The New Atomic TFX

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Quick update before the night dive:
bowing the stack spring into a slight banana eliminated the whine from the first stage. Quiet as can be now.
 
Quick update before the night dive:
bowing the stack spring into a slight banana eliminated the whine from the first stage. Quiet as can be now.
Banana.gif
 
Did you get an impression on ease of breathing TFX vs d400 in outrageously out of trim orientations? Wet breathing TFX vs d400?
The D400 was just as easy rolling on my back as the TFX. A joy when looking up. As for the Achilles heel position, my D400 @ 0.6" was not quite as wet as the TFX @ 0.9". Neither was bad at all, but getting a couple of drops of water in when your mouthpiece is lowermost is disconcerting. But it's not a position you hold for too long. Remember, I'm talking about past vertical, looking back between your legs. We're diving Devils Throat tomorrow, so I'll be better able to tell you about long runs in a near-vertical position after that. I don't expect any water just plain head down.
 
Same with my d400. Lets just enough water in to remind you to be careful when on your back. Which operator are you diving with?
 
Scuba Club Cozumel

For those following along, if you want to compare with the original pool test of multiple regs, that's on page 39:
The New Atomic TFX
 
Hi @rsingler

I would love to see the ANSTI flow curves on all the regulators you are testing.

Though the cracking pressure contributes to the work of breathing on inhalation, it is the work of breathing on exhalation that contributes most to the overall work of breathing. Anyone who has really huffed and puffed on their regulator is aware of this.

I love your personal testing, it reveals things only available by that method, objective data is also useful.
 
Day 4: TFX  vs Mares XR/HR & Poseidon XStream
Today was a fairly high current drift diving day.
For the morning dives, I used the newish Mares XR/HR. Unlike the previous decades of Mares seconds, this one is a balanced barrel second stage with a combined cracking/Venturi adjustment. It's intended for the tech community, and has a unique barrel that allows you to remove the lever without spreading the legs. I'm not so fond of the combined cracking/Venturi, but at least the action is smooth.
This reg was tuned to 0.9", and with a small case, did not freeflow when looking straight down. Breathing was light, with a barely palpable Venturi assist, though neither as light nor as smooth as the TFX. Exhalation was similarly easy, though not as easy as the D420. It probably matched the TFX in exhalation WOB, but felt just a shade rougher.

The Poseidon XStream requires a lower IP. I set a Mares 28XR at 118 and added the seconds. The TFX didn't measurably change cracking effort with the drop in IP (in fact, the reg will handle an IP of 20 psi without cracking out of specification range for most other regs!!!).
The XStream loved the lower IP. But as has been observed elsewhere on SB, it shuddered (perhaps from excess Venturi) right at the surface, though that disappeared by 30 feet. The XStream is better controlled than its Jetstream counterpart, and didn't blow at me on valve opening quite the way the Jetstream does. But it's not an air-sipping reg like barrel designs. The valve opens, and it closes. Still, inhalation effort was easy and consistent at all depths.
Where the XStream fell behind was on exhalation. The exhalation valve is relatively small, and I could just barely perceive some resistance. It wasn't enough to concern me (compared with the D400), but I actually think the TFX outperformed it. As @scubadada suggested, we're all waiting for an ANSTI loop on this reg.
But of more concern was the noise! The XStream just blasts by your left ear, and it's quite startling. It may have been magnified by the hood I wore for the night dive that I haven't worn on the other trials.

I clearly preferred the TFX.

Today we do Devil's Throat, so I'll be putting the D400 back on to compare breathing at high gas density. But I wish I could do all three, since the XStream has apparently passed the Norsok tests and I'd like to assess exhalation again at depth.

More to follow!
 
Day 4: TFX  vs Mares XR/HR & Poseidon XStream
Today was a fairly high current drift diving day.
For the morning dives, I used the newish Mares XR/HR. Unlike the previous decades of Mares seconds, this one is a balanced barrel second stage with a combined cracking/Venturi adjustment. It's intended for the tech community, and has a unique barrel that allows you to remove the lever without spreading the legs. I'm not so fond of the combined cracking/Venturi, but at least the action is smooth.
This reg was tuned to 0.9", and with a small case, did not freeflow when looking straight down. Breathing was light, with a barely palpable Venturi assist, though neither as light nor as smooth as the TFX. Exhalation was similarly easy, though not as easy as the D420. It probably matched the TFX in exhalation WOB, but felt just a shade rougher.

The Poseidon XStream requires a lower IP. I set a Mares 28XR at 118 and added the seconds. The TFX didn't measurably change cracking effort with the drop in IP (in fact, the reg will handle an IP of 20 psi without cracking out of specification range for most other regs!!!).
The XStream loved the lower IP. But as has been observed elsewhere on SB, it shuddered (perhaps from excess Venturi) right at the surface, though that disappeared by 30 feet. The XStream is better controlled than its Jetstream counterpart, and didn't blow at me on valve opening quite the way the Jetstream does. But it's not an air-sipping reg like barrel designs. The valve opens, and it closes. Still, inhalation effort was easy and consistent at all depths.
Where the XStream fell behind was on exhalation. The exhalation valve is relatively small, and I could just barely perceive some resistance. It wasn't enough to concern me (compared with the D400), but I actually think the TFX outperformed it. As @scubadada suggested, we're all waiting for an ANSTI loop on this reg.
But of more concern was the noise! The XStream just blasts by your left ear, and it's quite startling. It may have been magnified by the hood I wore for the night dive that I haven't worn on the other trials.

