Why use helium when deep sea diving?
Deep sea divers normally breathe a mixture of nitrogen and oxygen, called nitrox or EAN (Enriched Air Nitrox). While Earth’s atmosphere is 78% nitrogen and 21% oxygen, nitrox is typically 32-36% oxygen.
Increasing the amount of oxygen reduces the risk of decompression sickness, also known as ‘the bends’, which occurs when inert gases dissolved in the body under pressure form bubbles in the joints and tissue when the pressure reduces as a scuba diver returns to the surface. When diving it is essential to ensure your oxygen analysers are equipped for beyond your intended diving depths and working perfectly.
But in some cases instead of nitrox, divers use heliox – a mix of helium and oxygen – or trimix, which combines all three gases. So why use helium when deep sea diving?
Benefits of helium for divers
Helium has increased significantly in price since the start of the millennium, so it’s sensible to control its use through careful monitoring. But it still offers some persuasive advantages over a nitrox mix.
One of the biggest is the fact that helium does not have a narcotic effect. In some dives, both nitrogen and oxygen can induce a state similar to drunkenness. Adding helium to the mix reduces this so divers can think more clearly.
Using helium can also mean divers can take fewer stops on their return to the surface, without suffering decompression sickness.
Heliox, with zero nitrogen, can be recycled so the valuable helium is not lost. It is often used for deep sea diving operations in commercial contexts, where the expense can be justified and the improved protection against narcotic effects is required.
Why to control helium when diving
It’s important to control exposure to helium when diving. It conducts heat much faster than air – about six times faster – so it should not be used to inflate drysuits, due to the risk of hypothermia.
While helium reduces narcotic effects at high-pressure depths, it can still contribute to decompression sickness, so it’s crucial to monitor and control the precise balance of gases in heliox and trimix supplies.
Finally, a question we’re asked often: Does heliox give divers a squeaky voice? Yes, it does! The effect is the same as inhaling helium from a birthday balloon – and surface crews often pitch-correct radio communications to make them more understandable.