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Any disadvantages to a 300 bar cylinder?

Discussion in 'Dive Equipment' started by Jimnibimnibob, Jul 26, 2020.

  1. Jimnibimnibob

    Jimnibimnibob New Member

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    Hi,

    I have found a set if twin 8 litre 300 bar cylinders at a very good price. I am not interested in the fact that they are 300 bar, it's the fact that they are at the right price, but want to know if there are any disadvantages with 300 bar cylinders?

    Cheers

    James
     
  2. nickb

    nickb Well-Known Member

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    You will struggle to get anywhere that will pump them to 300 bar and, even if they do, the real gas laws will mean that you only end-up with about 270 bar of gas if you use ideal gas laws for your calculations.

    Having said that, they will be very nice to dive with, certainly better than 232 bar twin 10s which might be roughly the same in terms of available gas. 15 years ago I had a set of twin 7s that were great to dive with, much better than a single 15.

    As long as you're aware of the shortcomings, you should be happy with them.
     
  3. Vanny

    Vanny Well-Known Member

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    Wife’s twin 7 300’s dive nice , I think we’ve been here before , so as Nic says don’t expect a 300 fill. If your ok with the weight out of the water they should be fine.
     
  4. Jimnibimnibob

    Jimnibimnibob New Member

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    Cheers. I wascaware not to expect 300 fills. My main reason for twin 8's is they are as tall as 12's as 7's are too short for me. Can take them on club RIB as twin 12's aren't good for
     
  5. Wibble

    Wibble Fish don't talk
    UKD Supporter

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    They are heavy, so you'll need less lead.

    Had a pair of twin 7 x 300s. Sold them quite quickly to get a "more standard" twin 12 x 232. The 8's will be better than 12s on a RIB though.
     
  6. NickPicks

    NickPicks Active Member

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    300bar 8 litre cylinders weigh 12.4kg, only about 1kg less than 232 bar 12s (12.9-13.7), so the weight of lifting them won't be saving that much, although they'll have less volume, so you should need less lead, which will make it slightly easier to drag back up onto the rhib. (probably abour 3-4kg per cylinder)

    Cylinder weights from: https://www.subaqua.co.uk/cylinder-buoyancy.php?units=metric
     

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