buying tanks

[scubadiver888]

I've been reading some of the threads on tanks and realize there is a lot I don't know about tanks. Some of the stuff I've read:

- two tanks of a given capacity/material might weigh differently, i.e. two HP100 steels might not weigh the same.
- some tanks are not as easy to find a fill for, i.e. they need a certain compressor

What are all the things I have to consider when purchasing a tank?

If I buy my own tank I'd use it for wreck penetration. Most the wrecks are in the 90' to 110' range. I don't want something massively heavy if I don't have to have that. Right now I'm wearing 22lbs of lead with an AL80. So I have room to drop some weights if I go steel.

Anyone have sites for 'how to pick your tank'?

[Rainer]

So you don't know anything about cylinders, but you want them for wreck penetration?

Weird.

Originally Posted by scubadiver888

I've been reading some of the threads on tanks and realize there is a lot I don't know about tanks. Some of the stuff I've read:

- two tanks of a given capacity/material might weigh differently, i.e. two HP100 steels might not weigh the same.
- some tanks are not as easy to find a fill for, i.e. they need a certain compressor

What are all the things I have to consider when purchasing a tank?

If I buy my own tank I'd use it for wreck penetration. Most the wrecks are in the 90' to 110' range. I don't want something massively heavy if I don't have to have that. Right now I'm wearing 22lbs of lead with an AL80. So I have room to drop some weights if I go steel.

Anyone have sites for 'how to pick your tank'?

[tc_rain]

Here is a site with the specs on different tanks.

Scuba Cylinder Specifications from Tech Diving Limited - 928-855-9400

[RoyN]

I can't help you on the tanks, its pretty much what your comfortable with. You might want to go to your dive shop and ask them about it.

[scubadiver888]

No, I know some things about cylinders and I wonder if there is more information out there about them. Yes, my ULTIMATE goal is to use the cylinders for wreck penetration.

I know I have to start logging my SAC rate (approximately 0.77 cfm) and calculate my turning pressure, half enough air for if my buddy goes into free flow, etc. I know that were I want to be by the end of the summer, an AL80 is not going to cut it (unless I can GREATLY improve my SAC rate).

What I'm asking here is not what size cylinder is good for wreck penetration at 110' but are there things a novice wouldn't consider when purchasing a tank. Has someone put together a chart with all the differences for various cylinders? Are LP typically longer? larger in diameter? Do people use a certain cylinder because they know they can get a cave fill? Should I check local fill stations to see if that will be an issue?

Basically, is there something that pops to mind you think you'd like to share. Obviously this is going to be little bits of knowledge which will lead me to ask more questions and I do plan on asking my dive instructors similar questions.

Originally Posted by Rainer

So you don't know anything about cylinders, but you want them for wreck penetration?

Weird.

[rustyshakelford]

i dive with a LP108 and love it. if you can get it filled to 3000 you have tons of gas. double it up and you have a large set of doubles

it is a little heavier than the AL80 but i dont really notice it. the bouyancy caracterisitics are great with it also

brett

[scubadiver888]

Originally Posted by tc_rain

Here is a site with the specs on different tanks.

Scuba Cylinder Specifications from Tech Diving Limited - 928-855-9400

Thank you. This is the sort of thing I was looking for.

I'm also wondering if there are other things which matter but usually doesn't get discussed? For example, with diamonds they talk about the 4C's, cut, clarity, colour and carat. What they don't talk about is that you can take two diamonds of exactly the same 4C's put them side by side and one diamond will look soapy and dirty. The reason being that the soapy diamond has a mild blue fluorescence. Most literature for the average consumer does not talk about fluorescence.

Is there something which makes one tank different from another even though the main specs are the same?

[BSea]

I personally like LP 85's. But I can get higher than normal fills. When I bought mine LP tanks were quite a bit less than HP tanks, but that's not the case the last time I looked. Probably the most popular tank around my LDS is the HP 100. Then comes the HP 120 for those that want more gas. One thing to consider is how much you are willing to carry, and how the tank trims out for you. Both the LP 85 & HP 100 are similar in size to an AL 80, with much better buoyancy (better=less in this case).

I have a 120, but it doesn't trim out to well compared to my 85's. I have to wear it up too high for perfect trim. YMMV.

[scubadiver888]

Originally Posted by RoyN

I can't help you on the tanks, its pretty much what your comfortable with. You might want to go to your dive shop and ask them about it.

The big problem in my area is that most places only rent AL80s. I'd like to try out different tanks. I do plan on asking my local dive shop. I just thought I'd ask here too.

[BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)]

Do not penetrate wrecks without proper training and experience. There are countless ways to die doing this. I have never penetrated beyond the light zone, and even then one time we got blocked by a fallen panel while going up a stair way so we had to turn around. In the process of turning around my buddy (of course it was my buddy ) caused a complete silt-out that made his 24w HID completely useless. We had not run a line because we expected to be able to swim all the way through the wreck the way we had done before. Lots of bad things can happen down there.

By the time you are ready, you will likely have the answers to your tank questions. At a minimum you will have dive buddies or aquaintances who will be be more trustworthy and helpful than any anonymous poster on the internet. I don't see how you could get the experience and have it be otherwise.

That said- I understand you are ready to buy some tanks and don't want to have to re-buy down the road.

The answer is to buy 2 matched steel tanks of at least 100cf capacity. LP85 and LP95 tanks count if you can get overfills. These tanks need to be the same diameter, length, and capacity because you will want to double them later. If you get into wreck penetration you will want double tanks (backmount with isolation mannifold is most common). At a bare minimum I would want a large single with an H valve and a separate pony. Going in without two independent regulators is asking for trouble. If you go into any spaces in which side by side swimming with your buddy is not possible (almost all wreck penetration would qualify) then you will want to use a long hose configuration.

In pursuit of your goal, Cavern/Cave training would be very beneficial.