More Gas capacity.

Finally – adding a stage to my equipmentlist extends the limits of my dives significantly.

I decided to start with a 7L Luxfer Stage, which is not as bulky as a 80cft. but still has more capacity than a 40cft. .

When ive got multiple stages – the small 7L will contain the highest mix.

The cylinder is equipped with a Halcyon Valve and a Halcyon Rigginkit and Sherwood rubberknobs.

So the finest possible. I got it at the deepstop diving shop near mannheim where i found a very friendly and skilled team.

Ive rigged a oxygen cleaned Seemann SL25 and a SL600 second stage on it.

My first deeper dive with it in the sparmann quarry coming up on wednesday.

R.

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Posted on June 6, 2011, in Uncategorized. Bookmark the permalink. 2 Comments.

  1. Hi,
    I expect you to find the 7l tank rather unhandy. In general, it starts having a positive buoyancy with around 150bar and turns worse the emptier the tank gets. Since your tank is quite small, the situation appears quite soon after you start breathing. I found the upward movement annoying which is why I tend to use the 80cuft. Starting with 200bar in 21m allows me to finish decompression on 6m with something around 140bar. Consequently, the handling is much more comfortable.
    From my point of view, such small tanks, be it 40cuft or 7l make only sense as O2, 6m stage.
    Cheers
    Constantin

    • Hi Constantin,

      firstofall – thanks for the comment, getting a bit of feedback and discussions on my articles are well meeting my intentions towards this blog.

      ive done quite a few dives with 80cft multiple stages in Malta, couldnt make out a big difference towards the bouancy yet, aluminum tanks always have positive offset towards lower end of the pressure scale, thats normal.
      The bouancy of the tank also depends a lot on the mix i dive it with, if you use a higher (the more o2 the heavier the gas) mix for deco you shouldnt note a difference even at lower bars. Your diveweight should obviously trimmend on empty tanks allover. If youve done that properly, you shouldt be annoyed by your stages even if theyre all empty.

      By the way – a stage tank is not supposed to stay as horizontal as the diver is, normally the bottom of it floats up slightly which is also better streamlined. If it just swings back and forth underneath you, youve rigged your stage or your harness wrong. I dont notice my stage during diving.

      The thing is in Germany that you see a lot of the “walking divestore”-syndrome, people who posses 3x80cft stages take them also in a rather shallow lake, where it is absolutely unneccesary.

      I like to keep things as simple as possible – only dives in the 60m+ section with long BTs really make travelgas or a second deco gas really neccessary.
      If i just want to do an extended dive in a deeper quarry diving to maximum of 60m, the light setup with the seven liter has just worked perfect for me.

      Ive done some dives in the baltic sea last monday with about 150 minutes of runtime total in two dives including current, it never was a problem with the 7l, it was even better than the 80 cfts from malta (less drag).

      Youre right, as i mentioned in my article above, small tanks are usually used for the higher mixes,
      and 7L wouldnt be a wise choice for deep penetration diving. But im not planning on doing that – yet, are you ?

      Richard.

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