 0.57 0.47 0.37
50 2.26 2.17 2.07 1.97 1.87 1.77 1.67 1.57 1.47 1.37 1.27 1.17 1.07 0.97 0.87 0.77 0.67
60 2.56 2.47 2.37 2.27 2.17 2.07 1.97 1.87 1.77 1.67 1.57 1.47 1.37 1.27 1.17 1.07 0.97
70 2.86 2.77 2.67 2.57 2.47 2.37 2.27 2.17 2.07 1.97 1.87 1.77 1.67 1.57 1.47 1.37 1.27
80 3.17 3.08 2.98 2.88 2.78 2.68 2.58 2.48 2.38 2.28 2.18 2.08 1.98 1.88 1.78 1.68 1.58
90 3.47 3.38 3.28 3.18 3.08 2.98 2.88 2.78 2.68 2.58 2.48 2.38 2.28 2.18 2.08 1.98 1.88
100 3.77 3.68 3.58 3.48 3.38 3.28 3.18 3.08 2.98 2.88 2.78 2.68 2.58 2.48 2.38 2.28 2.18
110 4.08 3.99 3.89 3.79 3.69 3.59 3.49 3.39 3.29 3.19 3.09 2.99 2.89 2.79 2.69 2.59 2.49
120 4.38 4.29 4.19 4.09 3.99 3.89 3.79 3.69 3.59 3.49 3.39 3.29 3.19 3.09 2.99 2.89 2.79
130 4.68 4.59 4.49 4.39 4.29 4.19 4.09 3.99 3.89 3.79 3.69 3.59 3.49 3.39 3.29 3.19 3.09
140 4.99 4.90 4.80 4.70 4.60 4.50 4.40 4.30 4.20 4.10 4.00 3.90 3.80 3.70 3.60 3.50 3.40
150 5.29 5.20 5.10 5.00 4.90 4.80 4.70 4.60 4.50 4.40 4.30 4.20 4.10 4.00 3.90 3.80 3.70
160 5.59 5.50 5.40 5.30 5.20 5.10 5.00 4.90 4.80 4.70 4.60 4.50 4.40 4.30 4.20 4.10 4.00
170 5.90 5.81 5.71 5.61 5.51 5.41 5.31 5.21 5.11 5.01 4.91 4.81 4.71 4.61 4.51 4.41 4.31
180 6.20 6.11 6.01 5.91 5.81 5.71 5.61 5.51 5.41 5.31 5.21 5.11 5.01 4.91 4.81 4.71 4.61
190 6.50 6.41 6.31 6.21 6.11 6.01 5.91 5.81 5.71 5.61 5.51 5.41 5.31 5.21 5.11 5.01 4.91
200 6.80 6.71 6.61 6.51 6.41 6.31 6.21 6.11 6.01 5.91 5.81 5.71 5.61 5.51 5.41 5.31 5.21
210 7.11 7.02 6.92 6.82 6.72 6.62 6.52 6.42 6.32 6.22 6.12 6.02 5.92 5.82 5.72 5.62 5.52
220 7.41 7.32 7.22 7.12 7.02 6.92 6.82 6.72 6.62 6.52 6.42 6.32 6.22 6.12 6.02 5.92 5.82
230 7.71 7.62 7.52 7.42 7.32 7.22 7.12 7.02 6.92 6.82 6.72 6.62 6.52 6.42 6.32 6.22 6.12
240 8.02 7.93 7.83 7.73 7.63 7.53 7.43 7.33 7.23 7.13 7.03 6.93 6.83 6.73 6.63 6.53 6.43
250 8.32 8.23 8.13 8.03 7.93 7.83 7.73 7.63 7.53 7.43 7.33 7.23 7.13 7.03 6.93 6.83 6.73
260 8.62 8.53 8.43 8.33 8.23 8.13 8.03 7.93 7.83 7.73 7.63 7.53 7.43 7.33 7.23 7.13 7.03
270 8.93 8.84 8.74 8.64 8.54 8.44 8.34 8.24 8.14 8.04 7.94 7.84 7.74 7.64 7.54 7.44 7.34
280 9.23 9.14 9.04 8.94 8.84 8.74 8.64 8.54 8.44 8.34 8.24 8.14 8.04 7.94 7.84 7.74 7.64
290 9.53 9.44 9.34 9.24 9.14 9.04 8.94 8.84 8.74 8.64 8.54 8.44 8.34 8.24 8.14 8.04 7.94
300 9.83 9.74 9.64 9.54 9.44 9.34 9.24 9.14 9.04 8.94 8.84 8.74 8.64 8.54 8.44 8.34 8.24
Inert Gas Partial Pressure - Imperial

10/25/06
16
Appendix A (continued)
PPO2 Setpoint
