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phil_218
01-30-2010, 13:38
Yesterday I was at the local fire station getting my tanks filled. While there I was talking with the fireman about the tanks they use. He stated they use steel, aluminum, and now use mostly carbon fiber. I can see the appeal for them, because they'd want less weight to carry around in a fire. Have any of you heard talk about carbon fiber tanks being used in diving in the near future?

Just thought it was an interesting idea.

emclean
01-30-2010, 14:20
i would thing Carbon Fiber would be very positively boyent, and would require a lot more lead to dive with.

ScubaToys Larry
01-30-2010, 14:20
Then you'd have to wear a bunch more weight on your belt... that's why divers don't use them. In fact most prefer heavier steel tanks over aluminum.

acamato
01-31-2010, 00:12
Luxfer makes a hoop-wrapped composite scuba cylinder. It is 106 cu ft @ 4350 PSI. At that pressure you have to have a DIN valve.

Luxfer: SCUBA Cylinders: Specifications (http://www.luxfercylinders.com/products/scuba/specifications/us_imperial.shtml)


-4.8 lbs full
3.1 lbs empty

That is a 7.9 lb swing in buoyancy

Lone Frogman
01-31-2010, 02:06
Luxfer makes a hoop-wrapped composite scuba cylinder. It is 106 cu ft @ 4350 PSI. At that pressure you have to have a DIN valve.

Luxfer: SCUBA Cylinders: Specifications (http://www.luxfercylinders.com/products/scuba/specifications/us_imperial.shtml)


-4.8 lbs full
3.1 lbs empty

That is a 7.9 lb swing in buoyancy

And where are you going to get it filled? Can't get a full fill on a HP tank now.

comet24
01-31-2010, 02:14
While it sounds like a good idea a carbon fiber tank lacks the weight a diver needs to stay underwater. We all add weight in some form when diving. Strapping a carbon fiber tank to your BC would only increase the weight needed on your belt. Many divers dive steel because they want the extra weight in the tank for better balance underwater.

Just Dave
01-31-2010, 06:26
They're just not suitable for diving:
Mondo Expensive
Huge buoyancy swing
Limited lifespan
Delicate (meaning they don't take being dropped or scratched very well)

They're great for other applications like firefighting though.

in_cavediver
01-31-2010, 07:56
They're just not suitable for diving:
Mondo Expensive
Huge buoyancy swing
Limited lifespan
Delicate (meaning they don't take being dropped or scratched very well)

They're great for other applications like firefighting though.

Everything is true except the buoyancy swing. That is a constant between all types of tanks of the same capacity. Swing is merely a measure of the air available.

ScaredSilly
01-31-2010, 18:54
Everything is true except the buoyancy swing. That is a constant between all types of tanks of the same capacity. Swing is merely a measure of the air available.

Ditto that. What is more of a concern is the ending buoyancy. As such, this cylinder would require around 3 lbs of lead so that it would be neutral when just about empty.

phil_218
02-13-2010, 17:55
Good input, guys. I was thinking of the benefits to hauling lighter tanks to the entry point, but then you'd be hauling extra lead which would offset the benefit. See, just another reason to become an instructor with a divemaster working with you. lol

Tassie Diver
02-14-2010, 15:57
Don't under estimate the effect of wear and tear on tanks. Carbon tanks are fairly delicate (compared to steel/aluminium) and what looks like a little ding/gouge on a metal tank will end the life of a composite tank.

cycleBret
06-26-2012, 22:49
If you want to check out an awesome carbon set, Google Carbon Dive 300. it is a Worthington Cylinder product. it is a chromoly steel inner, carbon fiber outer tank. burst tests show a standard steel cylinder burst at 6,321 psi / 430 bar, but their tank burst at 12,510 psi / 851 bar. The 80 cu ft / 10 liter tank filled is -1 3/8 lbs, +7 lbs EMPTY, if there is roughly 1500 psi remaining of the 4,410 it can be filled to, the bouyancy is +4 1/5 lbs.

