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Types Of Scuba Secondary Air SupplyThree Options And Positioning Of Alternate Scuba Air Supplies
A scuba diving alternate air supply is vital for the diver and an out-of-air buddy. There are different types of alternate air supplies, depending on the type of diving.
For today’s sportdiver there are three systems for alternate air supplies: Alternate Second StageA supplementary second stage, sometimes called an octopus regulator, is standard scuba equipment. It is good practice to have a long hose on at least one regulator so it can be used effectively. Some divers secure the alternate second stage on their tank by a large rubber strap to keep it out of the way and not drag in the sand. This is not good practice; the second regulator should be kept on the chest, as described below. Ascent BottleAn ascent bottle is a tiny cylinder with separate regulator mouthpiece attached to the cylinder. The out-of-air diver breathes directly from this bottle. They hold enough for about 30 breaths on a shallow dive. They can be filled at a standard filling station, or from a scuba tank with the appropriate adaptor. The ascent bottle also covers the situation where the regulator first stage fails. Or that other major diving faux pas: running out of air, making an alternate second stage useless. The main limitation is size. An ascent bottle would contain enough air for an immediate ascent, however, it might not be enough if a decompression stop is required. Pony BottleThis is a second, smaller scuba system and is the safest system, but also the most expensive and cumbersome. It attaches to the main tank with a separate regulator. If the main regulator fails, or the main tank runs dry, it is a simple matter to change to the other tank. Pony bottles are suited for deep diving where a large, secure supply of air is needed to cover decompression stops for the main diver or an out-of-air buddy. Alternate Air Supply Set UpThree points require attention with any alternate air supply. 1) It must be easy to see by a diver in front. The best spot is somewhere in the triangle formed by the chin and hips. A bright coloured hose is useful for distinguishing the alternate air supply. 2) It must be easy to use. An out-of-air diver shouldn’t be wrestling with buoyancy compensator pockets, or fancy clips and buckles. During the pre-dive check the buddy should confirm the location of the alternate air supply and how to use it. 3) It must work. This doesn’t mean it just delivers air. It must be secured so it doesn’t fill with sand during the dive and must be able to supply air in a comfortable configuration with another diver. Too short a hose on an alternate air supply could present problems on ascent as the two divers’ buoyancy changes. Pony bottles and ascent bottles must be full before the dive. Using Scuba Alternate Air Supplies discusses which alternate air supply to hand over. Maintaining Alternate Air SuppliesAlternate air supplies should be checked as regularly as main supplies. Good practice is to take a few breaths on the alternate air supply on every dive as a check. Many accessories can make an alternate air supply system workable; angle fittings for the alternate air supply hose and an assortment of quick release buckles, straps and clips. There is no optimum setup for an alternate air supply. It is an individual choice, depending on style of diving, cost and training level of a diver. An alternate air supply must be easy to use and must work when required. If an alternate air supply gets an out-of-air diver safely back to the surface then it is a good system.
The copyright of the article Types Of Scuba Secondary Air Supply in Scuba Diving is owned by Bruce Iliff. Permission to republish Types Of Scuba Secondary Air Supply in print or online must be granted by the author in writing.
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