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 Rebreather line-up at OzTek4  |
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Steve
Meg Pilot / Dive-Oz Supporter
Perth
Australia
2259 Posts |
 Posted - 17 March 2005 : 07:53:47 AM
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quote:
Originally posted by The Phantom Wreck Rat
Many of them had mouthpiece and hoses that I would consider constrictive to good airflow and way too small but maybe I'm just a heavy breather.
I used to be worried about this as well until I saw the test bench data from Dreager and more recently had a chat with Gordon Smith about it. Without going into a long winded explanation, the hoses of the KISS and the YBOD are quite close in internal diameter. The YBOD’s DSV is way more open and has much larger air flow paths than the KISS OC/CC DSV. Naturally one would assume that the YBODs hoses and DSV have a lower WOB than the KISS, but the fact of the matter is they are the same (or so close it doesn’t matter for this discussion).
Flapper valves are where the bulk of the resistance comes from apparently. I’m not sure how small loop hoses and DSVs can be but I’m interested to hear your thoughts on this Scott.
Divers have to be safe when they go under the water. Two divers can't go down alone, so they have to go down on each other. (Becky age 8) |
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Steve
Meg Pilot / Dive-Oz Supporter
Perth
Australia
2259 Posts |
Posted - 17 March 2005 : 07:53:47 AM
|
quote:
Originally posted by The Phantom Wreck Rat
Many of them had mouthpiece and hoses that I would consider constrictive to good airflow and way too small but maybe I'm just a heavy breather.
I used to be worried about this as well until I saw the test bench data from Dreager and more recently had a chat with Gordon Smith about it. Without going into a long winded explanation, the hoses of the KISS and the YBOD are quite close in internal diameter. The YBOD’s DSV is way more open and has much larger air flow paths than the KISS OC/CC DSV. Naturally one would assume that the YBODs hoses and DSV have a lower WOB than the KISS, but the fact of the matter is they are the same (or so close it doesn’t matter for this discussion).
Flapper valves are where the bulk of the resistance comes from apparently. I’m not sure how small loop hoses and DSVs can be but I’m interested to hear your thoughts on this Scott.
Divers have to be safe when they go under the water. Two divers can't go down alone, so they have to go down on each other. (Becky age 8) |
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Jason M
Mk15 RB Pilot
Sydney
Australia
1771 Posts |
Posted - 17 March 2005 : 09:35:41 AM
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quote:
Originally posted by Steve
I used to be worried about this as well until I saw the test bench data from Dreager and more recently had a chat with Gordon Smith about it.
And
quote:
I’m not sure how small loop hoses and DSVs can be but I’m interested to hear your thoughts on this Scott.
One would reasonably assume that in relation to the breathing loop, the bigger the bore the better[1]. However, the Draeger FGG, which is the deepest rated rebreather I know of (200m) has a hose and DSV bore of 25mm. The inlet/outlet ports of the Mk15 centre section, and the breathing hoses, have a bore of 25mm. The Mk15.5 and Mk16 were increased to 28mm.
Modern rebreathers tend to have 30 to 32mm bores, which I think is sensible, however, the gas flow path has more to do with WOB than purely looking at the bore. A right angle bend in a 32mm bore will likely be harder to breathe through than a straight connection in a 25mm bore. You also have to take into account the resistance through the scrubber bed itself, and the rest of the loop. It's no use putting big bore hoses and mouthpiece on a rig with a pig of a scrubber or 90 degree bends. Sure, improving some parts is good, but you have to look at the whole of the loop.
Jason M.
[1] - Until you get to a point where the bore is too large, and gas speed drops to a speed that doesn't effectively hold the one way valves closed.
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Jason M
Mk15 RB Pilot
Sydney
Australia
1771 Posts |
Posted - 17 March 2005 : 09:35:41 AM
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quote:
Originally posted by Steve
I used to be worried about this as well until I saw the test bench data from Dreager and more recently had a chat with Gordon Smith about it.
And
quote:
I’m not sure how small loop hoses and DSVs can be but I’m interested to hear your thoughts on this Scott.