So simple comparison, 80 cu ft steel (st) -to- 10 liter CarbonDive 300 (C):

Weight: 27.7 lbs (st) / 21.1 lbs

Bouyancy: -9 lbs Full to -3 lbs Empty (st) -to- -1 3/8 lbs Full to +7 lbs Empty (C)

Usable capacity: 81 cu ft (st) -to- 106 cu ft (C), if 1600 psi is remaining, you use 81 cu ft of it, the bouyancy is +5 lbs, SO IN ACTUALITY, the steel and carbon tanks both gain 6 lbs of bouyancy if you use 81 cu ft, but the carbon tank still allows 50% more down time.

Size: 20" L x 7 1/4" D (st) -to- 21 1/2" L x 7 1/8" D (C)

I have read many posts and threads about the topic of Carbon tanks, I have come to one conclusion, people are forgetting the basics. Either tanks or weights, either way you carry the same weight to the water to obtain that peak bouyancy, the benefits to the carbon include these:
1) Stronger, by far
2) Lighter, requiring a wing or BCD with LESS lift, thus smaller, wreck divers, penetration divers, cave divers, listening?
3) Weight are necessary either way, wouldn't you want to be able to trim your belt, harness, tank(s), backplate PERFECTLY, the carbon tanks allow you to put some of that weight towards your chest, belly, and off your back, ABOVE your center of gravity. Let's be honest divers, even the best of us has caught ourselves wiggling, squirming, flailing, to go flat, belly down trying to obtain a perfect balance and streamline. With the ability to trim forward/under your center of gravity, imagine for just one second, you are drift diving no movement necessary, AT ALL, to maintain a streamlined, flat horizontal, belly down dive, just cruisin' with the drift, and staying on it longer.

Go to your local Fire station, ask these guys the physical abuse their SCBA's take. they will even maybe drop one on its end just to show you. These tanks are not the everyday run-of-the-mill weak "skeleton" frame carbon tanks, which do have the reputation to cracking or fracturing, thus never being good again. These CarbonDive tanks have a solid CHROMOLY STEEL core tank inside of them, that is twice heat treated, ultrasonically tested, AND hydro'ed, PLUS the Carbon Fiber shell exterior.

See you all under. Come up SMART, go home SAFE, LIVE TO DIVE AGAIN.

DiveHard
06-27-2012, 05:49
As a Cavern diver who uses steel tanks I see no real benefit to using lead if I don't have to. To the issue of adding weight for proper trim diving. Proper selection and placement of gear will in most cases negate the need for adding lead for buoyancy and or trim. That goes for most of the Cave/Cavern divers I know. IMO AL tanks are good for stage or bailout. Why add lead if you don't have to?

in_cavediver
06-27-2012, 06:16
If you want to check out an awesome carbon set, Google Carbon Dive 300. it is a Worthington Cylinder product. it is a chromoly steel inner, carbon fiber outer tank. burst tests show a standard steel cylinder burst at 6,321 psi / 430 bar, but their tank burst at 12,510 psi / 851 bar. The 80 cu ft / 10 liter tank filled is -1 3/8 lbs, +7 lbs EMPTY, if there is roughly 1500 psi remaining of the 4,410 it can be filled to, the bouyancy is +4 1/5 lbs.

So simple comparison, 80 cu ft steel (st) -to- 10 liter CarbonDive 300 (C):

Weight: 27.7 lbs (st) / 21.1 lbs

Bouyancy: -9 lbs Full to -3 lbs Empty (st) -to- -1 3/8 lbs Full to +7 lbs Empty (C)

Usable capacity: 81 cu ft (st) -to- 106 cu ft (C), if 1600 psi is remaining, you use 81 cu ft of it, the bouyancy is +5 lbs, SO IN ACTUALITY, the steel and carbon tanks both gain 6 lbs of bouyancy if you use 81 cu ft, but the carbon tank still allows 50% more down time.

Size: 20" L x 7 1/4" D (st) -to- 21 1/2" L x 7 1/8" D (C)


So you are basically comparing a larger composit cylinder to a typical steel smaller cylinder.


