Question Do we need environment sealed first stages ?

[CG43]

In another thread we talked a lot about environment isolated 1st stages.
Is this more of a buying argument or what advantage does something like this really offer?

There are at least three different types of 1st stages which must be assessed differently.
1. Membrane type
2. Piston flow through construction
3. Piston Flow by construction

For type 1 and 3, in my opinion, isolation is not necessary if done correctly .
With type 2. I am not sure and think that this question can only be clarified by experiments.
I'm interested to hear your opinion about it.

 

[tursiops]

In another thread we talked a lot about inviroment isolated 1st stages.
Is this more of a buying argument or what advantage does something like this really offer?

There are at least three different types of 1st stages which must be assessed differently.
1. Membrane type
2. Piston flow through construction
3. Piston Flow by construction

For type 1 and 3, in my opinion, isolation is not necessary if done correctly .
With type 2. I am not sure and think that this question can only be clarified by experiments.
I'm interested to hear your opinion about it.

Are you concerned about cold water or dirty water?

 

[jborg]

Also, what does your question really mean? E.g., does a membrane first stage need to be environmentally sealed in order to have proper cold resistance? -- No, see for example the Poseidon Xstream, where the icing problem is solved in a different way and it being open to the environment is in fact part of the solution. However, does this mean that environmental sealing is just unnecessary and any other first stage is equally cold resistant? Also no.

 

[Geo7]

In another thread we talked a lot about inviroment isolated 1st stages.
Is this more of a buying argument or what advantage does something like this really offer?

There are at least three different types of 1st stages which must be assessed differently.
1. Membrane type
2. Piston flow through construction
3. Piston Flow by construction

For type 1 and 3, in my opinion, isolation is not necessary if done correctly .
With type 2. I am not sure and think that this question can only be clarified by experiments.
I'm interested to hear your opinion about it.

It's a topic that has come up before, but the conclusion depends on the environment (reflected into considering cold water or dirty water, as tursiops asked).

For 3) diaphragm regs, I'd like to just say that growing up diving northern European lakes, a Poseidon Jetstream was the most freeze-prone reg you could have (apart from twin-hose regs, and I owned both). Only few people sealed their Poseidon 1st stages (with glycerin or vodka under a rubber cup), yet freezing Poseidons were/are unheard of. Even without environmental sealing, these diaphragm stages do not freeze easily. And as jborg said, the modern Poseidon Xstream 1st stage cannot even be sealed, and is in a league of it's own regarding freezing.

Then again, environmental sealing is easy to do on diaphragm regs and it keeps it clean and shiny inside, reducing maintanence time where there is less to clean. But if you look at the tiny Aqualung Core 1st stage, or the new Scubapro Mk11 Evo, they are so small and light in part due to not being sealed.

So for 1) diaphragm I'll argue that sealing not needed, but some people will appreciate that feature (for extra cold, or extra dirty). I think once we get diaphragm regs out of the way, we can get into the more controversial question of 2) balanced piston regs.

3) Unbalanced pistons: Should be small and simple (and cheap), and lower performing, so I'd say sealing is not so important.

 

[CG43]

Thank you for your answers.

tursiops
Mainly maintenance, anti-icing, dirty water (abrasive).
Secondäry size . weight , price .

Also, what does your question really mean? E.g., does a membrane first stage need to be environmentally sealed in order to have proper cold resistance? -- No, see for example the Poseidon Xstream, where the icing problem is solved in a different way and it being open to the environment is in fact part of the solution. However, does this mean that environmental sealing is just unnecessary and any other first stage is equally cold resistant? Also no.

being open to the environment is in fact part of the solution !
And how to do this really well, there are also examples with the Poseidon Xstream and the SP MK11 Evo
and at piston stages like the new SP MK2 Evo with the large slots or SP MK25 with its many big holes .
There may be others that I don't know now , and I guess other will follow .

Only few people sealed their Poseidon 1st stages (with glycerin or vodka under a rubber cup), yet freezing Poseidons were/are unheard of. Even without environmental sealing, these diaphragm stages do not freeze easily.

