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mulefeathers
08-23-2007, 08:32
Why would you want to dive with steel tanks? I know someone who sold off all of there AL tanks to go with steel. Myself I like to keep thing simple. I rented a steel tanks once because that is all they had. But just didn't see a big advantage. Please tell what the draw is to steel tanks over AL. Thanks

jeraldjcook
08-23-2007, 08:34
You can take weight off your belt. At the end of a dive, an AL80 is buoyant, while a steel will usually be a couple of pounds negative.

mwhities
08-23-2007, 08:35
Exactly.

Michael

cgvmer
08-23-2007, 08:35
I also rented them and loved them. They had more air in them, 100's they were negativly bouyant, removing weight from belt.

Others with more experience can give you more info.

Charlotte Smith
08-23-2007, 08:38
I go from having 12 lbs of weight added to my BC to none thus freeing up my pockets for other stuff but thats just me. I don't always use steel cause my hubby isn't always there to lug it for me but its nice to dive with steel, it holds more air for me...

Griff
08-23-2007, 08:42
I asked someone in my LDS this same question the other day.

With being able to take weight off and having more air/pressure, I asked why would anyone go with AL. He basically stated that Steel is more expensive and many people are too lazy to swap or don't have a First State that can handle the increased pressure.

jeraldjcook
08-23-2007, 08:46
I asked someone in my LDS this same question the other day.

With being able to take weight off and having more air/pressure, I asked why would anyone go with AL. He basically stated that Steel is more expensive and many people are too lazy to swap or don't have a First State that can handle the increased pressure.

An additional factor that influenced my to buy AL tanks is rust. I'd be paranoid like crazy that I'd get a wet fill. I know AL can oxidize, but at least the tank is cheaper.

mike_s
08-23-2007, 08:58
Here ya go.

1.) Steel tanks are more negative bouyant. That means that you can take lead off your weight belt. With my steels, I can take off about 6 pounds compared to an AL80.

2.) Steel is stronger than Aluminum is, thus allowing thinner tank walls, which allows more tank volume for the same physical size AL80. For example, a steel HP100 is about the same physical size as an AL80 is, but holds about 23 cubic feet more air. The end result is that you can stay down a lot longer with a tank that is about the same physical exterior size.

3.) If you diving a drysuit, you need extra negative weight to help "sink" you with the drysuit, air in it, and undergarments. Drysuit divers require more weight on their weightbelts. The fact that steels tanks are more negative is a bonus to a drysuit diver as he doesn't have to wear as much lead.

4.) You "can" overfill the LP steel tanks. Is this reccomended? No. But is it done? Yes. It's a fairly common accepted practice. What this buys you is more breathing gas, which of course is directly porportional to your bottom time. A LP108 normall fill is 2400. It's 'Plus' rated to 108cf at 2640psi. At 3000psi, you'd have 122cf and at 3500psi overfill you'd have 143cf. A set of double LP108's filled to 3500 would get you 286cf of air. this is pretty popular for deco or cave divers. You can't do that with an Aluminum tank.



So why do people still buy AL tanks? because that's what they were trained with and they are cheaper.

Jaymeany
08-23-2007, 09:08
Do you lose air in the neutrally buoyant Al? It claims to be the same physical size with thicker walls. Can you use a yoke on a Steel?

jeraldjcook
08-23-2007, 09:11
Do you lose air in the neutrally buoyant Al? It claims to be the same physical size with thicker walls. Can you use a yoke on a Steel?

I think they are 3300psi, usually with a yoke.

Yes, you can use a yoke on LP steel and MP (3442psi) steel but not HP steel.

mike_s
08-23-2007, 09:30
Do you lose air in the neutrally buoyant Al? It claims to be the same physical size with thicker walls. Can you use a yoke on a Steel?


You can put any valve on any tank. Din or Yoke.


however, if you've got a 3500psi tank, and you put a 3000psi valve, your valve is the limiting factor.

Peter_V
08-26-2007, 02:21
Aside from being less boyant (which means you need less lead) steel tanks are often lighter than aluminum ones.
When you add the lower tank weight with the lower weght on your belt, the total reduction can be impressive.
When I switched from AL80 to steel HP80 the total weight I had to carry dropped 20 lbs.

