Unexpected IP drift in a newly-serviced first stage

[Yellowdog]

Having taken apart several eBay used Atomic regulators recently ( switching from AL to Atomic regulators ) I have seen first hand the differences of sealed and unsealed piston regs. The unsealed B2 I purchased for @rsinglers regulator course showed much wear to the interior wall of the first stage body, although the piston looked to be in good shape. The first stage bodies of the used but sealed T2X and T3 reg sets I purchased for my own use looked new inside. The Monel pistons on both sealed regs did not fair as well and showed some corrosion similar to the pictures Rob posted above. Even though there was some residual pitting on the Monel pistons after I cleaned and polished them, they both functioned to spec when reassembled with a new service kit. For my part I would rather seal the first stage in order to protect the body while potentially sacrificing the piston than to leave unsealed and potentially damage the body by scraping abrasives into the body wall. If I have to polish the piston every few years and eventually replace in order to protect the body that seems like a good value trade to me. The pictures below are from a sealed but never serviced 7 year old T3. I wish I had taken pictures of the body after cleaning but even with magnification there was no visible wear to the body wall.

 

[Nemrod]

I think I am just going to continue to rinse my decades old piston first stages and hope for the best. Maybe whoever inherits them they will need to worry over scour marks from sand.

Aluminum oxide (corundum), Mohs hardness 9, getting past the sintered filter, well, that could be a problem.

Scubapro or Atomic, I was wanting a titanium first stage but now I want one of titanium infused with nickel and then hard chrome plated or perhaps just use lonsdaleite, harder than diamond in pure form. Titanium is a 6 on Mohs scale, quartz is 7 and steel is like 5.5 to 6.5 and stainless near 8 ish and chrome is 8.5, diamond is 10 and londaleite yet harder. So then, uh, where are you guys diving that the chrome plated piston cylinder body of your piston regs is being scoured by what?

Maybe Scubapro and Atomic just need to use a hard tool chrome plated nickel infused titanium and then grind the interior mating surface with a diamond hone and then a lonsdaleite knife edge to resist high velocity impact with aluminum oxide particles. I am not asking for much .

Or just dive with a diaphragm, nah, those rubber ambient diaphragms could explode or unseat or leak and then there is that push pin through the orifice, oh dear, they are just a kludge.

 

[Yellowdog]

I think I am just going to continue to rinse my decades old piston first stages and hope for the best. Maybe whoever inherits them they will need to worry over scour marks from sand.

Aluminum oxide (corundum), Mohs hardness 9, getting past the sintered filter, well, that could be a problem.

Scubapro or Atomic, I was wanting a titanium first stage but now I want one of titanium infused with nickel and then hard chrome plated or perhaps just use lonsdaleite, harder than diamond in pure form. Titanium is a 6 on Mohs scale, quartz is 7 and steel is like 5.5 to 6.5 and stainless near 8 ish and chrome is 8.5, diamond is 10 and londaleite yet harder. So then, uh, where are you guys diving that the chrome plated piston cylinder body of your piston regs is being scoured by what?

Maybe Scubapro and Atomic just need to use a hard tool chrome plated nickel infused titanium and then grind the interior mating surface with a diamond hone and then a lonsdaleite knife edge to resist high velocity impact with aluminum oxide particles. I am not asking for much .

Or just dive with a diaphragm, nah, those rubber ambient diaphragms could explode or unseat or leak and then there is that push pin through the orifice, oh dear, they are just a kludge.

Yep - I am probably overthinking it.

 

[Geo7]

Both sides of the argument have a point: I often recommend unsealed pistons like Scubapro Mk25 or Atomic to divers who dive warm, clear water (Mediterranean, tropics...). The Scubapro Mk25 for travel (to access parts and service in areas of the world where Atomic isn't known). Flow through pistons have a great form factor, light weight, and hose routing, few moving parts, are forgiving to service.

But here in Southern California the waves suspend sand and silt, and the tiny quartz crystals in combination with salt crystals do have the long-term effects on the piston or chromed brass body, as described above. So the Atomics can be sealed and while the sealing is messy, they then become bullet proof regs that can do anything, including freezing water.

In SoCal, one could get by with unsealed regs, and as Rob and Lex have explained in previous threads: with good rinsing and regular maintanence the reg will still last a decade or two before the scratches become a problem. If the sealing is not done well and then service is delayed, the reg still suffers corrosion btw. But if done well, the reg is good for several years. So for titanium Atomics that require service only every 3 years, sealing is not too inconvenient for me.

Yes a diaphragm reg solves that dilemma, and the modern Sherwoods are the best of both worlds, but the Atomics still appeal the most to me. Or our dream, the titanium Scubapro Mk2 that you brought up in another thread. That reg would be so easy to unscrew and clean every few months, flip the seat, replace 1-2 LP o-rings...

 

[lexvil]

I think I am just going to continue to rinse my decades old piston first stages and hope for the best. Maybe whoever inherits them they will need to worry over scour marks from sand.

Aluminum oxide (corundum), Mohs hardness 9, getting past the sintered filter, well, that could be a problem.

Scubapro or Atomic, I was wanting a titanium first stage but now I want one of titanium infused with nickel and then hard chrome plated or perhaps just use lonsdaleite, harder than diamond in pure form. Titanium is a 6 on Mohs scale, quartz is 7 and steel is like 5.5 to 6.5 and stainless near 8 ish and chrome is 8.5, diamond is 10 and londaleite yet harder. So then, uh, where are you guys diving that the chrome plated piston cylinder body of your piston regs is being scoured by what?

Maybe Scubapro and Atomic just need to use a hard tool chrome plated nickel infused titanium and then grind the interior mating surface with a diamond hone and then a lonsdaleite knife edge to resist high velocity impact with aluminum oxide particles. I am not asking for much .

