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Scuba Forum / General / July 2007any system to catch bubbles underwater
Hi, This might sound crazy but being a marine biologist and amateur u/w photographer I've often thought how good it would be to eliminate the bubbles generated from conventional open-circuit SCUBA gear. I can't seem to find any information about a system designed to capture bubbles underwater, except of course the expensive and difficult to use closed-circuit rebreather systems. I was just wondering if anyone knows of a device or method to do this with open-circuit scuba or is it impossible? Mark > This might sound crazy but being a marine biologist and amateur u/w > photographer I've often thought how good it would be to eliminate the > bubbles generated from conventional open-circuit SCUBA gear. Eliminate them or just get them out of your way? Routing the exhaust behind your head like was done with the old 2-hose regs would work... Or you could just quit breathing... <snicker> http://grumman581.googlepages.com/welcome-rec-scuba > Hi, > [quoted text clipped - 6 lines] > knows of a device or method to do this with open-circuit scuba or is > it impossible? I friend of mine was diving at a forbidden spot, and in order to dissolve the bubbles, he kept waving his one hand in the escaping stream. Now this could be farther extended upon. Use the business part of a small scooter as a hat, and feed it by a cord from your torch's battery packs 2nd socket. Matthias PS: best is to use a set of counter revolving propeller blades, because of the neutralizing momentum > I friend of mine was diving at a forbidden spot, and in order to dissolve > the bubbles, he kept waving his one hand in the escaping stream. Those that think making large bubbles into smaller ones makes them invisible on the surface have obviously never seen an airstone at work. This process does, however, seem to reduce the impact of bubbles on fish. Most I know of have done it with a double hose regulator as Grumman suggested or with an extension to the exhaust to effectively do the same thing. Lee > Hi, > [quoted text clipped - 8 lines] > > Mark Pull the neck seal up till its just above your nose. Now you have you're own rebreather system, just add a bit of air via the inflator every now and again to keep it fresh and dumpt the stale via your cuff dump ;-) > Hi, > [quoted text clipped - 8 lines] > > Mark http://www.vintagescubasupply.com/regs.html nos...@all.please.net wrote: > http://www.vintagescubasupply.com/regs.html One thing to be aware/cautious of is that old single stage doublehose regulators were typically 2500psi max. My recollections are that there's some techniques for bubble-reduction on Open Circuit that involve making the system bleed semi-continuously a small stream, rather than a big exhaust burp ... but that this technology had gotten classified because of its "low signature" characteristics that made it be militarily useful. Of course, any flavor of rebreather will generally do better than OC, simply because it doesn't exhaust as much air per unit time, with or without a diffuser adaptor. -hh > My recollections are that there's some techniques for bubble-reduction > on Open Circuit that involve making the system bleed semi-continuously > a small stream, rather than a big exhaust burp Basically direct all exhaust gas to a leaky BC... <grin> I don't think its possible to eliminate bubbles because you need them for breathing purposes. If you eliminate the bubbles then you're cutting your oxygen.  Signaturephilmoreslim http://www.scubish.com > I don't think its possible to eliminate bubbles because you need them > for breathing purposes. If you eliminate the bubbles then you're > cutting your oxygen. Closed circuit rebreather. Thanks for all the responses. So it doesn't look like there's some ready-made off-the-shelf product out there to do what I want. That's a pity, its something I always thought would be so handy, especially for u/w photography which can be so difficult with the incessant clamour of bubbles scaring the subjects away. I guess rebreathers are the only solution to this problem, a shame they're so expensive. Can anyone recommend a good link to a reasonably priced unit? Cheers > I guess rebreathers are the only solution to this problem, a shame > they're so expensive. Can anyone recommend a good link to a reasonably > priced unit? Reasonably priced rebreather? I don't think those words can be used in the same sentence... You best bet if you want to do it on the cheap is to just try redirecting your exhaust bubbles away from you with a long hose or something... > Thanks for all the responses. So it doesn't look like there's some > ready-made off-the-shelf product out there to do what I want. That's a [quoted text clipped - 5 lines] > they're so expensive. Can anyone recommend a good link to a reasonably > priced unit? http://www.submatix.com/ They have an SCR, a KISS system, and I would bet, in the near future a fullblown ECCR. All modular design. With the integrated weights, in a shell drysuit and Weezle Extreme, I needed 12 kg of weights. Ask me for any questions. Matthias > Thanks for all the responses. So it