I have read many posts and threads about the topic of Carbon tanks, I have come to one conclusion, people are forgetting the basics. Either tanks or weights, either way you carry the same weight to the water to obtain that peak bouyancy, the benefits to the carbon include these:

This is actually not true. You do not 'always' carry the same physical weight to the water for a given capacity of air. A good example of that is the OMS LP85 tank vs the Luxfer AL80 tank. These two tanks are the same weight on land. When empty, under water the OMS LP85 is neutral and the Luxfer AL80 is 4lbs positive. This means you have to carry 4lbs of lead to make the tank neutral for the AL tank and therefore the rig is 4lbs heavier overall.



1) Stronger, by far

Dubious. A tank needs to be only as strong as required to meet design spec. There is no useful difference for the end-user.


2) Lighter, requiring a wing or BCD with LESS lift, thus smaller, wreck divers, penetration divers, cave divers, listening?

Lift is determined by the total package, not just the tank. Since you now have a positively buyant tank when empty, you have to add lead and your wing now has to lift the weight of the lead as well. Lift is also required for 'swing' in the tank. The more air you carry, the more swing in wieght you get and the more lift you need to handle the 'full' tank(s).

Since I dive caves with double LP104's, in you suggestion, I would take my PST tanks which are negative empty and replace them with these. I still have the 16+lbs of air swing and now add 20+lbs of lead for the positive buoyancy characteristics of the tank and I still need my 50lb wing once everything is said and done.


3) Weight are necessary either way, wouldn't you want to be able to trim your belt, harness, tank(s), backplate PERFECTLY, the carbon tanks allow you to put some of that weight towards your chest, belly, and off your back, ABOVE your center of gravity. Let's be honest divers, even the best of us has caught ourselves wiggling, squirming, flailing, to go flat, belly down trying to obtain a perfect balance and streamline. With the ability to trim forward/under your center of gravity, imagine for just one second, you are drift diving no movement necessary, AT ALL, to maintain a streamlined, flat horizontal, belly down dive, just cruisin' with the drift, and staying on it longer.

The question of wieght is personal. There may be advantages to using lead and there are advantages to not using lead. There is no concrete answer for every diver.


Go to your local Fire station, ask these guys the physical abuse their SCBA's take. they will even maybe drop one on its end just to show you. These tanks are not the everyday run-of-the-mill weak "skeleton" frame carbon tanks, which do have the reputation to cracking or fracturing, thus never being good again. These CarbonDive tanks have a solid CHROMOLY STEEL core tank inside of them, that is twice heat treated, ultrasonically tested, AND hydro'ed, PLUS the Carbon Fiber shell exterior.

See you all under. Come up SMART, go home SAFE, LIVE TO DIVE AGAIN.

I own a few carbon fiber tanks. They have the same issues all composite tanks have. They are much better than the old fiberglass hoop wrapped tanks but they are far from perfect.

TommyB
06-27-2012, 10:33
2) Lighter, requiring a wing or BCD with LESS lift, thus smaller, wreck divers, penetration divers, cave divers, listening?
I'm reading. not sure I'm listening though :)


3) Weight are necessary either way, wouldn't you want to be able to trim your belt, harness, tank(s), backplate PERFECTLY, the carbon tanks allow you to put some of that weight towards your chest, belly, and off your back, ABOVE your center of gravity. Let's be honest divers, even the best of us has caught ourselves wiggling, squirming, flailing, to go flat, belly down trying to obtain a perfect balance and streamline. With the ability to trim forward/under your center of gravity, imagine for just one second, you are drift diving no movement necessary, AT ALL, to maintain a streamlined, flat horizontal, belly down dive, just cruisin' with the drift, and staying on it longer.
I cave 3 to 4 times a week. I don't use any/extra weight.
Dry Suit, with 400 gram polar-tech undies.
side mounting either HP 100's or LP 95s. (both Worthington)

For drifts it's either HP80's or HP 100's doubles again Worthington using a transpac eg softplate.
So, I'm going to have to disagree with

Weight are necessary either way
I guess if I dove AL's i'd have to use weights.