Doesn't sound like much, but one of my favorite dive spots has a staircase with 97 steps to get in/out of the water. Plus the trek to the parking lot.

mcc2318
11-26-2007, 15:09
i think for alot of people they would rather save the money on the AL

in_cavediver
11-26-2007, 17:41
i think for alot of people they would rather save the money on the AL

Yep, cost can be a deciding factor when comparing a $150 tank to a $350 tank. Of course, you make the same decisions with Regs, BC's and the rest of your dive gear. Its all competing for the same small dollars available for gear.

The sad part is that a steel tank can make diving much more enjoyable by dropping the out of the water weight for diving. If memory serves, going from an AL80 to a steel 100 allows you to carry 12lbs less weight (or 1/3 or the weight of an AL 80)

tedwhiteva
11-26-2007, 18:07
The ONLY reason I can imagine for aluminum vs steel is cost, for all the reasons others have said

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
11-26-2007, 19:50
Aluminum used to be much cheaper than steel. It's still cheaper, but when you also consider that a steel tank might last you twice as long I think steel is now actually cheaper over the long run. Try to sell a 15 year old aluminum tank. No problem selling a 15 year old steel tank with recent vip.

quasimoto
11-26-2007, 20:03
I asked someone in my LDS this same question the other day.

With being able to take weight off and having more air/pressure, I asked why would anyone go with AL. He basically stated that Steel is more expensive and many people are too lazy to swap or don't have a First State that can handle the increased pressure.

I assume that you meant first stage? If so I don't see where a first stage would make a difference. Some will say that you need DIN for the HP's but I know of a couple that use yoke. Probably not something that I would do.

whitenoise
11-27-2007, 04:25
I think it's a regional thing as well. Over here I don't think AL is the "done" thing. It's steel all the way for sure.

Kabniel
11-28-2007, 14:18
I assume that you meant first stage? If so I don't see where a first stage would make a difference. Some will say that you need DIN for the HP's but I know of a couple that use yoke. Probably not something that I would do.

Yoke or A-clamp is only rated to 232 bar isn't it? if you put a yoke on a 300 bar cylinder you're exceeding the manufacturers rating. I think if you did that you'd be saying goodbye to your o-rings before long

Puffer Fish
11-28-2007, 14:20
I assume that you meant first stage? If so I don't see where a first stage would make a difference. Some will say that you need DIN for the HP's but I know of a couple that use yoke. Probably not something that I would do.

Yoke or A-clamp is only rated to 232 bar isn't it? if you put a yoke on a 300 bar cylinder you're exceeding the manufacturers rating. I think if you did that you'd be saying goodbye to your o-rings before long
You are very correct about that, even with harder o-rings... been there, done that.

in_cavediver
11-28-2007, 17:51
I assume that you meant first stage? If so I don't see where a first stage would make a difference. Some will say that you need DIN for the HP's but I know of a couple that use yoke. Probably not something that I would do.

Yoke or A-clamp is only rated to 232 bar isn't it? if you put a yoke on a 300 bar cylinder you're exceeding the manufacturers rating. I think if you did that you'd be saying goodbye to your o-rings before long

For those English unit minded people, 232 bar is 3365psi and 300 bar is 4351psi. Now, many current 'HP' tanks are the 3442 variety and they ship with convertible valves so yokes are OK though a bit out of spec. Basically, your operating in the safety range of the part. For 80psi over spec, I doubt you'd ever see a problem. Heck, the gauge may not be accurate enough to even tell you that much.

That said, DIN is still better. Go DIN, for everything!

Mycroft
12-16-2007, 10:03
I own a pair of E8 130 cft HP steel tanks. I have operated them as both DIN and Yoke tanks at 3442 PSI.

Usually I use them as DIN, but on a liveaboard where I took one, they only had yoke fills, so I ran the tanks as yoke and then had the yoke to din converter on my reg.

Why steel over alum? Simple enough. A back fill BC is designed to keep a diver in a good position, especially a photographer. However, it works much better with a steel tank to shift weight back on the body.

