Converting 2 steel 10L 300bar tanks to doubles

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Groot

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Messages
5
Reaction score
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Location
Norway
# of dives
200 - 499
I have been diving for a while now and I have been thinking to go over to diving doubles. I have a few single scuba tanks, but only 2 10L 300bar tanks that are identical. So I was thinking to buy new valves and tank bands to convert those to doubles. I didn't want to buy a new set of tanks mainly because of the price, as I live in norway and a new set of D12 is around 9000 NOK, but a conversion kit is around 4000 NOK, but also i felt like my single tanks would go to waste just sitting there. I was wandering what some of the issues or considerations there are when converting singles to doubles? I have heard that a lot of people don't like twin 10L 300bar tanks because of their bouyancy and trim characterisitics, but is it really that bad?
 
Pair of valves with manifold, pair of bands.

It's worth getting a pair of manifold plugs at the same time in case you want to 'convert' them back to singles. They would make good sidemount cylinders with the modular valves.

Second-hand is a lot cheaper. It will be hard to find the 10 litre bands as they're more rare than 12 litre bands.

12 litre twinsets are far more common. 300 bar cylinders will be heavy and it's hard to get a 300 bar fill.
 
Maybe not, depending on who you are and where you are. The "problems" with the setup would be that the 10x300s are quite negative on their own, and that they are somewhat shorter than a 12x232. However since you're diving dry the extra negative buoyancy might not be a problem, and if you're not tall the trim might be fine. Main downside for me would be that they're still as f*king heavy as D12s...

For reference my local diving (Sweden, dry) is usually with a D7x300. For me that's an awesome setup trim wise because I'm a short guy, and buoyancy wise I anyway need to add a 4Kg v-weight, so a few extra kilos in the tanks themselves wouldn't have hurt when in the water.

At least ECS 10x300s have the same diameter as 12x232s (171mm) so tank bands shouldn't be a problem.

(Getting a 300 bar fill shouldn't be a problem for you in Norway, and if it were you would already be aware since you have them as singles. :wink: Besides, D10x275 or whatever it actually becomes when you are in the water is still plenty of gas for recreational diving.)
 
I convert sometimes AL80s to doubles and back to singles. Just using stainless steel bands und diving them independend. Quite an easy deal and good to dive (first tank from 200 to 120 bar, 2nd from 200 to 40 and 1st again from 120 to 40). Two reg swaps and 2 spgs - no big deal.

If you just want more air without accelerated decompression, then you can combine a 15 liter single tank with a 7 liter or 80 cuft aluminum pony stage. Mensioned as an flexible alternative.

Otherwise, for the way into tech diving selling the 10s for a manifolded double 12 is the way to go.
 
Thanks for the input everyone. I ready know about the issues with gett a proper 300bar fill, though some places actually manage to do one. I already use 12kg of extra lead during the winter, so some extra negative buoyancy is actually welcome. My only concern in this case is the trim of the double 10's. I am 187cm tall, so they may be a but too short for me.
 
Have bought several second hand 12 litre twinsets over the past few years. They do come up, especially if you’re not looking for them! Anyway, keep an eye out and be ready to grab a decent deal.

The main problem with twinsets is testing them. In the UK we need an oxygen clean every 15 months and a visual or hydro test every 30 months. This costs about £50/€60/$70 per cylinder plus a charge for dismantling and reassembling a twinset. Tiffany they’re being sold without a test then you need a money back guarantee that it’ll pass, if not then they’re worth a lot less.
 
Hi
Go on Finn.no. Find a used set of D12 232 Bar. Don't even think about putting 2 300 Bar 10L bottles together. They are WAY to negative in the water and they will be hell to dive! They are a safety risk and it should no be done! If you sell your 10Ls and add the 4K you wanted to spend on a manifold you easily have enough for a freshly tested used D12.
 
Ok, you have good arguments there. I think I need to reconsider my plans.
 
Are any of your other tanks twinupable
 
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