Pony Bottle setup

Discussion in 'Basic Scuba Discussions' started by mrivken, Nov 26, 2009.

  1. mrivken

    mrivken Angel Fish

    # of Dives: 100 - 199
    Location: Pleasanton, CA
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    I did search and read existing pony(bailout not staging) bottles related threads but have few unanswered questions anyway:

    1. People mentions using DIN regulators for pony to make setup more streamline.
    I am diving in area where Yoke used exclusive . So, if I buy DIN regulator and bottle with DIN valve, how I will able to fill bottle ? Do I need to put valve insert every time befor filling and take it out before mounting regulator or some simpler method exists ?

    2. How often it needs to be refilled (of course if it was not used/freeflowed) ? I assume that I will need to take few breathes before each dive (normal pre-dive check) but with smallish 13CF bottle it can deplete bottle fast enough.

    3. What type of pony gauge you would recommend:
    a) mounted directly on the bottle;
    b) using hose strapped to the octopus;

    BTW: I am planning to keep it strapped under bladder wing of my Ranger LTD with regulator pointed down.

    Thank you,

    MR
     
  2. idocsteve

    idocsteve Humbolt Squid

    # of Dives: 200 - 499
    Location: NY-Long Island-Suffolk County
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    I dive in the NE Atlantic and use a single AL80 with a 19 cubic foot pony bottle for bailout purposes as I have not yet taken the plunge to a doubles set up with a sling bottle. A 13 is a bit small for use as a bailout from any real depth.

    It's strapped to the main tank. I like that set up because it's behind me, out of the way and secure.

    My pony bottle uses a yoke valve, which I recommend since that's what's available in your area. I don't see DIN being all that much more "streamlined" than yoke.

    My pony bottle has a little mini gauge that screws right into the first stage, it doesn't have a hose, and it's easy to tell at a glance if it's close to full. I have no clue what you mean about that stuff about "valve insert before filling and mounting regulator". One breath before each dive of the day won't deplete the tank all that fast and you need to make sure it's delivering breathing gas, that's the only way to do it.

    I change the gas in that tank once a year, assuming of course that I haven't used the tank.

    I have taken it to Florida on one occasion since I knew I'd be solo diving. The dive shop did a quick visual and refilled it for me on the spot.
     
  3. RonFrank

    RonFrank Orca

    # of Dives: 200 - 499
    Location: Conifer, CO
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    I use a 19CF bottle, and would recommend that size even if a couple friends are happy with the 13CF.

    I'd skip the DIN setup unless you use DIN for other valves. There is little point in using DIN for the sake of using DIN.

    I mount my pony on my tank. I do so as I often carry a camera UW, and don't want to have a bottle in my way (Sling). However some of my buddies sling their pony's, and that works very well also.

    I use a standard first stage, a Zeagle ZX octo, and a standard brass gauge. I've read less than flattering things about the tiny pony gauges, and if they are mounted on the first stage you can't read them easily.

    Honestly an SPG is not all that necessary except for the fact that these bottles don't carry much air, and if they have a slow leak, they maybe empty when you need them if you have no way to monitor the pressure.
     
  4. keithdiver

    keithdiver Humbolt Squid

    # of Dives: 200 - 499
    Location: Upstate NY
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    First of all you want to figure out what type of diving you are going to do. Are you diving with doubles or single tank? If you are nitrox certified you should fill the tank with 40% nitrox. My advice would aslo be to get a tank that is bigger than 13cu. you want something that can get you out of a jam if you have one. I would look at nothing smaller than a 30 cu. it is all negative weight, and it will not hurt you carrying it. As far as a reg , look at one that is 02 clean Oms workhorse, zeagle, somewhere in that line. You also do not want a peanut gage for air, you want something that you will be able to read without a problem..
     
  5. Michael_Lambert

    Michael_Lambert Barracuda

    # of Dives: 500 - 999
    Location: Bradford, Ontario, Canada
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    I think this is bad advice.

    Nitrox or not, You need to carry the gas that is required for your dive. Using a pony as an emergency air source would mean you want to have a mix in it that will match your bottom mix.

    Having a 40% mix in your emergency gas supply and diving to 130 feet might not be wise.

    For the hassles involved with diving a stage or pony i would recommend at least a 40CF. We dive with 80's only due to where and how we dive, however the cost involved for a 19CF and regs and rigging you might as well sling a 40 and have enough gas to work with.. When diving fun local dives i will carry a 40 of 50% just for cleaning up on our safety.
     
  6. willembad

    willembad Nassau Grouper

    # of Dives: 500 - 999
    Location: As far away from salt water as you can get in Flor
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    So you recommend a pony big enough to bail out on from considerable depth but wants him to fill it with a gas he can not use at that depth?

