Piston regulators and the environmental goo!

[White Knight]

Piston regulators and the environmental goo! I need the expert technical and real life advice from my online SCUBA buddies regarding this whole environmentally sealed first stage piston regulator stuff? In short, manufactures of first stage piston regulators (prone to freeze up's and junk in the water--so I am told) offer the "Environmental seal" as a fix. If I understand the concept, a rubber seal is wrapped around the first stage where the ocean water would usually be allowed to flow through to the piston. Under this sealed off area, a gooey silicone substance is packed in?
First, am I close with my understanding? If so, is this a viable way to deal with the problem? This "seal" surely isn't water tight? Won't the seal leak salt water in still, but this time will keep it in--as opposed to not having a seal? And although the seal will keep most dirt out, it seems to me that the dirt that does make it in will be trapped? Lastly, won't the goo leak out fairly rapidly, leaving a pocket of "sealed in saltwater?"
I am contemplating purchasing a Scuba Pro or an Atomic?thus the questions.
Thanks

 

[Thalassamania]

Piston regulators and the environmental goo! I need the expert technical and real life advice from my online SCUBA buddies regarding this whole environmentally sealed first stage piston regulator stuff? In short, manufactures of first stage piston regulators (prone to freeze up's and junk in the water--so I am told) offer the "Environmental seal" as a fix. If I understand the concept, a rubber seal is wrapped around the first stage where the ocean water would usually be allowed to flow through to the piston. Under this sealed off area, a gooey silicone substance is packed in?
First, am I close with my understanding?

Yes.

If so, is this a viable way to deal with the problem?

Yes.

This "seal" surely isn't water tight?

Pretty close, the goop is not water soluble either.

Won't the seal leak salt water in still, but this time will keep it in--as opposed to not having a seal?

Even without a "seal" the goop will pretty much stay put.

And although the seal will keep most dirt out, it seems to me that the dirt that does make it in will be trapped?

Dirt will not get anywhere near the moving parts and sealing surfaces.

Lastly, won't the goo leak out fairly rapidly, leaving a pocket of "sealed in saltwater?"

No, it will stay put.

I am contemplating purchasing a Scuba Pro or an Atomic?thus the questions.
Thanks

If this is a real concern for you ... get a diaphragm regulator, a much better solution if you need a sealed first stage. Take a long hard look at the Oceanic EOS.

 

[DA Aquamaster]

First, am I close with my understanding?

That is pretty much how it works. There are some minor variations on the theme. Nitrox regs that use this approach use an O2 compatible grease like Christolube which is a little runnier and a bit more water soluable than silicone. This, and concerns for cross contamination of silicone on the tools and workbench between nitrox and non nitrox regs was the reason SP stopped using the Silicone Protected Environmental Chamber(SPEC) system and went to the less than 100% effective Thermal Insuslating Sytem on their piston regs.

If so, is this a viable way to deal with the problem?

The SPEC system worked great - as long as the ambient chamber was properly packed and the right grease was used. The Silicone SP used was thicker than the silicone grease available from Trident. With the thinner silicone grease, you may need to repack it mid season. But when properly done, the first stage is very freeze resistant.

This "seal" surely isn't water tight? Won't the seal leak salt water in still, but this time will keep it in--as opposed to not having a seal?

The above response answers a lot of this, but yes, if you let the chamber get partially empty you end up with salt water in the chamber where it basically stays. Over the short term it is not a problem as the silicone will still be stuck to the metal parts and protect it from corrosion to some degree. It however becomes a problem in cases where the owner decides to skip an annual service.

And although the seal will keep most dirt out, it seems to me that the dirt that does make it in will be trapped?

Yes, it does get trapped and the silicone you remove at the next annual service will be quite dirty. The particles are however very small and do not seem to create any noteablel degree of wear (there is after all lot of lubricant in there) unless again the owner decides to skip an annual service or two.

Lastly, won't the goo leak out fairly rapidly, leaving a pocket of "sealed in saltwater?"

Hot weather and or leaving the reg out in the sun will warm the silcione grease and cause it to thin and leak out faster. Over time this can be a serious issue, so again topping it off mid season can be important.

Improper packing where voids result deep inside the ambient chamber and or between the spring and piston is a bigger issue as they compress with depth, allow water into the chamber and over time the water will migrate to the interior voids. So proper packing is key and not many Scubapro techs out there still know how to do it well as Scubapro has not supported SPEC systems in over a decade.

