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JugglingMonkeys
01-05-2008, 15:29
I'm going to start buying some tanks now.
Please share your advice.

My ultimate goal is to have perhaps 3 tanks.
Probably 2 regular AL-80s and 1 HP100.

Which should I reserve for Nitrox - the AL80 or the HP100?
Then I'll keep the others for air.

Thanks!

terrillja
01-05-2008, 16:05
I'm going to start buying some tanks now.
Please share your advice.

My ultimate goal is to have perhaps 3 tanks.
Probably 2 regular AL-80s and 1 HP100.

Which should I reserve for Nitrox - the AL80 or the HP100?
Then I'll keep the others for air.

Thanks!

Depends on your diving...

I'd say the HP 100, since it would give you more time at depth, where you would be getting close to your NDL.

Personally, I can get premix a a few shops around here, so I do not need O2 clean tanks, and therefore do not have any specified nitrox tanks. See what you can get for nitrox fills around where you dive, if you can get premix a dedicated tank is not necessary.

JugglingMonkeys
01-05-2008, 16:28
See what you can get for nitrox fills around where you dive, if you can get premix a dedicated tank is not necessary.

thanks! Great advice. I'll do that.

so a dedicated tank is not necessary for premix?

CompuDude
01-05-2008, 16:45
There are four primary ways of delivering Nitrox.

1) Partial Pressure Blending. Take an empty tank (it can be done non-empty, but more math is involved so many shops won't), add pure oxygen, top off with air to get the desired %. The tank must be oxygen-cleaned, because for a time, it contains pure oxygen. This method is most common, because it's the most inexpensive way for a shop to advertise the ability to sell nitrox. Capable of delivering any Nitrox mix you could possibly want, all the way up to (obviously) pure o2.

2) Membrane systems. This is an expensive piece of machinery, that has special filters installed. As it pumps air into a tank (like any other compressor), the air passes through a filter that filters out some of the Nitrogen, leaving air with a higher than normal oxygen content. The air that hits the tank is no higher than the normal 40% upper limit for recreational nitrox, so the tank does NOT need to be o2 cleaned. Capable of delivering any Nitrox mix you could possibly want, up to 40%.

3) Banking. The shop mixes Nitrox ahead of time through whatever method they want. The resulting mix is stored in large high pressure storage cylinders, all interconnected, and when someone wants Nitrox, they just hook up a hose between your tank and theirs, and the gas flows from the bank's tanks directly into yours. They can offer any mix they want, but unless they have more than one bank, they can only offer one mix at a time, since that's all the tanks store. Usually stores offer 32% only, some stores will also bank 36% for those wanting a richer mix, but 32% is the norm. Since the Nitrox is pre-mixed, your tank never touches pure oxygen so it does NOT need to be o2 clean.

4) Stik blending. There's only one shop around here that uses stik blending, and I haven't seen their rig, but the essence of this one is a combination of PP blending and a temporary bank, where the gas is premixed into temporary location, and then pumped into the tank. More complicated than other methods, but just like banking, your tanks never touch the pure stuff, so no need for o2 clean.

So essentially, for the four main methods of offering Nitrox, only ONE of them requires tanks to be o2 cleaned. Check your local shops and find out what methods they use, and make your decision about keeping tanks o2 clean accordingly. It's unfortunately that PP blending is no inexpensive for the shop, and thus so common, because o2 clean is a PITA and a waste of a good tank, IMO. There are only two local shops that I know of that do PP blending, and I won't get Nitrox fills at either of them, because I refuse to keep a tank set aside for just their shop.

terrillja
01-05-2008, 17:10
The way they do it near me is what they called atmospheric blending, basically they add pure o2 where the intake is, so the air coming into the compressor is enriched to 40%, then they bank it. They then draw from the banks and mix to your desired mix. They have had it tested and it's verified safe, so apparently that is method #5.

in_cavediver
01-05-2008, 21:40
The way they do it near me is what they called atmospheric blending, basically they add pure o2 where the intake is, so the air coming into the compressor is enriched to 40%, then they bank it. They then draw from the banks and mix to your desired mix. They have had it tested and it's verified safe, so apparently that is method #5.

