Many claims that the Sherwood Magnum Pro's regulator is only suitable for diving in water temperature over 50 degrees. The company also claims that Sherwood Octo is suitable for water temperature above 50 degrees on their website. However, I notice that EN250 is stamped on both Magnum Pro and the Octo. From my understanding, EN250 indicates that a regulator can operate at water temperature of 40 degrees. I am just wondering whether I can use my Magnum Pro in water temperature sub 50 degrees.
Can I use my Sherwood Magnum Pro in sub 50 degrees of water?
- Thread starter MoorishK
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Tanks A Lot
Contributor
Sherwoods documents do not make it crystal clear which standard their regulator fulfills.
EN250 clearly states:
If your regulator is marked with only EN250 and no temperature indication, Sherwood thereby says that it has tested the regulator at a minimum of 4°C (39°F) at 6 bar (50 m/ 164 f). The EN250 mark without temperature indication must be present on both, the first and second stage.
Icing up of a first or second stage is induced by the environments temperature and amount of gas flow, which is directly proportional to depth, or two people breathing from it. All regulators will freeze up if gas flow or temperatures are low enough. Some of them are cleverer engineered than others, e.g. Poseidon has done this extremely clever, even when while not environmentally sealed. I would argue especially because they are not environmentally sealed, they are superior to most other regulators on the market with regards to external ice build-up.
Contaminated air with a high moisture content will make any regulator ice up, regardless of make. This internal "freezing" is almost impossible to combat.
For comparison, the ScubaPro MK10 has been used ad nauseum by divers in temperatures below 10°C. It is a (usually) unsealed piston first stage. That being said, it has iced up for some people when under extreme demanding conditions. Some people take their trusty MK2+ down in the conditions, but are well aware of the possibility of icing up. In the end it comes down to your personal acceptance of risk.
On a personal note, I'm not a big fan of what Sherwood calls their Air-Assisted Depth-Compensation (A2-DC). It is a pneumatic compensation actuated by a small Schrader valve. This alone would put me off from using it under extreme conditions. I do not have any data or tests for this opinion, but the engineering side doesn't look like it would hold up well when ice builds up.
EN250 clearly states:
If your regulator is marked with only EN250 and no temperature indication, Sherwood thereby says that it has tested the regulator at a minimum of 4°C (39°F) at 6 bar (50 m/ 164 f). The EN250 mark without temperature indication must be present on both, the first and second stage.
Icing up of a first or second stage is induced by the environments temperature and amount of gas flow, which is directly proportional to depth, or two people breathing from it. All regulators will freeze up if gas flow or temperatures are low enough. Some of them are cleverer engineered than others, e.g. Poseidon has done this extremely clever, even when while not environmentally sealed. I would argue especially because they are not environmentally sealed, they are superior to most other regulators on the market with regards to external ice build-up.
Contaminated air with a high moisture content will make any regulator ice up, regardless of make. This internal "freezing" is almost impossible to combat.
For comparison, the ScubaPro MK10 has been used ad nauseum by divers in temperatures below 10°C. It is a (usually) unsealed piston first stage. That being said, it has iced up for some people when under extreme demanding conditions. Some people take their trusty MK2+ down in the conditions, but are well aware of the possibility of icing up. In the end it comes down to your personal acceptance of risk.
On a personal note, I'm not a big fan of what Sherwood calls their Air-Assisted Depth-Compensation (A2-DC). It is a pneumatic compensation actuated by a small Schrader valve. This alone would put me off from using it under extreme conditions. I do not have any data or tests for this opinion, but the engineering side doesn't look like it would hold up well when ice builds up.
Thank you very much for your detailed answer. Yes, on the second stage there is the stamp of EN250A without the temperature indication. However, it's really weird as I have previously reached out to Sherwood regarding the minimum operational temperature for Magnum Pro. The answer I got was: "Magnum Pro is OK to be used at water temperature above 50 degrees." I am also curious as to why would they make a Blizzard Pro if Magnum Pro can do the same job? And what are the difference between Magnum Pro and Blizzard Pro? Lastly, may I ask the reason as to why you feel like the pneumatic compensation actuated by a small Schrader valve is not suitable for cold water use?
Tanks A Lot
Contributor
Like I said before, I do not have any real concrete evidence or data to suggest that it isn't suitable and Sherwoods EN250 rating certainly means that it does hold up to 50 meters at 4°C.
However, if you look at the mechanism above, it becomes clear that the mechanism is very much dependent on the proper functioning of this Schrader valve. Should the movement of the parts in contact with the Schrader valve, namely the actuators above it, be impaired by ice, the mechanism would fail to keep working. This would spell trouble upon depth changes and the associated changes needed in intermediate pressure.
Ice build-up usually affects the whole first stage, as can be seen by this picture from DiveLab. You may find their whole article an interesting read.
Again, the EN250 rating means that this regulator works perfectly fine for the earlier mentioned temperature ranges. But I believe the way it is engineered makes it inferior with regards to ice resistance than some other regulator.
The Sherwood Blizzard and Sherwood Magnum Pro both use the same first stage, namely their 9000 series. Do keep in mind that cold water performance is not only dependent on the first stage, but also on the second stage.