And that extra 50 cft comes in real handy. As a big guy, I got thru an alum 80 faster then my buddy does. With the 130, we come up when HE rums out of gas, not me.

divingmedic
12-26-2007, 20:43
I dove with steel 95's the first time a few weeks ago. I dove with 8 pounds instead of 16 with a 5mm wetsuit. One day I even forgot my weight belt and didnt know it till I got back on the boat.

Hollywood703
12-27-2007, 12:41
Do you lose air in the neutrally buoyant Al? It claims to be the same physical size with thicker walls. Can you use a yoke on a Steel?

I think they are 3300psi, usually with a yoke.

Yes, you can use a yoke on LP steel and MP (3442psi) steel but not HP steel.

what do you consider HP? Worthington tanks are 3442 and are considered HP at 3442 and you can use a Yoke....I have yet to see any recreational tanks that go much higher than that.

CompuDude
12-27-2007, 14:01
Do you lose air in the neutrally buoyant Al? It claims to be the same physical size with thicker walls. Can you use a yoke on a Steel?

I think they are 3300psi, usually with a yoke.

Yes, you can use a yoke on LP steel and MP (3442psi) steel but not HP steel.

what do you consider HP? Worthington tanks are 3442 and are considered HP at 3442 and you can use a Yoke....I have yet to see any recreational tanks that go much higher than that.

Technically you are only supposed to fill them to 3300 when you use the yoke insert. People ignore this all the time, however, and seem to be ok. Far more likely to blow an o-ring and delay your dive when you hook it all up, however. DIN is best if you're going HP (or psuedo-HP, like all of the exemption tanks that come in barely under 3500 psi so they're not forced to use DIN-only valves).

WD8CDH
12-27-2007, 14:14
Aluminum used to be much cheaper than steel. It's still cheaper, but when you also consider that a steel tank might last you twice as long <snip>.

Why do you say that a steel tank will last twice as long as an aluminum one? (Assuming 6061 aluminum)

Ron

CompuDude
12-27-2007, 14:27
Aluminum used to be much cheaper than steel. It's still cheaper, but when you also consider that a steel tank might last you twice as long <snip>.

Why do you say that a steel tank will last twice as long as an aluminum one? (Assuming 6061 aluminum)

Ron

Aluminum is not as strong as steel, and after 20 years (sometimes less) I wouldn't want to use one. There are quite a few shops that won't fill Aluminum tanks more than 15 years old, regardless of hydro status. Whether they're correct or not, if you bring your tank into one of those shops, you won't be using your tank that day.

Steel tanks nearly 100 years old are still in service... and it's VERY common to see Steel 72's manufactured in 1970s still kicking around in daily use. I recently sold some tanks that were made in '91, and still going strong. The resale value was a LOT higher than a similar aluminum tank would have been for many of these same reasons.

carbon13
12-28-2007, 06:47
For me diving with less lead is important... I carry a bit more weight than I should :smiley30: (nothing a bit of exercise can't fix) so diving a steel tank means less lead.
I also dive a weight integrated BC, so the extra pounds of lead required for an AL tank makes the BC tooooo heavy out of the water - particularly if doing a shore dive and there is a bit of a walk :)

SarahBella
12-28-2007, 08:13
Santa brought me a Faber 80 and I am really excited to dive it-I carry over 20lbs of lead when I dive in my two piece wetsuit with an AL80-I am hoping to drop 6 lbs of lead due to the boyancy of the tank. It also works out well because the Faber weighs a little less and is smaller than the AL80 I used to dive. Santa Rocks!

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
01-02-2008, 14:53
Aluminum used to be much cheaper than steel. It's still cheaper, but when you also consider that a steel tank might last you twice as long <snip>.

Why do you say that a steel tank will last twice as long as an aluminum one? (Assuming 6061 aluminum)

Ron

Aluminum is a great metal for some applications.

However, when I was designing machines for a living for most things we did not really consider the endurance limit for designs using steel since fatigue is not usually the limiting factor. Even very low loads if repeated enough will fatigue aluminum while steel could have an indefinite life at the same load. Steel also has a larger plastic range which tends to make failure less dramatic.

In summary, steel is more abrasion resistant, more ductile, more fatigue resistant and has a larger plastic range. Aluminum is lighter and does not need to be painted/coated to resist corrosion. As a cool water diver I find aluminum being lighter to be a disadvantage. So, for me the only advantage of aluminum tanks is that they do not need to be painted to resist corrosion.