Depth 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8
91.65 1.56 1.46 1.36 1.26 1.16 1.06 0.96 0.86 0.76 0.66 0.56 0.46 0.36 0.26 0.16 0.06
12 1.96 1.87 1.77 1.67 1.57 1.47 1.37 1.27 1.17 1.07 0.97 0.87 0.77 0.67 0.57 0.47 0.37
15 2.26 2.17 2.07 1.97 1.87 1.77 1.67 1.57 1.47 1.37 1.27 1.17 1.07 0.97 0.87 0.77 0.67
18 2.56 2.47 2.37 2.27 2.17 2.07 1.97 1.87 1.77 1.67 1.57 1.47 1.37 1.27 1.17 1.07 0.97
21 2.86 2.77 2.67 2.57 2.47 2.37 2.27 2.17 2.07 1.97 1.87 1.77 1.67 1.57 1.47 1.37 1.27
24 3.17 3.08 2.98 2.88 2.78 2.68 2.58 2.48 2.38 2.28 2.18 2.08 1.98 1.88 1.78 1.68 1.58
27 3.47 3.38 3.28 3.18 3.08 2.98 2.88 2.78 2.68 2.58 2.48 2.38 2.28 2.18 2.08 1.98 1.88
30 3.77 3.68 3.58 3.48 3.38 3.28 3.18 3.08 2.98 2.88 2.78 2.68 2.58 2.48 2.38 2.28 2.18
33 4.08 3.99 3.89 3.79 3.69 3.59 3.49 3.39 3.29 3.19 3.09 2.99 2.89 2.79 2.69 2.59 2.49
36 4.38 4.29 4.19 4.09 3.99 3.89 3.79 3.69 3.59 3.49 3.39 3.29 3.19 3.09 2.99 2.89 2.79
39 4.68 4.59 4.49 4.39 4.29 4.19 4.09 3.99 3.89 3.79 3.69 3.59 3.49 3.39 3.29 3.19 3.09
43 4.99 4.90 4.80 4.70 4.60 4.50 4.40 4.30 4.20 4.10 4.00 3.90 3.80 3.70 3.60 3.50 3.40
46 5.29 5.20 5.10 5.00 4.90 4.80 4.70 4.60 4.50 4.40 4.30 4.20 4.10 4.00 3.90 3.80 3.70
49 5.59 5.50 5.40 5.30 5.20 5.10 5.00 4.90 4.80 4.70 4.60 4.50 4.40 4.30 4.20 4.10 4.00
52 5.90 5.81 5.71 5.61 5.51 5.41 5.31 5.21 5.11 5.01 4.91 4.81 4.71 4.61 4.51 4.41 4.31
55 6.20 6.11 6.01 5.91 5.81 5.71 5.61 5.51 5.41 5.31 5.21 5.11 5.01 4.91 4.81 4.71 4.61
58 6.50 6.41 6.31 6.21 6.11 6.01 5.91 5.81 5.71 5.61 5.51 5.41 5.31 5.21 5.11 5.01 4.91
61 6.80 6.71 6.61 6.51 6.41 6.31 6.21 6.11 6.01 5.91 5.81 5.71 5.61 5.51 5.41 5.31 5.21
64 7.11 7.02 6.92 6.82 6.72 6.62 6.52 6.42 6.32 6.22 6.12 6.02 5.92 5.82 5.72 5.62 5.52
67 7.41 7.32 7.22 7.12 7.02 6.92 6.82 6.72 6.62 6.52 6.42 6.32 6.22 6.12 6.02 5.92 5.82
70 7.71 7.62 7.52 7.42 7.32 7.22 7.12 7.02 6.92 6.82 6.72 6.62 6.52 6.42 6.32 6.22 6.12
73 8.02 7.93 7.83 7.73 7.63 7.53 7.43 7.33 7.23 7.13 7.03 6.93 6.83 6.73 6.63 6.53 6.43
76 8.32 8.23 8.13 8.03 7.93 7.83 7.73 7.63 7.53 7.43 7.33 7.23 7.13 7.03 6.93 6.83 6.73
79 8.62 8.53 8.43 8.33 8.23 8.13 8.03 7.93 7.83 7.73 7.63 7.53 7.43 7.33 7.23 7.13 7.03
82 8.93 8.84 8.74 8.64 8.54 8.44 8.34 8.24 8.14 8.04 7.94 7.84 7.74 7.64 7.54 7.44 7.34
85 9.23 9.14 9.04 8.94 8.84 8.74 8.64 8.54 8.44 8.34 8.24 8.14 8.04 7.94 7.84 7.74 7.64
88 9.53 9.44 9.34 9.24 9.14 9.04 8.94 8.84 8.74 8.64 8.54 8.44 8.34 8.24 8.14 8.04 7.94