There are a couple piston designs around that use a sealed ambient chamber where air is bled into and retained in the chamber by various valves, but they are complex and tend to be problematic in service. Sherwood uses a bleed system on some of their models where the chamber is not sealed and where the excess air bubbles out in a slow stream. It has the virtue of simpicity, even it it will never pass a bubble check.

I agree with the suggestion above that if you really need a cold water reg, get a diaphragm reg that also has a diaphragm sealed ambient chamber. Not all diaphragm regs are fully sealed. The Scubapro Mk 17 is currently one of the best, and in my opinion the best cold water first stage available and it offers more than enough flow rate for any technical or recreational diving need.

If you decide to go the SPEC route, get a used Mk 20 with the later MK 25 piston and then add the late production MK 15/early production Mk 20 SPEC boot. It is a lot wider than the earlier narrow SPEC boot used on the Mk 10, Mk 10 Plus and early Mk 15. The extra width provides some room for expansion of the silicone and helps to both retain the silicone and keep the seawater out.

 

[Nemrod]

The environmental danger to piston regs is grossly exaggerated. I have MkV clones that have been in service with but a rinse for over 25 years. Unless you frequent cold, sub 50 degree water, don't worry about it.

Besides, I have dove California, west coast, Great Lakes, and numerous 48 degree locations with no freeze ups, just not an issue, colder than that, I won't be there.

N

 

[Nemrod]

This will not be useful for cold water but for dirty water, take a bike tube from a racer, the thin butyl or latex type and cut a sleeve about one inch long. Place it over the MkV and then with a touch of Aqua Seal adhere the edges. Then take a sharp awl and poke it at the "ports" puncturing the tube with a tiny hole. Water passes though the holes but dirt, gunk, sand, animals do not. Peel it off after the dirty water dive and rinse.

N

 

[beanojones]

The environmental danger to piston regs is grossly exaggerated. I have MkV clones that have been in service with but a rinse for over 25 years. Unless you frequent cold, sub 50 degree water, don't worry about it.

Besides, I have dove California, west coast, Great Lakes, and numerous 48 degree locations with no freeze ups, just not an issue, colder than that, I won't be there.

N

I put my little but in here. Piston regs crap out from corrosion in the tropics. Here we like env. systems to prevent corrosion not freezeup.

Unblanced pistons are still used, because cheap and easy to O/H. But Diaphragm regs are naturally environmentally sealed so people use them instead mostly.

Many many crapped out SP pistons from corrosion. And even the whole body splits from corrosion. (like I think DrBill had).

 

[Nemrod]

I put my little but in here. Piston regs crap out from corrosion in the tropics. Here we like env. systems to prevent corrosion not freezeup.

Unblanced pistons are still used, because cheap and easy to O/H. But Diaphragm regs are naturally environmentally sealed so people use them instead mostly.

Many many crapped out SP pistons from corrosion. And even the whole body splits from corrosion. (like I think DrBill had).

Corrosion is corrosion, tropics or elsewhere, if you dive it a lot, then clean it a lot.

N

 

[DA Aquamaster]

Unblanced pistons are still used, because cheap and easy to O/H. But Diaphragm regs are naturally environmentally sealed so people use them instead mostly.

Many many crapped out SP pistons from corrosion. And even the whole body splits from corrosion. (like I think DrBill had).

Some but not all diaphragm regs are environmentally sealed. In "unsealed" diaphragm designs, the spring and spring pad are still exposed as they are in the unsealed ambient chamber - but the seat carrier and other moving parts are on the sealed side of the diaphragm as it is an upstream design.

 

[Thalassamania]

Some but not all diaphragm regs are environmentally sealed. In "unsealed" diaphragm designs, the spring and spring pad are still exposed as they are in the unsealed ambient chamber - but the seat carrier and other moving parts are on the sealed side of the diaphragm as it is an upstream design.

This is why I've had a bias toward the the diaphragm design going back to the days of the Voit Swimmaster MR-12.

 

[halocline]

I've serviced decades-old MK5s that spent much of their lives in Roatan, and never noticed any unusual corrosion. I certainly think Roatan qualifies as tropical.

OTOH, I also serviced a relatively new MK20 that had been used on cayo cochinos for a season without a single fresh water rinse; the user was doing marine biology research and there was no access to a fresh water rinse tank. It was pretty crispy.