Or just dive with a diaphragm, nah, those rubber ambient diaphragms could explode or unseat or leak and then there is that push pin through the orifice, oh dear, they are just a kludge.

Back in the olden days I felt the same about diaphragms but there are much better materials that is about all I use now, haven’t had a single diaphragm issue, so mush more stabil in the IP department.

dive a lot from the california (where diving started / Sam Miller just popped into my mind ) and you’ll be filling your reg with abrasives fast enough, it take years for sure but it does happen and is preventable.

 

[lexvil]

Both sides of the argument have a point: I often recommend unsealed pistons like Scubapro Mk25 or Atomic to divers who dive warm, clear water (Mediterranean, tropics...). The Scubapro Mk25 for travel (to access parts and service in areas of the world where Atomic isn't known). Flow through pistons have a great form factor, light weight, and hose routing, few moving parts, are forgiving to service.

But here in Southern California the waves suspend sand and silt, and the tiny quartz crystals in combination with salt crystals do have the long-term effects on the piston or chromed brass body, as described above. So the Atomics can be sealed and while the sealing is messy, they then become bullet proof regs that can do anything, including freezing water.

In SoCal, one could get by with unsealed regs, and as Rob and Lex have explained in previous threads: with good rinsing and regular maintanence the reg will still last a decade or two before the scratches become a problem. If the sealing is not done well and then service is delayed, the reg still suffers corrosion btw. But if done well, the reg is good for several years. So for titanium Atomics that require service only every 3 years, sealing is not too inconvenient for me.

Yes a diaphragm reg solves that dilemma, and the modern Sherwoods are the best of both worlds, but the Atomics still appeal the most to me. Or our dream, the titanium Scubapro Mk2 that you brought up in another thread. That reg would be so easy to unscrew and clean every few months, flip the seat, replace 1-2 LP o-rings...

The best first stage could happen if scubapro or Atomic took the Sherwood SR sealed idea and made them.

 

[Nemrod]

Back in the olden days I felt the same about diaphragms but there are much better materials that is about all I use now, haven’t had a single diaphragm issue, so mush more stabil in the IP department.

dive a lot from the california (where diving started / Sam Miller just popped into my mind ) and you’ll be filling your reg with abrasives fast enough, it take years for sure but it does happen and is preventable.

Why exactly is a stable IP really all that important for a balanced second stage? Diaphragm regulators have their pluses and minuses, being easier to environmentally seal is a plus, if it is really that important. I think they do have definite advantages in very cold water. I have both and am completely happy with my piston first stages. My fav right now is a Mark 2 Evo piston with G250s. And I was right beside somebody in this thread when they were trying out that TFX at 138 feet. Well, I only went to 128 feet because nowadays I have this idea that 70 yo guys do not need to be going into deco on a single tank . The regulator performed well. Yeah, I bumped my ceiling at the end, dang it, I was being preoccupied with the other goings on and not paying attention to my goings on.




I thought diving started in France? I am pretty sure folks were diving in Florida near about the same time as California. And most "tech" diving equipment like wings and plates seem to have a Florida cave origin including Hogarthian (I understand the gent may not like that term but it is what it is) concepts, not California. Even Sea Hunt was mostly filmed in Florida, not California. Y'all dive out there?

 

[lexvil]

Why exactly is a stable IP really all that important for a balanced second stage? Diaphragm regulators have their pluses and minuses, being easier to environmentally seal is a plus, if it is really that important. I think they do have definite advantages in very cold water. I have both and am completely happy with my piston first stages. My fav right now is a Mark 2 Evo piston with G250s. And I was right beside somebody in this thread when they were trying out that TFX at 138 feet. Well, I only went to 128 feet because nowadays I have this idea that 70 yo guys do not need to be going into deco on a single tank . The regulator performed well. Yeah, I bumped my ceiling at the end, dang it, I was being preoccupied with the other goings on and not paying attention to my goings on.




I thought diving started in France? I am pretty sure folks were diving in Florida near about the same time as California. And most "tech" diving equipment like wings and plates seem to have a Florida cave origin including Hogarthian (I understand the gent may not like that term but it is what it is) concepts, not California. Even Sea Hunt was mostly filmed in Florida, not California. Y'all dive out there?

If the French do it it’s not diving

steady IP in respect to servicing and indicating stability over time and it’s not fair to compare the cockroach of Regs (mk2) to anything, if they could turn the main body 90° it would be tempting to use nothing else.

california diving is for divers, it’s much harder than the bath water “diving” done in the dangling part of the country.

 

[Geo7]

In my understanding: Jaques Yves Cousteau co-developed the double hose reg in southern France during WW2, but by the time recreational SCUBA diving was a small developing industry, Southern California had quickly become an important center that drove innovation. I think some of the first SCUBA courses outside the military were offered by LA County lifeguards or similar, before we had recreational agencies like we know today. Later the Florida cave divers discovered their breakthroughs in technique and equipment, which have influenced diving elsewhere.

To get back on topic (and again from my understanding off the top of my head): the first regs were diaphragms, but some early models had pins breaking and failed closed, and when Scubapro brought the flow-through piston to market that performed well and did not fail closed, that design became popular. Then tech diving popularized diaphragm regs, and as Lex and Rob said, that design has been modernized and now probably dominates the market.

 

[rsingler]

Yep - I am probably overthinking it.

No, you're not. My dive buddy @Nemrod is just a curmudgeon, even if he's right 51% of the time.

And deco on single tank? Shoot! By the time my deco cleared, I still had 1000psi in the bottle, and there were a dozen spare regulators within 20 feet. I'll bet @Nemrod was better, and my wife still had 1250.
Christine dropping into Devil's Throat right behind @Nemrod :