Poseidon Extreme Vs. "Standard" design regs

[Mark Vlahos]

I am looking at getting regulators for double tanks. I will use the regs in caves and at depths of around 150 feet on air or NITROX gasses. I am not now trained in the use of breathing gasses that contain Helium but I might be someday and I want to consider regs that will not have problems with it. I am considering all of the usual suspects like high end regulators from Apeks, Aqualung, ScubaPro, DiveRite, Zeagle, and others. Frankly, most of these major companies produce regs that are very similar in design and performance. I understand the differences between piston and diaphragm first stages, but for the most part all of the second stages pretty much work the same.

And then there is Poseidon. The Extreme series regulators are cut from a different cloth. The first stage design looks good but seems almost too simple, begging the question that if it is so simple and rugged, why is it the only one like it? If it is so good why aren't the other companies swarming to copy it?

The second stage is an upstream design, these are not popular. Poseidon seems comfortable with the upstream design they use.

I guess what I am really asking is the Poseidon regs look really good to me, but the design philosophies are so different. Is there some inherent flaw in the concept or is it so different, almost revolutionary, that the rest of the industry is stuck in a rut making pretty much the same regulator, while Poseidon is in a class by itself (and is this class superior)?

The regulators are very expensive, some of the other regs I have been looking at are close in price but others are less than half the cost (Apeks for example). Is it worth the considerable price difference? Deep inside a cave is definitely NOT the place I want a failure, but I don't want to throw my money away.

Mark Vlahos

 

[padiscubapro]

I am looking at getting regulators for double tanks. I will use the regs in caves and at depths of around 150 feet on air or NITROX gasses. I am not now trained in the use of breathing gasses that contain Helium but I might be someday and I want to consider regs that will not have problems with it. I am considering all of the usual suspects like high end regulators from Apeks, Aqualung, ScubaPro, DiveRite, Zeagle, and others. Frankly, most of these major companies produce regs that are very similar in design and performance. I understand the differences between piston and diaphragm first stages, but for the most part all of the second stages pretty much work the same.

And then there is Poseidon. The Extreme series regulators are cut from a different cloth. The first stage design looks good but seems almost too simple, begging the question that if it is so simple and rugged, why is it the only one like it? If it is so good why aren't the other companies swarming to copy it?

The second stage is an upstream design, these are not popular. Poseidon seems comfortable with the upstream design they use.

I guess what I am really asking is the Poseidon regs look really good to me, but the design philosophies are so different. Is there some inherent flaw in the concept or is it so different, almost revolutionary, that the rest of the industry is stuck in a rut making pretty much the same regulator, while Poseidon is in a class by itself (and is this class superior)?

The regulators are very expensive, some of the other regs I have been looking at are close in price but others are less than half the cost (Apeks for example). Is it worth the considerable price difference? Deep inside a cave is definitely NOT the place I want a failure, but I don't want to throw my money away.

Mark Vlahos

When I dove OC, I used poseidons for a long time, I tried just about every reg out there and I always end up going back to the poseidons.. nothing breaths like them at depth.. The older first stages are a bit of a trick to work on but work well..

The new extreme first stages can deliever more gas than anthing else I have ever tried.. I have tried various regs at depth having two people trying to braeth off of them and see how they fair.. Alot of regs that perform great don;t perform as well during this test... I have done this with Atomics (they did ok), scubapro mk25 was good, apeks did slightly better, the older posiedons a bit better than that, but the extreme was unbelieveable, none of the people could tell the difference of one diver or two trying to breath off the same first stage.. These are subjective tests and the results could probably vary at various intermediate pressures.

The original poseidon took alond time to copy its ideas (they were patented) but people like oceanic and sherwood have licensed them in the past, and some now use feautes in theor own designs.. The new extreme designs are patented as well and the design is simple and very effective.. I think others will try and do similiar designs but it will be tricky not infringing on some of the patents..

To give you an idea of the flow rates capable (these ballpark numbers are from memory for exact numbers check each manufacturer's specs) the flow rate the xtreme is capable of is around 5500 lpm where a typical high performance first stage is typically somehwere around 2500 lpm or less ..

The posedions are the only reg in the world that meets CE breathing standards all the way to 200m..

 

[rescuediver009]

He is right, and if you can afford it and can have them serviced, I would definetely consider them. I used the original extreme design under the ice and it worked great. When the apeks required some fiddling with the adjustment (because it was tuned to well) the xstreme was doing fine. Their design on the first stage eliminates the need for any kind of environmental separation altogether. Simply, it vents the first stage so well that there is nowhere for the water to accumulate. This design has been copied by the likes of the legend and other regs.
The only reason that I think no one copied it is because of the upstream design the tends to stray from recreational principles. The copies of sherwood and other companies just used the jetstream second stage.

I would strongly recommend the poseidon.

