Latest ScubaLabs reg test - huh?

[stuartv]

Hi @stuartv

Over the years, I have struggled with trying to understand the ANSTI simulator testing of regulators. Some background for the testing equipment can be found at Ansti Test Systems Ltd under products/Life Support Equipment Test Facility.

The graphics results in the recent Scuba Diving article are mislabeled and make it harder to understand. The first parameter listed should be RMV rather than BPM, i.e. 37.5 RMV. The breathing rates used are actually 15, 30, and 25 breaths/min @ 2.5 liters per breath. This generates the RMVs of 37.5, 75, and 62.5 liters per minute, corresponding to 1.32, 2.65, and 2.21 cubic feet per minute.

Thank you for that bit of info! That puts things much more in perspective.

I have the computer-recorded-via-AI gas consumption data from pretty much every dive I have ever done. My highest RMV over the course of a whole dive was 1.36cu-ft/min, on a 20 minute dive with a max depth of 45'. Looking at the dive's data, I can see a stretch early in the dive with a sustained RMV over 3.0 for around 3 minutes, with a peak of 3.6 cu-ft/min. That was just me. The dive was just over 1 year ago and my notes tell me where I was and who I was with, but I don't really remember the dive specifically. It was just practice in the local quarry.

I might throw out that dive's data as an outlier. I don't think I had a 3-minute long free-flow, but maybe I'm just really forgetful.

I have numerous other dives where I have short periods of an RMV over 2.0, even though the overall dive average is only a little over 1.0.

So, a test that simulates RMV of 1.32 and 2.65 seems completely relevant to me. A reg that would give me any noticeable increase in WOB in the scenario where I am sharing with a buddy and we are, for example, working to get back to an anchor line is probably one I would prefer to avoid.

However, what @tbone1004 said about diver orientation and how that affects the results also means the Scuba Labs results are not really something I can necessarily draw any conclusions from.

Hmmm...

I am still curious about different reg designs and how one setup could become a little harder to breathe when face-up and another setup could become a lot harder to breathe when face-up. I would have thought that if the regs are the same distance apparent, then the change in WOB would be the same when you invert the orientation.

The Deep6 Signature is basically a Version 2.0 of the HOG Zenith. It is the same basic design but has some minor tweaks that make it a bit better than the Zenith. Parts kits are interchangeable on the regulators fwiw. If you are looking at HOG for that reason, the Deep6 will breathe a bit better and are of a bit higher quality due to the internal material improvements, and represent a better value since they include the first service for free and also include the first set of parts kits for free

Are you saying the parts kits are interchangeable between a HOG D3/Zenith and a Deep6 Signature 1st/2nd?

 

[cerich]

Well..here is my take on it, and I did discuss with Scubalab my thoughts. the offered to send me the raw test results but I have not gotten them yet.

The Deep 6 signature is very close to the HOG/Zenith combo. I have some passing familiarity with both The Deep 6 second is slightly better with my turbo poppet. Look at the ratings it got compared a couple years back compared to the Deep 6 Signature. It simply doesn't make sense. Sample variation doesn't even explain what I am seeing in the review.

That aside, I KNOW that there were a whole bunch of regs in that review that outperform the unbalanced reg that earned top spot. Yet Scubalabs is saying the unbalanced outperformed them. I've spoken with others on the reg making side including folks that I compete with and they agree...not possible. In particular the at depth part.

The "objective" testing simply doesn't jibe with what I and others experienced in reg testing and design know.

The subjective comments in this case I put much more faith in.

 

[Akimbo]

It looks like West Marine is selling all or most of the Mares line, along with Dacor, JBL, and others: Diving | West Marine

 

[scubadada]

...However, what @tbone1004 said about diver orientation and how that affects the results also means the Scuba Labs results are not really something I can necessarily draw any conclusions from...

It appears the ANSTI testing is done in a face forward position, the approximate position in which much of diving is done, rather than face down or face up. The comments about swim position (face forward), face up (looking up), and head-down (face-down), are part of the ergonomic testing done by the test divers, in the water.

 

[Akimbo]

It appears the ANSTI testing is done in a face forward position,...

ScubaLab Dive Lab can position in any orientation in their ANSTI machine. I believe it is called out by the EU and USN standards. This makes sense to me since it is the worst position on most regulators for exhalation resistance and is probably your orientation in an emergency (get to sunshine) situation.

