The New Atomic TFX

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rsingler

Scuba Instructor, Tinkerer in Brass
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Location
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Well, it's out. I had the pleasure of listening to Dean Garraffa introduce AA's new second stage (and tweaked T3 first stage), and I can't wait to get my hands on one. Mr. Garraffa was with Scubapro back in the day, and along with Doug Toth (who designed the D400), they came over and formed Atomic Aquatics and created a scuba manufacturing company with a quality niche that few can match.

Where to start?
For those of us old enough, the center-balanced second stage valve design has held sway for longer than the current barrel design second stage valve. Smaller spring forces; lower possible cracking effort; it had the potential for effortless breathing. But the complexity of Tony Christianson's record setting Pilot regulator valve drove a search for a simpler design.
Pilot Valve.jpg

The Pilot and the Air1 that followed had great valves, but could be wet breathers with their untethered upper diaphragm edge. And so Doug Toth's D300, D350 and D400 took the low-cracking-effort lead and were the regs I first started diving (attached to a Mk10). To say that they were a challenge to service is a bit of an understatement, and my first service disaster with the technician perforating my diaphragm drove me early on into DIY. I may have thousands of dollars in D-series spares which I now believe will be obsolete.

If you look at the TFX valve, the similarity with the D400 is hard to ignore.
Valve1.jpg


Scubapro returned decades after abandoning the D400 with their D420, and the excitement amongst the center-balanced community was palpable. With a plastic knife edge that is replaced with each service, the D420 obviated the one nagging problem with the old D's: a knife edge that was easily nicked, requiring significantly more seating force to seal. Now you'd get a new knife edge with each (very expensive) service kit.
Housing3.jpg

But the D420 departed in a big way from the D400: it got rid of the coaxial diaphragm/exhaust valve in favor of a standard "aft" placement of a larger valve that assisted exhalation WOB, and made for a great ANSTI loop. Indeed, on my deep water test of the D420, it's exhalation breathing performance was superior to my fave - the D400. Alas, it required a 1.3" cracking effort because the exhalation valve was so much higher in the water column than the diaphragm, and out of the water, it breathes like a pig. But no matter - once in the water, inspiratory effort drops to near zero, and it's a pleasure to use.
Until you roll on your back. If you're a photographer and look up shooting under a ledge, it's not a great reg. My D400 was far preferable because it didn't care what position it was in. But few folks can get the D400 reg serviced, even fewer have spares, and getting the "scrotum" cover off the case has made for a lot of bad jokes.

Enter the TFX. Take everything you love about a center-balanced design concept, and make it better!
1) In true Atomic fashion, the internals are titanium;
2) take that center balanced valve and machine it Atomic-style; in other words, perfectly;
3) take the knife edge orifice and return it to that sharp edged beauty that allows a cracking effort of 0.5";
4) make the orifice replaceable inside the valve housing, so it costs less;
5) make the orifice floating! Now the pressure comes off when the reg isn't pressurized, and seat longevity increases exponentially; EDIT: It doesn't really do that...
6) make the case easy to open up - hooray;
7) and unlike the D420, RETURN TO A COAXIAL DIAPHRAGM/EXHAUST (with a bigger valve)!

Now all we have to do is teach two generations of regulator techs how to work on a center-balanced design again.
But there's more.

I've screen-grabbed some shots from the introductory videos that have been released and want to show why I think this will make my D400 (not to mention my new D420) obsolete.
 
Why is this reg better than [insert brand here]?
Two things: a center-balanced valve and case geometry
(and titanium and floating orifice and easy service and Atomic quality).

Valve2.jpg

Center Balancing
Instead of balancing the valve down the tiny bore of the poppet into a tiny balance chamber, let's supply the gas from the middle and use the force against the bottom end to balance the opening force against the knife edge on the top! It means only a very light spring is required. And the flow path from the valve to the mouth opening is about 10% of the path that a barrel reg's air has to travel. Huge flow!!

Case Geometry
CGF1.jpg

In the standard diving position, the standard reg has an exhaust valve that's half an inch higher in the water column, while the coaxial design has zero case geometry fault.
CGF3.jpg

That means the coaxial design is inherently dryer.
But it really shines in the face down position:
CGF2.jpg

In this position, the standard case has a diaphragm that's 1.2" lower in the water column. If your valve isn't at least that stiff, it will open due to the ambient pressure of its lower position in the water, and the gas will just gently bubble out the exhaust leaflet (e.g., freeflow). And if you've tuned your reg light, it'll probably breathe wet.