    Willem
     
  7. idocsteve

    idocsteve Humbolt Squid

    # of Dives: 200 - 499
    Location: NY-Long Island-Suffolk County
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    I'm curious what you heard about the tiny pony gauges that are less than flattering? It's a simple device, I can't imagine what problems there would be.

    Regarding "reading them easily", yes it's nearly impossible to see the gauge unless you get within a few inches of it, while diving that would be almost impossible but that's not when you're going to check it. Like you said, the gauge is only necessary to monitor for leakage over time, and that's done when you check the gauge during your predive check.
     
  8. Michael_Lambert

    Michael_Lambert Barracuda

    # of Dives: 500 - 999
    Location: Bradford, Ontario, Canada
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    I have dove several times using the "Button Gage" and found it nice, out of the way and when needed easy to view.
     
  9. bamamedic

    bamamedic Humbolt Squid

    # of Dives: 200 - 499
    Location: Somewhere between "hold my beer and watch this!" a
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    I wouldn't have a problem putting a button gauge on a pony bottle...however, if you're mounting the bottle valve down, it's going to be impossible to read the button gauge unless you unclip the bottle.

    Big thing is to make sure you can reach the valve in whatever configuration you mount it in.

    As far as pony bottle size goes....what's the maximum depth that you plan on diving with this setup? Assume a significantly elevated SAC rate due to stress, add an extra minute or two for solving a problem at depth if it occurs, and a 30fpm ascent rate, and make sure that the 13 c.f. cylinder holds enough gas for the diving you plan on doing.
     
  10. AndyNZ

    AndyNZ Scuba Instructor

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    Opinions are like ar$eholes - everyone has got one. I suggest taking a good look at the various responses and choosing the most sensible advice.

    As has been pointed out, using DIN for the sake of DIN is somewhat arbitrary. My suggestion would be to set it up with a DIN-K valve (this is a 200bar DIN vavle, that you screw an insert into to make it yoke) and a regulator that can be converted to DIN easily (e.g. Scubapro, Apeks). Set it up as a yoke and see how you go with it. If you find the yoke assembly is catching or is in danger of being hit hard enough to dislodge it, then shift everything over to DIN.

    Then just buy a DIN fill adaptor - it takes a couple of seconds to screw in to the valve by hand when filling and isn't an inconvenience.


    There's no real answer to this question other than "it depends". It will need filling every time you decide to do a dive where the pressure has dropped to a point where it doesn't contain enough gas to enable you to surface safely.

    The only way you can know what this pressure threshold is, i if you work out your breathing rate and understand how to do minimum gas calculations. Do a search for "minimum gas reserve" or "rock bottom" and you'll find plenty of examples of how to do these calcs.

    FWIW, my personal opinion is that a 13 cu ft bottle is too small for all but the shallowest of dive. I would urge you to take a good look at your diving profiles, and do the calculations to work out how much gas you need to surface safely from the depths you are planning to dive to - not just now, but in the future. To my mind, a 13 cu ft bottle is just about big enough for an average diver to make an emergency ascent from somewhere in the 20-30m range, but with no safety stops or much vestige of control. I'd definitely look into a 19 cu ft or larger.


    I prefer to have an SPG on a 6" hose that bends back on itself and is tied with a loop of caveline. It's nice and clear, easy to read and doesn't get in the way. But, this only really works if you are carrying the bottle as a "slung" tank.

    If you go with another form of carrying, you need to take a good look at your hoses - where they are, how long they need to be, whether they cause confusion etc. Your pony SPG needs to be very distinctly placed and recognisable from your main gauge. It's a real bu&&er when you realise half way through the dive that you've been looking at your pony gauge by mistake, and in fact your main tank is near empty when you thought you had 200bar.....


    This begs a whole set of questions - firstly, are you taking the pony on every dive? If you get everything set up perfectly for the pony, then you decide to leave it behind.... does it change anything on the rest of your configuration? One of the nice things about a slung pony is that it changes nothing - it's a self contained unit, you pick it up and clip it on when you need it. It also give you better access to the valve, easy visual contact with the SPG etc. You can also unclip is during the dive - either because you need to pitch it, or because it's easier to give it to someone who is OOG than to share air etc.

    Have a look at how to calculate the size of bottle you need, if it's bigger than 13 cu ft then have a look at how to sling a tank. If you can get by with a 13 cu ft, and want to carry it in your Ranger then make sure you get it right - hoses all the right length (you may need custom made hoses), things positioned so they don't cause confusion etc etc.

    Also, be vary wary of having any gas mix in your pony that is different from you backgas. Switching to a richer nitrox mix is very uncool, switching to a leaner mix is less immediate but it does potentially push you into having a deco obligation due to the switch - that your computer won't know about, and do you have enough gas in a 13 cu ft tank to extend your safety stops enough to clear it????
     
