Suunto EON Core Brugervejledning

Multigasdykning

Suunto EON Core giver mulighed for gasskift under et dyk mellem de gasser, der er defineret i menuen Gas(es) (Gas(ser)). Under opstigning får du altid besked om gasskifte, når der er en bedre gas tilgængelig.

Du kan for eksempel have følgende gasser ved et dyk til 55 m (180,5 fod):

• tx18/45, MOD 58 m
• tx50/10, MOD 21 m
• oxygen, MOD 6 m

Under opstigningen får du besked om at skifte gas ved 21 m (70 fod) og 6 m (19,7 fod) i overensstemmelse med den maksimale driftsdybde (MOD) for gassen.

En pop-op-meddelelse giver dig besked, når du skal foretage gasskift, som vist nedenfor:

Ændring af gasser under et dyk

Ændring af gasser er kun til nødstilfælde. Hvis en dykker pga. uforudsete hændelser mister en gasblanding, kan dykkeren tilpasse sig situationen ved at slette den pågældende gasblanding fra gaslisten Suunto EON Core. Dette giver dykkeren mulighed for at fortsætte dykket og modtage de korrekte dekompressionsoplysninger, der beregnes af dykkercomputeren.

Hvis en dykker i et andet tilfælde går tom for gas og har brug for en gasblanding fra en dykkermakker, er det muligt at tilpasse Suunto EON Core til situationen ved at tilføje den nye gasblanding til listen. Suunto EON Core omberegner dekompressionen og viser de korrekt oplysninger til dykkeren.

For at aktivere ændring af gasser skal du slå funktionen til i indstillingsmenuen under Dykkeindstillinger/Parametre/Redigér gasser.

Når den er aktiveret kan du under et multigasdyk tilføje en ny gas samt vælge en eksisterende gas på gaslisten for at fjerne den.

Isobaric counterdiffusion (ICD)

Isobaric counterdiffusion (ICD) occurs when different inert gases (such as nitrogen and helium) diffuse in different directions during a dive. In other words, one gas is being absorbed by the body while the other is being released. ICD is a risk when diving with Trimix mixtures.

This may happen during a dive, for example, when Trimix gas is switched to Nitrox or light Trimix. When the switch is made, helium and nitrogen rapidly diffuse in opposite directions. This produces a transient increase in total inert gas pressure which can lead to decompression sickness (DCS).

Currently there are no algorithms that can address ICD. Therefore, you need to take it into account when planning Trimix dives.

You can use Suunto EON Core to plan your Trimix usage safely. Under the Gases menu, you can adjust oxygen (O₂) and helium (He) percentages to see the change in partial pressure of nitrogen (ppN2) and the partial pressure of helium (ppHe) values.

An increase in partial pressure is indicated by a positive number, and a decrease by a negative number. The changes in ppN2 and ppHe are displayed next to each gas mixture that that you want to switch to. Maximum Operating Depth (MOD) is assumed to be the depth when start to use the gas mixture.

An ICD warning is generated when the gas switch depth is greater than 10 m (30 ft) and either:

1. The change ppN2 increases by more than +0.5, or
2. The change in ppHe increases by more than +0.5 and ppN2 decreases by more than -0.25.

If these limits are exceeded with a gas switch, Suunto EON Core indicates the risk of ICD as shown below:

In this example, the available gas mixtures for a deep Trimix dive are:

• Trimix 15/55
• Trimix 35/10
• Trimix 50/10
• Oxygen

Suunto EON Core highlights the dangerous ICD condition when the gas mixture switches from 15/55 to 35|10 at a depth of 34.4 m.

If this gas switch is made, the change in ppN2 and ppHe are far beyond the safe limits.

One way to avoid the ICD risk is to increase helium content in the 35/10 gas mixture to a 35/25 Trimix mixture. This would keep the changes in partial pressure at a safe level and remove the danger of sudden ICD.