Technically Speaking

By Bill Nadeau

Let us address the first issue ­ labelling the gases. With regards to cylinder labelling the most important factor determining how it is to be marked are the cylinder contents. Unfortunately many divers still dive with air, and as such air is considered the norm. Therefore labelling an air cylinder with 'air' markings is really unnecessary UNLESS the diver or accompanying divers maybe assuming that at sometime that particular tank may actually have something other than air in it. The scenario I am referring to is a tank that is some times filled with nitrox or trimix. This tank should have the proper gas labels affixed to it but because it is filled with air for this particular dive everyone in the dive team needs to be aware of its present normoxic^ß content. This is accomplished by labelling the nitrox or trimix mix as 'AIR'. This will eliminate any confusion or mistakes made by assumption. Keep in mind that air is another form of nitrox, we just do not formally address it that way due to industry definitions.

As for labelling the tanks themselves you need to follow industry standards. These will include the proper size, colours and terminology. Basic nitrox (EAN22-EAN40) requires a green and yellow band at least 6 inches in width to circumnavigate the most visible part of the tank. The tank also needs to have a contents label and some form of inspection qualifying the tank for nitrox usage. Each training agency has different approaches as to how this is accomplished but the bottom line is the tank needs to be obvious to the divers where and when it can be used safely. Two goodfriends that I dive with, Mike Perdue and Greg Mossfeldt were awesome at this. In addition to affixing the standard commercial nitrox/trimix/deco labels that are available they would also affix duct tape with bold figures indicating what gases were in the mix in positions on the tanks so that everyone including themselves could see ­ even during the dive.

Next a diver must consider how he or she is going to properly identify what gas each regulator is going to deliver. This practice is not reserved exclusively for different gas mixes but gas options as well, such as an alternate second stage (octopus) for an out of air diver or a regulator attached to a pony bottle. In basic open water training we are taught to store the alternate regulator in an easily accessible place and perhaps mark it with a brightly coloured regulator cover. With multiple gases we follow the same principle. Alternate gases are marked with tags or retainers that are obvious by touch, sight and placement. The regulator that carries my own oxygen decompression gas is attached to a green hose, is painted green itself and is clearly marked 'O2' on the purge button. It is also a different model regulator from the rest of my second stages so that in a total blackout situation I can still 'feel'' it as being the oxygen regulator.

Labeling is only one tool we can use to ensure that a diver uses the proper gases and gas delivery systems at the right time. Another tool is configuration. Again what determines how we configure gases and second stage regulators are the environments, the equipment we are using and the activity we are participating in (like overhead cave, wreck, deep or a 60-foot reef dive). Essentially we want to place the cylinders and the regulators in such a way that they are streamlined, well balanced, easily deployable and can be removed and replaced without any effort or difficulty. For most sport divers pony bottles are attached in some fashion to their main tank. The well-marked second stage can then be stored where any other octopus is secured ­ somewhere in the triangle (an area encompassing a divers chest, from his/her chin to both sides of his/her stomach). With twins some divers elect to wear their alternate regulator in a neck lanyard. Oxygen and deco regulators should have protective caps on the mouthpieces making it very obvious to the diver what it is when this regulator is deployed for use. Around my green oxygen decompression second stage (which is secured to my stage bottle with a green snorkel keeper) I have a small piece of surgical tubing looped around the mouthpiece. To actually breath from it I have to take the time to pull this tubing off thus preventing me from accidentally using this regulator at depth.

A diver needs to practice how to use each of his/her gas delivery systems. It is one thing to be well equipped and look technically correct but one must be properly trained to use the different gear they have. When I received the email about the article of the diver who began his dive with the wrong regulator I immediately thought about how labelling was not necessarily the problem. That diver needed to first understand the purpose of a pony bottle. If he had practised out of air scenarios he then should have gone to his alternate (which would have been his primary gas supply) and not increased the risk of the other diver by using up his buddies gas supply. Proper training would have also taught him to reason through his gas loss, determine a more appropriate action or even prevent the problem altogether by doing a proper buddy check before the dive began.

Finally I must stress that divers who carry additional gases with out the proper training can get themselves into trouble. The theory that because one has more gas and can stay down longer and/or go deeper may lead individuals to proceed beyond their means. Ever noticed why companies who teach people to drive automobiles do not use fast cars. Hmmm some logic there I think!