Potential Safety Improvements in Rebreather Design

[descent]

I dive a hybrid rig ... I love information, but do not like my CCR doing things for me (despite my acceptance of the solenoid on my hybrid revo...it's just better at adding tiny squirts of O2 than I am).

Thank you for taking the time to write such an interesting and insightful post. I have re-read it several times, and expect to revisit it again after I read some of Paul's posts about the design of your unit over on that other forum.

You make several important points that might be easy to miss in a heated and polarizing debate.

Especially noteworthy: it's easy to forget that electronic controls are not an either/or proposition, black or white. If the manufacturer grants us access, we can detune them until they have hardly any influence.

 

[Dr. Lecter]

Just to be clear, the revo ADV is a purely mechanical thing, basically a lever-driven demand valve just like a 2nd stage. It has no electronics or sensor (other than the lever). Still, detuned or not it presents some risk of unintended gas addition to the loop.

The solenoid on the other hand is very much a sensor driven piece of electronic gas injection...and honestly, I don't think I have access to detune it (SW's fast/slow injection model choice aside) at all, much less to electronically shut it off or isolate it while diving. Like the ADV, if it goes wonky the solution is to shut and feather the valve feeding the reg/downstream parts of the system.

 

[Brad_Horn]

From a cursory look at this, they have some very good points about Failure Modes and Effects Criticality Analysis (FMECA) being done on the rebreathers. Apparently, this is required for the CE Mark, but is deemed to be confidential information and so is not publicly released.

John. Nothing (now) confidential at all about their FMECA, see Deep Life Design Team: Design Submission for Open Revolution for a copy. It makes an interesting comparison with what others provide.

The top document provides some interesting testing of their exhale CO2 monitor; which before anyone jumps in and points out the obvious, isn't shipping yet - but you can also see it demo'd at https://www.facebook.com/pages/Open-Safety-Equipment-Ltd/151298954899613?sk=videos