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Scuba diving gas analysis – keep safe, keep diving

Read our blog to find out more about the different types of gases you can use to dive and how Analox Sensor Technology can help with any scuba diving gas analysis issues you have.

If you plan to scuba dive, you need to know about the different gases available. Many people think that you can breathe the same air underwater that you breathe on the ground.

However, this is not the case. Regular air contains a high amount of nitrogen (78%), which can do strange things to your body when you are underwater and under pressure. On deep dives, too much nitrogen can have an narcotic effect (known as being ‘narced’) which can have dangerous consequences.

In this blog post, we take a look at the different gas blends which can be used when scuba diving, and how gas analysis is so important when planning a dive.



Nitrox (often referred to as ‘enriched air nitrox’ or ‘EANx’) is a gas mix composed of nitrogen and oxygen, and can be identified by the green and yellow markings on gas canisters.

As nitrox contains more oxygen than is normally in the atmosphere (20.9%), it allows divers to dive underwater for longer, without the need for decompression stops, and reduces the risk of decompression illness which is caused by an excess of nitrogen.

However, there are risks with diving with nitrox, and special training is required before using it on a dive. Oxygen levels need to be monitored in order to avoid oxygen toxicity, which can have an effect on the nervous system.

It is essential to analyse your nitrox gas before using it, in order to ensure the gas mix is right, and to allow you to plan the depth, time and decompression stages during your dive. Analox offer the O2EII Pro nitrox analyser which allows divers to check the gas mix directly from the gas canister, or while the diver is connected to their regulator. Small, lightweight and rugged, the O2EII Pro can be taken anywhere.

O2EII Pro nitrox analyser

O2EII Pro nitrox analyser



Trimix consists of oxygen, nitrogen and an inert gas (normally helium) and can be identified by the brown, black and white markings on gas canisters.

Adding inert gas to the mix allows divers to dive deeper than they could with nitrox (with less risk of becoming narced) and is often used in technical (‘tec’) diving. In 2001, John Bennett became the first diver to dive to 1,000ft using trimix.

The advantage of trimix is that it can be custom-blended to suit each dive, allowing the diver to precisely control the levels of oxygen they receive.

The disadvantages of trimix is that it can be expensive (especially if you use helium as it is a very scarce gas) and custom-blending gases can be hard-work. Helium can also make divers feel colder than normal (it has a high thermal conductivity) and can cause a condition known as ‘high pressure nervous syndrome’ if not used correctly.

The Analox ATA Pro trimix analyser can check the levels of gas in your mix, giving you peace of mind when planning a technical dive. Lightweight, portable and comprehensive, it takes readings directly from the tank.

ATA Pro trimix analyser

ATA Pro trimix analyser



Heliox is a mixture of helium and oxygen and is normally used in saturation diving and deep diving.

In saturation diving, the helium can make the divers sound very high pitched and they may need to have their speech ‘de-scrambled’ on the surface so that people can understand them.

Argox (argon and oxygen) and hydrox (hydrogen and oxygen) can also theoretically be used, but heliox is most frequently used when diving as it is less dangerous.

Heliox is even more expensive than trimix as the concentration of helium is higher.

Did you know that heliox is also used in medicine? The mix of helium and oxygen reduces airflow resistance and can be used to help people with lung disease breathe easier.

In commercial diving, the Analox O2NE+ oxygen depletion monitor can be used to measure levels of heliox. The benefit of the O2NE+ is that it is not cross sensitive to helium, so will not cause false positives.

O2NE + oxygen depletion monitor

O2NE + oxygen depletion monitor

So, keep safe when scuba diving with an Analox monitor to help analyse the gas you breathe.

Author: Kate Ingham, Digital Marketing Executive

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Founded in 1981, Analox Sensor Technology provides niche and custom gas detection solutions to industries including beverage and fast food, commercial diving and laboratories. Analox has over 325 years of collective, specialist electronics and software engineering expertise, as well as a worldwide distributor network. Contact us to see how we can provide expert gas monitoring solutions and help you achieve your goals.

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