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  1. #11
    GUE Tech and Cave Instructor johnkendall's Avatar
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    Quote Originally Posted by Mark Chase View Post
    Line that would have been more efficiently laid using a CCR

    The RB80 was a solution looking for a problem

    I have discussed a French cave trip with two RB80 users (one a GUE instructor) and they both agreed it was a nightmare to use for multilevel French caving.

    They are inherently dangerous (which is ironic) which was demonstrated with the hypoxic incident well documented by GUE

    They are overly complex in terms of dive planning and execution and as one RB80 owner & different GUE instructor said to me, they breath like sucking honey through a straw

    I haven't dived a RB80 but I have dived a ED04 clone unit.

    You could argue that the RB80s offered a solution to unreliable electronics of the MK1 Inspo Classic, but we have moved on since 2000 and modern ECCR and MCCR units are now very reliable and many times more efficient and practical than the RB80

    A better question would be how many m of line have been laid by RB80s in the last five years?

    Not so many id bet.

    The RB80 is a thing of the past, and thank god for that.
    I own and use both a CCR and an RB80. In some situations the RB80 sucks. In others it's awesome. Amount of line laid by RB80 divers in the last 6 years, hard to tell, but by my count just from the projects in Florida, it's probably around 100,000 feet. There are also projects elsewhere in the world using them. On many of these dives, the CCR would not necessarily be appropriate, and generally wouldn't really be much more efficient in the water.
    The RB80 is not a good unit for multiple ups and downs, nor do I like it in the ocean, but for long duration, constant depth stuff, it's awesome.

    Sent from my Pixel 2 using Tapatalk
    John Kendall
    GUE Instructor Trainer, Tech and Cave Instructor www.johnkendall.com
    www.santi-store.co.uk - Santi Drysuits, Undersuits and Accessories

  2. #12
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    Quote Originally Posted by JonG View Post
    Just curious to find out what people's thoughts are on the above, there are obvious pros and cons and differences between them.

    My unit came with a manifold designed to distribute 1 gas to multiple destinations, I am more thinking of a manifold or block for distributing 2 or more gases to multiple locations.

    This could include actual switching blocks designed for the purpose or simple tapped manifolds that could be connected to 1 or more gas sources relying on the tank valve as the point of isolation of each gas.
    My thoughts are divided on the matter.

    When I built my unit my mate gave me some advice on it which was to put it together as simple as you possibly can at first and dive it for a year before you make any modifications to it.
    Quite a bit later I added an ADV.

    Now I'm considering adding an extra fitting to let me use the on board oxy through the BOV and potentially add a spare 3l.

    A weakness of the current design is not being able to use offboard dil, but I'm not sure I'm that fussed as it's easy enough to breath a bit in from the BOV and add it to the loop.


    But I wouldn't want to make anything complicated with multiple fittings (multiple failures and multiple potential fook ups!)

  3. #13
    Established TDF Member MikeF's Avatar
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    Lads, amusing as it is can you quit the pissing contest and address the question?'


    Quote Originally Posted by JonG View Post
    Just curious to find out what people's thoughts are on the above, there are obvious pros and cons and differences between them.

    My unit came with a manifold designed to distribute 1 gas to multiple destinations, I am more thinking of a manifold or block for distributing 2 or more gases to multiple locations.

    This could include actual switching blocks designed for the purpose or simple tapped manifolds that could be connected to 1 or more gas sources relying on the tank valve as the point of isolation of each gas.
    IMHO Switch blocks with multiple gasses are an accident waiting to happen. Don't do it.

    What are you trying to achieve?

    Is it multiple gas's into a BOV or into the loop? Either way the potential to select the wrong gas or have gas leakage into the loop with no feedback on what you are actually breathing could have very bad consequences.

    I looked at this early on in my ccr days. Built the valve block, tested it in the garage, then started thinking a bit more and applied a bit of fmeca analysis and rapidly decided the potential for bad things to occur was way too high for my liking. I then redesigned the plumbing on the unit to allow any gas source to be plugged into the unit and feed ADV / MAV & BOV from a common manifold. The disadvantage being you have to physically unplug the gas you don't want and plug in the gas you do want instead of turning a valve or pressing a button. The advantage being you have to consciously unplug the gas you don't want and plug in the gas you do want. Thus massively reducing the chances of the wrong gas being introduced for any reason without me knowing.

  4. #14
    Part time bubble-free.
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    Quote Originally Posted by WFO View Post
    My thoughts are divided on the matter.

    When I built my unit my mate gave me some advice on it which was to put it together as simple as you possibly can at first and dive it for a year before you make any modifications to it.
    Quite a bit later I added an ADV.

    Now I'm considering adding an extra fitting to let me use the on board oxy through the BOV and potentially add a spare 3l.

    A weakness of the current design is not being able to use offboard dil, but I'm not sure I'm that fussed as it's easy enough to breath a bit in from the BOV and add it to the loop.


