I have an assignment about deep sea diving and of course it involves some gas mixtures to be used. I just don't know what suitable gas mixtures do I have to use in order for this diving to be safe and successful. The scenario is this:
1. A shipwreck is located at a depth of 220m.
2. Up to 5 dives will be needed (per diver) to bring valuable to the surface.
Note: You could you different gas mixtures for this. How much of the different gas mixtures do I need?
HELP PLEASE!
• The majority of gas used in most SCUBA tanks is compressed air. This air is composed of the same elements everywhere - 21% Oxygen 79% Nitrogen. Advanced SCUBA divers may use an "enhanced" mixture of 32% (up to about 40%) Oxygen with the balance being Nitrogen. The number of divers who use a mixture like this is about 2 to 5% of all certified divers. Less than 1% of all divers may use a special Tri-mix of some rather exotic gases to allow very deep dives - however, it takes years of instruction and training to use these exotic mixes.
http://www.worlddivingreview.com/scuba-diving-safety-know-your-breathing-gases
http://njscuba.net/gear/trng_12_calculators.html
To choose suitable gas mixtures for deep-sea diving, we need to consider the depth of the dive and the duration of each dive. The key factors to account for are the risk of decompression sickness (DCS) and oxygen toxicity.
1. Start by determining the maximum depth limit for the gas mixture. The depth limit for recreational divers using air (21% oxygen, 79% nitrogen) is typically considered to be around 40 meters. Beyond this depth, the risks of nitrogen narcosis and oxygen toxicity increase. Since your shipwreck is located at a depth of 220 meters, using air alone is not feasible or safe.
2. To reduce the risk of nitrogen narcosis and oxygen toxicity, you can consider using a mixture of gases known as trimix. Trimix is a combination of oxygen (O2), nitrogen (N2), and helium (He). The helium helps to dilute the nitrogen and reduce its narcotic effects, while the oxygen content can be adjusted to avoid oxygen toxicity.
3. There are various blends of trimix that can be used for deep-sea diving, depending on the desired depth and the time spent at each depth. The most common trimix blends include:
a. Trimix 18/45 (18% oxygen, 45% helium, 37% nitrogen): This blend is suitable for dives around 70-90 meters and is commonly used for technical diving.
b. Trimix 15/55 (15% oxygen, 55% helium, 30% nitrogen): This blend is suitable for dives around 90-120 meters and is commonly used for deep technical diving.
c. Trimix 10/70 (10% oxygen, 70% helium, 20% nitrogen): This blend is suitable for dives around 120-150 meters and is commonly used for very deep technical dives.
4. As you mentioned that up to 5 dives will be needed per diver, you'll need to determine the gas consumption for each dive. Gas consumption depends on various factors such as the depth, bottom time, ascent rate, and gas utilization rate. It is recommended to consult diving tables, dive planning software, or consult with an experienced technical diver to estimate the gas requirements for your specific scenario.
In summary, for diving to a depth of 220 meters, you would need to use trimix gas mixtures like Trimix 18/45, Trimix 15/55, or Trimix 10/70. To determine the exact gas quantities needed, you will need to consider the specific dive profiles and consult appropriate resources or experts in technical diving.