High Pressure Fibre Tanks for shore diving???

[turnburglar]

Hey Divers,

I moved back to southern California, and while the funds are tight I can't afford to do all my diving off a boat.

I was looking around at tanks and noticed that fire fighters use a fibre wrapped tanks filled to 4500 psi (300bar). Some online specs indicate these tanks are much lighter than our Al or steel tanks we prefer for diving. Would these be a reasonable option? The main purpose for wanting a lighter higher pressure tank, is from a SI joint injury thats never been fully resolved, that makes lugging tanks for shore diving more miserable than it already is.

Would my 1st stage even be able to handle that kinda output pressure? (hollis DC1/212)

 

[teknitroxdiver]

The only fiber tank option for scuba is the Luxfer 106. Problems with it include being life-limited to 15 years, requiring a hydro every 3 years instead of 5, and the low chance of actually finding someone to give you a 4350 psi fill. It's also actually 2 pounds heavier than a standard aluminum 80, and the cost is very high.

If minimum weight is your main goal, an HP80 is 4 pounds lighter than an aluminum 80, and you'll be able to lose at least 4 more pounds in lead you won't need.

 

[Edward3c]

Hey Divers,

I moved back to southern California, and while the funds are tight I can't afford to do all my diving off a boat.

I was looking around at tanks and noticed that fire fighters use a fibre wrapped tanks filled to 4500 psi (300bar). Some online specs indicate these tanks are much lighter than our Al or steel tanks we prefer for diving. Would these be a reasonable option? The main purpose for wanting a lighter higher pressure tank, is from a SI joint injury thats never been fully resolved, that makes lugging tanks for shore diving more miserable than it already is.

Would my 1st stage even be able to handle that kinda output pressure? (hollis DC1/212)

Most of the weight you carry is to compensate for the volume displacement not the cylinder.

Using the metric system a 10Lt tank has 10kg lift and a 12Lt is 12kg lift from the displacement.

I have both, but use the same weighting. I take 3.5kg off when using 300bar cylinders.

 

[Storker]

Do you need any weight with you current tank setup? If you do, what would be the advantage of switching to (a) lighter tank(s)?

On the pressure issue, I use 300 bar tanks (10 liters). Pro, they're more negative than 200 or 232 bar tanks with the same capacity, so less weight on my belt. Con, when you pass 250 bar, compressibility kicks in. So, my 10L 300 bar tanks hold ~10% less gas than 200 or 232 bar tanks with the same nominal capacity (12L 232 bar, or 15L 200 bar).

 

[jseyfert3]

Yeah, I was a volunteer firefighter. The 4500 PSI tanks are used so we can have a smaller and lighter tank for the same given volume of air. Size is a concern when you have to crawl through holes, and weight is important because unlike scuba diving, you have to carry the weight the entire time. When you dive, the tank becomes weightless.

There was a big thread on here about carbon fiber tanks earlier. Basically, if salt water gets under the fibers, it'll ruin the tank, possibly with disastrous results. Because of this, that's why there's only one carbon fiber tank approved for diving (the one mentioned above). Bottom line is do not try using a firefighter's fiber tank for scuba!

Don't forget that a lighter tank (of the same displacement) means that you need more weight on yourself. Of course you can carry weight belts and tanks separately to the shore, you can't carry part of a tank.

I don't know if anyone does this, but could you perhaps use two smaller (regular aluminum or steel) tanks in a doubles setup, carry them down to the beach separate, then put together before you enter the surf? The idea would same amount of air as a AL80, be less weight to carry, but more trips. I'm not sure what's worse for you, the weight or taking extra trips. Just an idea.

 

[teknitroxdiver]

I don't know if anyone does this, but could you perhaps use two smaller (regular aluminum or steel) tanks in a doubles setup, carry them down to the beach separate, then put together before you enter the surf? The idea would same amount of air as a AL80, be less weight to carry, but more trips. I'm not sure what's worse for you, the weight or taking extra trips. Just an idea.

That's a good idea. He could sidemount a pair of LP50s or AL40s. Only 19 pounds and 15 pounds each respectively, and as you say, they could be carried to the surf independently.

 

[turnburglar]

Bottom line is do not try using a firefighter's fiber tank for scuba!

Awesome thanks man. It was firefighter tanks that I was looking at.

I think my best bet is gonna be to buy a HP100, as it should allow me to ditch some lead from the belt when I normally dive AL80's, and carry significantly more gas than an AL80. The best process I think I have found is to completely gear up at the truck, and walk down to the beach: instead of lugging sets of boxes or tanks up and down the stairs or pathways.

 

[tep]

Maybe off topic, but if the concern is getting gear from the vehicle to the dive site...

What do you use to haul your gear?

I love the foldable cart - bought mine at Costco, but this is the same one on Amazon

https://www.amazon.com/Mac-Sports-C...&qid=1489873447&sr=8-3&keywords=foldable+cart

 

[Remy B.]

I use Worthington Steel Carbon tanks, it has almost the same capacity as a Al-80 and weight a lot less and it has the size of a AL-40, but these tanks are sold in the EU, don't know if you can buy them online, but then end up that they are not authorized in the USA, same happen with the USA D.O.T tanks they are not allowed here in Nederland or at least nobody will fill them unless you have your own compressor.

 

[Storker]

I use Worthington Steel Carbon tanks, it has almost the same capacity as a Al-80 and weight a lot less and it has the size of a AL-40

If I do a quick back-of-the-envelope calculation, a tank with "almost" the same capacity as an Al80 but with the size of an Al tank with half the capacity should have a working pressure of around 400 bar.

So I'm wondering: Where do you get a 400 bar fill?