What is the most bulletproof 1st stage of all time?

[Bob DBF]

drops to a relative IP of 120 at 33 feet. The 14.7psi of the extra atmosphere of depth is transmitted back via the second stage circuitry, and opposes the absolute IP coming from the first. With a balanced second stage, you may or may not notice anything. By the time you reach 99 feet, the ambient pressure has increased 44 psi. That means a relative IP of 91 psi, and your regs will be breathing a bit (or a LOT) stiffer.

Since my diving was in an area, at that time, you would need a shovel to get to 60' , when the dry bleed quit, it didn't affect my breathing on the second, not to mention the fact that when l started diving, regulator performance was gauged by whether it performed at all, instead of how well it performed.

 

[halocline]

Wouldn’t a Sherwood with a clogged dry bleed filter be effectively an unplanned simple piston Mk2 equivalent. If so, why not choose the Sherwood for this additional benefit?

I assume you mean 'unbalanced' not 'unplanned'. The answer is no. The sherwood with a clogged dry bleed valve will not accurately compensate for depth changes, which makes the regulator almost useless at any sort of depth. I believe that you are confusing environmental sealing (that's the dry bleed part) with depth compensation, something that all regulators need in order to work. With the Sherwood design, as ingeniously simple as it is, if that little valve gets clogged, the pressure in the ambient chamber won't equalize and as a result you have no (or very sluggish) depth compensation.

For any regulator to work, IP must remain reasonably constant over whatever the ambient pressure is at a given depth.

 

[tursiops]

delete

 

[runsongas]

mk5 spec because you could DIY the rebuild kit if you had to, not sure on ease of doing that for the conshelf or mistral.

 

[Eric Sedletzky]

mk5 spec because you could DIY the rebuild kit if you had to, not sure on ease of doing that for the conshelf or mistral.

Well, that begs the question about the MK2 also, 2 o-rings and a little thing of silicone. The first stage seat can be flipped. How many years can the first stage seat last before it completely melts down? What happens when it completely melts down?
Can it be resurfaced by sanding it on a flat piece of fine sand paper or a nice flat polished rock you found on the beach provided you can get it straight? The IP drops but how much?
With the MK 2 there are very minimal tools required to do a hack service. You can use a high pressure hose or fine thread 5/16” bolt and a rod of some kind or a Phillips screw driver and a ball peen if you have to go get it open instead of a hook spanner or even a pair of hook pliers. I know I’m giving some of you perfectionists heartburn by suggesting such a thing but in a dire situation with limited resources it’s true!
And if unbalanced is a thing then think about this: they get hard to breathe at lower tank pressures and you have plenty of warning. You should be ending your dive anyway and you shouldn’t be caught deep with tank pressure so low that an unbalanced reg gives you grief, you should be at you safety stop and paying attention. Nothing like a natural built in knuckle head alarm to get your attention!!
Thinking about it, the best bullet proof reg if you’re stuck on a desert island is kind of moot if you have no way of getting air fills. Lets pretend you have an unlimited supply of tanks to use.

 

[MichaelMc]

Thinking about it, the best bullet proof reg if you’re stuck on a desert island is kind of moot if you have no way of getting air fills

Yeah! As long as the reg out lasts the compressor parts, filters and the generator, the reg isn't the limit on diving. And if we brought a compressor, 10 service kits and two spare regs are just a tiny bag of parts.

The goal of being bullet proof is to increase durability. The dirt simpleness of the Mk2 is attractive, but less so if never rinsing it is bad. Sealed goes a long way toward preventing problems of abuse or hard use.

The Poseidon ruby ball Mk3 is a clean reliable design, as I understand, plus the two dynamic o-rings are fully inside a dry chamber. Pair it with a 109 if you want, though I'm waiting for the turret version.

Images taken from: How does the Poseidon Xstream first stage work?

 

[happy-diver]

Remember the Professor

I remember Mary Ann

Nothing like a natural built in knuckle head alarm to get your attention!!

0645 Professor "All right Mary Ann start pumping." Ginger "All right Mary Ann start pumping" divers

 

[ThatDogDontHunt]

Since my diving was in an area, at that time, you would need a shovel to get to 60' , when the dry bleed quit, it didn't affect my breathing on the second, not to mention the fact that when l started diving, regulator performance was gauged by whether it performed at all, instead of how well it performed.

As mentioned way above, does the Sherwood get any bonus points for ease of field service? How many special tools are required by some regs?

The Sherwood design seems to not require any special tools (almost no tools other than a paper clip?)

 

[happy-diver]

With quite a liberal dose of silicone 111 on the body threads outside
my o2 clean Mk IIs, I slam them against as tree and unscrew by hand

 

[Diverspoint]

SP MK10+ simply because I have used mine for about 28 years with about 7 services altogether. With 4000+ dives on it.

With my original190 attached to it