Suunto HELO2 manual Altitude diving, Oxygen exposure

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10.2.3. Altitude diving

The atmospheric pressure is lower at high altitudes than at sea level. After traveling to a higher altitude, you will have additional nitrogen in your body, compared to the equilibrium situation at the original altitude. This "additional" nitrogen is released gradually over time and equilibrium is restored. It is recommended that you acclimatize to a new altitude by waiting at least three hours before making a dive.

Before high-altitude diving, the instrument must be set to the Altitude Adjustment mode to adjust the calculations for the new altitude. The maximum partial pressures of nitrogen allowed by the mathematical model of the dive computer are reduced according to the lower ambient pressure.

As a result, the allowed no-decompression-stop limits are considerably reduced.

10.3. Oxygen exposure

The oxygen exposure calculations are based on currently accepted exposure time limit tables and principles. In addition to this, the dive computer uses several methods to con- servatively estimate the oxygen exposure. For example:

•the displayed oxygen exposure calculations are raised to the next higher percentage value

•for recreational scuba diving, the recommended upper limit of 1.4 bar PO2 is used as a default

•the CNS % limits up to 1.6 bar are based on 1991 NOAA Diving Manual limits

•the OTU monitoring is based on the long-term daily tolerance level and the recovery rate is reduced

Oxygen related information displayed by the dive computer is also designed to ensure that all warnings and displays occur at the appropriate phases of a dive. For example, the following information will be shown before and during a dive when the computer is set in mode:

•the selected O2% on the alternative display

•OLF% alternative display for either CNS% or OTU% (whichever is larger)

•audible alarms are given and the OLF value starts to blink when the 80% and 100% limits are exceeded

•audible alarms are given and the actual PO2 value blinks when it exceeds the preset limit

•in dive planning, the maximum depth according to the O2% and maximum PO2 selected

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Contents HelO2 Page Welcome to the World of Suunto Diving Instruments Care and Maintenance of MY Suunto Diving Computer Using HelO2 with Dive Manager and Dive Planner Welcome to the World of Suunto Diving InstrumentsPhysician regarding your fitness before diving Or professional diving activitiesOr death USE BACK-UP INSTRUMENTS! Make sure that you use back-up ASC Time symbol and the upward pointing arrowStop, and Rgbm adjustments are correct Diving with the dive computerBatteries. Recycle or dispose of used batteries properly Before the instrument has counted down the no-fly timeSuunto HELO2 AT a Glance Button symbols and functionsSymbol Button Press Main functions Navigating in the menusDown Long Enter Setting mode Setting the date Time mode settingsSetting the time Setting the unitsAC water contacts Setting the backlightSetting the tones Suunto Technical Rgbm Before DivingPlanning your dives Mixed gas diving Emergency ascentsDive computer limitations Audible and visual alarms Alarm indication Alarm reasonOut of calculation limits Alarm indicationError conditions Gas mixPairing and code selection Wireless transmissionInstalling the wireless transmitter Omitted decompressionTransmitting data Display IndicationDive Mixed GAS Dive mode settingsSetting the gases Setting the personal/altitude adjustments Setting the depth alarmSetting the dive-time alarm Before you have ascended above this depthSetting the tank pressure Setting the sample rateSetting the tank pressure alarm Setting the HP codeActivation and pre-checks Accessing Dive modeDive mode activation Diving at altitude Battery power indicationAlt. adjustment value Altitude range How the Altitude value is set Personal adjustmentsPersonal adjust- Condition Desired tables Ment value Before divingMandatory Safety Stops Safety StopsRecommended Safety Stops Other personal injury, and deathDeep stops Basic dive data DivingDiving-related information Decompression dives Ascent rate indicatorBookmark Ceiling, ceiling zone, floor and decompression range Than at the ceilingDisplay above the floor Accident, you should stay somewhat below the ceilingDisplay below the floor Display at the ceiling zoneDefault gas mix settings Diving in Mixed GAS modeBefore diving in Mixed GAS mode Oxygen and helium displaysOxygen limit fraction OLF Gas change and multiple breathing gas mixesDiving in Gauge mode Surface interval Alarms Symbol on displayAfter Diving Dive numberingRepetitive dive planning Plan modeDive Planning mode PLANnodec Flying after divingMixed GAS mode, it does not affect the calculations PLANNoDec modeMemory mode Dive numbering shown during dive planningDive logbook MEMLogbook Dive history Suunto Dive Planner SDPDive Planner. It ensures that you have a valid decompression Suunto Dive Manager SDMPage Care and Maintenance of MY Suunto Diving Computer Water Contacts and Push ButtonsWarranty FAQsBattery replacement and strap kits must be used Replacing the battery Battery ReplacementBattery kit Required toolsMade in a proper manner to avoid any leakage of water into Battery compartment lid, indicating a leakWireless transmitter battery replacement TransmitterTransmitter battery kit Stalling the transmitter batteryPage Technical Data Battery RgbmAfter dive planning Diver safety and Suunto Technical Rgbm modelSuunto Technical Rgbm decompression model Altitude diving Oxygen exposurePatent notice Intellectual PropertyCopyright Trademark 12.2. CE DisclaimersUser’s responsibility Warranty Period Exclusions and LimitationsLimitation of Liability Access to Suunto warranty serviceOther important notices Page Disposal of the Device Glossary EAD EANNo DEC Time Customer Service Contacts CopyrightPage TWO Year Warranty Page Page Suunto Oy 4/2009