One would reasonably assume that in relation to the breathing loop, the bigger the bore the better[1]. However, the Draeger FGG, which is the deepest rated rebreather I know of (200m) has a hose and DSV bore of 25mm. The inlet/outlet ports of the Mk15 centre section, and the breathing hoses, have a bore of 25mm. The Mk15.5 and Mk16 were increased to 28mm.
Modern rebreathers tend to have 30 to 32mm bores, which I think is sensible, however, the gas flow path has more to do with WOB than purely looking at the bore. A right angle bend in a 32mm bore will likely be harder to breathe through than a straight connection in a 25mm bore. You also have to take into account the resistance through the scrubber bed itself, and the rest of the loop. It's no use putting big bore hoses and mouthpiece on a rig with a pig of a scrubber or 90 degree bends. Sure, improving some parts is good, but you have to look at the whole of the loop.
Jason M.
[1] - Until you get to a point where the bore is too large, and gas speed drops to a speed that doesn't effectively hold the one way valves closed.
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The Phantom Wreck Rat
Dive-Oz Supporter
Wollongong
Australia
1488 Posts |
Posted - 17 March 2005 : 11:06:38 AM
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Yeah I agree WOB is more involved than just one part. Scrubber design, flapper valves and bends in gas flow are the most relevent but intuitively I would go for larger bore hose than smaller. For example, I have one of those wizbang snorkles woth the slats in the top that supposedly make it a dry snorklel but I cant use it as I easily overbreathe it. The slats bend the air flow and reduce the bore size at that point and make it essentially useless unless breathing in a very relaxed state. Surely there is a formula for calculating the gas flow characteristics in a rebreather which includes all the variables? I guess an engineer would know this. I still wonder how much real R&D is done on this or if manufacturers just work to the standard bore size, scrubber design etc etc that has gone before, test the final product for WOB on a machine, and hope for the best. I would think that all the money they supposedly spend on these things they would be able to come up with something that would reduce the CO2 problems associated with working at the extreme depth rebreathers are sometimes being used at.
To me it just seems rebreathers are still at the 'Model T' stage. ie. a Homebuilder with enough cash can easily produce something similar. I'm still waiting for a company to step up and develop the 'Formula 1'.
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Edited by - The Phantom Wreck Rat on 17 March 2005 11:12:33 AM |
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The Phantom Wreck Rat
Dive-Oz Supporter
Wollongong
Australia
1488 Posts |
Posted - 17 March 2005 : 11:06:38 AM
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Yeah I agree WOB is more involved than just one part. Scrubber design, flapper valves and bends in gas flow are the most relevent but intuitively I would go for larger bore hose than smaller. For example, I have one of those wizbang snorkles woth the slats in the top that supposedly make it a dry snorklel but I cant use it as I easily overbreathe it. The slats bend the air flow and reduce the bore size at that point and make it essentially useless unless breathing in a very relaxed state. Surely there is a formula for calculating the gas flow characteristics in a rebreather which includes all the variables? I guess an engineer would know this. I still wonder how much real R&D is done on this or if manufacturers just work to the standard bore size, scrubber design etc etc that has gone before, test the final product for WOB on a machine, and hope for the best. I would think that all the money they supposedly spend on these things they would be able to come up with something that would reduce the CO2 problems associated with working at the extreme depth rebreathers are sometimes being used at.
To me it just seems rebreathers are still at the 'Model T' stage. ie. a Homebuilder with enough cash can easily produce something similar. I'm still waiting for a company to step up and develop the 'Formula 1'.
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Edited by - The Phantom Wreck Rat on 17 March 2005 11:12:33 AM |
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Bern
150+ Posts
Lane Cove
Australia
177 Posts |
Posted - 17 March 2005 : 12:08:32 PM
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quote:
Originally posted by The Phantom Wreck Rat
Yeah I agree WOB is more involved than just one part ... I'm still waiting for a company to step up and develop the 'Formula 1'.