    But I wouldn't want to make anything complicated with multiple fittings (multiple failures and multiple potential fook ups!)
    With respect to the OP's question, I guess it's the old old story of CCRs - what are you using the unit for and how much risk do you want to take?! One of the previous posts mentioned using a switch block for a FFM which makes perfect sense and is a really simple setup (no different to using a BOV really). I think your mate's advice is pretty sound - I made quite a few changes to mine but have reverted almost to stock config as the changes I made were fine but although I gained with one hand, I lost with the other. Turns out the stock config actually works pretty well in almost all situations! I'm also fortunate in that my CCR allows me to use offboard gases by default and that is something I have actually had to use (I ran low on dil on a dive and could supply from offboard). Having that quantity of gas available on tap means I can flush to my heart's content more or less when I want to. So, if my CCR couldn't do that, I'd modify it so it could. For me, that's a must. I did consider adding access to the onboard O2 to the BOV but ended up not bothering. I'd always have a rich stage with me (typically 68-72%) for "bigger" dives and if I wasn't carrying it, I wouldn't have enough deco to need that on-board O2 anyway. Initially I wanted access to everything all the time but nowadays, I'd rather keep my bailout as bailout and the CCR for CCR - the BOV is there to get me onto the stage regs, and if I need to bail onto the stage reg, I won't be switching back (the BOV is supplied from offboard or inboard, typically the former). Either way, all of the above is done without extra manifolds and switch blocks - just disconnect one and connect the other. There's many ways to skin the cat it seems.

  5. #15
    Where'd The Bubbles Go ....? Capt Morgan's Avatar
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    I once seen a unit with that many manifolds and switch blocks it would need a flow diagram to understand. It allowed multiple mixes to go to multiple locations while isolating other locations, looked like an explosion in a spaghetti factory and probably about as useful.

  6. #16
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    Quote Originally Posted by Capt Morgan View Post
    I once seen a unit with that many manifolds and switch blocks it would need a flow diagram to understand. It allowed multiple mixes to go to multiple locations while isolating other locations, looked like an explosion in a spaghetti factory and probably about as useful.
    I think I might recall that one. It looked
    like the sales team at swagelock had a good year!

  7. #17
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    I am currently very ambivalent about this, I have dived the KISS in pretty much its simplest format for about a year, incl. removing the 1 gas/multiple destination manifold that it came with and just considering a few options (plus drysuit is in for a new neck seal so had too much time for thinking over weekend).

    I used to dive a 3 way block into an AGA for quite some time, 2 independents, isolated at the pillar valve and block (different valve knobs for each at the block) and a 3rd cylinder isolated at the pillar valve and tapped into the block. This was a deco mix usually in an inverted 3l between the twins an it worked fine and I never had an issue with it or following the protocols required to use it.

    With CCR I am thinking about offboard gases to the BOV and wing, as opposed to offboard to the loop, which would be a royal PITA to achieve on my rig cos its old and was never tapped to allow this config. later models were. I can however add via the BOV if necessary, the ADV could also be off the block/manifold I guess as an option.

    With any gas switch UW there is a risk and a number of steps to achieve the switch. I dive with a gag so moving to an off board 2nd stage if the BOV is only fed from 1 stage is another step, plus a bailout 2nd stage is rarely used and tested at depth, whereas my BOV is tested every dive at depth.

    As and when I require a hypoxic dil and hypoxic deep bailout, in the (arguably unlikely) event of needing a breathable gas in the hypoxic zone, if the BOV is only plumbed to deep bailout there are several steps to get to that gas during a potentially stressful and time crunched window, in comparison with a sequence of open/closed valves, perhaps not dissimilar to travel gas switches on OC. This also seems to be beneficial to avoid a situation where loop pp02 is crashed low due to an ADV failure.

    This also seems simpler than unplugging/plugging, with less moving parts, less added parts, less failure points and nothing to deploy/stow, less maintenance etc. IMO.

    So long as stages are in the right place at the beginning on the surface, and the pillar valve is the primary or maybe only source of isolation the system becomes pretty simple IMO?

    At the moment the biggest potential issue I can see is the risk associated with multiple gases through a single potential failure point, which although via predominantly captive o-rings, could result in major loss of any gas that was routed through the manifold/block and switched on, unless each connection had its own isolation into the block, but this then increases moving parts and failure points!

    It'll probably come to nothing but like to think through the options in case it is worthwhile even if only for a particular depth/application.

  8. #18
    Old but keen Mark Chase's Avatar
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    Thanks John (Kendall) yes I can see how on a constant depth dive a PSCR would be beneficial.



    Re switching blocks for the KISS JJ Etc.


    I reely struggle to see an advantage, but find it easy to see down sides

    That said I tried five different CCR as an owner and 11 in total, before getting my head around what I felt was important and usable

    I also tried many many different configs and had a lot of fun in doing so, so don't let me or anyone else put you off messing around with units.

    There's nothing wrong with trying something and then ruling it out or in on personal preference.


 
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