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What Is In a Scuba Tank?

   November 11th, 2022   Posted In: Articles   Tags:

What Is In a SCUBA Tank

Have you ever wondered what is in SCUBA tank? Well keep reading to find out

Self-Contained Underwater Breathing Apparatus

Scuba tanks aren’t just for looks. They’re a central piece of equipment for divers. They hold breathable gas under immense pressure, which allows you to remain underwater for longer periods of time. This is why scuba stands for Self-Contained Underwater Breathing Apparatus!

Many people believe all scuba tanks hold 100% pure oxygen. While they do hold some oxygen since our bodies need it for survival… there are other gas mixtures available that make diving much safer.

Why is it unsafe to dive with pure oxygen?

Diving deeper than 20 feet with pure oxygen can be dangerous because of central nervous system (CNS) oxygen toxicity. CNS oxygen toxicity can cause convulsions, which underwater, can lead to drowning and death. Only technical and experienced divers should consider using pure oxygen.

Gas Mixtures Found in Scuba Tanks

different scuba tanks

The kind of gas that goes in a diver’s tank depends on preference, dive type, and more. Below are some of the more common mixtures you may encounter.

1. Atmospheric Air

  • Most recreational scuba tanks contain this. It’s filtered and compressed air. Just as in the atmosphere, it is composed of about 79% nitrogen, about 21% oxygen, and small amounts of trace gases.
  • Atmospheric air is the gas of choice for most dive resorts. Why? Because it’s cheap, it’s easy to get (because it’s all around us), and it contains enough oxygen to sustain divers underwater.
  • Downside: Your tissues absorb nitrogen during your descent and bottom time. This increases the risk of nitrogen narcosis, which can cause problems with coordination and judgement.

Therefore, 40m is considered the safest depth you can go on atmospheric air tanks.

2. Nitrox

  • Nitrox was designed to reduce nitrogen problems with longer dives. It has a higher oxygen concentration and a reduced nitrogen concentration compared to what you’d find in atmospheric air tanks. The reduced nitrogen levels allow divers to extend bottom times and minimize nitrogen loading.
  • Downside: The potential for oxygen toxicity. At lower depths, our bodies absorb more oxygen. If oxygen is consumed at toxic levels, divers can convulse and eventually drown.

Consequently, Nitrox is only safe for use within the recreational diving limit of up to 130ft.

3. Trimix

  • Trimix is for technical divers. It was created to mitigate the dual hazards of oxygen and nitrogen at depths beyond 130 feet (50m). It contains nitrogen, oxygen, and helium. Why helium, you might ask? Helium doesn’t react with our bodies at conventional depths. So, replacing some of the nitrogen with helium lets us dive deeper with reduced risk of complications.
  • Downside: Cost. Helium is very expensive. Another downside is that you will lose heat faster than you would with Nitrox or air.

4. Heliox

  • Heliox is commonly used by the commercial diving industry in place of trimix. Like trimix, it contains helium and oxygen, but it does not contain nitrogen. Removing nitrogen from the mix dramatically increases the diving depth and time limits. And since it has a lower percentage of oxygen than nitrox, the risk of toxicity is also reduced.
  • Downside: Cost. Helium is very expensive. Another downside is that you will lose heat faster than you would with Nitrox or air.

Other gas mixtures encountered in deep sea diving include:

  • Hydreliox– Combines oxygen, hydrogen, and helium and allows divers to go as deep as 400m and still have a clear head.
  • Hydrox– A special blend of oxygen and nitrogen used for deep dives beyond 500m.
  • Neox– Another deep diving gas mixture mostly used in military applications.

The Verdict…

What’s inside your scuba tank matters! Professional divers never go without checking what’s inside their tank before heading into the water. For safety reasons, you should make this your priority, too!

Crysta is a valuable member of Wetsuit Wearhouse, currently working as a customer service lead. She has a passion for writing, and considers herself a bookworm. She’s lived on the Eastern Shore in Maryland, down in southwest Florida, and now resides in a small town in Pennsylvania. She loves all things related to nature, and can always be found outside when the weather is warm. (When she isn't helping customers find the perfect wetsuit, that is.)

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