And with the Worthington LP77 at only 200 bucks there is no way I'd buy a new aluminum 80 tank.

jeepbrew
01-24-2008, 10:32
So, as everyone else has stated - Go With Steel!!

WD8CDH
01-24-2008, 12:53
When highly stressed, aluminum does fatigue more than steel but at the stress levels of a 3000psi cylinder, it is insignificant for over 100,000 fill cycles. That is one fill per day for about 275 years. The 6061 alloy tanks have a significantly better safety record than steel. Even the old "bad" alloy had about the same safety record as steel. Most steel tank failures are from the inside out where you can't see them. (wet fills)

In the more common sizes, steel tanks have far better buoyancy characteristics than aluminum, especially 3442psi steel tanks but in the real world, an aluminum tank will most likely out live a steel one if treated similarly.

Personally, I really don't like the aluminum 80 either but I prefer my quad 20 tank rig (80cf total) made from aluminum over my Worthington HP80. Of the tanks made today, I usually prefer aluminum for 40 cf tanks and below and steel for the larger tanks but I am very picky on my fills in the steel tanks.

SkuaSeptember
01-24-2008, 13:38
I prefer my quad 20 tank rig (80cf total) made from aluminum over my Worthington HP80.
I've seen a set of triples, but never a quad. Got any pictures?

navyhmc
01-24-2008, 14:39
One item I have been told about AL vs. Steel with regards to nitrox: An AL takn is easier to O2 clean than a steel tank. Why, I do not know for certain, it seems that hydrocarbons have a greater affinity to stell than AL. A local LDS tech says that he sometimes has had to tumble a steel tank 3-4 imes and it still doesn't totally clean it.

I will be tlaking with him again on Saturday and totally confirm, but that's one reason you see a good number of newer doubles on E-Bay; they can't get a good O2 clean for cave and tech.

YMMV of course.

Puffer Fish
01-24-2008, 15:40
When highly stressed, aluminum does fatigue more than steel but at the stress levels of a 3000psi cylinder, it is insignificant for over 100,000 fill cycles. That is one fill per day for about 275 years. The 6061 alloy tanks have a significantly better safety record than steel. Even the old "bad" alloy had about the same safety record as steel. Most steel tank failures are from the inside out where you can't see them. (wet fills)

In the more common sizes, steel tanks have far better buoyancy characteristics than aluminum, especially 3442psi steel tanks but in the real world, an aluminum tank will most likely out live a steel one if treated similarly.

Personally, I really don't like the aluminum 80 either but I prefer my quad 20 tank rig (80cf total) made from aluminum over my Worthington HP80. Of the tanks made today, I usually prefer aluminum for 40 cf tanks and below and steel for the larger tanks but I am very picky on my fills in the steel tanks.

There has been a major change in the alloy being used for steel tanks, particularly the 3442, which are chrome Moly steel. Sometimes how something rusts (oxidizes) is more important than that it rusts.

With steel, the biggest concern has been pitting, which is far less likely with Aluminum (possible, just less likely). However, there are steels that are far better than aluminum, just they were not being used for tanks.

What you want is a steel that flash surface rusts, rather than pitting. I don't know the specific chrome moly alloy they are using (if someone does, I can look up it's properties), but looking at the inside of the steel tanks I have, after 3 years, they are still smooth.

I don't put regular air in mine, so it could be just from the quality of the air, time will tell.

Puffer Fish
01-24-2008, 15:45
One item I have been told about AL vs. Steel with regards to nitrox: An AL takn is easier to O2 clean than a steel tank. Why, I do not know for certain, it seems that hydrocarbons have a greater affinity to stell than AL. A local LDS tech says that he sometimes has had to tumble a steel tank 3-4 imes and it still doesn't totally clean it.

I will be tlaking with him again on Saturday and totally confirm, but that's one reason you see a good number of newer doubles on E-Bay; they can't get a good O2 clean for cave and tech.

