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Fidelis

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TL/DR: Poseidon XStream, Mares Abyss 22 Navy II, and Interspiro RS4 have been harshly tested to 198ft at 29 ± 1°F (-1.7 ± 0.6°C). This exceeds any nationally approved standard.

Information in this post is only as good as the date of this post, the Navy may add or subtract something from their list.

Longer exploration:

If you like the reg you are using, and are comfortable with the amount of risk you are assuming, more power to you.

I have not seen this information gathered in one place before in a post, so I am making it for the benefit of others to better help then choose the degree of risk they want to assume.

As we all (should) know, there are no US standards for recreational SCUBA gear. There *is* in Europe and the current standard is EN250:2014. We also know that manufacturers can get away with saying something without actually saying something, so we have to rely on certain standards/testing.

Unfortunately, it costs a great deal of money to get a copy of EN 250, so I am gleaning information from various sources.

If your regulator is marked with or the documentation says it meets "EN 250:2014" then it has been tested to 50 m/164 ft and water temperatures as low as 4 °C/39.2 °F.

If your 1st stage is marked "EN250A" then it is approved for the above *WHILE* you are sharing air.

However, there is an exception to this marking and that is "EN250 >10 °C". These regulators are only approved for use in water temperatures above 10 °C/50 °F. No good for cold water diving.

So as long as my reg is marked EN 250:2014/EN250A, I'm good right? Well, that depends on how bullet proof you want your reg in cold water. (Again, assume the level of risk you and your dive buddy are comfortable with)

Personally neither of those temperatures give me a warm an fuzzy because:
a) Salt water can go below the freezing point of fresh water.
b) The water temperature under ice in fresh water can very easily be hovering riiiiight above 0 °C/32 °F. And water can do funky things between 0 and 4 deg.

So if I want to go ice diving in the future or want to have room for safety, then I need to plan for more severe conditions than the EN 250:2014 standards. Or at least that is my personal opinion.

Are there any official standards that are more severe than this? Kinda . . .

Once could point to to United States Antarctic Program (USAP) Dive Guide. (Link below)
They use Sherwood Maximus SRB 7600, but according to the John Clarke article:
For instance, the 1991 Sherwood SRB3600 Maximus regulators long used by the U.S. Antarctic program have been highly modified and “detuned” to prevent free-flows.
I can't speak as to what they do to their current regs, but it does make me suspicious.

The U.S. Navy Experimental Diving Unit (NEDU), however, puts regulators through hell testing for cold water.

From the John Clarke link below: (BTW, he helps run this testing)
NEDU performs a survival test on regulators, and any that pass the harshest test are then tested for ease of breathing. The so-called “freeze-up” evaluation breathes the regulator on a breathing machine with warmed (74 ±10°F; 23.3 ±5.6°C) and humidified air (simulating a diver’s exhaled breath) at 198 feet sea water (~6 bar) in 29 ± 1°F (-1.7 ± 0.6°C) water. Testing is at a moderately high ventilation rate of 62.5 L/min maintained for 30 minutes. (In my experience a typical dive duration for a dry-suit equipped diver in Antarctica is 30-40 min.)

Only 3 regulators have passed this grueling testing and made it onto the list for "Approved for Navy Use" (ANU) list: (Link below, Section 1.3)(current as of 1/28/23)

Poseidon XStream
Mares Abyss 22 Navy II
Interspiro RS4

I hope this helps someone when considering what cold water regulator to choose.

Sources:
 
Do you mean that the divers around the world using other brands/models in icy freezing waters and in diving under ice for years without issues are wrong?
 
I have had my RG2500s down 130+ in 34 degree water in the great lakes and ice diving many times and never had an issue.
 
Hey new guy perhaps with modified presentation after a thousand more posts these seasoned performers
may see an attempt at imparting information, rather than viewing your impartation as a declaration of war

Thanks for your effort!

and you didn't use a "humbly your servant forever" smiley
 
Do you mean that the divers around the world using other brands/models in icy freezing waters and in diving under ice for years without issues are wrong?
Nope.

Like I said, if it works and you are willing to assume that degree of risk, that is your choice. Go for it.

However, any assumption of risk should be informed, and that is all I did, provide the limits of the standards testing and why I am choosing to go beyond those standards.

Also I could not find where anyone had gathered standards information together in regards to cold water regs.
 
When I first began diving, there were only about two real contenders for cold water or ice diving -- ScubaPro and Poseidon; and we went with the latter, because they gave us a great deal -- and ScubaPro, at that time, much like now, never met a list price that they didn't like.

I never had issues of any of the various models free-flowing, even in waters below freezing; but we were also well-equipped with vodka-filled antifreeze caps or others with ethyl alcohol / glycerin mixtures in the older first stages. It was a real white-knuckled event for me when I first used an Xstream below 5˚C, considering that no chemical or physical barrier was provided to prevent potential freezing; and the thing really looked so damn exposed.

I even carried a "vodka-insulated' old Cyklon 300 as a pony, just in case.

But what it came down to, wasn't necessarily any particular regulator brand, whether it had earned some coveted EN250 status, but how that gear was treated before hitting the cold water; and I saw a number of regulators, over the years, at various price points, function just beautifully in the cold -- just as I had seen a number of them fail to one degree or another, regardless of cost or brand, just due to mishandling . . .
 
When the military comes up with their “list of approved“ anything, that list is contingent on what price the military can get these items for and the service contracts that are associated with them. Having also retired from the military, it was very uncommon to have better general equipment than what can be obtained by civilian counterparts. While a number of other regulators most likely passed the tests, they were not picked up because the money side of the equation did not work out. There is much more going on behind the scenes than just what regulator performed better. I realize it’s a great selling point but being endorsed by .mil is not all it’s cracked up to be.
 

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