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View Full Version : What to look for in used tanks?



Scout
08-11-2007, 09:30
Hello,

New poster and recently certified diver here. I'm interested in purchasing tanks simply for the convenience of not having to drive across town to the dive shop every time I want to dive. However, I don't think I'll be able to dive locally more than 10 or so times a year, other than trips to exotic places.

So, to get the cost down, I've been keeping my eyes open for used tanks. What should I look for? AL or steel? If the tank hasn't been hydro'd recently, is that a problem, other than the cost of the hydro? Is there a particular brand to look for, or, avoid?

Thanks!

Scout

cummings66
08-11-2007, 10:34
For the price of an AL tank I'd probably buy new, otherwise they're worth $50 or $60 in current hydro and vis.

Make sure they're clean and not oxidized/rusted and that it's a fairly new tank if AL. Steel I might want to do a visual before I bought or have an agreement that it pass the visual/hydro test as needed.

ReefHound
08-11-2007, 17:33
To be honest, I'm not sure it is worth buying used. Seems to me people want too much for them, especially when they are out of viz or hydro. I've bought a lot of used scuba gear, from computers to regs to BCs, but I would only buy used tanks from someone I knew and was sure wouldn't screw me.

DivingsInMyBlood
08-11-2007, 17:36
hello and welcome, buying your own tank seems like a good idea if you plan to dive a bit locally.

chinacat46
08-11-2007, 21:15
I'd make sure it had a recent hydro and make the sale contingent on the tank passing a visual inspection. Even if it had a visual last week it could have been dropped or damaged in some way so I'd want it inspected if it wasn't new. Of course that will add to the cost of the tank so YMMV.

cummings66
08-11-2007, 22:36
Yeah, but around here a visual is less than $20 everywhere you go. I get my tanks O2 cleaned and inspected for that price.

rubberduck
08-17-2007, 07:55
Also avoid the older ones made before 1988. They are made of a weaker aluiminum alloy and many shops will not fill them anymore.

One recently blew in a dive shop in RI.

mike_s
08-17-2007, 09:09
Hello,

New poster and recently certified diver here. I'm interested in purchasing tanks simply for the convenience of not having to drive across town to the dive shop every time I want to dive. However, I don't think I'll be able to dive locally more than 10 or so times a year, other than trips to exotic places.

So, to get the cost down, I've been keeping my eyes open for used tanks. What should I look for? AL or steel? If the tank hasn't been hydro'd recently, is that a problem, other than the cost of the hydro? Is there a particular brand to look for, or, avoid?

Thanks!

Scout


Here's something to look for.

1.) Does the tank have air in it when being sold. An empty tank is an indicator of a leaky valve and also an indicator that there might be moisture inside the tank which can cause corrosion. An empty tank that you don't know anything about SHOULD be visually inspected before used to make sure the inside is ok

2.) Check to see when the tank was originally made. Aluminum tanks made by Luxfer before May 1988 were made of 6351 aluminum alloy which is susceptible to SLC (Substained Load Cracking). There are many of these tanks still in use, but people are leary of them. you will have a hard time in many areas finding a dive shop that will fill them. Some shops won't fill any tanks before 1989 regardless of brand. Which is stupid, but oh well. Best thing to do is to avoid these tanks by not purchasing any Luxfer tanks made before May 1988.

3.) Visually inspect the outside of the tank yourself before buying. Look for corrosion, pitting, etc. Read the numbers on the tank yourself. I bought a tank off EBAY once and the guy lied about what the tank was for example. Of course he wouldn't repsond afterwards.

4.) Brands to avoid? besides the above, some people don't like the Genesis (Asashi) spun steel tanks. These are pretty rare to come across with all the other tanks out there. Some people like them though.

5.) Steel or Aluminum? I think you'll find most people who have steel prefer the steel tanks. They are more negative bouyant and you don't have to wear as much weight. Also the High Pressure (HP) tanks can hold more air for their physical size. For example, a HP100 is about the same size as an AL80, but holds 22.3 cubic feet of more air. The only thing about steel tanks is they typically cost more.

6.) Tanks not in Hydro: Usually not a problem but you run the risk that it won't pass hydro, though this is rare. It's just a risk and expense you take. Check your LDS for hydro costs & visual costs and factor that into your price for purchase. Or you can go direct to the hydro facility like many of us do. It's a little cheaper typically that way. Note not all hydro facilities do visual stickers and air fills, so you might still have to go to your LDS.