91 9.83 9.74 9.64 9.54 9.44 9.34 9.24 9.14 9.04 8.94 8.84 8.74 8.64 8.54 8.44 8.34 8.24
Inert Gas Partial Pressure - Metric

10/25/06
17
APPENDIX B - PRESSURE CONVERSIONS
Units of pressure are converted according to the following primary definitions (Ref. 1):
1 atm = 760.000 torr
1 bar = 100,000 Pa
1 psi = 6,894.76 Pa
1 torr = 133.322 Pa
Units of pressure expressed as water depth below sea-level are converted using the following additional
standard definitions as adopted by the Undersea and Hyperbaric Medical Society:
1 bar = 32.6457 fsw (assumes seawater density = 1.02480 gm/cc)
1 msw = 10.0000 kPa (assumes seawater density = 1.01972 gm/cc)
1 bar = 33.4702 fsw (assumes freshwater density = 0.999552 gm/cc)
1 msw = 9.80229 kPa (assumes freshwater density = 0.999552 gm/cc)
Units of pressure expressed in terms of geometric altitude above sea level are converted using defining
equations for the U.S. Standard Atmosphere,1976 (Ref. 2). These equations give pressure P in
atmospheres absolute (atm abs) as functions of geometric altitude above seal-level A in kilometers (km):
PA
=−
⎡
⎣
⎢⎤
⎦
⎥
−
28815
28815 6 5
5
.
..
.25588 ; A < 11 km
[]
PA=⋅ ⋅−0 22336 015769 11.exp.(); 20km > A ≥11 km.
These equations are inverted to obtain the following expressions for geometric altitude A in kilometers (km)
as functions of pressure P in atmospheres absolute (atm abs):
()
(
)
A
P
=
−+
⎡
⎣
⎢⎤
⎦
⎥
⎧
⎨
⎪
⎪
⎩
⎪
⎪
⎫
⎬
⎪
⎪
⎭
⎪
⎪
28815 28815 525588
65
..
.
.
exp ln ln
; absatm0.22336P >
A
P
=−
⎛
⎝
⎜⎞
⎠
⎟
⎧
⎨
⎪
⎪
⎩
⎪
⎪
⎫
⎬
⎪
⎪
⎭
⎪
⎪
11 0 22336
015769
ln .
.; absatm0.22336Pabsatm0.05403
≤
<
The above expressions cover the relationship between geometric altitude and atmospheric pressure over the
entire physiological range; from below sea-level to above the Armstrong line at 62,800 ft (19.14 km), where
atmospheric pressure equals the vapor pressure of water at 37°C (47 mm-Hg). In this physiological region,
the U.S. Standard Atmosphere, 1976, of the United States Committee on Extension to the Standard
Atmosphere (COESA) is the same as COESA’s “U.S. Standard Atmosphere, 1962,” and is identical with the
International Civil Aviation Organization (ICAO) “Manual of the ICAO Standard Atmosphere,” as revised in
1964. The definition of the Standard in this region was also adopted in the ISO Standard Atmosphere (ISO
1973) by the International Standards Organization (ISO) in 1973.