The manufacturer also has to pass the tests with a complete regulator set and only this set then gets the EN250 compliance. It may be that Sherwood didn't bother or didn't want to test the Magnum Pro for cold-water performance. This could be due to sales reasons, as this gives the Blizzard a distinct spot in the line-up. Sometimes manufacturer decisions with regards to segmenting regulators are not based on engineering, but rather sales figures. Aqualung is the true specialist in this discipline.
To drive this point home, compare their current Oasis with the Blizzard. These two regulator sets are virtually identical. They have the exact same first stage and the second stage merely differ in their purge covers. For what it's worth, the other second stages are not that much different either.
Sometimes it is a fools errand to look for engineering differences in a manufacturers line-up, they are more often than not very similar. Regardless, only certain combinations get certified, as this costs money.
However, if you look at the mechanism above, it becomes clear that the mechanism is very much dependent on the proper functioning of this Schrader valve. Should the movement of the parts in contact with the Schrader valve, namely the actuators above it, be impaired by ice, the mechanism would fail to keep working. This would spell trouble upon depth changes and the associated changes needed in intermediate pressure.
Ice build-up usually affects the whole first stage, as can be seen by this picture from DiveLab. You may find their whole article an interesting read.
Again, the EN250 rating means that this regulator works perfectly fine for the earlier mentioned temperature ranges. But I believe the way it is engineered makes it inferior with regards to ice resistance than some other regulator.
The Sherwood Blizzard and Sherwood Magnum Pro both use the same first stage, namely their 9000 series. Do keep in mind that cold water performance is not only dependent on the first stage, but also on the second stage.
The manufacturer also has to pass the tests with a complete regulator set and only this set then gets the EN250 compliance. It may be that Sherwood didn't bother or didn't want to test the Magnum Pro for cold-water performance. This could be due to sales reasons, as this gives the Blizzard a distinct spot in the line-up. Sometimes manufacturer decisions with regards to segmenting regulators are not based on engineering, but rather sales figures. Aqualung is the true specialist in this discipline.
To drive this point home, compare their current Oasis with the Blizzard. These two regulator sets are virtually identical. They have the exact same first stage and the second stage merely differ in their purge covers. For what it's worth, the other second stages are not that much different either.
Sometimes it is a fools errand to look for engineering differences in a manufacturers line-up, they are more often than not very similar. Regardless, only certain combinations get certified, as this costs money.
Thank you so much for the explanation! Do you have the chart for Magnum Pro regulator?
Tanks A Lot
Contributor
While the attached don't clearly state Magnum Blizzard on them, they are close enough as explained above.
The main difference between the Brute and Magnum is the adjustable venturi lever. There isn't much of a difference between the Magnum and Oasis/Blizzard. The Oasis/Blizzard have their fancy MVR on the valve housing, but god knows if that makes any difference at all... They do specify different cracking efforts with the Magnum being slightly harder to crack.
The Magnum is likely a Brute second stage with the adjustable venturi lever from the Oasis/Blizzard. All first stages are the same.
On a sidenote, Sherwood didn't even have their wits together when labeling the schematics, as the numbering is off by one at least for the Oasis/Blizzard.
The main difference between the Brute and Magnum is the adjustable venturi lever. There isn't much of a difference between the Magnum and Oasis/Blizzard. The Oasis/Blizzard have their fancy MVR on the valve housing, but god knows if that makes any difference at all... They do specify different cracking efforts with the Magnum being slightly harder to crack.
The Magnum is likely a Brute second stage with the adjustable venturi lever from the Oasis/Blizzard. All first stages are the same.
On a sidenote, Sherwood didn't even have their wits together when labeling the schematics, as the numbering is off by one at least for the Oasis/Blizzard.
Thank you! I apologize for my ignorance, but what is MVR? Since I may dive in 45 degrees of water, I am actually considering switching my second stage from Magnum Pro to Blizzard Pro. Do you feel like that this may be a good idea?
I dive a Sherwood Blizzard and regularly (December to May) dive in water below 10’C. I’ve never had a freezing problem unlike my Apex buddies. This includes ice diving. I’ve made over 1k dives on my current Sherwood, as I dive year round.
Tanks A Lot
Contributor
It is not your ignorance, but my ability to type which is at fault here. It is MRV, not MVR. Sherwood calls a system of vanes that the air flows over MRV (Moisture Retention Vanes). It supposedly captures some of the exhaled moisture and upon inhalation the air gets slightly moisturized. A marketing trick if you ask me. I can't possibly see how this would make a noticeably real world difference. But I'm always happy to be proven wrong!
The Blizzard supposedly has a stiffer exhalation valve, yet the drawings specify the exact same part number.
The Blizzard has a brass poppet housing which would be better than the Magnums polymer housing at thermal conductivity.
Is that enough to warrant the change, I don't know to be honest.
Furthermore you mention that your Magnum is clearly marked with a EN250A without any temperature indication. This means it has successfully endured the stress tests at 50 meters at 4°C. Sherwoods website indicates something else, but I doubt there is a mistake in the markings. I suspect that marketing has more to do with in pushing people to buy the Blizzard.
If you have more extreme diving planned than the demanded 50 meters at 4°C as demanded by the EN250A stamp, then upgrading to the Blizzard may be a wise choice. For extreme conditions, every bit helps and the Blizzard supposedly has some upgrades in that regard. If you do not do more extreme dives, than I would not upgrade, as it seems like a waste of money to me.
Thank you for the clarification. Regarding cold water performance, do you feel like Blizzard may be a good choice? Is there any other regulator recommendations that you may have?
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