Underwater Breathing Systems —What Are Your Options?
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RESCUE TECHNIQUES
Dive / Rescue Series:
Ten years ago, a major concern in underwater operations was that J. many divers failed to wear and use their inflatable life jackets during rescue procedures. “Horse collars! Fenzys! BC’s (buoyancy compensators)! You’ve got to be kidding! We got ours from the airlines.”
These were typical comments from divers when questioned on their life jackets. Today, BC’s are commonly used.
In 1986, the main concern among divers has shifted to the use of breathing systems and which one produces the most effective results. There are three different methods:
- The buddy breathing system (two divers sharing one second stage mouthpiece);
- The octopus breathing system (two second stages coming off of one first stage);
- The redundant breathing system (an additional tank with regulator).
In reality, these choices are for the sport diving industry only. I believe that rescue personnel have only one option: the redundant breathing system.
In this third article in the dive/ rescue series, we will discuss the various advantages and disadvantages of each of the three different methods.
Buddy breathing
During your basic self-contained underwater breathing apparatus (SCUBA) course your instructor may have explained to you that when you run out of air you should swim to your buddy, tap him on the shoulder, and signal that you need air.
At this point, he is supposed to inhale a comfortable breath and pass the mouthpiece over to you. Buddy breathing is great in pool training as a SCUBA/buddy exercise, but that’s where its effectiveness ends.
The rescue diver often finds himself in situations where he is diving alone and he cannot rely on a buddy to share his mouthpiece. His back-up diver may be at the surface waiting at the ready. Other times, the water conditions will not allow for rescue personnel to be within visual contact of another diver. In fact, in most cases, it is extremely impractical for a rescue diver to rely on a back-up “buddy.” The loss of air supply is the foremost concern of the underwater rescuer.
Because of the potential danger involved with buddy breathing, most teams are now using an octopus type system. This system involves carrying a back-up, second stage mouthpiece in order to avoid buddy breathing.
Octopus breathing
The octopus system works like this: If my buddy needs air I can give him a breathing unit without giving up my own ability to breathe. We can now surface in a controlled manner. This works out well as long as we can find each other and as long as there is enough air left for both of us to make a slow and controlled ascent. The octopus mouthpiece is strictly to help a buddy diver while putting yourself in as little danger as possible.
In 1969 on Palancar Reef in Cozumel, Mexico, a diver I had never seen before came to me asking for air at 95 feet. The next time I saw my mouthpiece was at the surface! Had I been carrying an octopus unit, it would have made that ascent a lot easier for me. If I had been using a redundant breathing system, both of us would have been assured of a comfortable ascent.
Many teams have the following standing rule: A diver must leave the bottom with no less than 750 psi of air and arrive on deck with no less than 500 psi. This amount of air (750 psi, or 18 cubic feet) is barely enough to sustain the diver for more than three or four minutes if he cannot surface for some reason. Whether the diver is waiting for a surface back-up man who can come directly to him via his surface tending line or if he must wait for his underwater buddy to find him, he still needs enough air to hold out.
The best the underwater buddy can do in most cases is bring the other diver a half full SCUBA tank, which they will both share. The surface support diver may be set up with a full 3,000 psi (80 cubic feet) and an octopus. However, once he gets to the diver who is in trouble, they will both have a limited shared supply of air, and the “buddy” diver cannot resurface alone. Using the octopus method may have compounded the original problem.
The rescue diver’s life is the single most important consideration. He should be trained so that when something goes wrong he will stop, signal, and slowly begin to deal with the problem at hand. Even when a minor problem continues for more than 30 seconds, the backup diver should enter the water, and within another 15 seconds be in full deployment. Obviously, in a situation where the diver is in immediate need of assistance and emergency deployment is called for, more stringent measures must be taken.
The back-up diver’s job is to assist the rescue diver. His first priority is to check the rescue diver’s breathing and then check his air supply. The back-up diver must then attempt to bring the situation under control. When the first diver becomes untangled, they will surface together.
The diver must be assured that he has an adequate air supply at all times. The diver should be carrying his own back-up air source. His life cannot depend on someone else’s ability to function under pressure. If a diver is well trained he can learn how to handle any situation except, of course/the sudden loss of air.
Redundant breathing
The redundant breathing system comes in two forms:
- Pony bottles. These are small tanks that can be attached to single or double tank harnesses, but are equipped with their own regulator;
- Twin backpacks. These are two single tanks that each have their own regulator.
The purpose of pony bottles is to give the diver an extra air supply and to eliminate his reliance on buddy breathing. Pony bottles have been in use for a long time. They come in many different shapes and sizes (15-35 cubic feet), and can be heavy and cumbersome.
The new, small, light-weight aluminum pony makes it a much more efficient system. When used in conjunction with a single or double tank, it provides an additional independent, self-supporting breathing system. It is an excellent back-up method and allows a diver to share his air without putting either himself or his partner in extreme danger.
The twin pack that consists of two singles, each carrying their own regulator and submersible pressure gauge, is a popular system in the northeast. Most divers who use this rig and start with full tanks breathe one down to approximately half.
At this point, they switch over to the second tank. If the second tank fails to function, they can still go back to using the oxygen in the first unit. This will provide them with enough air so that they will be able to safely return to the surface.
This system eliminates the dependence on diver assistance. Whether the diver is on his first or second tank, this system allows each person to have his own regulator and enough air for resurfacing.
The major disadvantages of using the backpack method are the same as using pony bottles: they are both bulky and leave many appendages hanging from the diving unit.
However, if the regulator hoses are attached properly, you will be able to keep them under control. Then, you will find that the redundant breathing system will work extremely well.
We have found that women rescue divers have success with either the pony bottles or the twin backpacks, using twin 50’s or 68’s. This works out well because women normally consume less air than men while diving.
Summary
Remember, we do not have visual contact with our rescue diver. We cannot see if there are any early warning signs that he may be in trouble or involved in a dangerous situation.
