How to choose a tank

[ACR]

General interest question:

Do you generally choose a tank based on it's dimensions or based on it's fill volume? For example, for a smaller diver does it make more sense to purchase a tank that is shorter despite the lower volume? is the reverse true for larger divers?

Do you factor in the tank radius? 7 1/4" vs 8"

 

[mike_s]

You choose it based on it's dimensions, weight on land, its fill volume, its pressure rating, it's metal (steel or aluminum) and its bouyancy characteristics and your air consumption rate.

Radius is not much of a concern unless you're trying to fit it into a custom size tank rack on your own boat..

Dimensions - Dimensions might be a concern for a shorter diver who might now want a HUGE tall tank because of it hitting them in the back of the head, etc.

Weight on land - weight on land might be a concern also for a smaller diver. It's hardler for a small frame person (child, lady, etc) to carry a HP133 that weighs 40 pounds on land.

Volume - Fill volume required would depend on your dive time/depth (air required) and your air consumption rating. You often see smaller people diving with an AL63 or a Steel 72 because they don't need the extra weight, size or air for the dive they are doing.

Pessure rating - you can get high Pressure (HP) tanks that fill to 3500psi. But can your shop fill it that high and is your regulator rated for that or does it have the typical required DIN fitting for that.

Metal - tanks come in Aluminum or steel. The most popular tank is the Aluminum 80 (AL80). Steel tanks are prefered by many divers because of their bouyancy characteristics and on HP tanks, the ability to hold more volume per physical size.

bouyancy characteristics - an AL80 is lighter in the water than a Steel 80 for comparible size tanks. Therefore you have to wear more lead on your weightbelt with the AL 80 compared to the steel 80. each tank has different bouyancy characteristics depending on size, volume, pressure, manufacturer, etc. You'll find many people here prefer the steel tanks based on the bouyancy characteristics, but steel tanks typically cost a little more also.

air consumption is pretty simple. It's how much you breath in cubic feet per minute.


As a side note, I noticed your location is in Canada. If I were you, I'd look at one of the Worthington Steel tanks, since they are made in Canada and you won't have to pay the duty on them like folks in the US have to do (as part of the purchase price). It will most likely be a better deal. (this is in theory that you can buy that tank there at a decent price compared to the US and what an AL80 cost with canadian import fees)

 

[ACR]

I can pick up a Worthington Steel tank for around 350 to 400 bucks at my ALDS depending on it's capacity. An AL 80 is about 180 or so. I'm not sure how that compares to the price in the US.

 

[nereas]

If you are an amateur diver, as I am guessing, then normally the first question that you need to decide is between aluminum or steel tanks.

Generally for wetsuit diving, aluminum is preferred. And for drysuit diving, steel. However, aluminum tanks have a limited life, compared with steel, which are almost infinite. Therefore most people prefer to buy their own steel tanks.

The next issue is size. If your lungs are average size, then an average size tank of around 80 cu ft is fine. For larger divers, 100 cu ft, and for smaller divers, 65 cu ft, are normally preferred. The average dive to the typical average depth normally lasts around 30 mins, and tanks of this size matched to the diver's physiology work well.

If you are going to mix steel tanks with a wetsuit, then you should also consider a double-bladder wing. These are available from Oxycheq. That gives you some redundancy in your lift capability, since you would not be wearing a drysuit, and because steel tanks are "negatively buoyant."

I have had my own tanks for many years, so I do not know what the current prices are. But $450 each sounds typical. Make sure you take the valve off and look inside with a light to see if there is any rust. A rusted steel tank is no good.

 

[Jimmer]

100 cubic foot hp steels are very common around here. They are really really nice tanks for singles and make excellent double tank setups as well for moderate depth if you get into deco. You'll see a lot of guys around here diving them. If you're interested I can get one for you to try out sometime.

Jim

 

[Ice9]

My only comment is in regards to the finish of the tank. Try to stay away from the tanks with a rough finish, because stickers tend to not stick as well on these. My next tanks will be smooth finished...

 

[mike_s]

Generally for wetsuit diving, aluminum is preferred. And for drysuit diving, steel. However, aluminum tanks have a limited life, compared with steel, which are almost infinite. Therefore most people prefer to buy their own steel tanks.

[snip]

If you are going to mix steel tanks with a wetsuit, then you should also consider a double-bladder wing. These are available from Oxycheq. That gives you some redundancy in your lift capability, since you would not be wearing a drysuit, and because steel tanks are "negatively buoyant."

I don't 100% agree with this. Many wetsuit divers dive steel tanks. Yes most steel tanks are more negatively buoyant, but your body is positive buoyant and add wetsuit to it and that makes it more buoyant.

So diving a steel tank in many instances just means you have to wear 4 pounds of lead verses 10 pounds of lead compared to an AL80.

Of course this all depends on the tank, the diver, the wetsuit, etc.


So that doesn't mean you have to have a double-bladder BC either.


Now... there are some tanks that are REALLY negative in the water, such as the old 3180psi Fabers. I can see a need for double bladders there for safety purposes perhaps, especially if you have steel-double-tanks plus a backplate and diving wet.

But as a hard rule, no it's not required. I think you'll find most of the people here who own steel tanks dive them wet.


But you'll also find few people who own a drysuit and tanks that dive aluminum also, all because of weight/buoyancy.

 

[SteveAD]

If you are an amateur diver, as I am guessing, then normally the first question that you need to decide is between aluminum or steel tanks.

Generally for wetsuit diving, aluminum is preferred. And for drysuit diving, steel. However, aluminum tanks have a limited life, compared with steel, which are almost infinite. Therefore most people prefer to buy their own steel tanks.

.

Limited Life? well ok Aluminum tanks will ONLY last about 20 years or so. I wish anything else I bought would last that long.

 

[vshearer]

After you get the first couple of tanks you will get the tank bug. You will constantly scan classifieds, craigslist, and other sources (and even the local dive shops for they do have some good deals on new tanks as well) for the great deals and then you will end up with a wide selection to choose from...

 

[ACR]

After you get the first couple of tanks you will get the tank bug. You will constantly scan classifieds, craigslist, and other sources (and even the local dive shops for they do have some good deals on new tanks as well) for the great deals and then you will end up with a wide selection to choose from...

... AND I'll have lot's of space to store them since my wife will have moved out. :11doh: