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Mixed Gas Diving 
CCR or Open circuit

There are a range of mixed gas courses available and we teach them all at Seaways Dive Centre. The courses can be run for either Open Circuit divers or CCR. The CCR course contains open circuit skills as well, to cover all bailout options.

  • Sports Mixed Gas - 50 metres  Normoxic gas, 1 stage cylinder - Open Circuit or CCR

This course teaches the skills and theory needed to increase your safety in the 40 to 50 metre range with the use of normoxic trimix.  Gas mixtures with an oxygen content between 18% and 23% are described as normoxic.  Anyone currently diving in the 40 to 50 metre range on air should consider this course to enhance your safety by lowering narcosis levels and reducing breathing gas density at depth.

  • Explorer Mixed Gas - 60 metres - Normoxic gas, 2 stage cylinders - Open Circuit or CCR

The Explorer mixed gas course is a 1 day add on to the Sports Mixed Gas and students need the use of 2 stage cylinders. 

  • Advanced Mixed Gas- 80 metres - Hypoxic mixes, 2 + stage cylinders - Open Circuit or CCR

The AMG course takes around 5 days of your time and is highly practical.  All our training is in the sea and you learn a number of extra skills while operating from boats. For this course, you need to be in practice with your present equipment and have good buoyancy skills

What you need

For the mixed gas courses you need your own dive equipment.   For Open Circuit, you need  twin-set and off board gas cylinders.  For CCR divers you must own your own unit and have off board cylinders for bailout. Seaways can help with some stage cylinders if needed.  If you are considering any of these courses, talk to us first so that we can determine your present experience level and work out the best approach for you.  All our courses are done in the sea using suitable dive vessels diving real dive sites.

Why Dive Mixed Gas?

Mixed gas is used to make your deeper diving safer.  The Normoxic course for divers approaching the 40 metre range and thinking of going to 50 metres will greatly reduce narcosis and improve decision making, putting you back in control. 

As we go deeper, we need to reduce the amount of nitrogen to control narcosis and reduce the amount of oxygen to reduce the risk of oxygen toxicity. We also need to reduce the density of the gas being breathed. The lowest cost way of doing this is to use a mixture of Oxygen, Helium and Nitrogen.  Here at Seaways, your course will include all the relevant theory and practical skills to get you ready for your new adventure.

Compressor Operator

How do compressors work?  What maintenance do they need?  How clean should the air be?  How do I safely fill cylinders?  Answers to all these questions and more while you learn how to do it on this 1 day course!

Mixed Gas Blender 

The gas blender course covers the mixing and preparation of mixes such as Nitrox, Trimix and Heliox - in fact it is what you need if you are involved in preparing gas mixes for diving. You also need the certificate if you want to buy the gases from the major gas supply companies.  The course covers theory and practical mixing and analysing.

photo by Grace Bint

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