doesn't look like there's some > ready-made off-the-shelf product out there to do what I want. That's a [quoted text clipped - 5 lines] > they're so expensive. Can anyone recommend a good link to a reasonably > priced unit? Hit eBay, there are several for sale. >> I guess rebreathers are the only solution to this problem, a shame >> they're so expensive. Can anyone recommend a good link to a reasonably >> priced unit? > > Hit eBay, there are several for sale. By the widows of former owners? > >> I guess rebreathers are the only solution to this problem, a shame > >> they're so expensive. Can anyone recommend a good link to a reasonably > >> priced unit? > > Hit eBay, there are several for sale. > By the widows of former owners? I hope not. I've been doing some reading on the net about rebreathers and they sound exciting on the one hand but scary and dangerous on the other. Not sure if I'm into my gear enough to be able to a) learn how to safely dive with these things and b) maintain them to a workable standard. The system I was thinking of was for a typical open-circuit system. In my head I'm imagining having dual tanks on your back. One with compressed air that you breathe from via a normal open circuit SCUBA setup, and the other an empty evacuated tank that your exhaled breath can be drawn into, hence eliminating bubbles. Sounds easy, but I'm guessing its probably not feasible otherwise surely someone would have already invented it, right? I'm even thinking you could even have a small tank to draw your exhalations away which you only use for crucial moments in the dive such as zeroing in on that elusive new species of fish you're trying to photograph or swimming into caves and caverns. Any mechanical engineers out there that could tell me if this idea sounds feasible or not? Thanks for all the replies thus far. Mark leucopogon <leucopogon@gmail.com> pounded away at his keyboard resulting in: :I'm even thinking you could even have a small tank to draw your :exhalations away which you only use for crucial moments in the dive :such as zeroing in on that elusive new species of fish you're trying :to photograph or swimming into caves and caverns. Any mechanical :engineers out there that could tell me if this idea sounds feasible or :not? Once the pressure inside this tank gets to 50 psi or so, it will need some sort of pump to get air into it. Dan Bracuk Never use a big word when a diminutive one will do. > Once the pressure inside this tank gets to 50 psi or so, it will need > some sort of pump to get air into it. Which is why you should use a tank unfilled to a void pressure of -2000 PSI or so, so that a lot of air can come in before you need a pump, thus limiting the number of moving parts in your contraptions. Beware that when diving the water pressure will add up to the negative pressure inside the tank, so you'll have to keep an extra safety margin compared to filling a tank. You should also set it up with a regulator mounted upside down, otherwise you risk being sucked inside the tank. This may also happen if the inverted regulator goes on free flow, and I believe this is one of the reasons such contraptions are not more widespread. >Which is why you should use a tank unfilled to a void pressure of >-2000 PSI or so, hmmm..... it's going to be REALLY hard to get that. > hmmm..... it's going to be REALLY hard to get that. Nawh, you just gotta do your diving a bit deep... Around 4500 ft should do it... An AL80 isn't going to last for that many breaths at that depth though... Should be good for a REALLY GOOD narc... > >Which is why you should use a tank unfilled to a void pressure of > >-2000 PSI or so, > > hmmm..... it's going to be REALLY hard to get that. Well, given the risks involved (being sucked in) most dive shops would rather not unfill your tanks, unless you can show them that you know what you're doing of course. >> >Which is why you should use a tank unfilled to a void pressure of >> >-2000 PSI or so, [quoted text clipped - 4 lines] >rather not unfill your tanks, unless you can show them that you know >what you're doing of course. Is there a specialty certification for that? I know a normal OW cert will let you do it to 500 PSI without consequence and I've gotten down to 15 PSI in my garage by simple valve adjustment but I think you will have to have something special to get to -2000 PSI. Even my space suit is only rated to 0 PSI ambient, or 100 mTorr at best. > leucopogon <leucopo...