YMMV of course.
Navy, that is due to surface roughness, making tumbling almost impossible as a cleaning method. Not the right way to do that actually.

coyote
01-24-2008, 16:19
Tank buoyancy never bothered me much. An AL80 with 500psi and a reg attached will still sink. Steel tanks mean less weight in the BC. It never struck me as a big deal.
But I'm all about bottom time. And a 120 or 130 CF steel tank completely changes how you can dive. Diving conservatively, 130cf means a nice loooong dive. Put EAN in one of those big steel tanks and you're really ready to rock and roll. :smiley20:

WD8CDH
01-25-2008, 09:45
I prefer my quad 20 tank rig (80cf total) made from aluminum over my Worthington HP80.
I've seen a set of triples, but never a quad. Got any pictures?

Hi SkuaSeptember,

I put up most of my gear in preparation for heart surgery but I will take them out soon to take some pictures.

Puffer Fish,

Not only are there better steel alloys (like in my Worthington HP80), there are also better aluminum alloys. My Quad 20's are a 7000 series alloy which allows 3000psi in a tank that would only allow 2015psi if it was 6061 alloy. The tanks are DOT.

If an aluminum 80 was made out of 7000 alloy, it would be able to hold 120cf at a working pressure of 4500psi. It would then have similar buoyancy and capacity as a steel HP 120 but be a little smaller and unfortunatly, would require the higher fill pressure.

jeepbrew
01-27-2008, 18:30
Diving conservatively, 130cf means a nice loooong dive. Put EAN in one of those big steel tanks and you're really ready to rock and roll. :smiley20:

You got it. I typically dive Nitrox in a steel HP130. :smiley20:

navyhmc
01-27-2008, 22:07
One item I have been told about AL vs. Steel with regards to nitrox: An AL takn is easier to O2 clean than a steel tank. Why, I do not know for certain, it seems that hydrocarbons have a greater affinity to stell than AL. A local LDS tech says that he sometimes has had to tumble a steel tank 3-4 imes and it still doesn't totally clean it.

I will be tlaking with him again on Saturday and totally confirm, but that's one reason you see a good number of newer doubles on E-Bay; they can't get a good O2 clean for cave and tech.

YMMV of course.
Navy, that is due to surface roughness, making tumbling almost impossible as a cleaning method. Not the right way to do that actually.

Sounds good. What's a "better" method?

cummings66
01-28-2008, 11:19
You use chemicals to O2 clean tanks,.

My steel tanks used to be O2 clean and it's as easy to clean them as it is AL. There are many chemicals used to do the cleaning but some prefer things like Simple Green while the old school guys like Phosporic Acid, some like the newer non toxic things. You should have seen how the Navy cleaned theirs, it's in their diving manual if I remember correctly. Been a while since I read it.

Chemicals make the world go round.

Puffer Fish
01-28-2008, 11:54
You use chemicals to O2 clean tanks,.

My steel tanks used to be O2 clean and it's as easy to clean them as it is AL. There are many chemicals used to do the cleaning but some prefer things like Simple Green while the old school guys like Phosporic Acid, some like the newer non toxic things. You should have seen how the Navy cleaned theirs, it's in their diving manual if I remember correctly. Been a while since I read it.

Chemicals make the world go round.
Matt, thanks for answering him...a mild alkaline cleaning solution works wonders and makes sure the inside of the tank will not be rusting from the cleaning later.

cummings66
01-28-2008, 17:32
Yup, Simple Green has an alkaline pH of 9.5 according to their website and to be honest it's the favorite of most O2 cleaners I've run across. There is another company out there that makes a commercial cleaner and additive that is supposed to prevent flash rust, but it's pretty expensive.

I probably should have O2 cleaned my tanks today, we had them apart turning them into doubles but due to time constraints we just did a quick vis inspection and reassembled them. Later on in a few months I'll do the O2 cleaning and get the sticker on it, but until I start using Nitrox again I'm not going to worry about it.

Grin
01-29-2008, 10:11
It would probably be hard to find non O2 cleaned and ready steel tanks new these days anyway. I have bouhgt 4 Steel tanks in the last couple years and all were ready to go. Worhtingtons.

cummings66
01-29-2008, 10:59
But it won't be clean after a years worth of diving. I've heard that sometimes the tanks that are suppoosed to be clean sometimes are not good enough for PP fills. Best to check.

