Introduction
Scuba diving is an exhilarating activity that allows us to explore the wonders of the underwater world. As divers, we have the option to dive on regular air or use a gas mixture called nitrox. In this article, we will provide a detailed comparison between scuba diving on air and nitrox, highlighting their differences, benefits, and considerations.
When it comes to scuba diving on air, one of the main advantages is its wide availability. Most dive centers and resorts offer air fills, making it convenient for divers to access. Additionally, diving on air is generally cheaper than diving on nitrox, making it a more budget-friendly option for many divers.
However, nitrox diving has its own set of advantages. One key benefit is the extended bottom time it provides. Nitrox contains a higher percentage of oxygen, which reduces the risk of nitrogen narcosis and allows divers to stay underwater for longer periods. This is especially beneficial when exploring deeper dive sites or conducting longer dives.
Another advantage of nitrox is its potential for shorter surface intervals. Since nitrox reduces the amount of nitrogen absorbed by the body, divers may experience faster off-gassing times, allowing for shorter intervals between dives. This can be particularly beneficial during multi-dive days or liveaboard trips where maximizing dive time is important.
It’s important to note that diving on nitrox does come with certain considerations. For instance, divers need to be certified in nitrox diving and have the proper training to analyze and calculate nitrox mixtures. Additionally, diving on nitrox requires special equipment, such as dedicated nitrox tanks and oxygen analyzers, which may not be readily available at all dive centers.
In conclusion, both scuba diving on air and nitrox have their own advantages and considerations. While air offers convenience and affordability, nitrox provides extended bottom time and potentially shorter surface intervals. As divers, it’s important to weigh these factors and choose the option that best suits our diving needs and goals.
How Nitrox differs from Air
Regular air, which is what we breathe on the surface, is composed of approximately 21% oxygen and 79% nitrogen. Nitrox, short for “NITrogen-OXygen”, on the other hand, is a gas mixture that contains a higher percentage of oxygen and a lower percentage of nitrogen and typically this ranges from 22% to 40% oxygen.
However, the most common nitrox mixtures used by recreational divers are EAN32 and EAN36, which contain 32% and 36% oxygen respectively.
Nitrox is also known as Enriched Air Nitrox (EAN) or Oxygen Enriched Air (OEA). Whatever the breathing gas is called, the cylinder will be marked with Yellow and Green markings or labels, compared to the plain or black/white marking for standard air cylinders.
So what are the limits for Nitrox
| Nitrox Mix | Oxygen Percentage | Recommended Depth Limit |
|---|---|---|
| Nitrox 32 (EAN32) | 32% | 34 meters (112 feet) |
| Nitrox 36 (EAN36) | 36% | 28 meters (92 feet) |
| Nitrox 40 (EAN40) | 40% | 22 meters (72 feet) |
So why are the maximum depths lower than normal air?
As strange as it may sound, Oxygen at too higher Partial Pressure of Oxygen (PPO2) can be toxic. On the surface 100% oxygen is save to breath but when we dive the gas we breath is under pressure.
At sea level or 1 atmosphere (1 BAR) pressure the PPO2 of air is 0.21 (21%). For every 10m (33 feet) we descend the pressue increases by 1 atmosphere (1 BAR). So at 10m (33 feet) the pressure is 2 atmospheres (2 BAR) and at 30m (66 feet) the PPO2 of air is 0.42 rising to
Nitrox Oxygen Content
Nitrox comes in various mixtures, commonly known as EANx (Enriched Air Nitrox). The oxygen content in nitrox can range from 22% to 40%. Let’s take a closer look at the benefits and maximum depths for each type of nitrox:
- EANx22: This nitrox mixture contains 22% oxygen. It allows for longer bottom times and shorter surface intervals compared to diving on air. The maximum depth limit for EANx22 is 40 meters (130 feet).
- EANx32: With 32% oxygen, EANx32 provides even longer bottom times and shorter surface intervals. The maximum depth limit for EANx32 is 34 meters (112 feet).
- EANx36: Nitrox with 36% oxygen content offers extended bottom times and shorter surface intervals. The maximum depth limit for EANx36 is 29 meters (95 feet).
- EANx40: This nitrox mixture contains 40% oxygen, allowing for significantly longer bottom times and shorter surface intervals. The maximum depth limit for EANx40 is 24 meters (80 feet).
Pros and Cons of Air and Nitrox
Air:
- Pros: Widely available, less expensive, suitable for most recreational dives.
- Cons: Limited bottom time, longer surface intervals, increased risk of decompression sickness.
Nitrox:
- Pros: Longer bottom times, shorter surface intervals, reduced risk of decompression sickness.
- Cons: Limited availability, additional training required, increased risk of oxygen toxicity at deeper depths.
Training Requirements for Nitrox
Using nitrox requires specialized training to understand the risks and benefits associated with diving with higher oxygen levels. Most scuba certification agencies offer Nitrox Diver courses, which cover topics such as gas analysis, oxygen exposure limits, and dive planning with nitrox.
Summary and FAQ
In summary, diving on air and nitrox each have their advantages and considerations. Nitrox allows for longer bottom times and shorter surface intervals, but it requires additional training and careful planning. It is important to choose the appropriate nitrox mixture based on the planned dive depth. Here are answers to some commonly asked questions:
- Is nitrox suitable for all types of diving?
- Can I use nitrox with my current dive computer?
- How do I analyze the oxygen content in a nitrox tank?
- What are the signs of oxygen toxicity?
- Can I switch between air and nitrox during a dive?
- What precautions should I take when diving with nitrox?
- Can I get nitrox fills at any dive shop?
- Is nitrox more expensive than air?
- Can I use nitrox for technical diving?
- Is nitrox beneficial for shallow dives?