7.) Is it worth buying used? Depends all on price. Typically AL80's are going for about $150 online right now even through Scuba Toys. LP has a sale on them for $115 right now. most LDS's charge $170 to $200 for them. A used AL80 will usually go between $25 and $125 bucks depending on if it's agie, it's condition, whether it's in need of hydro/vis or if it's all current and maybe o2 clean and full of nitrox. Consider that O2 cleaning costs about $25 to $50 on average and that a 32% nitrox fill is about $10 bucks depending on where you live. That can easily make a tank more valuable to a buyer who'd have to spend that.

There is nothing wrong with a used tank if you can get a good deal on it. But if it's out of hydro, needs a vis, needs O2 cleaning, and needs a nitrox sticker band, needs a nitrox fill, factor all your costs and see what the difference in buying the tank used and what a new tank is. If the new tank is close in price, I'd buy the new one. If it's a good deal, I'd buy the used tanks.

hope this all helps. happy shopping.

BSea
08-17-2007, 09:54
I have bought 5 used tanks (all steel). Some have been in hydro, and some haven't. So far I've never had 1 fail a hydro. But to be fair, 3 were current for hydro & VIP.

I avoid tanks with rust spots & 1/2" valves. Even though I have a set of 38's with the 1/2" valves, I won't buy anymore. They are just too much of a hassle. To be fair, they are doubles, and have to be tweaked to keep from leaking, but the valve threads need to be taped, and they don't have an o-ring seal.

I've been told to avoid the steel tanks with the built in feet. They are rare, but they are out there.

I bought my AL pony used also, but it had a fresh hydro & VIP. and was only 5 years old.

subsur
08-19-2007, 10:53
i don't know where you live but if you wear a lot of exposure protection i'd suggest getting a steel tank. the price on used steel tanks goes down slowly. so if you buy it new and for a good price, it might be a low devaluating thing. I were buying a used steel tank, or any tank for that matter, i'd want the owner to do a VIP test and hydro (if it's exrired or due soon). if you're buying on-line, ask for pictures. it the tank is perfect inside but a bit corroded outside, you can easily repaint it.

Scout
08-19-2007, 13:43
Hello,

New poster and recently certified diver here. I'm interested in purchasing tanks simply for the convenience of not having to drive across town to the dive shop every time I want to dive. However, I don't think I'll be able to dive locally more than 10 or so times a year, other than trips to exotic places.

So, to get the cost down, I've been keeping my eyes open for used tanks. What should I look for? AL or steel? If the tank hasn't been hydro'd recently, is that a problem, other than the cost of the hydro? Is there a particular brand to look for, or, avoid?

Thanks!

Scout


Here's something to look for.

1.) Does the tank have air in it when being sold. An empty tank is an indicator of a leaky valve and also an indicator that there might be moisture inside the tank which can cause corrosion. An empty tank that you don't know anything about SHOULD be visually inspected before used to make sure the inside is ok

2.) Check to see when the tank was originally made. Aluminum tanks made by Luxfer before May 1988 were made of 6351 aluminum alloy which is susceptible to SLC (Substained Load Cracking). There are many of these tanks still in use, but people are leary of them. you will have a hard time in many areas finding a dive shop that will fill them. Some shops won't fill any tanks before 1989 regardless of brand. Which is stupid, but oh well. Best thing to do is to avoid these tanks by not purchasing any Luxfer tanks made before May 1988.

3.) Visually inspect the outside of the tank yourself before buying. Look for corrosion, pitting, etc. Read the numbers on the tank yourself. I bought a tank off EBAY once and the guy lied about what the tank was for example. Of course he wouldn't repsond afterwards.

4.) Brands to avoid? besides the above, some people don't like the Genesis (Asashi) spun steel tanks. These are pretty rare to come across with all the other tanks out there. Some people like them though.

5.) Steel or Aluminum? I think you'll find most people who have steel prefer the steel tanks. They are more negative bouyant and you don't have to wear as much weight. Also the High Pressure (HP) tanks can hold more air for their physical size. For example, a HP100 is about the same size as an AL80, but holds 22.3 cubic feet of more air. The only thing about steel tanks is they typically cost more.