Actually its method 4. Basically the nitrox stik is nothing more that a tube on the intake to cause turbulence in the gas flow. The turbulence ensures gas mixing because a pocket of pure o2 (or close) in a non-o2 compressor would be very bad.

There are a couple companies that sell 'stiks' and Vance Harlow in the Oxyhackers guide give directions on making one yourself. Perhaps your shop has a DIY version?

terrillja
01-05-2008, 22:08
Actually its method 4. Basically the nitrox stik is nothing more that a tube on the intake to cause turbulence in the gas flow. The turbulence ensures gas mixing because a pocket of pure o2 (or close) in a non-o2 compressor would be very bad.

There are a couple companies that sell 'stiks' and Vance Harlow in the Oxyhackers guide give directions on making one yourself. Perhaps your shop has a DIY version?

This definitely looked like a DIY version, the hose was coming out of the intake, so I couldn't see exactly what was inside the intake, but duct tape was involved for sure. We went over the way they make the nitrox briefly during my nitrox class. Pretty much what they said was they add O2 until the intake is at 40%, then bank it. How the magical blending works inside the intake, who knows.

Grin
01-06-2008, 10:12
The problem with having some steel tanks and some AL80s is, it is a little hassle keeping your correct weight. When you go from the steel tank to a AL80 you will need to add something like 5 lbs of lead to your settup. If you can get 3 HP100s your really happening (I know! They are expensive!). Otherwise you might just stick with 3 AL80s to keep your operation simple. The other issue is: When you convert to HP tanks you should use DIN valves(you don't have to, but you really should). More than likely your AL80s are Yoke, and your Reg is Yoke. So now you have that hassle to figure out. It's all deal-with-able, but it's all just more to think about and remember. Starting with all DIN stuff is a good idea, and having all the same tanks is very nice too. Normally I dive steel tanks but I have some yoke valved AL80s that are not worth selling, I rarly use them. Only when doing multipe days in a row, are they good for anything. Since, I don't have to go get fills after a days diving to go again the next day. I have a DIN/Yoke adapter for my reg, and I add 5 lbs of weight for the bouyancy issue when goig to a AL80.
I think you should dive all NITROX every dive if it's easily available. I don't even dive air when doing shallow dives anymore. Another point to keep it simple.

All same tanks, all Nitrox = simple no brain style.

Different tanks, some nitrox, different valves = now you have to think a little. I hate thinking!

cummings66
01-07-2008, 12:08
A couple times people have mentioned the TROUBLE of keeping things straight, weight being different etc. People, that's why you keep logs, you note the gear config so you can refer back to it. Do you honestly think it's tough to remember to add a few lbs of lead when you dive with AL tanks? I'm not as young as some of you that seem to have trouble in that regards and I'm not as sharp as I used to be, yet I have no trouble. I doubt anybody else would have that problem either. Buy what you can afford in order to dive as you wish.

BSea
01-07-2008, 12:12
A couple times people have mentioned the TROUBLE of keeping things straight, weight being different etc. People, that's why you keep logs, you note the gear config so you can refer back to it. Do you honestly think it's tough to remember to add a few lbs of lead when you dive with AL tanks? I'm not as young as some of you that seem to have trouble in that regards and I'm not as sharp as I used to be, yet I have no trouble. I doubt anybody else would have that problem either. Buy what you can afford in order to dive as you wish.
Exactly. If you dive enough, you'll know the weight configuration soon enough. Just keep good notes in your log till it becomes 2nd nature.

cheebaweebie
01-07-2008, 12:19
My LDS carries a bank of 32% then blends O2 for a richer mix. They don't require your tanks to be o2 cleaned prior to filling with nitrox. Which is cool.
I have as part of my tank collection 2 Steel HP 120s, 2 AL 80's and 1 steel LP 77.
It is a pain in the A** to ensure you have the proper weight especially when diving different wetsuits depending on water temps. I usually ddive my steel tanks first and if we have time for a third tank dive or if were doing drops and hunting ledges, doing 2 or 3 drops per tank, I still dive the steels first then move to the AL's that way once my weight is right, it's set. I usually have my weight spot on though becuase I dive so much.

