Spare Air
MarkM Any one here use one of those small Spare Air cylinders. Are they worh the money. I mostly dive overseas so do not want the hassle of a pony cylinder.
ian.wood0 Mark, "Owt is better than Nowt" as they say. However!!! Unless they are refillable you wont get a pressurised container on board the plane.
parahandy Mark, These bits of kit don't have a lot of credibility amongst experienced divers Owt is better than Nowt" I agree, but in this case I would consider the money better spent, with a 3lt pony Cylinder and regulator. Having tried my mates spare air a few times in "simulated" out of air situations, in shallow water I didn't consider its use a practical option, with its severely limited air capacity its doubtfull in a stress environment if it would allow you a safe return to the surface. This of course is purely a personal opinion based on my experiences. The manufacturer claim of course tells otherwise!!!!!!. Discussions on spare air have rambled on on various forums with the same consensus, in that it doesn't really deliver the goods.
ian.wood0 Went into Mikes Waterfront Warehouse in Warrington yesterday I went into the toilet and thought of you........ On the wall was an advert for spare air ( best place for it i would say!) I priced it up at £190 for a few bob more you could have yourself a pony and reg. They also told me that it has to be filled by means of your main cylinder the same as you would for a crack bottle. In my opinion it would be a wiser choice to purchase a pony as it would not take up much more space and the procedure for getting it onto a plane would be the same. I dont know if you are aware that some airlines now allow a extra allowance for diving equipment upto 10 kilos. I never dive without a backup air supply by the way of a 3 litre pony. Again a spare air is better than nothing but go for a pony cylinder. Happy diving Ian
AndyC I have both a spair-air and a pony bottle which I use for different types of diving. If just doing relaxed recreational diving at shallower depths <20m then I am more than happy to just use a spair-air. Remember what it is for - to allow you to get to the surface at a controlled rate whilst still being able to breath. It has a few minutes worth of air in it for this purpose. I can quite happily pull it out of its holder and stick it in my mouth under any amounts of stress. I don't see how thats any harder than unclipping a reg for a pony bottle and putting that in your mouth. On deeper dives I take the pony bottle as it allows me to make a slow ascent and safety stops etc. Then when deep/technical diving I obviosuly have twins & stage bottles etc. If you are doing non deco diving then your worst alternative in an emergency would be to make an emergency ascent - would you rather do that or stick a spair-air in your mouth and breath happily as you ascend. I have travelled several times with a spair-air and would heavilly recommend that you take the instructions with you so you can show them that it's empty without having to strip the whole thing down.
Davey_Willo I'm not sure if I agree with you on this one Andy, Your logic holds good if the diver carrying the 'Spare air' is early into a recreational dive to say 20m, but what if that diver is 25-30 minutes into the dive, even at these relatively shallow depths the tissues would be fairly well saturated by that time. If he were then suddenly faced with an OOA situation, his overriding concern would be to get to the surface quickly as there would be no way of knowing which breath from the 'Spare air' bottle would be his last breath, the diver would probably go straight up, probably too quickly, probably not doing any stops and surely getting bent in the process. If that same diver was carrying a pony bottle, confidant in the knowledge that he had plenty of air to not only ascend at the correct speed but to do his safety stop, then that particular diver would have experienced a scare but not a DCI hit. Would I prefer having a 'Spare Air' rather than no air? of course, that goes without saying.. Would I suggest spending money on a 'Spare Air' bottle rather than a Pony bottle? then the answer would have to be No... Best regards Dave
AndyC I totally agree that the things are pretty expensive for what they are - If I had my time again then I would probably have just bought the pony bottle. But Mark mentioned that he didn't want a pony bottle and 2nd set of regs due to his travel. Bearing that in mind I think the spair air is still a pretty good thing to take diving with you (I know most people think they are stupid, but someone has to speak from the other side). As long as you are diving within no-deco limits then you are 'theoretically' safe to go straight to the surface. Which would you prefer to do - make a dash for the surface exhaling all the way or simply stick a spair-air in your mouth and know that you have a couple of minutes to make a steady ascent in. I realise that you won't have enough air for a 3 min safety stop but remeber that's all it is - a 'safety' stop - not a required deco obligation. As something small to go travelling with if you don't want to buy a pony bottle and another set of regs then I think they are a reasonable alternative. As I mentioned before I use mine on <20m dives and practice using it and although I have never had to use it for real in simulations it has been fine. I realise most people are against them so I am happy to disagree on the issue. At least Mark will get two perspectives to consider!!
