Help purchasing a tank.

[Sonic04GT]

When I return from Iraq I want to purchase a tank so my buddy and I can dive on our own. Should I go with steel or alluminum? I have the Atomic B2 reg in DIN and I'm kind of sick of using the yoke adapter so I'd like to get a DIN tank. No problems mixing air and nitrox right? Nitrox cert will probably be my first priority when I get back.

This is what my local dive shop has to offer.
Find your Scuba Tank at DiversDirect.com your source for Dive Equipment.

I've only got 10 dives that I squeezed in before I went overseas but I don't recall having any problem with bouyancy with the tank pressure at a "low" level. Maybe I was a little overweighted.

I normally dive with 10lb weights I believe, I weigh 155lbs, and usually dive with just a bathing suit and rash guard. Probably switching to a 3mm wetsuit.

The 80 cu ft catalina any good? great price.

worth the additional money to go 100 cu ft?

Thanks,

Chris

 

[ScubaSteve]

When I return from Iraq I want to purchase a tank so my buddy and I can dive on our own. Should I go with steel or alluminum? I have the Atomic B2 reg in DIN and I'm kind of sick of using the yoke adapter so I'd like to get a DIN tank. No problems mixing air and nitrox right? Nitrox cert will probably be my first priority when I get back.

This is what my local dive shop has to offer.

I've only got 10 dives that I squeezed in before I went overseas but I don't recall having any problem with bouyancy with the tank pressure at a "low" level.

I normally dive with 10lb weights I believe, I weigh 155lbs, and usually dive with just a bathing suit and rash guard. Probably switching to a 3mm wetsuit.

The 80 cu ft catalina any good? great price.

worth the additional money to go 100 cu ft?

Thanks,

Chris

A couple of notes. Generally there is a problem mixing air and nitrox tanks because of special cleaning requirements for Nitrox. Secondly, what type of diving are you going to be doing? What do you want to get out of a tank? Are your SAC's somewhat matched?

If you want to stay down a bit longer then a larger tank may be beneficial to you. I have two steel HP120's and love them. I dive with a buddy that dives AL80's and our SAC's are not too far apart most dives so I usually have lots of air left over, but when it comes to a dive where I breathe heavier or we go deeper.....I like having the extra. Because it is a big steel tank it is heavier allowing me to take weight off my belt/or integrated.

If all you want is a tank to breathe from for relatively shallow depths (by this I mean recreationalOW or AOW) and your SAC's are close, get the AL80...save the extra couple hundred bucks and buy another piece oif gear.

 

[Sonic04GT]

This will be for recreational diving OW and soon AOW, mostly lakes where I'll be until I get back to FL a year later. If I remember correctly, my SACs are decently matched. Diving on air I usually run out of bottom time slightly before I run out of air around the 60-80 foot range but then again, having the extra bottom time with nitrox, it wouldn't be bad to have a little extra air to stay down longer. I'll probably go with the AL80 as that is what I have done all my dives with. I'll talk to my buddy and see what he plans on getting because it'll be pointless for me to have to capability to stay down longer when he can't. The reason I ask about mixing is because I'll have to dive air up until I get my nitrox cert but that should be right away anyways.

 

[ScubaSteve]

This will be for recreational diving, mostly lakes where I'll be. If I remember correctly, my SACs are decently matched. Diving on air I usually run out of bottom time slightly before I run out of air around the 60-80 foot range. I'll probably go with the AL80 as that is what I have done all my dives with. The reason I ask about mixing is because I'll have to dive air up until I get my nitrox cert but that should be right away anyways.

You can get your tank certified for Nitrox when the time comes, but you will not be able to mix gases (i.e. you will not be able to dive air with that tank) so unless you will only dive nitrox, I would suggest keeping the tank as Air. I got nitrox certified but do not do enough repetitive diving around here to see any benefit from the Nitrox and therefore did not switch any tanks over. So, it all depends on what your diving will be. I agree with sticking with the AL80 because of the cost. I still have mine.....but when I saw the opportunity and need, I moved to the steel. When my buddy and I started diving, my SAC was much higher than his so the steel was truly beneficial. My rate has improved drastically so it now leaves me with extra air.....and I am OK with that.