I clearly preferred the TFX.

Today we do Devil's Throat, so I'll be putting the D400 back on to compare breathing at high gas density. But I wish I could do all three, since the XStream has apparently passed the Norsok tests and I'd like to assess exhalation again at depth.

More to follow!

So in summary: today, your time, was a TFX superiority day :)
 
I used the newish Mares XR/HR. Unlike the previous decades of Mares seconds, this one is a balanced barrel second stage with a combined cracking/Venturi adjustment. It's intended for the tech community, and has a unique barrel that allows you to remove the lever without spreading the legs. I'm not so fond of the combined cracking/Venturi, but at least the action is smooth.
You had me at spreading the legs.
 
Day #5 - TFX vs D400 at max safe gas density

Today we dove Devil's Throat to 136 ft. Picked up 8 minutes of deco because we all hung around at 136' making sure everybody came out. That gave me plenty of time to breathe hard on both regs.
As you'll recall from @Dr Simon Mitchell 's presentation, 6.5 g/l is the inflection point after which CO2 retention became a real issue for exercising rebreather divers. Granted, OC might have less risk in this regard, but the point is, 136' on Air is already over 6.5 g/l.

Head down position
First, while descending through the throat, there are two passages where you are literally vertical head down. Both regs were absolutely dry in this position. Keep in mind the regulator position when head-down vertical. Since you are looking in the direction of travel, the reg is held with the top cover at ~225° and the diaphragm/exhaust valve is vertical. While this doubtlessly admits a few drops of water as the exhaust valve flutters during exhalation, the water collects in the head and is expelled as you roll horizontal.
The only time I've had a wet TFX or D400 is looking  past vertical head down (like looking back between your legs) which puts the exhaust valve high and the mouthpiece low. I'll test that again tomorrow against a stiffer TFX tuning.

Inhalation
Inhalation was a delight from both regs. With the low diaphragm both valves are preloaded by ambient pressure and are ready to open, held back by positive pressure in the case (because the diaphragm is lower measured from your throat than the cracking effort). Thus, all you have to do to breathe is inhale and the air flows. (To prove to yourself that the valve is always ready to open in the standard diving position, just take your mouth off the mouthpiece - it freeflows like crazy as soon as that positive pressure maintained by your mouth seal is removed.)

 Exhalation
Exhalation was the whole reason for this repeat test against the D400.
I am unclear on what your expectation is for a D400 with a TFX diaphragm. Do you think that combo will be an overall nicer reg than either of the two alone? Or is this just your nostalgia prompting you to stick with the D400, but improve it?
As you know, @James79 is interested in creating a diaphragm retainer with a larger top circle and lower collar, to potentially facilitate Exhalation WOB by using the TFX diaphragm instead.
The D400 suffers from increased exhalation work of breathing because of three factors:
- a small exhalation valve
- a circuitous exhalation pathway, and
- small cover holes for exhalation without wings that might "chimney" the bubbles.

In my test on the Spiegel Grove at 120' that was the data set behind Regulator Geeks #3 a year ago, I noted the difference in exhalation effort between it and standard barrel regs (and the D420). I was concerned that a diver might be at risk for a CO2 hit during exercise at max gas density. But I was gas and deco constrained to a very short test (just three quick heavy hyperventilation cycles) because I was comparing so many regs.

Today, we hit and held at 136' with air (6.6 g/l). I didn't feel stupid, though I'm sure I was. In any case, I was collected enough to compare the two regs as we waited for the rest of the group to emerge from the Throat.
To my pleasant surprise, although I could feel a clear difference between the TFX and the D400, holding position in current was not stressful on my old favorite: the D-series. I had no doubt that I could increase my effort if needed, and maintain it without feeling short of breath or working too hard. I'm no longer concerned about a CO2 hit with the D400, though the TFX was WAY easier.

So that means that IF we can come up with a diaphragm retainer that has a lower collar and accomodates a larger exhaust valve, and design a new cover that's easier to remove and has larger, directed exhaust ports, we will have a reg that has better exhalation WOB, and there will be a potential source of diaphragms for this aging reg. I'm down to my last five, and my last two from a SB friend who recently got them from Germany for me, were beyond expensive. Any way you look at it, the D400 remains a fantastic reg, albeit with huge service challenges.

But the TFX is better. And is easy to service. And has a sharp knife edge. And is titanium.

I've deliberately beat up this reg. I've not used a case, and have tried to ignore it when it falls on the deck or the ground on my 60" hose at day's end during packing up. I just jumble it up with my gear during tank changes and transport. I'll include a picture at week's end, to show how it's held up. I can't speak to scratches on the plastic, as it's hard to tell when it's wet. But the soft purge cover has really performed well, and I have no indication that it's at all fragile. It's VERY lightweight.

I'm out of regulators to try, but it has beaten every one I brought. It's only slightly better than my G250 and T3, moderately better than the Mares XR/HR and C370, and (to my surprise) definitely better than the XStream.

Stiff tuning test for wet breathing in the 210° position next (and last).
IMG_20231109_163559_1.jpg
 

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