For this reason, most long-hose divers with yellow regulator covers that I've seen put the yellow on their primary and not their backup. Of course, the argument then is that it confuses the same good-intentioned recreational divers, who wonder why you're always breathing off of your octo.
DIR compliant regulator?
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For this reason, most long-hose divers with yellow regulator covers that I've seen put the yellow on their primary and not their backup. Of course, the argument then is that it confuses the same good-intentioned recreational divers, who wonder why you're always breathing off of your octo.
lamont
Contributor
I used to use apeks and had a variety of AT[X]40/50/100/200 regs. I never noticed much of a breathability difference between any of them. I would have recommended AT50/ATX50 regs with DS4 first stages since they're cheap, breathable and are adjustable underwater (I don't know about the new XTX ones, but i'll bet the XTX50s breathe almost identical to the XTX200s).
When I bought atomics, I went with the Z2s and have been happy with those. I haven't tried the rest of the line out, but I don't think I'm missing anything...
So, "quality regulator" does not necessarily mean the most expensive ones you can find. The advice is really to avoid some of the awful bargin basement ones and the ones often sold as dedicated octos.
It seems like every reg manufacturer makes a high-end line of regulators, where the low end of that line has the same underlying engineering and breathes just as well as the $2000 titanium one with the gold plated accents and diamond studs....
When I bought atomics, I went with the Z2s and have been happy with those. I haven't tried the rest of the line out, but I don't think I'm missing anything...
So, "quality regulator" does not necessarily mean the most expensive ones you can find. The advice is really to avoid some of the awful bargin basement ones and the ones often sold as dedicated octos.
It seems like every reg manufacturer makes a high-end line of regulators, where the low end of that line has the same underlying engineering and breathes just as well as the $2000 titanium one with the gold plated accents and diamond studs....
PfcAJ
Contributor
I didn't want a yellow back-up because I didn't want to get in a situation where a well-trained, good-intentioned, recreational diver came up to me in an OOG situation and grabbed for my yellow octo....with it being around my neck and them yanking on it, I'm likely to get upset.
With the black, it's stealth....they'll never see it and go straight for what's in my mouth
You're on the wrong boats! :blinking:
Many divers prefer the hose routing possible with the Mk 25 (and first stages with similar layouts incorporating an L shaped first stage and an end port in a swivel turret).
Personally, on a set of doubles I prefer the Mk 17 as it has a more conventional port layout (1 HP port and 2 LP ports per side) found on various first stages (such as Apeks, Aqualung and Poseiden) that allows you to mount each first stage on the right or left post with 2 or 3 hoses routed essentially straight down off each reg. I think it is slightly cleaner than the Mk 25 style routing, but both work well and it is a personal choice.
However, on a single tank rig, the Mk 25 hose routing is much cleaner. When you go beyond 2 LP hoses on one Mk 17 you have to mount the reg right side up and you get hoses coming off each side rather than straight down. Messy in my opinion.
With regard to the primary and secondary regs, both of them should offer the same level of performance. And remember that you will be using the secodary reg in the event you are donating gas.
In the past there has been lots of discussion of failure modes and second stage design with a resulting theory being that you should have a balanced primary second stage and an unbalanced secondary second stage to reduce the chance of the same environmental conditons causing both second stages to fail.
As a reg tech I think that is bascially flawed thinking. Second stage failures are rare and most are precipitated by a first stage problem with IP. Any second stage failure that results in a failure to deliver air (as opposed to a free flow) is exceptionally rare and is all but never going to happen twice on the same dive regardless of the second stage designs you use.
Unbalanced designs have to have more spring pressure on the seat to keep it closed and this additional pressure is present even when the reg is depresurized. That leads to more seat wear and a tendendcy for an excessively large seatign groove to develop faster. That in turn increases the potential for a slight freeflow to develop sooner than in a balanced second stage.
Plus when you add in another design, you complicate your logistics in terms of parts and tools needed in the field in the event you need to make a repair. Also, an unbalanced second stage is much more sensitive to changes in IP. So unless all your first stages are tuned to the same IP, it can be problematic to switch an unbalanced second stage from one first stage to another. Personally, I use the same second stage model on all my back gas and deco regs (G250) and then carry a spare on a trip so that I can resolve any mechanical issue that may develop by just swapping the second stage rather than tearing the reg apart in the field.
All other things being equal, an unbalanced design can have inhalation efforts as good as a balanced design, assuming both are used on a balanced first stage. The R109/R156 and G200/G200B comparisions are good examples as the regs are identical in every way except for balanced versus unbalanced poppets in each pair. However most of the time, all things are not equal and it is common for unbalanced regs to have higher inhalation efforts and increased work of breathing that can result in CO2 retention that can in turn make the diver more prone to Ox tox and nitrogen narcosis.
So unless you are really using an unbalanced reg like a G200 that will in fact compare well to its balanced counterpart (a G200B or the same except also adjustable G250 in this case) you are far better off using two balanced regs. It should be noted here that Scubapro no longer sells any unbalanced regs that are otherwise identical to their balanced regs. That ended when the G200 was discontinued. The current R series regs all use the basic R190 poppet and have nothing in common with any of the balanced second stages and in general have much poorer performance.