Puffer Fish
01-07-2008, 12:23
A couple times people have mentioned the TROUBLE of keeping things straight, weight being different etc. People, that's why you keep logs, you note the gear config so you can refer back to it. Do you honestly think it's tough to remember to add a few lbs of lead when you dive with AL tanks? I'm not as young as some of you that seem to have trouble in that regards and I'm not as sharp as I used to be, yet I have no trouble. I doubt anybody else would have that problem either. Buy what you can afford in order to dive as you wish.

I have tha added issue of having to put weights on the tank bands, if I am using an AL80, or at the end of the dive, my bp/w will throw me face first when inflated...but I have the pouches on my band.. and know what the correct is...so the adjustment is easy.

I'm with you on this one, but then I have 3 different size tanks already.

Grin
01-07-2008, 12:54
All I was saying was to try to keep it as simple and thought free as possible. I also know what weight is needed, but I had to experiment to get to this point, and I do forget on occassion. Why would anyone want to screw with it if it's avoidable is my point. I also have 4 different wetsuits and three different tank types. I sure wish I had all the same tanks, how sweet that would be! And I don't keep dive logs, I don't think anyone I have dove with for the last 5 years owns a divelog.

CompuDude
01-07-2008, 13:40
All I was saying was to try to keep it as simple and thought free as possible. I also know what weight is needed, but I had to experiment to get to this point, and I do forget on occassion. Why would anyone want to screw with it if it's avoidable is my point. I also have 4 different wetsuits and three different tank types. I sure wish I had all the same tanks, how sweet that would be! And I don't keep dive logs, I don't think anyone I have dove with for the last 5 years owns a divelog.

I'm with you re simplicity. All of my tanks are within 1.5# of each other in buoyancy, on purpose. I change weight when I go from wet to dry, doubles to singles, and I have a completely different weighting arrangement for my pool rig with regular BC (the only place I use Al.80s, also). But other than that, no matter which singles tanks I grab (except in the pool sessions) my weighting does not change. Took some time to get everything dialed in, of course, but my log books were invaluable in that regard. I feel sorry for anyone who has to figure out as many combinations as I have without keeping a log. It's just silly not to.

navyhmc
01-08-2008, 00:13
As far as tanks, since my recent older AL80 issues, I'm looking at LP 121's Solves all my problems.

JugglingMonkeys
01-08-2008, 04:51
Thanks all for the great advice!

So to keep it simple from the beginning - same tanks.

And I assume those should be the HP100s - rather than AL80s?
If I can afford them...

Jipps
01-08-2008, 10:08
I'm going to start buying some tanks now.
Please share your advice.

My ultimate goal is to have perhaps 3 tanks.
Probably 2 regular AL-80s and 1 HP100.

Which should I reserve for Nitrox - the AL80 or the HP100?
Then I'll keep the others for air.

Thanks!

As far as getting tanks, personally I will only buy steel tanks. They are more expensive, but i like the smaller sizes and also not having to change my weight when i dive.

As far as the nitrox goes, I only dive nitrox so all of mine will be nitrox, but if you are only doing one, do the biggest one.

CompuDude
01-08-2008, 14:06
Thanks all for the great advice!

So to keep it simple from the beginning - same tanks.

And I assume those should be the HP100s - rather than AL80s?
If I can afford them...