MarkM Well I never just popped down the road for a couple of pints get back log on and what do I find, let me tell you, an informed and valued response to my question. I posted the same question some time ago on a US Forum and from the response I got you would think that turning up for a dive with a Spare Air would condemn me to a certain death. Well following the good advice here I am going to get one, the hassle of taking a pony abroad is not worth it, although when funds are available I will get a pony for UK diving. Now here is another one for you having decided to make the purchase should I get the Nitrox version of the plain old air version. Mark
AndyC I would recommend you get the plain air version. Remember you fill them from a normal scuba tank on the boat etc. So unless you can guarantee that every time it gets filled it will be using EANx clean air then the first time you fill it from a non ENAx clean source it would need to be O2 cleaned again. If you are planning on just using it as an emergency source (which is all it is usable as) then is all you want is something to breath as you ascend to the surface and plain old air will be fine for that. Having a Nitrox version is just a marketing gimmick - In an emergency you are not going to be worried about trying to extend bottom times by using Nitrox!! I would also recommend you get the A clamp like adapter that lets you fill it direct from a scuba tank without the 'universal refill adpter' bits that go on your first stage - They just look like something else that may fail in my opinion. Look at the 'scuba tank refill adapter' : http://shared.creativelinkpartners.com/cgi-bin/shop/cart.cgi?
AndyC Be warned you may still get a few strange looks on a dive boat - I will agree on the fact that the majority of people don't think they are worth it. At the end of the day though if you don't want a pony bottle and regs etc would you rather have a few strange looks but something to breath in an emergency?? From your comments about travel I assume a reasonable amount of your diving may get done in holiday destinations ? In most holiday destinations people would probably look just as strangely at you if you turned up with a pony bottle. In all the times I have recreationally (as opposed to tech) dived in Australia and on trips up to the Great Barrier Reef I haven't yet seen anyone else with any form of redundant air source. So on that basis no matter what you have you will be in a better position than most of them. You will probably find people with such alternate air sources on your normal diving in the UK at which point you want to buy a pony bottle anyway!!
divermole Heres some more calcs on the spare air. It holds 85 litres at 200 bar so its its 0.42 litres in size Assuming our 40 lpm panic breath rate (and I've seen higher), lets see what depth we can bail out from assuming no safety stops and a 10 m/min ascent rate 10m bail requres 80 l so OK (Just) 20m bail requires 120 l so your dead 30m bail requires 160 l so your very dead Even Assuming a 20l breath rate (and many people use more than this at rest) 10m bail requres 40 l so OK 20m bail requires 60 l so your OK 30m bail requires 80 l so your OK (just) No way can most people control their breathing to this level in an OOA situation By the way a 5 m safety stop needs 60l per min so the spare air can just cover a 1 mins safety stop when FULL!!! And then we need to add a RESERVE! In other words. The unit is far too small to be any more than a placebo
divermole We tested a spare air in Stoney Cove many years ago at 36m. Got 3 3/4 breaths of of it before it clammed up. Its a liability as it makes you think your safe where in fact it doesn't hold enough gas to even do a fast ascent to the surface from depth, let alone a controlled one with safety stops. Take a proper redundant air supply for your dive. Easy to do the calcs Assuming 232 bar and a 40 lpm panic breath rate from 30m with a 3 min safety stop needs 3mins at average of 15 m = 300l 3mins at 5m = 180l total =480l/232 = 2.07 l tank required. The Spare Air is much smaller than this, a 3l pony covers it with some spare for extra stops. Plus later in your dive career if you get up to twins and deeper stuff you can use the pony for deco mix.
Mr Magoo Very interesting topic (for me). I've just qualified (PADI Open Water) and therefore am theoretically qualified to dive to 18m. As an aside, I'm also insured to dive to 18m on my standard insurance policy. As such, I don't plan to be diving any deeper than 18m in the short term, at least until I have a large number of dives above 18m under my belt (I currently have 8). I then may consider going down to 30m. I also plan to do no compression dives for the forseeable future. For someone who is limiting their dives to 18m with no decompression stops, isn't the spare air option a viable one in an emergency? I tend to agree with AndyC who says
quote:
If you are doing non deco diving then your worst alternative in an emergency would be to make an emergency ascent - would you rather do that or stick a spair-air in your mouth and breath happily as you ascend.
