CO2 build up during 65m (210 ft) dive.

[o-ren-ishii]

Guys,

Absolutely fantastic thread. Thanks especially @Dr Simon Mitchell and @boriss for clearing up and @beester for the initial report.

I dive a JJ in GUE config too, and was "experimenting" with scrubber time. If you do the math for a RVM of 20 you'll get something like 481 mins (2.7Kg 797, 4% usage o2 converted to CO2), which is way more than the CE 180mins. But I do multiple dives per canister, also based on the research done on storing the canister between dives. I'm happy to do 300 mins so far.

But this thread has made it more clear to me the Scrubber durtion is actually a function of time and RVM (and temp) instead of just time. So thank you for that.

 

[fsardone]

Guys,

Absolutely fantastic thread. Thanks especially @Dr Simon Mitchell and @boriss for clearing up and @beester for the initial report.

I dive a JJ in GUE config too, and was "experimenting" with scrubber time. If you do the math for a RVM of 20 you'll get something like 481 mins (2.7Kg 797, 4% usage o2 converted to CO2), which is way more than the CE 180mins. But I do multiple dives per canister, also based on the research done on storing the canister between dives. I'm happy to do 300 mins so far.

But this thread has made it more clear to me the Scrubber durtion is actually a function of time and RVM (and temp) instead of just time. So thank you for that.

don't forget depth. the whole thread hinged on that ….

 

[Markus MDDT]

Made me think.....
Im asking myself: What is the job I want my scrubber to be able to handle? A RMV of "normal" <20l/m is rarely an issue for the scrubber. There are examples of scrubbers lasting VERY long time. But IF the **** hits the fan and I get really stressed and scared I don´t want the scrubber to screw me over on top of all the other issues....I would then have a REALLY bad day. This scope tells me that all the talk about normal RMV is really not that important. The testing that the guys do for CE is therefore relevant. I want the scrubber to handle a very high respiratory rate when Im at my maximum depth and scared shitless. Adhering to this "rule" gives me the warm fuzzy feeling I like when Im diving.
JJCCR, coldwater, Sweden, MOD1,

Just my thought reading this thread! Thanks guys!

 

[fsardone]

Made me think.....
Im asking myself: What is the job I want my scrubber to be able to handle? A RMV of "normal" <20l/m is rarely an issue for the scrubber. There are examples of scrubbers lasting VERY long time. But IF the **** hits the fan and I get really stressed and scared I don´t want the scrubber to screw me over on top of all the other issues....I would then have a REALLY bad day. This scope tells me that all the talk about normal RMV is really not that important. The testing that the guys do for CE is therefore relevant. I want the scrubber to handle a very high respiratory rate when Im at my maximum depth and scared shitless. Adhering to this "rule" gives me the warm fuzzy feeling I like when Im diving.
JJCCR, coldwater, Sweden, MOD1,

Just my thought reading this thread! Thanks guys!

In diving (and aviation for the matter) when everything goes well you are far enough from the limits of technical capability of the equipment and well within the ability of the operator to feel overly safe.

When the proverbial hits the fan …. well the respiratory (and cardiac) rate goes up, gas consumption out of the roof. While problem solving down the drain. You then start taxing yourself and the equipment. batter have enough of those margins.

The safety margin are there just in case you need them.
If you read the blueprint for survival of Sheck Exley there is a classical reason why you need the rule of thirds (and a few others).
Blueprint for Survival pdf
Rulebooks are written in blood. I feel it is better to abide them rather become a contributor.

In normal situations you come out with a third of the gas unused .,. (use scrubber diluent bailout) but when you need it you might find out that if you are very good at managing it … it is barely sufficient.
In ordinary conditions safety margin appear to be very large and overly conservative.
When you need them they are frightening tiny.
We never bailout. But if we really loose the loop it is enough what we took along?
If we find ourself cought in that nasty current, is the scrubber (and our physical fitness) up to the task?
The answe better be yes …. or else!
Just my .02£