 

[Greg Barlow]

To give you an idea of the flow rates capable (these ballpark numbers are from memory for exact numbers check each manufacturer's specs) the flow rate the xtreme is capable of is around 5500 lpm where a typical high performance first stage is typically somehwere around 2500 lpm or less ..

The posedions are the only reg in the world that meets CE breathing standards all the way to 200m..[/QUOTE]


I agree that the Xstream is an excellent design, but the flow rate of the first stage is actually around 4,200 lpm, which works out to around 150 scfm. That is pretty much a standard for many of today's "mid to higher end" balanced diaphragm designs. Scuba Pro's MK16, along with Mares's V16 have virtually the same gas flow rate. It is pretty tough to get a flow rate above 4,500 on a balanced diaphragm design due to the limited orifice size that can be engineered into a unit that isn't montrous in size.

A balanced piston first stage is able to use such a large orifice that flow rates of 5,000 lpm are pretty much the standard.

Of course, when you consider the maximum flow rates of second stages, and the actual work load that a person can sustain, such flow rates become little more than a bragging point. Any reg that can meet 4,000 lpm and has a decent second stage can typically meet US Navy Class "A" standards.

In fact, Poseidon lists their Xstream second stage as having a capacity of around 2,150 lpm. This means that if the first stage is flowing at around 4,200, then two second stages in a free flow would just barely exceed the first stage's capability.

Also, I don't believe that CE standards actually exist for depths of 200m. What I believe Poseidon was alluding to is that their WOB still meets the CE standard of less than 3.0 j/l at those depths. This was using a heliox blend, so the reg would have the advantage of moving gas considerably less dense than if it were attempting to move air at those depths. The higher the helium portion, the easier the process of moving the gas. Testing air at depths exceeding 60m is in my opinion pointless anyway, as NOBODY should be breathing air at depths greater than 50m.

When I worked for Rodale's magazine, one of the testers used trimix on a ANSTI machine to actually see the difference in WOB at 60m. A drop in excess of 0.5 j/l was the figure if my memory serves me correctly. The greater the depth the more the difference due to gas density.

Please don't get me wrong...The Poseidon Xstream is a great reg. It is one of the prime examples of the many great models that are available to today's divers. Divers have never had it so good....

Greg Barlow
Former Science Editor for Rodale's Scuba Diving Magazine

 

[Kleber Verraes]

Mark,

I know the Poseidon regulators quite well and the latest model (Xstream) is really the best regulator you can take with you under the water for deep diving. It is reliable, strong and has all the benefits of Poseidon's long experience with other excelent regulators, in particular the CYCLON model. In fact, the design of the 2nd stage has always been revolutionary at Poseidon, they never followed the other manufacturers "traditional" design. Poseidon's main characteristic has been the reduced size of their second stage and very solid 1st stages, ideal for diving in cold waters and extreme conditions. Accordingly, Poseidon is used by the German Navy, the US Navy and, of course the Swedish Navy.

Having said that, the only problem you can have (as a owner of a Poseidon) is if you live outiside Europe or North America. Then finding reliable maintenance (for the annual inspection and repairs) for Poseidon in Latin America can be a nightmare and a very costly experience. I am living in Brazil, here it is impossible finding spare parts or servicing for Poseidon. The only other manufahhtcturer in the world following Poseidon's concept and design is OCEANIC, from the US. In fact the OMEGA II model is almost a copy of a Poseidon, both the second stage and the first. I have two OMEGA II (with the DX-4 balanced diaphragm first stage/300 bar DIN). They are excellent and have been produced by OCEANIC, with this same design, for more than 20 years. At the end of the day, the quality of a reg is mesured by each and every diver under the water; when you breath very easily and you don't need to carry a heavy first stage in your mouth, then you know you got a goog regulator. If you want a very good regulator, but you live in a country without Poseidon authorised dealers, then the OMEGA II is the best for you (but you need the DX-4 Balanced Diaphragm first stage/300 bar DIN).

I am looking at getting regulators for double tanks. I will use the regs in caves and at depths of around 150 feet on air or NITROX gasses. I am not now trained in the use of breathing gasses that contain Helium but I might be someday and I want to consider regs that will not have problems with it. I am considering all of the usual suspects like high end regulators from Apeks, Aqualung, ScubaPro, DiveRite, Zeagle, and others. Frankly, most of these major companies produce regs that are very similar in design and performance. I understand the differences between piston and diaphragm first stages, but for the most part all of the second stages pretty much work the same.

And then there is Poseidon. The Extreme series regulators are cut from a different cloth. The first stage design looks good but seems almost too simple, begging the question that if it is so simple and rugged, why is it the only one like it? If it is so good why aren't the other companies swarming to copy it?

The second stage is an upstream design, these are not popular. Poseidon seems comfortable with the upstream design they use.

