Technology 丨 Three Small Steps to Make High-oxygen Diving Safer

Over the years, high-oxygen diving has brought many benefits to divers, including longer bottoming time, shorter surface rest time, increased number of repeatable dive times, and more.

However, things are always good and bad, and sometimes even worse. Due to the increase in r, hyperoxic diving has brought limitations on the depth of diving and other problems. The common misconception is that these hyperoxes are good for deep divers when diving.

When we use high oxygen diving, we recommend the following three most important steps to optimize your diving preparation and planning.

1, gas analysis

2, clearly marked

3, set dive computer table

Once you follow these three steps, you can set your maximum dive depth.

Gas Analysis: Keep your safety in your hands. This is completely taken from the diver, who is you and confirms that the high oxygen concentration of the cylinder will be used. Because each high-oxygen bottle has a different concentration and thus has a different maximum depth of immersion (MOD), you need to make sure that the maximum depth and oxygen partial pressure of the gas cylinder are within safe limits. Many experienced hyperox divers use 1.6 partial oxygen partial pressure limits in calm, warm waters, but have reduced oxygen partial pressure limits to 1.4 in colder or more complex environments.

Once your cylinder is filled, the filler will check the oxygen partial pressure of the cylinder's fill - we recommend that you confirm it at the same time - or you can check it yourself. Both methods are acceptable, allowing you to confirm that your cylinder is using the correct gas mixture, because in the end, this will be your own gas cylinder.

Clearly labeled: To complete this procedure, make sure that the cylinder has a fill date, oxygen concentration, maximum dive depth, oxygen partial pressure limit, user name, and gas analyst's name or initial. Your signature indicates that you have confirmed that the cylinder was received correctly and that the cylinder contains the correct proportion of the fill gas mixture.

It is important to analyze each gas cylinder that will be used and label the gas mixture one by one. Although it is constantly reiterated that the importance may seem daunting, we all know that high oxygen divers often get the wrong cylinder diving because they do not have this label or to analyze gas cylinders for gas mixture. Before you dive, you need to know the proportion of gas mixture in your cylinder. You can fully plan your dive and set your dive computer to avoid accidents.

Set up a dive computer watch: Before each hyperbaric dive, you must check that your dive computer's high oxygen set point is set correctly. This action is very important. Remember that there are two settings that must be remembered. One is the oxygen concentration setting and the other is the maximum oxygen partial pressure limit setting. Remember, some dive computer settings use "FO2" (oxygen concentration). In other words, in this case, 32% of the oxygen is equal to the oxygen concentration setting of 32.

Although different dive computers have different default settings for oxygen concentration and maximum oxygen partial pressure limit, most of the preset values ​​are biased conservative settings. In many cases, the preset oxygen concentration percentage is 21%, and the preset maximum oxygen partial pressure limit is set at 1.4. If you do not double-check these settings and adjust these values ​​correctly in accordance with the dive plan, you will not be able to fully obtain the benefits of using a high oxygen with the correct dive computer settings.

Ok! You now know how to plan your maximum dive depth and stagnation time. If you always remember to analyze, label, and set up your computer correctly, depending on your gas mix and your dive plan, then you are ready! Finally, remember! When diving with high oxygen, do not dive deeper than your maximum diving depth (MOD).

Do you remember when you first OPEN WATER, the coach may be discussing decompression theory, will you mention the special term “NITROX” when introducing specialty diving courses? What is a high oxygen diver? Is there a diving with high oxygen? What are the benefits? Today's Q&A briefly introduces the NITROX dive.

What is a high oxygen diving

NITROX diving is also known as Enriched Air Nitrox (EAN). EAN refers to mixed air with an oxygen ratio higher than 21%. The general air oxygen ratio is close to 21%, which means that the oxygen ratio of the mixed gas is higher than 21%, and the relative nitrogen ratio is less than 79%. The proportion of nitrogen is reduced, which means that the body absorbs less nitrogen at the same depth.

