Question Do we need environment sealed first stages ?

[rhwestfall]

 

[lexvil]

Need? No but prefer.

I have worn out the inside of a MK 25 where there is a lot of micro abrasives suspended in the water, it took 8 to 10 years and a lot of dives so is it a huge concern, no but I no longer dive unsealed piston regs, I just don’t see the point of knowing you are damaging your gear in this situation and have switched to sealed regs. At this time I’m doing a MK 11 EVO, not totally sealed environmentally but that’s because my MK 17 EVO-2 has yet to arrive. If you only dive a few times per year and or from a boat it is unlikely to matter and the MK 25 is an outstanding piece of gear.

 

[Tanks A Lot]

This is the first time I see this lol.

This used to be very popular in the German speaking market around 2003.

There were a couple of incidents around that time and the CBS got blamed for it. Back then the system wasn't as clever as it is now and had for example trouble with rapid depth changes among other flaws. Sherwood wasn't really responsive in this regard and ignored most concerns raised in this market back then. They did lose a fair chunk of their German speaking market due to that.

A few from the DIY crowd did exactly what CG43 described here and I would nearly bet that he is from a German speaking area

Edit says: Oh yes, ScubaBoard has a Location thing, haha!

 

[Eric Sedletzky]

I like piston regs, I don't care what people say.
Just the physics of how they work, the way the HP seat is captured, the ingenious design if the balancing system. One moving part, and the uninhibited flow just gives me a warm and fuzzy feeling inside knowing it's about the most fail proof design available.
I have several MK5's laying around. The one I use most was a gift from Couv so it means a lot to me.
I also have a MK20.
I'm currently trying out an all 316 S/S Scubagaskets piston reg that's a MK10 inspired design. It is an unsealed open to the elements breathable style reg. I'm putting it through the Norcal beach diving torture test to see how it holds up. So far so good.
I will probably tear it down after this season and see how it faired. My guess is it will be just fine.

I have a good friend that works down at a dive shop in San Pedro. They supply the university and all law enforcement/ government agencies their gear and service all their regs. the university uses MK25's and they are brutal on them. Thrown around, not always rinsed properly or
not rinsed at all, crusty green. They all get systematically torn down, soaked, rebuilt and sent out the door just like new, no problems. They are made for it. Scubapro must have a secret recipe to their alloy because it's truly remarkable.
What is too cold for an unsealed piston reg?
Nobody seems to have a real answer.
Grit? How come I've never seen little champaign bubbles coming out of the ambient chamber on any of my pistons? I feel ripped off man! I have nothing to bitch about.
I take a lot of what I read as mythology.
That's one thing scubaboard is great for,
providing a lot of great fictional reading.

BTW, I do also have a few Conshelfs around'(unsealed regs). The military tested them to 37 degrees to 173' fsw, good enough for me.
Just soak them well and run a hose in the adjustment hole where the spring sits against the back of the diaphragm, BFD. Every time I tear it down which is about every 6-7'years it all comes apart fine and corrosion is minimal. Just soak your stuff!
The rest is mythology.

 

[rsingler]

Now reconstituting my fifty year old Soviet oxygen booster, that is worthy of some of my time

Reminds me of the day I was invited over to tour an Antonov copy of our C141 when we were both at the same African airport during the Rwandan crisis.
It was just like happy's booster. Massively overbuilt. Huge structural members. Probably wasted half the useful load on excess airframe.
Looked like us on the outside, but inside it was dark and greasy, with tube radios and a Morse key in the nav station. Escape from New York stuff. But happy coulda' polished it up.

I take a lot of what I read as mythology.
That's one thing scubaboard is great at is
providing a lot of great fictional reading.

There he goes. Spoiling the fun for all us keyboard warriors!

 

[CG43]

I don't think you are actually asking a question. Rather, your mind is made up, you are defending that position, and you are determined to argue with anyone who disagrees.

Making assumptions about someone else's intentions when it comes to technical questions is not exactly a good style for someone who calls himself a scientist.

I claim to understand technical concepts of a simple machine such as a reg. and to be able to calculate some characteristics such as control characteristics and loads to a considerable extent. Corrosion and abrasion by particles in the water and many other things I can only estimate very imprecisely or guess. That's the main reason why I ask and hope that people who have more experience with it answer.
Depending on that, I will change my mind or not.

Then there is also the aspect that if the piston Oring glides over a surface with abrasion or corrosion products, a part of it can get into the air and thus into the lungs of the diver. This will probably be so little that no harm is likely, but it remains an uneasy feeling.
However this applies in general to all inner surfaces of respiratory systems.

 

[BoltSnap]

If you're questioning the reliability, endurance, and performance of the MK25 regulators, I suggest you come to Libya and see for yourself. The MK25 first stage (paired with the S600) is the most popular regulator here and has been since it came out. Remarkably, no one services their regulators. Commercial spearfishers use and abuse them, neglecting maintenance, yet they keep working flawlessly. The things I've witnessed here are astonishing. Commercial spearfishers take their MK25s down to depths of 50 and 60 meters to hunt the big ones (using air). After seeing this firsthand, I became a firm believer in Scubapro (and its derivative, Atomic). Other brands like Mares and Cressi simply can't compete, not even close.

P.S. The incidence of decompression sickness (DCS) is very high among these spearfishers. Practically every old-timer I've seen is dragging one leg because they got hit and received no treatment at the time.

 

[Geo7]

Isn't it interesting how very experienced divers / reg techs come to so different perspectives? People trying to decide on buying a reg must get confused, so I think it's worth considering what other factors make our opinions deviate:

Rob services many regs from Californian divers. Lexvil dives in northern California. Getting through the surf for beach diving gets suspended fine sand everywhere, and sealing a piston reg helps the reg last longer.

Boltsnap is talking about clear blue water in the tropics. And in my experience the Mediterranean is in the same category. In this kind of environment divers can enjoy a reg like the Mk25 for the performance, hose routing and quite cheap maintanence cost. The market has spoken, and diaphragm regs dominate for all the reasons covered in this and other threads. But it would be sad if people diving in perfect water avoided flow through piston regs based on the preferences for our more harsh environments.

 

[Centrals]

I have been using environmentally sealed diaphragm first stage (Apeks) for well over 25yrs.

 

[lermontov]

One of these days if God gives me the means, I want to go to Australia and dive with you. I want to visit your dive locker too.

ahh the wonders of the Antipodes, there are still pockets of anti authoritarian rebels who spurn the anxiety driven and fragile mindset of the litigious Americans.

There are people doing outrageously difficult cave dives in the Nullarbor and In NZ that dont have an instagram or facebook page and haven't heard of scubaboard