Puffer Fish
01-29-2008, 14:13
But it won't be clean after a years worth of diving. I've heard that sometimes the tanks that are suppoosed to be clean sometimes are not good enough for PP fills. Best to check.
After two years of reasonable usage (about 60 fills per tank), mine still looked like never been used. But I have only had Nitrox in them, two places that use blended gas and one that does partial pressure.

Super-Duper Scubasteve
01-29-2008, 15:02
Steel cylinders are heavier though it's adding on extra weight to something that is already pretty heavy.

Puffer Fish
01-29-2008, 15:27
Steel cylinders are heavier though it's adding on extra weight to something that is already pretty heavy.
Ah Steve, you need to read the entire thread...some steel tanks are lighter.

in_cavediver
01-29-2008, 18:51
Steel cylinders are heavier though it's adding on extra weight to something that is already pretty heavy.
Ah Steve, you need to read the entire thread...some steel tanks are lighter.

Puffer is right, see this chart:

http://www.huronscuba.com/equipment/scubaCylinderSpecification.html

A steel 80 is lighter than an Al 80, and allows you to carry 7lbs less lead to boot.

cummings66
01-30-2008, 14:30
Yup, that's the benfit of steel, some are actually the best thing since sliced bread.

jeepbrew
01-30-2008, 15:55
Sounds good. What's a "better" method?

I use the Simple Green method on my steel tanks... works well.

Aussie
01-30-2008, 21:44
You dont see many steels in remote and tropical locations (South Pacific, PNG, Indo). This is where the Al's are at there best. Luxfer also offer a 15 year warranty on their Ally cylinders which is interesting.

What do i dive with? Faber steel.

Aussie

JFH
02-07-2008, 10:31
I recently started converted to Steel LP 120s. The reason as stated earlier is they will overfill giving me almost the equivalent of 2 AL 80s. I can also whip them with other tanks to get extra dives. Got three dives on one tank the other day spearfishing in 80ft. I can't really say I would switch or buy steel 80s again. I have two, they are heavy, hold the same as the AL 80, and have had to be tumbled on the last VIP.

cummings66
02-07-2008, 11:58
What does the LP120 weigh? I'll bet doubled it'd kill me considering I think my doubled HP120's are heavy.

No Misses
02-07-2008, 12:57
Steel cylinders are heavier though it's adding on extra weight to something that is already pretty heavy.

I just did the math.

If I dive an AL80 with my 3 mil farmer john, I need to add 6 lbs of lead to my 5lb SSBP. That is 31.4 lbs (AL80) + 11 lbs = 42.4 lbs on my back, in the boat.

If I dive a Steel x7-100 (20% more gas) with the same farmer john I can remove the 6 lbs of lead. 33 lbs (x7-100) + 5 lbs = 38 lbs on my back, in the boat. (6lbs is the difference between the +4.4 lbs of an empty AL80 and the -2.5 lbs of an empty X7-100)

So you can see that diving with a steel 100 gives me 20% more gas and the total weight drops by 4.4 lbs.

Cylinder-- PSI---- Dia ---Height---Weight--- Buoyancy---- Ballast--------------- ----WOB
X7-100__ 3442 __7.25 ___24 _____33_____ - 10.0 : - 2.5__ 5 lb SS BP only__ __38
AL- 80 __3000__ 7.25___ 26.1 ___31.4____ - 1.4 : + 4.4__ 6+5lb SS BP_______ 42

So when it comes right down to it, the only reasons to dive AL is the cost and to match what you will dive on vacation (most rental tanks).

JM2c

JFH
02-07-2008, 13:15
What does the LP120 weigh? I'll bet doubled it'd kill me considering I think my doubled HP120's are heavy.
Sorry, don't know the weight but it is heavy. I use to give everyone a hard time that brought them on my boat cause you get a hernia lifting. They are nice underwater, like them better than the steel 80s. If you gonna wear doubles, I hope you are into power lifting.

BSea
02-07-2008, 14:29
What does the LP120 weigh? I'll bet doubled it'd kill me considering I think my doubled HP120's are heavy.
LP 121 is 47 lbs empty compared to 38 lbs for an HP 120. And the lp121 is 8 inches in diameter & an inch taller. Too big for me. I think the LP 95 is about as big as I'd want to double.