I guess what I am really asking is the Poseidon regs look really good to me, but the design philosophies are so different. Is there some inherent flaw in the concept or is it so different, almost revolutionary, that the rest of the industry is stuck in a rut making pretty much the same regulator, while Poseidon is in a class by itself (and is this class superior)?

The regulators are very expensive, some of the other regs I have been looking at are close in price but others are less than half the cost (Apeks for example). Is it worth the considerable price difference? Deep inside a cave is definitely NOT the place I want a failure, but I don't want to throw my money away.

Mark Vlahos

 

[Greg Barlow]

To give you an idea of the flow rates capable (these ballpark numbers are from memory for exact numbers check each manufacturer's specs) the flow rate the xtreme is capable of is around 5500 lpm where a typical high performance first stage is typically somehwere around 2500 lpm or less ..


I checked on this figure of 5,500 lpm and found that early printed materials from Poseidon were using this figure. Later, the owner's manuals were using the figure of around 4,000 lpm as the first stage flow potential. I checked with the Poseidon web site and they list 5,500 as the figure, but the supplied owner's manuals in English state 4,000 as the figure. Like I said earlier, when one considers the mechanical principles of a diaphragm design, flow greater than 4,500 is pretty tough to achieve. Plus, if the second stage has a high figure flow rate of 2,150 then the 5,500 figure becomes a moot point.

Regardless of the first stage potential, it is a fine regulator. The only debatable point that I can find with it is that of the upstream design of the second stage. Poseidon owners will pay a premium for hoses due to the overpressurization release built into the hose.

I believe that one of the wisest moves that the engineers went to was that of placing the exhaust valve on the front of the body. This should eleviate the wet breathing characteristics that were so common with the earlier models.

Greg Barlow

 

[padiscubapro]

To give you an idea of the flow rates capable (these ballpark numbers are from memory for exact numbers check each manufacturer's specs) the flow rate the xtreme is capable of is around 5500 lpm where a typical high performance first stage is typically somehwere around 2500 lpm or less ..

The posedions are the only reg in the world that meets CE breathing standards all the way to 200m..

I agree that the Xstream is an excellent design, but the flow rate of the first stage is actually around 4,200 lpm, which works out to around 150 scfm. That is pretty much a standard for many of today's "mid to higher end" balanced diaphragm designs. Scuba Pro's MK16, along with Mares's V16 have virtually the same gas flow rate. It is pretty tough to get a flow rate above 4,500 on a balanced diaphragm design due to the limited orifice size that can be engineered into a unit that isn't montrous in size.

A balanced piston first stage is able to use such a large orifice that flow rates of 5,000 lpm are pretty much the standard.

Of course, when you consider the maximum flow rates of second stages, and the actual work load that a person can sustain, such flow rates become little more than a bragging point. Any reg that can meet 4,000 lpm and has a decent second stage can typically meet US Navy Class "A" standards.

In fact, Poseidon lists their Xstream second stage as having a capacity of around 2,150 lpm. This means that if the first stage is flowing at around 4,200, then two second stages in a free flow would just barely exceed the first stage's capability.

Also, I don't believe that CE standards actually exist for depths of 200m. What I believe Poseidon was alluding to is that their WOB still meets the CE standard of less than 3.0 j/l at those depths. This was using a heliox blend, so the reg would have the advantage of moving gas considerably less dense than if it were attempting to move air at those depths. The higher the helium portion, the easier the process of moving the gas. Testing air at depths exceeding 60m is in my opinion pointless anyway, as NOBODY should be breathing air at depths greater than 50m.

When I worked for Rodale's magazine, one of the testers used trimix on a ANSTI machine to actually see the difference in WOB at 60m. A drop in excess of 0.5 j/l was the figure if my memory serves me correctly. The greater the depth the more the difference due to gas density.

Please don't get me wrong...The Poseidon Xstream is a great reg. It is one of the prime examples of the many great models that are available to today's divers. Divers have never had it so good....

Greg Barlow
Former Science Editor for Rodale's Scuba Diving Magazine[/QUOTE]


the poseidon 5500lpm rating is directly from their website on the extreme, that one I verified from their web site before posting....
http://www.poseidon.se/bild.dip?id=364

The 200m limit is just as you suggest.. There is no CE cert for 200m but the reg meets the normal limits at 200m

If all the regs stated could easily achive those rates there would be no noticible difference when 2 divers were breathing off a tank at depth, this was not what I have seen..

for laminar flow, we can say flow resistance is inversely proportional to the square root of the gas density.. basically if you double the density it takes about 1.4 times more effort to breath the gas..
The poseidons (second stages) tend to "force" gas into the divers mouth with just a small inhalation effort..