Now take my favorite thing to do: rolling onto my back to look at a shrimp clinging to the underside of a ledge:
CGF4.jpg

While the coaxial valve doesn't care, the standard reg's breathing effort is over two inches, because you have to suck the diaphragm down to neutral position AND add cracking effort!

There's just nothing like the combination of these two design factors. The D420 has the valve (albeit in plastic), but not the case geometry. It is a pretty stiff breather looking up.

Now let's look at Regulator Geek stuff...
 
Inside the titanium valve housing is a floating orifice! It's sealed with an o-ring, is easily replaceable and is sharp. That means both low cracking effort and long seat life.
Valve4.jpg

The seat that @Kupu worked so hard to duplicate (successfully!) in the D-400 is now a reversible seat! That means twice the longevity on top of a floating orifice which will decrease indentation.
Valve3.jpg


But it gets better.
The coaxial exhaust valve in the D400 was pretty small. I found that at 120 feet on nitrox, gas density made hyperventilating (to simulate hard work) palpably more difficult. But the TFX valve is larger...
Exh1.jpg

AND they've also done some magic with the exhaust gas pathway.
On top of a soft flexible silicone tee with extended wings,
Exh2.jpg

the pathway is designed to chimney bubbles up and behind your face. The chimney'ing may decrease exhalation WOB (haven't seen an ANSTI loop yet), and your face will be clearer than with other designs.
Exh3.jpg

Look at that right pic. It's like the bottom vents on the Pilot!
Can't wait to see WOB loops.
Now on to Atomic quality execution...
 
The lever is polished and is shaped like a cam
Lever1.jpg

Lever2.jpg

The lever arm is HUGE compared with the foot, and the polishing means friction is low.
Coupled with the extra valve opening from the cam and the short gas flow path to the mouthpiece, air delivery will hopefully be phenomenal.

There's therefore a substantial Venturi deflector to keep things under control on giant stride, because, like the D-series, there's no diver adjustment of breathing effort.
Venturi.jpg

Although the promo material suggests this isn't intended as a flow adjustment, I'll bet that at high gas density, it might be beneficial to close the gate a hair, because flow is so large.

Do I sound like a fanboi?
I was pretty stoked over the Scubapro D420, just because I loved my D400 so much. But my disappointment over the loss of the coaxial diaphragm/exhaust was huge, even though the reg breathed well in the standard position.

Given Atomic's reputation for quality manufacture, plus having the original designer of the D-series as a founding part of the company, I'm thinking (hoping?) that this is a Phoenix arising from the ashes. Can't wait for mine to arrive. I just swallowed hard over the price tag and hope this will last as long as my D350 (37 years and counting).

I think Atomic just hit one out of the park!
I think they're taking a huge risk trying to (re)introduce a valve design that was so technically excellent, but was packaged in a difficult-to-service container that techs learned to hate. I wish them success, because it's the return of my favorite regulator design of all time, in a package that's hopefully better, and certainly sexier. Yeah, the Pilot was magnificent. But (RIP) @Couv was right in his perennial refrain: too many moving parts!

It does carry an added safety factor in design that barrel regs don't: there's no orifice to screw in, thus dropping the lever when it's out of sight. Instead, tinkering with the spring tension under the lid doesn't affect the lever at all. It just changes cracking effort. If that fixes your freeflow, great! At the very least, a helpful knucklehead at the beach won't kill you at depth from having "fixed" your free-flowing barrel-design reg.

@Nemrod made a good point in another thread about the indestructible nature of Scubapro's GRP cases in his G260. We'll see if Atomic's execution using softer materials stands the test of time. It can't be worse than Scubapro's hardened rubber D400 scrotums after 37 years, can it?
But that valve, that valve! I'm stoked.

More to follow one Regulator Geeks night. Maybe the unboxing?

Pedigree.jpg


EDIT: For those who want to cut to the chase, there are 39 pages of speculation while we waited for a reg to arrive for pool testing. Those results are here: Pool Test

And then the open water tests in current in Cozumel are here: Open Water Test
 
I want one… would be super nice if they sold the 2nd stage on its own.
AA website doesn’t mention centre balanced valve, also no videos or animation. Pooh

Thanks Rob,

I figured it sure looks like a centre balanced valve from the body shape.
 
I came here to post this news release and of course was beat out LOL. Anyway how do we get a second stage when I already have two perfectly good ST1's that rsingler knows intimately!!!
 

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