I also agree with MarkM that carrying a 0.4l bottle on holiday is preferable to carrying a 3l bottle with additional first stage, regulator, pressure gauge and straps. DiverMole's calculations are interesting, but I would argue that even if you do use up the spare air before you surface, you're not dead, you would just make a controlled emergency swimming ascent from the point where it ran out and I would rather be doing this from 5-10m (30 seconds) than from 18m (1 minute). Not sure I understand DiverMole's calculations though. The maximum safe ascent rate on a no decompression dive is 18m per minute not the assumed 10m per minute in his calculations. Therefore from 30m it should take no more than 2 minutes (assuming no safety stop) to reach the surface. If the panic rate is 40l per minute and the bottle holds over 80l this should be enough to breath for the 2 minutes required to reach the surface. Have I got this wrong? As an aside, how does the buddy commando spare air bottle work? Is it attached to the BCD via a low pressure inflator hose? Can this system be used with other BCDs e.g. the Scubapro Glide 1000 with Air 2?
Dominic Humphries
quote:
As an aside, how does the buddy commando spare air bottle work? Is it attached to the BCD via a low pressure inflator hose? Can this system be used with other BCDs e.g. the Scubapro Glide 1000 with Air 2?
The buddy bottle has nothing between it and the jacket: You open the bottle, high pressure gas comes out, and fills the jacket. No low-pressure intermediates involved. The bottle is connected directly to the jacket via a bit of plastic. You could buy this adaptor from AP Valves and fit it on any BCD, so long as you didn't mind cutting holes in it. Back on the original topic: You could just buy a lightweight pony reg and hire the bottle when you get where you're going - Doesn't add much to the travel weight that way. I'd rather dive with no spare air and keep close to my buddy, than with one and risk a false sense of security. Even if I did decide to take a SA with me, I'd view it as a way of getting to my buddy without having to hold my breath for quite so long, rather than a way of getting to the surface. There are 10 kinds of people in the world. Those who understand binary and Those who don't
divermole 10m a min is the standard normal ascent rate used by most agencies. The 18 m/min was the very old US navy standard and was dropped 20 years ago by most folks and recent research says that even 10 is too fast There is no such thing as a no decompression dive and personally if I'm doing a No stop dive (exceedingly rare) I think its even more important to control your ascent rate and put at least 3 mins at 5 m in to be safe For example the BSAC recommend 6m/min at the surface
Mr Magoo Hi Dominic,
quote:
Even if I did decide to take a SA with me, I'd view it as a way of getting to my buddy without having to hold my breath for quite so long, rather than a way of getting to the surface.
Good point. Hi divermole, Thanks for taking the time to explain your reasoning. The 18m per minute I quoted was the maximum rate of ascent in an emergency as quoted in the PADI training literature, although the literature also states "A rate slower is acceptable, and appropriate." As for the no decompression/no stop dive, yes, you're right, I should have said a no stop dive as opposed to no decompression dive, but you knew what I meant . As you point out, a safety stop is recommended even for no decompression dives, but in an emergency, you can probably get away without the safety stop if you have planned your dive to avoid a decompression stop being required. Or so the training literature says ......
divermole Well theres a it in a nutshell Carry a Spare Air and HAVE to miss your safety stop and ascend rapidly Carry a pony and be able to ascend at a slow speed and do your safety stop You pays your money and you take your choice. Trouble i a wheelchair or worse awaits the person who makes the wrong one Much better still, educate yourself to be able to calculate your real bail out gas needs and calculate them for each dive, add a bit for reserve and carry the correct amount of bail out for the dive youre doing
Mr Magoo food for thought indeed divermole, a very interesting discussion. Thanks
Hamlet Even for a newly qualified diver just doing shallow dives, this has got to be a complete waste of money, why buy something that’s going to be redundant once you become more qualified. The pony and reg solution will always be of use, the spare air very questionable at best. Divermole, are you the same divermole that posts on “Scubaboard”, the Inspiration buddy? Regards, Dave.
divermole Yep, I am. Not too many moles like getting wet !!!! At least on the Yellow Peril, a 3 litre tank is a 10 hour supply!!!!!!!!