IMO, if money is tight, pick up a cheap, used Al.80 now, just to get you going. Then buy HP100s as you can afford them, and sell off the Al80 (unless you want to go tech and use it as a stage later) for pretty much what you paid.

It'll be complicated from a weighting standpoint to switch back and forth, but there are benefits to knowing your proper weighting using the most common cylinder in the world in addition to your personal HP100s.

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
01-08-2008, 14:36
I prefer the Faber cylinders but another possibility is a set of new Worthington LP77s. Compare to an AL80 (77cf): competitive price, smaller size, same capacity (more if you can over-fill), no short fill worries, and better buoyancy characteristics.

Since Nitrox gives you more bottom time you might go with bigger tanks for Nitrox.

My main LDS banks 30% premix since 32% is too rich for the most popular wrecks around here. I need an O2 clean tank for custom mixes since they use partial pressure blending. This is a pain in the arse since the local quarry does not offer Nitrox or OCA. It would be very convenient to have some tanks just for air to use at the quarry. It would save a lot of trips to the LDS. Not to mention that Nitrox and OCA cost significantly more than regular air at the LDS.

kancho
01-09-2008, 20:31
LP or HP tanks which are better?

terrillja
01-09-2008, 20:37
LP or HP tanks which are better?
They are different, LP is easier to get filled completely, since the pressure is lower, and they can be overfilled, however HP is more compact.

BSea
01-09-2008, 23:15
LP or HP tanks which are better?I personally like LP tanks. But I can get them over filled locally. And if you want steel, but are concerned about the price, LP might be the way to go just because they cost less initially.

Puffer Fish
01-10-2008, 05:34
LP or HP tanks which are better?
Depends. On a weight basis, the HP tanks. And you can always use one of the larger HP tanks as a LP tanks, if you want to.

Cost varies a lot, and if you find a used tank, it will most likely be LP, so there are more deals out there...

Buoyancy is usually better with the HP tanks... better being that they tend to be not as heavy (again, there are exceptions).

I prefer the HP tanks, as all five of mine (soon to be 6) are Faber FX tanks, but the tech guys seem to like the LP tanks...

In south florida, Worthington HP's seem to rule...

in_cavediver
01-10-2008, 06:38
LP or HP tanks which are better?

Generally for the same physical size, the HP tank is more versatile but more costly. For instance, the LP85 and HP100 are almost identical in everything but fill pressure. If you get a short fill on the HP100, you basically have an LP85. Its the same way with the LP104 and HP130.

Think of it as a 'legal' overfill anytime you want it.

kancho
01-10-2008, 08:17
Thanks.. I guess ST doesn't have LP tanks available online. I was wondering what is the price difference.

cummings66
01-10-2008, 18:38
The LP85 is about 2 inches longer and that's why for some it is better than an HP100, trim issues considered. I think it's a good tank and due to it being longer is one reason I'd use it for doubles, but not single. For a single I'd always be using an HP tank for weight issues alone.

Puffer Fish
01-10-2008, 21:25
The LP85 is about 2 inches longer and that's why for some it is better than an HP100, trim issues considered. I think it's a good tank and due to it being longer is one reason I'd use it for doubles, but not single. For a single I'd always be using an HP tank for weight issues alone.
Ah, here are the various tanks from Worthington and Faber (the most common out there right now:

Faber LP85 - 26
Faber FX -100 - 25.39

Worthington LP85 - 24.7
Worthington X7 -100 - 24

You can get a short lp or a long one.. and the opposite.

WD8CDH
01-11-2008, 10:03
I would reserve the larger tanks for Nitrox since you would most likely need the benifits on longer dives.

I prefer the 3442psi steel tanks over the LP steel tanks because they give me the most air for the least weight.

All of my rigs have different buoyancy so I have the additional weight precalculated to make any of them the same buoyancy as the most negative set that I have.

Bill100
01-12-2008, 18:46
I started out with alum80's and then bought steel 100's. I no longer use my alum80's. I would go steel all the way (except for stage). Bill