I think it has moved beyond the "Model T" - vis-a-vis AP Valves' work on the Insp and Evo - the concept is tried and proven. Didn't the EC approval process ensure that it met certain design standards with regards to WOB and PPO2? More successful dives have been done on AP's units than on any other to my knowledge. Mind you I am not saying these units are perfect, there's always room for improvement. Even a cursory look at the professional finish and detail of the Evo and its impressive electronics proves it's leagues ahead of the competition. This unit makes the rest look like little more than homebuilds. I think it will be years before something comes along that will knock AP off its imposing perch. IMHO.
cheers
Bern |
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Bern
150+ Posts
Lane Cove
Australia
177 Posts |
Posted - 17 March 2005 : 12:08:32 PM
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quote:
Originally posted by The Phantom Wreck Rat
Yeah I agree WOB is more involved than just one part ... I'm still waiting for a company to step up and develop the 'Formula 1'.
I think it has moved beyond the "Model T" - vis-a-vis AP Valves' work on the Insp and Evo - the concept is tried and proven. Didn't the EC approval process ensure that it met certain design standards with regards to WOB and PPO2? More successful dives have been done on AP's units than on any other to my knowledge. Mind you I am not saying these units are perfect, there's always room for improvement. Even a cursory look at the professional finish and detail of the Evo and its impressive electronics proves it's leagues ahead of the competition. This unit makes the rest look like little more than homebuilds. I think it will be years before something comes along that will knock AP off its imposing perch. IMHO.
cheers
Bern |
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The Phantom Wreck Rat
Dive-Oz Supporter
Wollongong
Australia
1488 Posts |
Posted - 17 March 2005 : 12:39:07 PM
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Bern, I think you'll find the Insp started off as a homebuilt as did many of them (Kiss for example). The production materials look nice but nothing that anyone with access to palstics moulding couldnt do. The design was tried and tested many many years before AP came about and just because it passes EC approval doesnt mean much. My car passes many govt and other approvals but is far from formula 1. I guess I'm waiting for someone to really refine the design or come up with something new. I know the cryogenic rebreather design is too impractical and expensive but at least its different ;)
"A man alone, is in bad company." Jacques Yves Cousteau |
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The Phantom Wreck Rat
Dive-Oz Supporter
Wollongong
Australia
1488 Posts |
Posted - 17 March 2005 : 12:39:07 PM
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Bern, I think you'll find the Insp started off as a homebuilt as did many of them (Kiss for example). The production materials look nice but nothing that anyone with access to palstics moulding couldnt do. The design was tried and tested many many years before AP came about and just because it passes EC approval doesnt mean much. My car passes many govt and other approvals but is far from formula 1. I guess I'm waiting for someone to really refine the design or come up with something new. I know the cryogenic rebreather design is too impractical and expensive but at least its different ;)
"A man alone, is in bad company." Jacques Yves Cousteau |
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Robert
Megalodon RB Pilot
Brisbane
Australia
1195 Posts |
Posted - 18 March 2005 : 12:35:27 AM
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OK, my take (I'm leaving the Meg out due to obvious bias):
Ourobouros - This is one possibility for me in the future. It will be interesting to see where this is in a couple of years. Re the buddy display, I would have thought it would save quite a bit of space to use LEDs like the Cis.
Mk 15.x - This is the other possibility for the future. Brilliant design that has so far remained one of the most capable units on the market.
Eagle - This has a heap of potential, but I'd probobly skip over to a Mk15.x instead.
Inspiration - Without the new electronics, it is looking dated. With the vision electronics, it is looking expensive. Neverless, it will probably hold a large market share for years.
Evolution - I can't see this one taking off, to be honest. To be specific, I can't see the types only wanting a limited-capacity unit forking out for one of these when they can pay a much lower price for a SportKISS.
KISS - I think this unit will end up being phased out in favour of the SportKISS.
SportKISS - This one may take off, as I think there's a large photography market that could buy in for non-traditional reasons (bascically stealth to get closer to fish).
C96 variants - I really can't see much point backmounting one small tank. This unit would have much more appeal to me with the O2 on the front and sidemounted dil (ie John Volathen's unit).
Azimuth - Being an SCR, I can't see the point, but others probably can.
Stingray - Didn' get a close enough look at this one to justify a comment.