In the 1970s and 1980s many old Poseidon and Dräger 1st membrane stages were used for ice diving in Germany. I am not aware of a single case where one of these reg. is frozen while diving. Both 1st stage are not even optimally open to the water.

The diaphragm of the first stage is not a good conductor of heat. Nevertheless, there is always a certain amount of heat from the adjusting spring side to the inside (IP space). This is actually desirable, but water cools down when it is in the spring space. For this reason, the water should be replaced often .
Actually incomprehensible that there are constructions that do not promote this exchange.
A single opening or only 4 thin holes are not optimal.

But there is a much more important reason why a wet room should be well ventilated.
You have to be able to rinse it well. And It should dry quick and well to avoid corrosion .
Is it possible to rinse and dry well through one small opening? My experience says no.

Sticky mud or abrasive water ?
Under these circumstances it always takes time to clean diver and gear.
You have to rinse the reg. in water anyway. Additional work is not caused by not sealed reg.

Abrasive particel ?
In the water chamber of a membrane reg. there are no parts that slide on each other.
Even if there are abrasive particles in the water, they will not cause wear .

Maintenance sealed vs open first membrane stages .
The sealing is done by a thin elastic membrane and the sealing must be checked periodically.
If water penetrates undetected it promotes corrosion and since the water is not exchanged, the risk of freezing is greater. You need more maitenace .

After all this, where is the advantage of isolating a membrane stage from water?

 

[Bigbella]

Also, what does your question really mean? E.g., does a membrane first stage need to be environmentally sealed in order to have proper cold resistance? -- No, see for example the Poseidon Xstream, where the icing problem is solved in a different way and it being open to the environment is in fact part of the solution. However, does this mean that environmental sealing is just unnecessary and any other first stage is equally cold resistant? Also no.

That's definitely the case with the XStream, open as it is to the water and great in the cold; but I still prefer to use older Poseidon models (2800-3900s) for work in "questionable waters", such as harbors, while collecting sediment samples, etc, fitted with their rubber environmental caps, for hygienic purposes and simply to avoid grit -- used empty while in shallow waters or vodka-filled in deeper areas . . .

 

[Umuntu]

But if you look at the tiny Aqualung Core 1st stage, or the new Scubapro Mk11 Evo, they are so small and light in part due to not being sealed.

The Core also came in a “Supreme” version which is environmentally sealed. I have one as a travel reg. It is identical in appearance to AL’s current “Helix Pro” regulator.

Helix Pro: Dive regulator | Aqualung®

The Helix Pro mid-range regulator with balanced first and second stages - our core range. The Helix Pro represents the DNA of Aqualung regulators. It is certainly the best value for the coming years. It benefits from the patented ACD technology - the first stage is fully protected, even when the...

uk.aqualung.com

 

[rsingler]

I thought you'd never ask!
I see it's time for the annual posting of my favorite unsealed piston pictures.

You cannot make an unsealed piston last 40 years. Some won't last 15. When Scubapro abandoned SPEC boots, they condemned their piston customers to buying a new reg before they might otherwise have needed. Which was the point, after all.

Piston reg?
Sealed Atomic or dry Sherwood.
I won't dive a Mk25.

 

[scubadada]

Hi @rsingler

I only have Mk25s that are 23 years old, so far, so good, your word is taken as gospel, I would take care.

 

[happy-diver]

Dudes, your piston oring will happily move over and seal those shonky surfaces for years and years

Dudes when you eventually have a failure to communicate between your brass copper and chrome
you polish it all out pristinely again, wIth your sandpaper on a stick, to fight again many more dives

For a better sealing surface than the factory started you with

I have collected decades old ocean brass that could be screwed back to where it was screwed from

And always fill your outboard of sealing orings threads with silicone it's dive regs not wrist watches


Hey did you know they write the books to suit the product and the extra products they want to sell

And the reg teaching guys are bound by the books

How many of you O2 clean your hoses

Yeah special grease and orings my arse