using luxfer carbon fiber tanks on rebreathers

decoweenie

I used to have the Draeger composite spheres on the MK-15.

IIRC, they have 15 years lifetime but not supposed to be pressure-tested during this period. I believe something to do with expansion when overpressured will harm the composite integrity...

__________________
"...after a while you get bored offering advice to a bull that like to keep butting the fence with its head rather than walking through the open gate..."

- Rebreather World PM

zeroviz

I use carbon/fibreglass composite cylinders on my Kiss. The fibreglass layer is outer most to protect the carbon underneath.
The liner is aluminium. The aluminium neck of the cylinder is prone to corrosion....I don't think it's a particularly marine friendly grade, and needs
protecting with a layer of epoxy resin.
There is some discolouration of the epoxy of the cylinder, and I have made covers to protect them from knocks.
As for value for money, well in some backwater pacific countries even a 3 litre aluminium cylinder is like US$ 200 and I got the composites at a better price than that so it made sense to me,....for travel they're great.

paulraymaekers

hello, 2 or 3liter??? and what's the weight?

paul

__________________
www.rEvo-rebreathers.com

.... the earth is flat, Elvis is alive, and radial scrubbers give longer dwell time than axials...

Skipbreather

I’ve been using composite tanks for years. They come in several varieties/ fibers/ etc. The type that has been around the longest is the hoop wrap cylinder. It was first introduced to the fire fighting world over 30 years ago and to the SCUBA world by Luxfer just 3 or so years ago. Hoop wrap tanks look like- but are not- a standard aluminum tank that has it’s sides reinforced with wraps of fiberglass. They come in various pressure ratings from 150 to 310 bar.

The other type of cylinder is called “full wrap” or similar. Those are basically a very thin aluminum balloon attached to a full strength neck (for the valve) that gets reinforced entirely by over wrapping fibers of glass, Kevlar, and/ or carbon. These are much lighter and these days more favored for that reason in SCBA applications- and are more expensive. Again pressures range from 150 to 310 bar. There are many sizes of full wrap composite O2 cylinders sold. Small, light ones are popular with the infirm who must carry O2 with them. Large tanks are used in aviation where their weight advantage makes their staggering cost worth while.

To the best of my knowledge all composite tanks that are approved for service by the USA’s DOT have a 15 year life span from date of first manufacture/ factory hydrotest. After that it is illegal to fill them per DOT. The hydro interval for most tanks is 3 years although some recent manufacture carbon full wrap cylinders have a 5 year interval. AFAIK the 15 year death sentence still applies. If buying tanks on ebay be careful- know the manufacture date. If the seller cannot or will not tell you the tank’s age, you’re being scammed. Be VERY specific asking for manufacture date, not the latest hydro date. There are some real dirt bags out there.

The Luxfer website has some very useful pages full of specs in both imperial and metric speak. Do not limit yourself to just the SCUBA pages. Check out the life support and medical pages as well. Luxfer: Setting The Standard Worldwide

I routinely use 310 bar hoop wrap tanks made by Luxfer, their L45W SCBA tank, for stages. I stuff nearly 50 cf of gas into a cylinder only 1 inch taller and 1 inch larger across than an aluminum 19.

Hope this helps,
Ken

paulraymaekers

thanks Ken,

so seams that lots of people use the tanks for diving, thow not certified for it (like the SCBA tanks)
??? can we not convince LUXFER to rate them for diving also??? :-)

regards
paul

__________________
www.rEvo-rebreathers.com

.... the earth is flat, Elvis is alive, and radial scrubbers give longer dwell time than axials...

zeroviz

Hi Paul

The 3 litre is 2.4 kg and the 2 litre 1.8 kg.
Its a pity the valves aren't lighter




Neil