Measure scrubber runtime?

[Tassi Devil Diver]

It's electronics. Dr Murphy tells us it will fail. If you have no backup plan, guess who is going to have some guessing to do?

Yes they most certainly do, and having gone through 13 probes in three years (all replaced under warranty) I am very much aware of the possibility of failure. In the case of an rMS failure, just revert back to the recommended scrubber times we were all taught during our MOD1 which are very conservative. Pretty simple really .

 

[Gareth J]

It's electronics. Dr Murphy tells us it will fail. If you have no backup plan, guess who is going to have some guessing to do?

CCR diving is all about having a backup plan.

Year on year, electronics are getting more reliable, but as you correctly say, Dr Murphy tells us the electronics will fail. Often at the most inopportune moment.
I dive an Inspiration, I have dived all three generations of the controller from the classic, to the vision, and now the 2020. I only dived the classic for a short period, and never experienced the electronics die - which was not unknown, because it was easy to crack the housings. I had two vision failures, one early on, which died totally, one at then end when the depth sensor gave up the ghost.
I suspect I have had one CO2 hit, which I believe was the result of settling of the scrubber in transportation, I flew it to Egypt with the scrubber pre-packed. (Elevated breathing rate, fatigue and a thumping headache).

I appreciate the extra data that each evolution of controller has given me, from PO2 only on the first to bluetooth on the current. In truth, the biggest benefit of the 2020 is that the newer colour screen, which makes reading the displays much easier.
A lot of the extra data is nice to have, rather than need to have, like the digital compass. Ultimately, PO2 is the only need to have (if you have time and depth an a secondary instrument).

I do like the temp stick, its not perfect, but it does give me a good feel for how the unit is behaving. I could add the CO2 sensor, but have never felt the need. I always dive with a secondary independent computer.
Upgrading to the BOV was probably the most sensible upgrade I have invested in.

I learnt using runtime, I always carry a hard table both for a normal CCR dive, and a bailout version. The scrubber was heavlly tested, and has excellent (conservative) rules of use, so loss of the temp' stick is an inconvenience, not a concern. (Which has been proven time and time again by the temp stick).

So, as long as I have a working PO2 display, I can revert to the hard table, and runtime, or follow any decompression data my independent computer is giving me.
If I lose all the electronics (including the HUD), then I can bailout using my bailout runtime, or follow the independent computer.

If you are not prepared to have a backup plan, you shouldn't be diving CCR.

 

[Dr Simon Mitchell]

Hello,

We published a fairly comprehensive evaluation of the Revo RMS and Inspo temp stick 2 years ago.

I was surprised at how accurate both were in predicting CO2 breakthrough (except at the surface!).

You can download the publication from PubMed Central here:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6526050/pdf/DHMJ-49-48.pdf

Simon

 

[Wibble]

Hello,

We published a fairly comprehensive evaluation of the Revo RMS and Inspo temp stick 2 years ago.

I was surprised at how accurate both were in predicting CO2 breakthrough (except at the surface!).

You can download the publication from PubMed Central here:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6526050/pdf/DHMJ-49-48.pdf

Simon

Excellent info. Thank you for posting that.

 

[Tassi Devil Diver]

We published a fairly comprehensive evaluation of the Revo RMS and Inspo temp stick 2 years ago.

From the report

Conclusion: When operated at even shallow depth, temperature sticks provided timely warning of significant CO2 breakthrough in the scenarios examined. They are much less accurate during simulated exercise at surface pressure.

The rEvo warned conservatively in all five tests (approximately 60 minutes prior). Inspiration warnings immediately preceded breakthrough in six of eight tests, but were marginally late in one test and 13 minutes late in another.

 

[hroark2112]

Marginally late sounds like marginally dead.

 

[uwxplorer]

Expand - I'm always looking to improve.

You typed, or the result of your action was, the sentence:

I almost never dive without a bailout cylinder.

The logical corollary is that you sometimes dive without a bailout. Which can be deadly, unless you are trying out your rebreather in a 3 feet deep jacuzzi under supervision...

 

[uwxplorer]

Yes they most certainly do, and having gone through 13 probes in three years (all replaced under warranty) I am very much aware of the possibility of failure. In the case of an rMS failure, just revert back to the recommended scrubber times we were all taught during our MOD1 which are very conservative. Pretty simple really .

The problem is, the rMS is "allowing" divers to push their scrubbers way past the manufacturer's recommended duration. Ergo, according to your own logic, the diver would in general have to immediately abort their dive if the rMS crapped out on them. Which might be fine if they have planned their dive with this in mind, but if they had not (I know divers who are ridiculously light on bailout), then a whole game of unknowns would suddenly open up to them...
I would treat the rMS exactly as a pO2 sensor in this respect (except that you cannot flush a rMS and you don't have redundancy).

 

[Gareth J]

The logical corollary is that you sometimes dive without a bailout. Which can be deadly, unless you are trying out your rebreather in a 3 feet deep jacuzzi under supervision...

I think it was inferred, but for clarity. I normally dive with an off board Ali80 for bailout. On extremely rare occasions, I dive without the Ali80, reverting to the 3 litre onboard bailout. This is on a shallow dive, 15m or shallower, and where my buddy has full independent bailout. It is rare luxury to not be carrying the ali80.

 

[wedivebc]

The same reason there is no temp stick in a Meg, Kiss, Triton, Optima, SF2, Hollis, RB80, and others. It's an unneeded complication.

And the fact that AP owns the patent on the temp stick