  11. Jorgy

    Jorgy Manta Ray

    # of Dives: 500 - 999
    Location: Syracuse, NY
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    I have a 19 CF pony......

    First a button gauge, too small and hard to read........

    Small OMS gauge on 6" HP hose - worked well but made a "big" clump of stuff at the top of the tank, I sling my pony on my left side and I run my back gas gauge under my arm and clip it on my D-ring, so with my pony gauge it meant two gauges right next to each other........

    So I settled on a 1" gauge - see picture below, large enough to read but small enough to not be in the way.........

    I top off my pony every time I fill my tanks......I take a few breaths of the tank on each dive to check it works and practice deploying it.......so I loose a bit every dive......

    My LDS tops them off for free, so it is no big deal........

    Hope this helps...........M
     

    Attached Files:

  12. elan

    elan DIR Practitioner

    # of Dives: 200 - 499
    Location: Toronto, Ontario, Canada
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    The OP has clearly mentioned that he is rigging a bailout bottle. Readability of the gauge is irrelevant under water. It's only used to check if you have enough gas or not to bailout while preparing for a dive. You do not include bailout bottle into the dive gas calculations so knowing the current pressure of the bailout bottle is useless. Once **** hits the fan you just start your bailout. There is no point of looking at the gauge :)
     
  13. bamamedic

    bamamedic Humbolt Squid

    # of Dives: 200 - 499
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    I understand your point, but at least for me, it would be kind of nice to have a pressure gauge that's readable underwater....particuarly on a deeper dive, when trying to decide if one has enough gas to stay for a safety stop.
     
  14. AndyNZ

    AndyNZ Scuba Instructor

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    There are two school's of thought on that - my personal view is that there is every point in looking at the gauge.

    For example, you may have forgotten to close the tank valve during the dive and a small freeflow has led to you having half a tank... so 6 cu ft of gas (the same size as my drysuit inflation bottle!). You are at 30m, is 6 cu ft enough to get you up? Do you end the dive, do you close the tank valve and go shallower to a depth where 6 cu ft is enough.... and so on.

    Another example, you've bailed out and an ascent... a 13 cu ft is woefully small in my opinion. Is it better to be able to see the gauge and how fast it is dropping (so you can either vary your ascent rate or relax your breathing)or would you rather you just run out of gas half way up?

    There is no definitive answer as to whether or not you should be able to see the gauge or not - you are correct, as am I. We make a choice to decide what to do - but simply telling someone what to isn't giving them the option of informed choice! :D
     
  15. idocsteve

    idocsteve Humbolt Squid

    # of Dives: 200 - 499
    Location: NY-Long Island-Suffolk County
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    The idea is to have enough gas remaining in your primary tank for the safety stop, which should be considered mandatory for dives greater than 60 feet.
     
  16. AndyNZ

    AndyNZ Scuba Instructor

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    If you've had to bail out, thanks say to a catastrophic equipment failure (tank neck o-ring... rare but possible), you're relying on the pony.

    Yes, you should size your pony so that it contains enough gas to do the ascent and a safety stop... but you can only size it on the basis of a best gas of what your stressed SAC rate is.

    If you can see the gauge, you can choose to shorten or extend your safety stop depending on what led up to the bail out. If you can't see your gauge, you're just shooting blind.
     
  17. bamamedic

    bamamedic Humbolt Squid

    # of Dives: 200 - 499
    Location: Somewhere between "hold my beer and watch this!" a
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    I guess I just assumed that if I'm bailing to my bailout bottle, that something horrible has happened to my primary tank (massive freeflow, alien zombies stealing my gas, oh, I don't know) and I'm stuck having to ascend on my bailout bottle...thus, having to complete a safety stop on my bailout bottle.
     
  18. idocsteve

    idocsteve Humbolt Squid

    # of Dives: 200 - 499
    Location: NY-Long Island-Suffolk County
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    I see your points.
     
  19. elan

    elan DIR Practitioner

    # of Dives: 200 - 499
    Location: Toronto, Ontario, Canada
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    If you include your pony into the gas calculations for the dive it's a bad thing IMHO. You suppose to have enough gas in your main tank to be able to ascend from any point of your dive together with your buddy breathing harder than usual.
     
  20. idocsteve

    idocsteve Humbolt Squid

    # of Dives: 200 - 499
    Location: NY-Long Island-Suffolk County
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    I made the same assumption you did when reading the post you and I both quoted.

    That's true in a nonemergency routine dive situation, as opposed to an emergency that has depleted your primary much sooner than expected.

    Read the three posts above yours, it's clarified rather well.
     

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