6.) Tanks not in Hydro: Usually not a problem but you run the risk that it won't pass hydro, though this is rare. It's just a risk and expense you take. Check your LDS for hydro costs & visual costs and factor that into your price for purchase. Or you can go direct to the hydro facility like many of us do. It's a little cheaper typically that way. Note not all hydro facilities do visual stickers and air fills, so you might still have to go to your LDS.

7.) Is it worth buying used? Depends all on price. Typically AL80's are going for about $150 online right now even through Scuba Toys. LP has a sale on them for $115 right now. most LDS's charge $170 to $200 for them. A used AL80 will usually go between $25 and $125 bucks depending on if it's agie, it's condition, whether it's in need of hydro/vis or if it's all current and maybe o2 clean and full of nitrox. Consider that O2 cleaning costs about $25 to $50 on average and that a 32% nitrox fill is about $10 bucks depending on where you live. That can easily make a tank more valuable to a buyer who'd have to spend that.

There is nothing wrong with a used tank if you can get a good deal on it. But if it's out of hydro, needs a vis, needs O2 cleaning, and needs a nitrox sticker band, needs a nitrox fill, factor all your costs and see what the difference in buying the tank used and what a new tank is. If the new tank is close in price, I'd buy the new one. If it's a good deal, I'd buy the used tanks.

hope this all helps. happy shopping.
Thanks! This is exactly the detail I was looking for! Can any tank that's only used air be used for Nitrox in the future?

Scout
08-19-2007, 13:46
I have bought 5 used tanks (all steel). Some have been in hydro, and some haven't. So far I've never had 1 fail a hydro. But to be fair, 3 were current for hydro & VIP.

I avoid tanks with rust spots & 1/2" valves. Even though I have a set of 38's with the 1/2" valves, I won't buy anymore. They are just too much of a hassle. To be fair, they are doubles, and have to be tweaked to keep from leaking, but the valve threads need to be taped, and they don't have an o-ring seal.

I've been told to avoid the steel tanks with the built in feet. They are rare, but they are out there.

I bought my AL pony used also, but it had a fresh hydro & VIP. and was only 5 years old.
Thanks! What is the normal valve size? Is the valve size clearly marked on the stem? What is the standard valve size?

finflippers
08-19-2007, 15:19
Thanks! This is exactly the detail I was looking for! Can any tank that's only used air be used for Nitrox in the future?
Yes but it will have to be O2 cleaned first. Unless you get premixed Nitrox less then 40%.

If you are looking for an aluminum tank I would go ahead and get new. It will take all the guess work out of how the tank has been treated in the past plus by the time you buy a used tank and get hydro and vis. you are usually only saving a little compared what you can buy one at ST before you take into account the discounts.

BSea
08-20-2007, 04:52
I have bought 5 used tanks (all steel). Some have been in hydro, and some haven't. So far I've never had 1 fail a hydro. But to be fair, 3 were current for hydro & VIP.

I avoid tanks with rust spots & 1/2" valves. Even though I have a set of 38's with the 1/2" valves, I won't buy anymore. They are just too much of a hassle. To be fair, they are doubles, and have to be tweaked to keep from leaking, but the valve threads need to be taped, and they don't have an o-ring seal.

I've been told to avoid the steel tanks with the built in feet. They are rare, but they are out there.

I bought my AL pony used also, but it had a fresh hydro & VIP. and was only 5 years old.
Thanks! What is the normal valve size? Is the valve size clearly marked on the stem? What is the standard valve size?
The standard size is 3/4. But I think there are some older HP steels that have a unique tread size, or maybe slightly smller than a 3/4 (I don't know the specific details). Even if you get 1 of these, you will probably be ok if it has the valve attached.

Charlotte Smith
08-20-2007, 06:45
I would buy new! It is your LIFE that depends on your tank.......just save your money and get the new one...then you know you are safe!

fire diver
08-20-2007, 08:15
I would buy new! It is your LIFE that depends on your tank.......just save your money and get the new one...then you know you are safe!

What are you worried about being wrong with a used tank? Are you afraid the 1/2" of AL might have a 1/1000" scratch in it? That the paint might look bad? Tanks are big, heavy, and tough. Go to an industrial gas supplier and watch them move tanks!