Optima - This is obviously still in development. I'd like to see more than the same prototype that's been to the last few shows.
Thanks,
Robert |
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Robert
Megalodon RB Pilot
Brisbane
Australia
1195 Posts |
Posted - 18 March 2005 : 12:35:27 AM
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OK, my take (I'm leaving the Meg out due to obvious bias):
Ourobouros - This is one possibility for me in the future. It will be interesting to see where this is in a couple of years. Re the buddy display, I would have thought it would save quite a bit of space to use LEDs like the Cis.
Mk 15.x - This is the other possibility for the future. Brilliant design that has so far remained one of the most capable units on the market.
Eagle - This has a heap of potential, but I'd probobly skip over to a Mk15.x instead.
Inspiration - Without the new electronics, it is looking dated. With the vision electronics, it is looking expensive. Neverless, it will probably hold a large market share for years.
Evolution - I can't see this one taking off, to be honest. To be specific, I can't see the types only wanting a limited-capacity unit forking out for one of these when they can pay a much lower price for a SportKISS.
KISS - I think this unit will end up being phased out in favour of the SportKISS.
SportKISS - This one may take off, as I think there's a large photography market that could buy in for non-traditional reasons (bascically stealth to get closer to fish).
C96 variants - I really can't see much point backmounting one small tank. This unit would have much more appeal to me with the O2 on the front and sidemounted dil (ie John Volathen's unit).
Azimuth - Being an SCR, I can't see the point, but others probably can.
Stingray - Didn' get a close enough look at this one to justify a comment.
Optima - This is obviously still in development. I'd like to see more than the same prototype that's been to the last few shows.
Thanks,
Robert |
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Jason M
Mk15 RB Pilot
Sydney
Australia
1771 Posts |
Posted - 18 March 2005 : 07:52:09 AM
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quote:
Originally posted by Robert
Evolution - I can't see this one taking off, to be honest. To be specific, I can't see the types only wanting a limited-capacity unit forking out for one of these when they can pay a much lower price for a SportKISS.
I think they will, for the same reasons that people buy the Inspiration over the Classic KISS.
quote:
SportKISS - This one may take off, as I think there's a large photography market that could buy in for non-traditional reasons (bascically stealth to get closer to fish).
Hands up everyone who knows of a sport diver who's ordered one of these. Now, hands up everyone who knows a tech/deep diver who's ordered one. Why is Gordon the only person who sees this as a sport unit?
quote:
Optima - This is obviously still in development. I'd like to see more than the same prototype that's been to the last few shows.
Exactly. Why would you go to the trouble of carting an out of date prototype rebreather half way round the world for a show? Maybe because you're having trouble getting the real thing sorted?
Ooh, I missed this in my original post....
The Missing In Action Award
SMI Prism.
For a unit that is supposed to be in production and shipping, you'd reckon they'd at least get one to the show for display, not to mention the ten that were ordered and 50% paid for almost a year ago. (oops I did mention it!)
Jason M. |
Edited by - Jason M on 18 March 2005 07:57:35 AM |
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Jason M
Mk15 RB Pilot
Sydney
Australia
1771 Posts |
Posted - 18 March 2005 : 07:52:09 AM
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quote:
Originally posted by Robert
Evolution - I can't see this one taking off, to be honest. To be specific, I can't see the types only wanting a limited-capacity unit forking out for one of these when they can pay a much lower price for a SportKISS.
I think they will, for the same reasons that people buy the Inspiration over the Classic KISS.
quote:
SportKISS - This one may take off, as I think there's a large photography market that could buy in for non-traditional reasons (bascically stealth to get closer to fish).
Hands up everyone who knows of a sport diver who's ordered one of these. Now, hands up everyone who knows a tech/deep diver who's ordered one. Why is Gordon the only person who sees this as a sport unit?
quote:
Optima - This is obviously still in development. I'd like to see more than the same prototype that's been to the last few shows.
Exactly. Why would you go to the trouble of carting an out of date prototype rebreather half way round the world for a show? Maybe because you're having trouble getting the real thing sorted?
Ooh, I missed this in my original post....
