Hi john,
I'm a new diver but I can try to answer some of you question as best I can.
First, as far as I online guide, it might require a little searching, but it shouldn't be to hard to find. Just so you know all of that infomation is the very make-up of the open-water course. It will take you step by step through all of the gear necssary, it's use and proper care.
I can begin to answer some of the questions you asked here such as what is an octo"
An "octopus" or "safe second" is a term for an additional second stage regulator(the part you breath through). It is an additiional magin of safety for you and your dive buddy. It is attached to your "BC" Buoyancy compensator, which is a vest with air bladders. This bladders are inflatable, which will allow you to float in the water at whatever depth you wish. This works in combination with a wieght system to hepl you achive " neutral buoyancy" ie not sinking or floating upwards.
Nitrox is a term used to describe as a mixture of gases in your tank that is of a ratio
of 22% oxygen or higher. Normal room air is at a ratio of 21% oxygen and 79% nitrogen, which is what you have when standered "air".
The two most commonly used mixtures are "enriched air nitrogen 32" EAN32 and EAN 36. This means that the ratio in the mixture is either 32 or 36% Oxygen and the rest is nitrogen. The advantages of using nitrox are longer no-decompression limits( time spent at depth without needing to make a deconpression stop) shorter surface intervals ( time spent at suface off-gasing) and longer repeditive dives. The limitations of nitrox include additional training, it may require specical equipment purchases and nitro fills may cost more.
As far as what other gases that can be used for diving, there are several, but it definitely falls in to the technicial dive area and not recerational. From the 1993 navy dive manual vol 1 sec 2-5 gaese used in diving, it has a large list of other types of gases. Helium/oxygen is one still used today I believe. Hydrogen was expirmented with because of it similarity to helium, but the hazards of it's use lead to little more than that. Neon is another inert gas expirmented with, becuase of it's lack of narcotic properties that nitrogen poesses at certain depths. It also lack the speech distortion that helium causes, thus making it the subject of extensive expirmentation.
As to who can fill your tanks. That depend on your location relitive to a dive shop. It might be theortically possible to have dive tanks filled by a hospital air supply company. The problem with that is if they have the appropriate filling station and tools/connecting equipment neacssary. and they might not be willing to fill a container that is not their own. I would certainly ask. Another option is..although very expensive..is to purchase a fill staion of your own. These are monstorously expensive with prices starting at 2,500 and upwards of 10,000$. It possible to find browse places like ebay and the web for one of these fill stations. The only off set to this expence is that if you have to drive 90 miles to get an air fill, so would anyone else in your area. I would start searching for any local dive clubs and/or forums and see where they go. If they also have to go that far, the cost of buying a fill station might be off set by being the only guy in the area with one. supply and demand.
I think what you should do is decide why you want to begin scuba and how far do you want to go in it. If you're going to make four or five trips a year, buying a fill station is not for you. If you are going to use the certification while on vaction, there should'nt be any problem finding a dive shop in that area where you could rent everything you need. It really depends how often you plan to use or certification.
Well I hope I've given you some useful answers, I would highly recommend getting into scuba, I have only been certified for about three weeks and have totally jumped in head first. My nitrox class is next week and from there who knows. It is really one of the most enjoyable things I have done. Do not let youself be intimidated by technical term or insider jargon, pretty soon it will just be old news. Good luck with the class.
Be safe and happy diving.
sungod357