@gmail.com> pounded away at his keyboard > resulting in: [quoted text clipped - 8 lines] > Once the pressure inside this tank gets to 50 psi or so, it will need > some sort of pump to get air into it. Which is why one must empty the tank to a high negative pressure beforehand (-2000 PSI or so), eliminating the need for a pump (less moving parts = more reliable). Beware that in this case the underwater pressure will add up to the inside depression so one must take an extra safety margin compared to the tank's normal rated pressure. As the negative pressure is not as important, you will actually need a larger tank than for you air supply, not a smaller one. Also, to avoid the unpleasant experience of being sucked inside the tank, one should mount a regulator (inverted). There's still a risk in case of free flow, which may explain why such rig is not widely used. Cheers, Froggy > The system I was thinking of was for a typical open-circuit system. In > my head I'm imagining having dual tanks on your back. One with [quoted text clipped - 10 lines] > engineers out there that could tell me if this idea sounds feasible or > not? You're from Queensland, Austrailia, right? Perhaps you should go back to f.cking sheep... I suspect this diving stuff is a bit too complicated for you... > Thanks for all the responses. So it doesn't look like there's some > ready-made off-the-shelf product out there to do what I want. That's a [quoted text clipped - 5 lines] > they're so expensive. Can anyone recommend a good link to a reasonably > priced unit? I sense a pattern. First you look for a way to eliminate bubbles with open circuit. This is a pipe dream that betrays a fundamental failure to grasp some very basic physics of diving. You have 80 cubic feet of air in your tank, compressed, using a great deal of power, into less than 2 cubic feet, at around 300 times the intitial pressure. For you to breath it, it has to expand to almost its original volume, depending on depth. Now, if you don't carry a 600 lb. compressor requiring several hundred watts of power to re-compress your exhalation, just where do you expect to put it? (For those tempted to suggest a place, beware intestinal squeeze.) Next, you resign yourself to a rebreather as Plan B, and ask about a cheap one. Anyone who decides on rebreathers because a revelation after some period of being a diver opens their eyes to something they should have known in module one of the easiest Open Water course, and then seeks to choose one based on price, has no business anywhere near a rebreather. Rebreathers are complex pieces of equipment that require a great deal of knowledge to use safely, and someone who becomes a diver without realizing the necessity of bubbles on open circuit is not likely to attain that knowledge, and in rebreathers, cheap equals deadly. This combined with the entire thrust of your original post - a quest for a cheap, easy, have-your-cake-and-eat-it- too, magic bullet, genie in a bottle solution, militates against you having the emotional makeup that suits one for rebreathers, or anything other than cruise ship conga line diving, for that matter. People who take responsibility for themselves don't expect magic, no- effort, no cost solutions to complex problems. > I sense a pattern. First you look for a way to eliminate bubbles with > open circuit. This is a pipe dream that betrays a fundamental failure [quoted text clipped - 6 lines] > exhalation, just where do you expect to put it? (For those tempted to > suggest a place, beware intestinal squeeze.) Actually, there is a way: attach to the second stage a pump that will move a few thousand gallons of ambient water per minute and a diffuser that will break the exhaust into micro-bubbles. The exhaust gas will be absorbed by the water and - Voila! - no bubbles. I'm sure Scott could fix you up with one. esg > Actually, there is a way: attach to the second stage a pump that will > move a few thousand gallons of ambient water per minute and a diffuser > that will break the exhaust into micro-bubbles. The exhaust gas will be > absorbed by the water and - Voila! - no bubbles. > > I'm sure Scott could fix you up with one. For a nominal service fee, or for free, if you don't have VD. >> I sense a pattern. First you look for a way to eliminate bubbles with >> open circuit. This is a pipe dream that betrays a fundamental failure [quoted text clipped - 15 lines] > >esg 1. Get a float. Put a nice logo and maybe a dive flag on it. 2. Get a nice 130 foot soft, flexible 25 mm hose. 3. Attach one end of hose to float. 4. Attach other end of hose to exit ports of regulator 2nd stage. 5. Spend rest of day clenching teeth to keep regulator in mouth. 6. Spend evenings curing bruxism. 7. Market new invention to unsuspecting new divers. >>>I sense a pattern. First you look for a way to eliminate bubbles with >>>open circuit. This is a pipe dream that betrays a fundamental failure [quoted text clipped - 21 lines] > 4. Attach other end of hose to exit ports of regulator 2nd stage. > 5. Spend rest of day clenching teeth to keep regulator in mouth. Spend another day recollecting your lung tissues. Matthias > 6. Spend evenings curing bruxism. > 7. Market new invention to unsuspecting new divers. ;-)) Matthias >>Thanks for all the responses. So it doesn't look like there's some >>ready-made off-the-shelf product out there to do what I want. That's a [quoted text clipped - 33 lines] > People who take responsibility for themselves don't expect magic, no- > effort, no cost solutions to complex problems. I know what you did last summer... > I sense a pattern. First you look for a way to eliminate bubbles with > open circuit. This is a pipe dream that betrays a fundamental failure [quoted text clipped - 23 lines] > People who take responsibility for themselves don't expect magic, no- > effort, no cost solutions to complex problems. |
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