Our most common myth about high oxygen in recreational diving is that high oxygen can make you dive deeper and last longer. However, the actual situation is that high oxygen is a kind of gas suitable for shallow water diving compared with air, which allows divers to have a longer decompression limit at the same depth than air divers, reducing decompression sickness. And the possibility of nitrogen anesthesia occurring, reducing the decompression time and the time interval between repeated diving and many other advantages.

What are the benefits of using high oxygen diving?

Looking back at OPEN WATER's curriculum, the coach repeatedly reminded that excessive absorption of nitrogen was dangerous. When the body's absorption of excess nitrogen can cause the body to exclude excess nitrogen from the body during normal ascents, decompression procedures are required, but decompression diving is not recommended for general recreational diving. Therefore, using the NITROX Diving, the reduction in nitrogen absorption allows the diver to have more decompression time within the depth limit, and more time to enjoy the beauty of the water and improve the safety of the dive.

For the first time, the author felt that the power of NITROX was in Key West in Miami in 2000. I remember that the boat dive that morning was a 30-meter shipwreck. Two of the potential companions to the ship were high-oxygen cylinders that used a yellow-green look. At that time, there was no special attention. The AALDIN watch after watching the dive line to reach the target depth (about 27 meters) showed a no-decompression time of 19 minutes, which was due to the high visibility of the day and brought to the ship. For my shock, the 19-minute diving time is quite limited. Soon, the fellow divemasters told us to slowly rise and make a security stop. Our group of potential friends using the general air slowly climbed up to a safety stop of 5 meters. Visibility was very good (approximately 30 meters). At the depth of the safety stop, I could clearly see that the ship was lying still. The Spanish fishing boats on the seabed, and the two yellow-green-looking NITROX cylinders and the flashes of light that they photographed. At that time, the feeling of envy and kindness in psychology was hard to relieve.

We waited about 10 minutes after we boarded the two foreigners to board the ship and were very happy to tell us that there was just a large group of JACKs coming over and it was spectacular. I thought that if I could stay for 10 more minutes, then a group of spectacular JACK would not miss it.

Because of the special safety considerations associated with the use of the hyperbaric NITROX, special expertise in high-oxygen diving training is necessary. These courses usually include indoor theory courses, swimming pool training and marine internships.

Most of the courses also cover the following headings:

1. What is NITROX?

2. NITROX Physiology

3. NITROX diving equipment

4. Planning NITROX diving

The textbook also provides an NITROX decompression table that is different from general air calculations. This allows divers to calculate the maximum depth and no-decompression time, and how to use an oxygen analyzer to allow divers to measure the actual oxygen concentration in the cylinder and accurately plan the dive. .

When you decide to use the NITROX dive, you must follow the regulator manufacturer's instructions to determine if this type of regulator can be used up to 40% high oxygen. The high content of oxygen cannot be compatible with the helium oil of general maintenance regulators. Therefore, O-Ring and lubricating oils of high oxygen regulators can be used. Special materials must be used to eliminate inconsistencies.

Some regulators use special O-Ring and lubricants at the factory so that they can be used for high oxygen up to 40% (some can even use up to 80% NITROX). Please pay special attention if you purchase NITROX. For a compatible set of regulators, please do not mix the NITROX with general air bottle. However, if you use normal air, there may be a small amount of hydrocarbon residue in the regulator. When you decide to use NITROX again, please send the factory. Perform cleaning and maintenance work. Other parts, such as cylinders and valves, also use special materials and are often cleaned and maintained.

Does the site provide high oxygen?

Every day, every submarine in the world has new submersible stores that provide high-oxygen cylinder service. More and more sightseeing dive sites, diving yachts and submersible stores know the needs of divers and see the high oxygen diving facilities. The security and benefits it brings. The next time you plan to dive, please ask if there is a hyperoxic dive there and how much it costs. If you do, you must first take a course to obtain a high oxygen license, and then enjoy the safety and benefits of high oxygen.

What are the drawbacks?

Although hyperoxic diving has many advantages, it also brings about another potential threat - oxygen poisoning. The so-called "oxygen poisoning" refers to the body's inhaled oxygen partial pressure exceeds a certain value, and after a period of time, leading to a series of pathological changes in the body. It usually takes more than a certain depth.