 

[Bob DBF]

I am not sure what kind of clientele West would bring to the table.

For one I wish that some the dive shops I've gone into had the customer service that West Marine has. I'll have to look into this next time I'm West Marine and see what they know about this whole picture.


Bob

 

[tbone1004]

@scubadada I commented that I believe the test rig may be optimized for commercial diving where the diver is vertical in the water column. In scuba that is not the case so the regs will be designed for normal diver orientation which is closer to 45* vs. 90. Having the reg in that orientation will increase both inhale and exhale resistance.

@stuartv is it possible you were sharing air with someone for any portion of those dives? If not, could you have had the wrong tank size in the computer?
No offense, but I'd be surprised if you were in good enough shape to maintain a 1.3+cfm SAC rate for 20 mins without passing out.

Oh, of note for anyone that is curious. Scubalab is reporting the sum of inhale+exhale for total work of breathing. Not showing the curves is a bit unfortunate. If you look at the certified ANSTI curve for the Xstream, the WoB on inhale goes from something like 0.2j/l up to 0.25j/l across the entire depth range under test #3 which is 62.5lpm at 50m. The exhalation is what kills the numbers for that regulator where it increases from .6j/l at the surface to about 1.3j/l at 200m.
I would take a regulator with a flat inhalation effort regardless of depth at that effort that had the increasing exhalation WoB long before I would take one that had an even increase of both inhale and exhale.

 

[Jim Lapenta]

It looks like West Marine is selling all or most of the Mares line, along with Dacor, JBL, and others: Diving | West Marine

West Marine sells A LOT of products from HEAD Sports. Guess who owns MARES and, by default, DACOR? HEAD also now owns SSI. If you expand the reg description it talks about getting proper training with a link. Guess where the link takes you?
It's a non-sealed, balanced diaphragm reg designed for warm water diving. The kit seems to be aimed at boat owners who want something on board to use with low maintenance, already put together, and that they can get serviced when they go to buy something for the boat.

 

[KenGordon]

No offense, but I'd be surprised if you were in good enough shape to maintain a 1.3+cfm SAC rate for 20 mins without passing out.

Maybe he has very good regs so the WOB at 40l/min is not too much?

Dry suits and wings use gas too. Also when distracted by tasks a diver struggles with the breathing rate can really take off. So initial tries at shutdown, manipulating a lifeless body for rescue and so forth can really push it.

 

[stuartv]

@scubadada I commented that I believe the test rig may be optimized for commercial diving where the diver is vertical in the water column. In scuba that is not the case so the regs will be designed for normal diver orientation which is closer to 45* vs. 90. Having the reg in that orientation will increase both inhale and exhale resistance.

@stuartv is it possible you were sharing air with someone for any portion of those dives? If not, could you have had the wrong tank size in the computer?

The one dive showing an RMV of over 3 at times is possible that I was using a single tank and I have it wrong in the log. The log says I was in doubles, but I don't remember what I actually used that day. I think I was in doubles, but I could be wrong.

EDIT: Looking at my top 2 dives (for highest RMV). One has an RMV over 3 (max 3.86) for about 2.5 minutes. It also has a low of 0.39. And the dive average is 1.36. Another dive (showing RMV over 3) has a high of around 3.3 and a sustained period of over 2 for longer than 2 minutes. The average, for the whole dive, is 1.15. And a low, towards the end of the dive, of 0.43. So, I think they are both correct with regards to tank size. And no, I know I was not air-sharing on either dive. And, both dives had the high usage period towards (but not limited to) the beginning of the dive. In other words, it wasn't just the extra consumption from adding air to my drysuit and BCD, though that probably did contribute to it being SO high.

However, I have plenty of other dives showing a sustained (for a short time) RMV well over 1.30 and occasionally over 2.0.

So, again, my point is that I think the RMVs using 1.3 in the lab tests as their test capacity for a single diver seems fine. It may be higher than a lot of people, but it's not ridiculously high. Probably not even higher than 1 standard deviation. My normal RMV on dives where I am swimming, in a drysuit and doubles runs around .6. Doubling that in highly stressful conditions seems totally realistic.

Also, I played trombone for many years. Including marching while playing really loudly. My breathing capacity may possibly be somewhat higher than "average" (even though I'm a fat sack these days).