 

[djtimmy77]

Correct me if I am wrong, but you can use air in a nitrox tank if you get the fill from a place that is oxygen clean. For example, both places I fill my tanks (Force-E and Scuba Works) use partial pressure blending, so if I want an air fill it is no different than getting a nitrox fill other than the fact they don't put any pure oxygen in first.

 

[ScubaSteve]

Correct me if I am wrong, but you can use air in a nitrox tank if you get the fill from a place that is oxygen clean. For example, both places I fill my tanks (Force-E and Scuba Works) use partial pressure blending, so if I want an air fill it is no different than getting a nitrox fill other than the fact they don't put any pure oxygen in first.

You are not wrong. However, when I first got Nitrox certified, the only three shops that I asked about if they would put air in a Nitrox tank said no and I gave up looking. This is why I said "Generally there is a problem mixing....". In general terms, I believe it is easier to expect that a shop cannot do it until confirmed. If you find one that can near you, then you can adjust accordingly. If it is really that important to you and you are going to be doing that much Nitrox diving, then you can spend more time searching for a shop that will do it. They are out there but not all will do it.

 

[Spork]

When I return from Iraq I want to purchase a tank so my buddy and I can dive on our own. Should I go with steel or alluminum? I have the Atomic B2 reg in DIN and I'm kind of sick of using the yoke adapter so I'd like to get a DIN tank. No problems mixing air and nitrox right? Nitrox cert will probably be my first priority when I get back.

Well, the tank is not DIN or Yoke, the valve is. And since you have a DIN-reg then the DIN valve is the way to go.

If you get an oxygen-clean tank, then you can always fill nitrox-compatible air in it and it will still be good for nitrox-fills. If your LDS use inline och membrane filling for nitrox you don't have to worry. However, this is one thing you will pick up in a nitrox class. A tank is not certified for nitrox, only compatible with pure oxygen (or not).

 

[rstofer]

The entire subject of tanks is hard to pin down.

The Al 80 is cheap but you will have a tank that is as much as 5# heavier than a steel HP 100 (check the weight of the various Al 80s, there are some that are less than 36#). To add further insult, you will need to carry the heavier tank PLUS about 6# of lead to account for the difference in buoyancy. That relatively simple decision to buy the Al 80 comes complete with an 11# penalty, all else being equal. Does it matter? Well, not if you are young and fit. OTOH, when you get old, it matters. To be more technically correct, you are carrying an additional 2# of air in the HP 100 so the penalty is really only 9#. But you have more air.

However, the HP 100 requires a 3442 psi fill. You will almost NEVER get a complete fill on a boat dive. It is much more likely that you will get 3000 psi; perhaps less. So, you're really getting about 87 cf. Then again, there is no guarantee that the Al 80 will get a 3000 psi fill either! As to the 3300 psi Al tanks, they suffer from the same problem as the HP steels.

OK, the HP 100s (or larger) are the answer to a maiden's prayer! Well, not exactly... They are highly negative at the start of the dive. You need to verify that your BC can provide enough lift to stay buoyant at depth with a compressed wetsuit while you carry enough weight to be able to descend from the surface. This is really a BC issue but you need to think about how much buoyancy your wetsuit loses at depth as well as the difference in buoyancy between a full tank and an empty tank. For the HP 100, the difference is 8#. Over in the BCs forum there is a 'sticky' spreadsheet that deals with this. Play with it and see what comes out. The loss of boyancy in the wetsuit is somewhat of a guess. And you certainly don't want to be overweighted by several pounds!

While you are considering these buoyancy issues, consider what happens when you have a BC failure at the start of the dive. Even if you ditch your weights, you could be 6# negative from the BP/W and 10.5# negative from the tank plus, perhaps, 2# negative from the regulator. So, you are on the bottom with a compressed wetsuit and 18.5# negative with whatever positive buoyancy the wetsuit still provides. That wetsuit number is still a guess. But don't be surprised if you are actually 10# negative. This is what you'll have to swim off the bottom. You might not need to swim far until the wetsuit expansion takes over but you should at least be aware of the implications of a blown bladder.

A thinner wetsuit loses less buoyancy so the numbers can change substantially. Still, these things enter into the decision process for selecting a tank.