The Missing In Action Award
SMI Prism.
For a unit that is supposed to be in production and shipping, you'd reckon they'd at least get one to the show for display, not to mention the ten that were ordered and 50% paid for almost a year ago. (oops I did mention it!)
Jason M. |
Edited by - Jason M on 18 March 2005 07:57:35 AM |
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Richard Harris
DiveBum in training
Adelaide
Australia
519 Posts |
Posted - 18 March 2005 : 08:43:27 AM
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Excuse my ignorance but can someone explain how Colkan fits into the Mk series scheme. The history of these has always been confusing to me with the USN then Biomarine and Jurgensen etc. I am confused!!
What rb do Colkan make and do they have a website? Is Colin Wilcox = Colkan?
"Harry"
www.divedoc.net |
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Richard Harris
DiveBum in training
Adelaide
Australia
519 Posts |
Posted - 18 March 2005 : 08:43:27 AM
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Excuse my ignorance but can someone explain how Colkan fits into the Mk series scheme. The history of these has always been confusing to me with the USN then Biomarine and Jurgensen etc. I am confused!!
What rb do Colkan make and do they have a website? Is Colin Wilcox = Colkan?
"Harry"
www.divedoc.net |
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Jason M
Mk15 RB Pilot
Sydney
Australia
1771 Posts |
Posted - 18 March 2005 : 09:53:25 AM
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quote:
Originally posted by Richard Harris
Excuse my ignorance but can someone explain how Colkan fits into the Mk series scheme. The history of these has always been confusing to me with the USN then Biomarine and Jurgensen etc. I am confused!!
Well, it's a long story but I'll keep it short.
Biomarine invented the CCR1000.
Biomarine made minor changes to make the Mk15 and the USN bought them.
Biomarine upgraded the design and it became the Mk16.
Biomarine made a hybrid of the two for non-mine USN work and called it the Mk15.5. The USN decided to stick with the Mk16 but kept the original 26 Mk15.5's.
Carleton aquired all tooling and parts from Biomarine.
Colin Wilcox became the Australian dealer for Carleton, and he aquired all Mk15 and Mk15.5 parts from them as they weren't interested in anything but the Mk16. Colin also did all support and maintenance on the A5800, the RAN name for the Mk16.
Kevin Juergensen aquired Mk15's from the USN disposal. These he rebuilt and sold over a number of years. Total number around 10.
Peter Ready (and some other people independently) aquired some of the original 26 USN Mk15.5's, incomplete.
Peter Ready bought the rest of the components to get his Mk15.5's going from Colin. He then sold them as the Steam Machines SM1600. Total number around 12.
Colin built Mk15.5's, as he still does, from factory parts.
Colin sold his old company along with its RAN contracts and moved to the north coast, where he has bought a factory and is still making Mk15.5's and developing the Eagle.
quote:
What rb do Colkan make and do they have a website? Is Colin Wilcox = Colkan?
Yes, the name Colkan comes from COLin and KANe Wilcox. There are three rebreathers in thier line-up, the Mk15.5 mixed gas CCR, the Eagle mixed gas CCR, and the Cobra O2 unit. No website has been set up, though I've been hounding Col to get something up.
Jason M.
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Jason M
Mk15 RB Pilot
Sydney
Australia
1771 Posts |
Posted - 18 March 2005 : 09:53:25 AM
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quote:
Originally posted by Richard Harris
Excuse my ignorance but can someone explain how Colkan fits into the Mk series scheme. The history of these has always been confusing to me with the USN then Biomarine and Jurgensen etc. I am confused!!
Well, it's a long story but I'll keep it short.
Biomarine invented the CCR1000.
Biomarine made minor changes to make the Mk15 and the USN bought them.
Biomarine upgraded the design and it became the Mk16.
Biomarine made a hybrid of the two for non-mine USN work and called it the Mk15.5. The USN decided to stick with the Mk16 but kept the original 26 Mk15.5's.
Carleton aquired all tooling and parts from Biomarine.