If you are worried about the condition of a tank, have it vis'ed or hydro'ed. The only thing that can really go bad is oxidation (and it a LOT of that) or damage to the neck threads. All that can be checks with a $10 vis.

FD

mike_s
08-20-2007, 11:58
Thanks! This is exactly the detail I was looking for! Can any tank that's only used air be used for Nitrox in the future?


There are a couple different ways to make Nitrox. You either get it mixed or already banked.

If you are mixing it in the tank, which is also known as "Partial Pressure Filling" then they first start by putting 100% pure O2 in your tank and then filling it with O2 compatible air aftewards to the rated pressure (3000psi for most AL80's). If your local shop where you get your air fills uses this method, your tank will have to be O2 clean. Most shops charge around $25 to $40 bucks to o2 clean a tank. You will then be responsible for making sure that you only get fills with O2 clean air or nitrox or it could render your tank no longer O2 clean.

You should have an O2 clean tank for any o2 mixture that is above 40% put in your tank. With Partial Pressure blendins, since you start with 100% o2, it falls in this category.

Another way of getting nitrox is from an memberane system. the compresser pump air through a DNX membreane and the result is breathing gas that comes out at the rated nitrox blend. 32% for example. So no pure 100% o2 is ever introduced to your tank, you don't have to be O2 clean.

yet another way of getting nitrox blens is with the "stick" method. this is where they inject pure O2 in a blending vessel and mix it to the appropiate EAN mixture before it gets to your tank. The result is that only for example EAN32 or EAN36 as the mixture is set, gets pumped into your tank. You don't need an O2 clean tank for this either.

Any of these methods can be used to "bank" nitrox blends. All banking does is use several high pressure cylinders that are high capacity to "store" or bank gas blends for later use in order to not run the compressor as much. Many dive shops will bank nitrox blends. This is much quicker on busier saturdays to fill a tank instead of having to partial pressure blend it for example.

one other note, most shops like for you to have that nice big nitrox band sticker around your tank if you're going to put nitrox in it. You will also typically add a temporary sticker to the tank, usually painters tape, that indicated the blend of nitrox and sometimes the MOD (Max Operating Depth). That way you know exactly what blend of EAN is in the tank.

You should always analyze a nitrox tank after getting it filled just in case. Even if from a banked source. You don't want someone elses mixing mistage to cuase you to have a NDL or oxygen toxicity issue.

CompuDude
08-20-2007, 14:43
Geez, Mike, leave something for the rest of us to post!

LOL

(j/k, of course)

Actually, re Aluminum or Steel, I'd ask the OP where he lives and where he expects to dive. Cold water, like PNW, SoCal, New Jersey, etc., I'd say steel in a heartbeat. Warmer water like Florida and it could go either way.

Used is great way to save money. If you're buying used aluminum, they'll be cheap, so everything is less critical, just make sure they don't look too abused and are (IMO) no more than 10 years old. Steel tanks last forever... *IF* properly cared for... so they are a great investment IF you make sure they are in good shape before buying. Check carefully for rust and corrosion, and make sure any purchase is contingent on passing inspection. Any used steel should have a vis done immediately, IMO, unless it was *just* done prior to sale, and you trust the seller. Hydro is stickier, I am leery of buying any tank that is close to hydro's expiration unless you can get it hydro'd immediately. If you're not getting it hydro'd right away, it really becomes a trust issue with the seller. Are they local and someone you see on occasion, so you can track them down and threaten their local reputation if their tank ends up bad? Are they a friend who will do right by you? If so, no prob. Anonymous eBay seller? Not on your life.

I've been burned buying used tanks before. I paid $160 for a PST HP100 (score!) that was 9 months away from needing hydro. It failed when I took it in 9 months later. I looked at that 9 months as a rental fee and chalked it up to experience. Now I only buy used tanks that are ready for hydro, or I brace myself to lose some money if, in 2-3 years when it's time for hydro, it fails. If it passes, and you take care of your tank, you should have it for the rest of your diving career or until you get tired of it and sell it off.

Hollywood703
08-21-2007, 14:37
if you are going to buy steel, you can look for used...aluminum your better off buying new.

mcc2318
11-26-2007, 15:15
jst make sure in not to old and that its got a good hydro and vis testing