How To Select Scuba Tanks

Hi. I'm Howard Payne. I'm an instructor with Dive Wimbledon.

We're a 5 Star IDC Centre here in Southwest, London and I teach both recreational and technical diving and I've been diving for about 8 years. And today, I'm going to give you a little bit of advice on equipment and how to scuba dive. Okay, let's just take a look at the tanks that we use when we're diving.

Obviously, we got to have something that we can carry, all of the gas that we need to breathe underwater. We got a number of different types of cylinders. Broadly speaking, two main types, we have steel cylinders, these three are steel and we also have aluminium cylinders over here.

The way you can tell them apart is generally the steel cylinders have a rounded bottom on them so they tend to have a rubber boot in the bottom to stop them from falling over. Aluminium cylinders you can see over here have a flat bottom on them so they stand up on their own. One of the things that you need to be wary of is actually leaving cylinders standing up.

Normally, we would have them lying down if they're not attended or we're not actually working with them. For the simple reason that with 230 times atmospheric pressure inside these cylinders, a lot of energy is stored in there, a lot of compressed gas and it's very dangerous to leave them standing up. If it got knocked over and you hit the valve, then there are some nasty consequences.

So when we're not actually directly working with it, we would have it lying down so it can't get knocked over. In cold water, environments kind of temper water environments like here in the UK, we tend to like steel cylinders because they're actually little heavier in the water and it saves us adding a lot of extra weight on our weight belt. So they tend to work a little better.

Also slightly higher pressure, these are 230 valves where as aluminium cylinders are normally filled to just under 210 valves. So we can generally, for the same size of cylinder, get a little bit more gas in the steel ones and it takes a little weight off the belt. Two different types of fitting on the cylinders.

We have the traditional kind of A-clamp or yoke type fitting where the regulator clamps over the top of the valve and we also have the more modern ding fitting which is where the regulator actually screws into the valve itself, you can see that there. Different preferences, most screws that you come across are going to have this yoke or international style of fitting where as most technical divers that we come across would want to use a ding fitting because it's a little bit more secure. In terms of choosing a tank, when you first start out diving, most the time you're not going to need to buy a tank because almost all dive centres, us included here at Dive Wimbledon, have lots of tanks that they can lend you or rent you but once people start to dive more often, more regularly, they'll find that very often it's more convenient to have their own tank.

And some people even have two so they have spare if they're going out and doing a day's diving. So really you know, depending on where you are in the world and you know, how much weight you need to carry when you're diving will have a big effect on what tank you choose. Perhaps if you're in a warm water country, maybe you're out in the, you know the Red Sea or something like that, well then, an aluminium tank is going to make more sense but here in the UK, steel.

So just choose your tanks carefully. These little 10 litres tanks here are ideal for perhaps people who don't breathe so much, maybe women, who prefer not to carry some tanks that are heavy. These are what we call Dumb P-12s.

They're slightly shorter 12s, they are fatter and shorter. I'm not a big fan of these. They don't turn out very well in the water and they're slightly awkward shape.

The most common size that you'll see here in the UK which is what we have here on this BCD with t