Colin Wilcox became the Australian dealer for Carleton, and he aquired all Mk15 and Mk15.5 parts from them as they weren't interested in anything but the Mk16. Colin also did all support and maintenance on the A5800, the RAN name for the Mk16.
Kevin Juergensen aquired Mk15's from the USN disposal. These he rebuilt and sold over a number of years. Total number around 10.
Peter Ready (and some other people independently) aquired some of the original 26 USN Mk15.5's, incomplete.
Peter Ready bought the rest of the components to get his Mk15.5's going from Colin. He then sold them as the Steam Machines SM1600. Total number around 12.
Colin built Mk15.5's, as he still does, from factory parts.
Colin sold his old company along with its RAN contracts and moved to the north coast, where he has bought a factory and is still making Mk15.5's and developing the Eagle.
quote:
What rb do Colkan make and do they have a website? Is Colin Wilcox = Colkan?
Yes, the name Colkan comes from COLin and KANe Wilcox. There are three rebreathers in thier line-up, the Mk15.5 mixed gas CCR, the Eagle mixed gas CCR, and the Cobra O2 unit. No website has been set up, though I've been hounding Col to get something up.
Jason M.
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Bern
150+ Posts
Lane Cove
Australia
177 Posts |
Posted - 18 March 2005 : 10:31:26 AM
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quote:
Originally posted by The Phantom Wreck Rat
Bern, I think you'll find the Insp started off as a homebuilt as did many of them (Kiss for example). The production materials look nice but nothing that anyone with access to palstics moulding couldnt do. The design was tried and tested many many years before AP came about and just because it passes EC approval doesnt mean much. My car passes many govt and other approvals but is far from formula 1. I guess I'm waiting for someone to really refine the design or come up with something new. I know the cryogenic rebreather design is too impractical and expensive but at least its different ;)
"A man alone, is in bad company." Jacques Yves Cousteau
Phantom, I don't know that there is anything "new" to come up with in rebreathers. Afterall, the technology predates OC by many decades (I recall reading somewhere rebreather technology was being used or experimented with in the late 19th C. By WWI it was well established, along with submarines). It's basically a loop with a scubber inserted in the middle of it. The "new" technology part is all in the electronics, and the rest is just fiddling about with the basics, eg scrubber sizes and shapes, loop diameters, 2nd stage hose pressures, upstream, downstream vales etc - amounting to small improvements of efficiency that may help on a seriously deep dive. Other than Draeger and AP, what other biggish companies are building these? The rest are tinkerers in backyard-style workshops. The next best bet is possibly Delta P's Boris, but that's yet to be tested in the marketplace, and we're still waiting on the Nemesis.
Bern
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Bern
150+ Posts
Lane Cove
Australia
177 Posts |
Posted - 18 March 2005 : 10:31:26 AM
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quote:
Originally posted by The Phantom Wreck Rat
Bern, I think you'll find the Insp started off as a homebuilt as did many of them (Kiss for example). The production materials look nice but nothing that anyone with access to palstics moulding couldnt do. The design was tried and tested many many years before AP came about and just because it passes EC approval doesnt mean much. My car passes many govt and other approvals but is far from formula 1. I guess I'm waiting for someone to really refine the design or come up with something new. I know the cryogenic rebreather design is too impractical and expensive but at least its different ;)
"A man alone, is in bad company." Jacques Yves Cousteau
Phantom, I don't know that there is anything "new" to come up with in rebreathers. Afterall, the technology predates OC by many decades (I recall reading somewhere rebreather technology was being used or experimented with in the late 19th C. By WWI it was well established, along with submarines). It's basically a loop with a scubber inserted in the middle of it. The "new" technology part is all in the electronics, and the rest is just fiddling about with the basics, eg scrubber sizes and shapes, loop diameters, 2nd stage hose pressures, upstream, downstream vales etc - amounting to small improvements of efficiency that may help on a seriously deep dive. Other than Draeger and AP, what other biggish companies are building these? The rest are tinkerers in backyard-style workshops. The next best bet is possibly Delta P's Boris, but that's yet to be tested in the marketplace, and we're still waiting on the Nemesis.
Bern
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Rebreather line-up at OzTek4 |
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