 

[Greg Barlow]

(If all the regs stated could easily achive those rates there would be no noticible difference when 2 divers were breathing off a tank at depth, this was not what I have seen..

for laminar flow, we can say flow resistance is inversely proportional to the square root of the gas density.. basically if you double the density it takes about 1.4 times more effort to breath the gas..
The poseidons (second stages) tend to "force" gas into the divers mouth with just a small inhalation effort..[/QUOTE])


I am now wondering if the two figures posted by Poseidon are for air flow through the first stage port and for a heliox blend. If I owned one, I could set-up an experiment where the LP ports are left without the hoses and plugs to determine just how fast a tank of air could be emptied. You could then calculate the gas flow to a fairly accurate level. This may very well be what is going on with the two figures. Like I mentioned, I have an English copy of the owner's manual for the unit. It states under the technical informaton: "first stage flow rate (l/min): >4000 l/min (>141 scfm).

The laminar flow equation also makes me think that the higher flow is for the heliox blend. If a dive were being made to 200m and heliox 6/94 were used as the back gas then its lesser density could account for the figure of the 1.4 difference that you state. Mathematically, this would work out to around 5,500 l/min. Interesting....I wonder if any of Poseidon's engineers could answer this question...

Regardless, one other reason why many divers like the Poseidon's "trap door effect" is due to the mechanical properties of the servo valve. When the internal pressure drop opens the primary valve there is a sudden rush of gas. Myself, I never did care for this while using the older Poseidon models. It made me feel like gas was literally being blasted down my throat. When I was diving back in the 70s, the Poseidons without a doubt were the best for deep diving. I just never could get used to the "trap door effect". Others feel it is quite reassuring to have such large quantities of gas available. The last time I dove Poseidons was with recently serviced Jet Streams. They offered plenty of gas, but also made me feel like the inhalation was of a positive pressure mode.

Reports on the Xstream are mixed regarding this effect. Some divers state that it is like that of the earlier models, while others say it is much less pronounced.

I do know from speaking to other divers that own other brands of servo valve regs, that this is a common feeling with their models too. It may just be a mechanical property of using the servo mechanism.

Well....I've been thinking about buying a new reg....

Greg Barlow

 

[Mark Vlahos]

The flow rates look good for really deep stuff and provide a nice cushion for moderately deep stuff. In short the first stage looks like it is a winner on all counts, I don't see any major flaws. If there are any only time will tell, since the product is still relatively new to the market, it will take years for any long term problems to become fully evident.

The second stage is where I have some reservations. I have spoken with several shops and specifically the repair technicians. I have been told that there is a history on the older Jetstream second stage where you need to be extremely vigilant when it comes to rinsing after a salt water dive. Salt crystals can easily form on the surfaces inside the second stage leading to free flows and expensive repairs. The extreme second stage is an evolutionary design based on the Jetstream and while different may be subject to the same concerns. Only time will tell on this one, it is certainly possible that some of the differences between the two second stages address this specific problem.

Another issue with the extreme comes to light when your tank pressure becomes extremely low, it is also illustrated when you open the tank valve. At extremely low pressures the second stage has a deisgn that causes a free flow. When opening a tank valve before beginning a dive or even during a valve drill at the end of one this does not present a problem. If however circumstance has presented you with this problem during a dive your small amount of remaining air will bleed out of your tank and leave you with NO air sooner.

Before I get a lot of posts letting me know that I should never let my breathing gas get so low, let me say now that I already know that. I did however indicate in my initial post that I would be using these in a cave, and if I am doing a cave dive with a buddy that needs emergency assistance and he or I need to invade my 1/3 reserve gas supply that supply would need to be padded by the 200 or 300 PSI involved in the low tank pressure free flow issue. This would effect my turn pressure and would need to be considered in all aspects of gas planning for a cave dive. I think it would have less of an issue on an open water dive because of the free route to the surface. It would need to be accounted for in planning deep and or decompression dives or wreck penetrations.

The issue of the upstream versus downstream valve design seems in and of itself have no real problems when you consider the relief valve on the hose.

The long term concerns are about maintenance, and service relating to salt crystals, and my initial research is inconclusive as more time is needed. It should however be considered that Poseidon does not have a "free parts for life" type of parts warranty as many (but not all) other manufacturers do, so the salt crystal issue can get expensive. I understand that normal maintenance parts are relatively inexpensive, but if you need certain specialized parts the bill can add up quickly.

The low pressure free flow issue can be addressed in gas planning but if you find yourself in the unfortunate position of needing the last 200 PSI to get out of a really nasty predicament the price can be quite high.

Mark Vlahos

 

[Mark Vlahos]

By the way, I noticed that all of the posts in this thread are longish. These reflect well thought out and detailed replies, not quick 3 word answers that at best only reflect an opinion, but can have no supporting information.

Thank you, to all who have posted here for your time.

Mark Vlahos