Note: 1 atm abs = 1.01325 bar,
1 bar = 0.9869 atm abs

10/25/06
18
Appendix C - Altitude/Pressure/Depth Correction/Oxygen Concentration Table
Altitude Pressure Depth Correction 100% O2Oxygen Concentration
KFt KM ATA Bar Ft FW M FW PPO220.9% (.3) 20.9% (.1) 21% (.3) 21% (.1)
0.0 0.0000 1.0000 1.0133 0.03 0.01 1.0000 20.900 20.9 21.000 21.0
1.0 0.3048 0.9626 0.9754 0.84 0.26 0.9626 20.119 20.1 20.215 20.2
2.0 0.6096 0.9266 0.9389 2.08 0.63 0.9266 19.367 19.4 19.459 19.5
3.0 0.9144 0.8920 0.9038 3.27 1.00 0.8920 18.643 18.6 18.732 18.7
4.0 1.2192 0.8586 0.8700 4.42 1.35 0.8586 17.946 17.9 18.032 18.0
5.0 1.5240 0.8265 0.8375 5.53 1.68 0.8265 17.275 17.3 17.357 17.4
6.0 1.8288 0.7956 0.8062 6.59 2.01 0.7956 16.629 16.6 16.709 16.7
7.0 2.1336 0.7659 0.7761 7.61 2.32 0.7659 16.007 16.0 16.084 16.1
8.0 2.4384 0.7373 0.7470 8.60 2.62 0.7373 15.409 15.4 15.483 15.5
9.0 2.7432 0.7097 0.7191 9.55 2.91 0.7097 14.833 14.8 14.904 14.9
10.0 3.0480 0.6832 0.6922 10.46 3.19 0.6832 14.278 14.3 14.347 14.3
11.0 3.3528 0.6576 0.6664 11.34 3.46 0.6576 13.745 13.7 13.810 13.8
12.0 3.6576 0.6331 0.6414 12.19 3.72 0.6331 13.231 13.2 13.294 13.3
13.0 3.9624 0.6094 0.6175 13.01 3.96 0.6094 12.736 12.7 12.797 12.8
14.0 4.2672 0.5866 0.5944 13.79 4.20 0.5866 12.260 12.3 12.319 12.3
15.0 4.5720 0.5647 0.5722 14.55 4.43 0.5647 11.802 11.8 11.858 11.9
16.0 4.8768 0.5436 0.5508 15.27 4.66 0.5436 11.361 11.4 11.415 11.4
17.0 5.1816 0.5232 0.5302 15.97 4.87 0.5232 10.936 10.9 10.988 11.0
18.0 5.4864 0.5037 0.5104 16.65 5.07 0.5037 10.527 10.5 10.577 10.6
19.0 5.7912 0.4849 0.4913 17.30 5.27 0.4849 10.134 10.1 10.182 10.2
20.0 6.0960 0.4667 0.4729 17.92 5.46 0.4667 9.755 9.8 9.801 9.8
The altitude settings on the HS Explorer range from 0 to 9 and correspond to the table altitudes of 0.0 to 9.0
KFt.
For depth gauges which display the depth as a function of absolute pressure or bar as the HS Explorer does,
the linear depth to the surface can be calculated by adding the Depth Correction to the displayed depth. For
example, when diving at 5000 Ft./1.52 KM add 5.53 Ft./1.68 M to the indicated depth.

10/25/06
References:
1) Standard Practice for Use of the International System of Units (SI). Document E380-89a, American
Society for Testing and Materials. Philadelphia, PA, 1989.
2) U.S. Standard Atmosphere, 1976. United States Committee on Extension to the Standard
Atmosphere. National Oceanic and Atmospheric Administration, Washington, D.C. (NOAA-S/T 76-
15672): Supt. of Docs., U.S. Govt. Print. Off. (Stock No. 003-017-00323-0), 1976.
3) Decompression - Decompression Sickness, Professor Dr. med A. A. Bühlmann, Springer-Verlag
(ISBN 3-540-12514-9), 1983.
4) Tauchmedizin, Professor Dr. med A. A. Bühlmann, Springer-Verlag (ISBN 3-540-58970-8), 1995.
5) NOAA Diving Manual, Diving for Science and Technology. United States Department of Commerce.
National Oceanic and Atmospheric Administration, Washington, D.C, 1991.
6) U.S. Navy Air Decompression Table Handbook And Decompression Chamber Operators Handbook.
United States Department of the Navy. Naval See Systems Command, Best Publishing Company.
7) Decompression Theory, a monograph by B. R. Wienke, Ph.D., Los Alamos National Laboratory.
8) Mastering Rebreathers, Jeffrey E. Bozanic, Best Publishing Company, (ISBN 0-941332-96-9), 2002
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