If there was just one right answer, there would be just one kind of tank.

I would imagine that any place than can provide Nitrox can also provide clean air. Clean air is always used for partial pressure blending so, if that is the way the shop blends, they can provide clean air. Ask around.

At the moment I have 4 HP 100s, 2 Al 80s and 2 Al 50s. All are cleaned and labeled for Nitrox although the aluminum tanks contain clean air. I just label the aluminum tanks as O2=21% MOD=187'

Have fun with your decision making and your diving. Personally, I'm going to buy another pair of HP 100s (there are 3 of us so we need 6 tanks).

Richard

 

[Hatul]

When I return from Iraq I want to purchase a tank so my buddy and I can dive on our own. Should I go with steel or alluminum? I have the Atomic B2 reg in DIN and I'm kind of sick of using the yoke adapter so I'd like to get a DIN tank. No problems mixing air and nitrox right? Nitrox cert will probably be my first priority when I get back.

This is what my local dive shop has to offer.
Find your Scuba Tank at DiversDirect.com your source for Dive Equipment.

I've only got 10 dives that I squeezed in before I went overseas but I don't recall having any problem with bouyancy with the tank pressure at a "low" level. Maybe I was a little overweighted.

I normally dive with 10lb weights I believe, I weigh 155lbs, and usually dive with just a bathing suit and rash guard. Probably switching to a 3mm wetsuit.

The 80 cu ft catalina any good? great price.

worth the additional money to go 100 cu ft?

Thanks,

Chris

You're obviously diving in warm water. Compared to an Al80, going to Steel high pressure 100 I was able to drop 7-8lbs of lead. If you only dive with 10 lbs total that would be a problem for you with steel as you would not have enough ditchable weight left.

So if I were you I'd just get an Al 80 or low pressure steel. And unless almost all your diving will be with nitrox or you have unlimited budget, I'd go with air. The cost of fills is much less and you can rent a tank for Nitrox and buy another tank later for Nitrox.

For valve get either a DIN or a Pro (dual valve)

Adam

 

[BradButler01]

Lots of opinions here! Let me put my spin on it, see if y'all think that is a good summary:

The tanks:
- Catalina (or Luxfer for that matter) AL80's exist because they are cheap
- Steel tanks last longer when properly maintained, and are much easier to own (i own both)
- Worthington 100's give you additional air (even at 3000 psi rather than 3442+) over an AL80
- W. HP 100's are 4 pounds heavier than AL80s at 500 psi (in-water, so drop 4 from the belt)
- Dry, the HP 100 weighs about the same as an AL80 (~ 1 pound heavier w/o valve)

Valve:
- Most times, Worthington tanks come with the pro valve. That is a DIN valve with a dimple in the back and an threaded insert to convert it to yoke. They are great.

Nitrox options:
- Your first nitrox class should be pretty quick, so you may want to go ahead with it and not worry about this issue
- Most shops won't let you nitrox-wrap a tank without being certified
- If they do, you could wrap it with a nitrox band, then fill it only with air. Once you put nitrox in it, you'll have to analyze the gas after each fill.
- This whole thing about "nitrox clean" is BS. If a tank is not clean enough for premix nitrox up to 40%, its not clean enough for breathing air either. As for putting "dirty" air in a clean tank, if your LDS fills aren't grade E (nitrox-compatible air), then I wouldnt use that shop anyway. The way a custom mix is blended (without O2) is topping a short nitrox fill with grade-E air.
- NOTE: If you are thinking about O2 cleaning the tanks, and partial-pressure blending with O2 and O2 compatible air, the whole issue is different! But most shops I know either make or buy 32, 36, or 40% to avoid the painful process of O2 cleaning tanks that will never see a rich mix.

The main issue with premix nitrox in air tanks and air in premix nitrox tanks is the markings rather than the cleanliness. We want to avoid people mistanking one tank for the other. The big scary green stickers keep air divers from assuming a nitrox tank is their tank, and toxing on 36 at 120'.

If you are the only user of the tank, and you either fill it yourself or watch to make sure you're getting just air until you learn to analyze, you should be ok. But the better option is to just wait on the wrap sticker until after your class.

B+