As for having a cover that is removeable, I think it is a fine idea in theory but problematic in the real world. Some covers are very easy to remove and have few parts to lose (the G250 for example screws off, and when off you have the cover, a ring and the diaphragm). Others however have either more parts, small easy to lose parts or parts that have to be properly aligned or indexed to reassemble and that can be problematic in open water, in a high flow, system or in a siltout. So if you want to ascribe to the "taking the reg apart underwater is a plus" theory, be sure you look at exactly what will have to happen in order to do it with an eye to all the things that could go wrong in the dark or while bouncing up and down on a hang line in a current and then factor that into your reg selection choice.
There is no pin locking the cover in a G250 and I take the pins out of my two G250V's, so I maintain the ability to easily remove the covers but I have no plans to ever take the covers off under water. If I did so it would be a last resort kind of thing.
Personally, on a set of doubles I prefer the Mk 17 as it has a more conventional port layout (1 HP port and 2 LP ports per side) found on various first stages (such as Apeks, Aqualung and Poseiden) that allows you to mount each first stage on the right or left post with 2 or 3 hoses routed essentially straight down off each reg. I think it is slightly cleaner than the Mk 25 style routing, but both work well and it is a personal choice.
However, on a single tank rig, the Mk 25 hose routing is much cleaner. When you go beyond 2 LP hoses on one Mk 17 you have to mount the reg right side up and you get hoses coming off each side rather than straight down. Messy in my opinion.
With regard to the primary and secondary regs, both of them should offer the same level of performance. And remember that you will be using the secodary reg in the event you are donating gas.
In the past there has been lots of discussion of failure modes and second stage design with a resulting theory being that you should have a balanced primary second stage and an unbalanced secondary second stage to reduce the chance of the same environmental conditons causing both second stages to fail.
As a reg tech I think that is bascially flawed thinking. Second stage failures are rare and most are precipitated by a first stage problem with IP. Any second stage failure that results in a failure to deliver air (as opposed to a free flow) is exceptionally rare and is all but never going to happen twice on the same dive regardless of the second stage designs you use.
Unbalanced designs have to have more spring pressure on the seat to keep it closed and this additional pressure is present even when the reg is depresurized. That leads to more seat wear and a tendendcy for an excessively large seatign groove to develop faster. That in turn increases the potential for a slight freeflow to develop sooner than in a balanced second stage.
Plus when you add in another design, you complicate your logistics in terms of parts and tools needed in the field in the event you need to make a repair. Also, an unbalanced second stage is much more sensitive to changes in IP. So unless all your first stages are tuned to the same IP, it can be problematic to switch an unbalanced second stage from one first stage to another. Personally, I use the same second stage model on all my back gas and deco regs (G250) and then carry a spare on a trip so that I can resolve any mechanical issue that may develop by just swapping the second stage rather than tearing the reg apart in the field.
All other things being equal, an unbalanced design can have inhalation efforts as good as a balanced design, assuming both are used on a balanced first stage. The R109/R156 and G200/G200B comparisions are good examples as the regs are identical in every way except for balanced versus unbalanced poppets in each pair. However most of the time, all things are not equal and it is common for unbalanced regs to have higher inhalation efforts and increased work of breathing that can result in CO2 retention that can in turn make the diver more prone to Ox tox and nitrogen narcosis.
So unless you are really using an unbalanced reg like a G200 that will in fact compare well to its balanced counterpart (a G200B or the same except also adjustable G250 in this case) you are far better off using two balanced regs. It should be noted here that Scubapro no longer sells any unbalanced regs that are otherwise identical to their balanced regs. That ended when the G200 was discontinued. The current R series regs all use the basic R190 poppet and have nothing in common with any of the balanced second stages and in general have much poorer performance.
As for having a cover that is removeable, I think it is a fine idea in theory but problematic in the real world. Some covers are very easy to remove and have few parts to lose (the G250 for example screws off, and when off you have the cover, a ring and the diaphragm). Others however have either more parts, small easy to lose parts or parts that have to be properly aligned or indexed to reassemble and that can be problematic in open water, in a high flow, system or in a siltout. So if you want to ascribe to the "taking the reg apart underwater is a plus" theory, be sure you look at exactly what will have to happen in order to do it with an eye to all the things that could go wrong in the dark or while bouncing up and down on a hang line in a current and then factor that into your reg selection choice.
There is no pin locking the cover in a G250 and I take the pins out of my two G250V's, so I maintain the ability to easily remove the covers but I have no plans to ever take the covers off under water. If I did so it would be a last resort kind of thing.
orange_diver
Contributor
AFAIC, nothing. I dove with a yellow harness for over a year
doesn't mean your buddies were happy about it. :mooner:
Thankyou aquamaster thats what I was looking to here, I currently have a mk25/G250 and just kept hearing the other models of first and second stages (mk17, mk20, s600, etc..) tossed around in conversation, and after reading the DIR fundamentals book it had mentioned employing the use of balanced/unbalanced second stages. I just wanted to get some insight on that. Also whats the difference between the G250 and G250V?
The G250V is the reincarnation of the original G250 that was discontined in the 1990's. The differences are very minor and mostly cosmetic and both are an improvement over the G250HP that replaced the G250.
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