Gas Consumption & Management for Koh Chang Diving

Gas Consumption & Management for Koh Chang SCUBA Diving

Whether you're diving Koh Chang's shallow reefs or planning a technical dive to the HTMS Chang wreck at 30-40m, understanding gas consumption is essential. We as trained and certified SCUBA divers learn at the Open Water Diver course to monitor our gas supply closely, but are we really aware of our gas consumption rates and their impact on dive planning?

We learn at our entry-level courses the different Markings of the SCUBA Tank:

• DOT Number and Material
• Manufactory
• Serialnumber
• Hydrostatic Test
• Tank Size

Also, we learn to determine the remaining Tank Pressure by using the Pressure Gauge (SPG) or AIR integrated Dive-computer. Skills like Low on, Out of Air and CESA are helping us to understand the importance of the Breathing Equipment. And in the very unlikely event of an Out of AIR situation to react the correct way and safely accent to the surface. But do we know about our AIR Consumption in-depth? Most certified divers never really heard about SAC Rate and how to Calculate it. The Gas-Consumption Calculations coming to effect if you really plan your dive with your dive buddy yourself. And you would like to make sure from the beginning that your gas supply is sufficient for your planned dives. In technical diving, these calculations are there for a long time and standard in the Decompression Diver course. But also as a Sports Diver, it is a benefit if you know about your SAC rate.

Deep diving increases gas consumption significantly! Understanding your SAC rate is especially important for deeper dives. Learn more: Deep Diving – Limits, Planning & Safety

How to determine your Gas Consumption

Know the size of your SCUBA Tank: S-80 Aluminium = 11.1 L Normal Conditions: Decent to a depth of 10m look at your computer and SPG. start to swim normally for 10min and check how much gas you used. Hard Conditions: Decent to a depth of 10m look at your computer and SPG. start to swim as fast as possible for 10min and check how much gas you used. Take notes how much Gas you used in ether way on 10m of depth! You start on 10m of depth with 180 bar after 10min you check the pressure again and you have 150 bar left in your S-80 tank whats your SAC rate? 30 bar * 11.1 L (Tank Size) = 333 L / 2 bar (ambient Pressure at 10m) = 166.5 L / 10 min = 16.65 L / Min. (SAC) Now we know how many litres of Gas we are consuming on 10 m of depth in 10 min. and like this, we can figure out what kind of Gas Supply we need to have for our Dive-plan. Also we can use this to determine an average SAC Rate for example: I dived 60 min consumed 150 bar on an average depth of 12m. 150 bar * 11.1 L (Tank Size) = 1665 L / 2,2 bar (ambient Pressure at 12 m) = 756,81 L / 60 min = 12.61 L / Min. average (SAC)

Calculate a Decompression Dive Plan (Without CNS)

Calculate the surrounding pressure ATA

Calculate the surrounding pressure is part of every entry-level SCUBA diving course. The surrounding pressure increase every 10 m Water for 1 bar + 1 bar Atmosphär

Calculate the Gas Volume

To Calculate the gas volume needed in depth: SAC*Time*ata= for example 20 L* 15 min. * 4 bar = 1200 L

Calculate the Po2

To Calculate the Partial pressure of Oxygene: Gas*ATA= for example N32 = 0,32 bar*4 bar = 1,28 bar Po2

Calculate the Maximum Operating Depth (MOD)

To Calculate the MOD: (Max PPO₂ / O₂ Fraction) − 10 = for example N32 = 1.4 bar / 0.32 − 10 = 33.7 m MOD

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Dive with Chang Diving on Koh Chang!

Apply your gas planning skills at Koh Chang's premier dive sites! From fun dives to technical courses from beginner to professional level. Master gas management for our local sites including the HTMS Chang wreck, deep reefs, and Nitrox diving. Get your own safe and clean personal set of dive gear you can trust on all your adventures.