composite cylinders

[roakey]

Bob3 once bubbled...
How's your Swedish?

I dated a blonde once, does that count?

Roak

 

[DameDykker]

Just seen them here in Denmark. At 300 bars you really get a lot of air/mix. They are approximately double the price of normal cylinders. Accoding to the text:

How's your Swedish?

in the link they are made of carbon and polymeres (Swedish is very close to Danish) Though the info on the site is not very detailed. I'll visit the LDS with the bottles tomorrow and get some more info and get it to you as soon as possible.

 

[DameDykker]

Just checked today. The bottles at my LDS are made of a steel sleeve to contribute absolute no leakage and a carbon fiber reinforcement to provide structural strenght without the weight. They can be filled to 300 bar (4410 psi). They must be hydroed every three years - as opposed to the stell tanks which have a five year period between hydros. The new tanks have been approved by the Danish autorities. And accordig to the LDS most regulators will work at 300 bar delivery pressure without problems, however, air integraded computers might have problems.

I've checked my own Cobra and it has an operating interval of 0-300 bars, maximum pressure 360 bars, so that will be allright if I wanted to change tanks.

Hope that helped!

 

[JamesK]

Seeing as you mentioned using TriMix with these cylinders, I would like to point something out that I read the other evening.

In a book I am reading, "The Cave Divers" they discussed using full composite cylinders on some early deep exploration of a cave system in Florida, I believe it was Wakulla. They stated that the Helium would actually leak out of the tanks, and they would end up with a mix that had an extremely high PO2. This would happen after long dives, and resulted in some bad cases of oxtox and CNS hits. They said this happened because the He was lighter and smaller then the O2 that was in the tanks. The He being samller, was able to "squeeze" through material that made up the compsoite cylinder. I am not sure how accurate this is, but it is enough to make me want to do a LOT more research before considering using a full composite cylinder.

 

[DameDykker]

JamesK

You might very well be right. I used to work in a plant where the process involved Hydrogen flames, therefore, Hydrogen and Oxygen was piped in a lot of places. To test the absolute leak proof condition of all that tube every single piece was leak tested by applying hard vacuum on inside the fitting and then spraying Helium on the outside as Helium has extreemly small molecules. Inside the unit after the vacuum pump would then be a Helium detector to show any leaks. It is very difficult to get anything that leak proof! However, the actual mnufacture of the bottles will most likely know if their cylinders can be used with Helium/Trimix.

 

[Inspector]

Gentlemen,
Have a look at www.luxfercylinders.com then click on "scuba" It will provide current information on Luxfer's composite diving cylinder. Then goto www.psicylinders.com and click on the article titled "Presidents corner" You will find a comprehensive document on said same cylinders.

 

[canadiancavedigger]

and I ran across this domestic manufacturer that has DOT approved cylinders,whether these are scuba approved I do not know ..usefull?


http://www.bactechnologies.com/cylind.htm

 

[Daryl Morse]

Seeing as you mentioned using TriMix with these cylinders, I would like to point something out that I read the other evening.

In a book I am reading, "The Cave Divers" they discussed using full composite cylinders on some early deep exploration of a cave system in Florida, I believe it was Wakulla. They stated that the Helium would actually leak out of the tanks, and they would end up with a mix that had an extremely high PO2. This would happen after long dives, and resulted in some bad cases of oxtox and CNS hits. They said this happened because the He was lighter and smaller then the O2 that was in the tanks. The He being samller, was able to "squeeze" through material that made up the compsoite cylinder. I am not sure how accurate this is, but it is enough to make me want to do a LOT more research before considering using a full composite cylinder.

I can't comment on the specific case to which you refer, but helium is commonly used for leak testing because of its propensity to find its way through small porosities. Hydrogen is also very slippery, but since it has explosive tendencies, it's not used for leak testing. Any composite tank intended to be used for helium would have to have been designed and tested for such a purpose.

 

[Bob3]

Nothing like reviving a 2 year old thread.
Since this thread started back in '02, Luxfer has come out with a composite scuba cylinder, but the cost vs. life time of the critter makes it a big turnoff.

whether these are scuba approved I do not know ..

Those are the SCBA bottles, not really suitable for scuba.
It's still hard to beat a good steel bottle when it comes to price vs life expectancy.
Maybe in a few more years...

 

[Curt Bowen]

I kinda doubt if the composite bottles are DOT approved, but I'll check. Some of their old steel cylinders were made in West Allis (Milwaukee) of all places.

The composites are supposed to be good for a 40 year minimum.

How's your Swedish?
http://www.dyk-brand.se/sidor/interspi.htm

Bob


I was thinking of these cylinders for my rebreather and foreign travel.

The 18 cfft / 3 liter cylinders i use now are heavy for air travel.

Once I get to the destination I am diving, its easier to just ad weight.