Bp240/bmr500, BG174
A likely useless question :
Met an old timer who said he could taste the beginnings of a scrubber break through/bypass. Reading online I came across how co2 reacts with h2o and forms carbonic acid... Which can be tasted...
Is this potentially practical? Antadotally confirmed?
Regards,
Cameron
Last edited by Sparedone; 22nd July 2017 at 05:15.
I've only deliberately run the sorb to temp stick alarm aka "you're really pushing your luck now" twice, when comparing 797 to some other cheap sorb I was getting (the 797 was more expensive but dollars per hour worked out better value).
Both those times the loop tasted sour and nasty to me.
I have no idea, though, whether it was because I knew I was getting close to the bone and made it up or if the loop was actually getting noticeable acidic.
Not something I'd ever consider relying on as a warning.
Inspiration, Sentinel, Dolphin
Hi,
As I unfortunately had to suffer repetitive CO2 hits (10+) years ago with my defective Sentinel oring scrubber. I feel confident to comment on this topic. Taste is maybe not the most appropriate term I would rather speak about a set of feelings and behaviours.
Suffocating, need to breath, breathing distress, confusion, oppression, unability to swim, but no 'taste' per se. these symptoms are getting worse with effort and depth of course.
When CO2 is high in the loop it makes almost impossible to bailout as you cannot hold your breath even for a few seconds; BTW it can be a test i.e. how long can you hold your breath. Having high oxygen in the loop doesn't help as breathing is controlled by CO2 level not the O2 level.
I took me too many dives before I identified a fauly Oring on the canister letting a CO2 bypass
While there is some truth to CO2 being detectable. I remember playing around at a movie theater as a kid and we filled plastic bags with the remnants of an empty CO2 bottle from the soda machine. Enjoying the simple physics of a heavy gas that fell quickly. Get a strong hit of CO2 and it was not a pleasant experience. Pretty much a 100% CO2 shot.
There were other antics played out with bored teenagers in the back room that included blasting CO2 out of cylinders in a poor attempt to get a little dry ice. Knowing what I know now there was some seriously high CO2 levels in that back room. You couldn't tell. Some fast food stores and convenience stores have killed people with CO2 leaks from the soda machines when they malfunction. Lethal doses and people couldn't detect it. To the point that there are now CO2 alarms in some locations.
I don't see how the problematic levels of CO2 in a rebreather are going to be detected when much higher levels are not noticed. Consider the creep factor, it isn't a switch thrown where one breath is perfect and the next is a problem. It is a slow transition.
Inspo HH + classic Dolphin Ray
When was the Sentinel on the market again?Originally Posted by wizebt
Wish that would be true, when I had my CO2 hit diving an Inspo, there was no creep at all.. I went from all good to heavy hyperventilating within less than 10 seconds!
Recalculation of the gas consumption gave me a SAC of 70l/min ! I essentially emptied a 40 cft in 3 min at 30 m depth!
BTW there was no taste that I recall.. but a real breakthrough failure of some sort and a scrubber nearing capacity might also be some different ball game, I would not rely on a taste, and there is a lot of old "heros" in RBW diving.. Like diving 100m with 2x 7 L Bailout etc..
I call them lucky, nothing else..
No relevance to the topic I believe though. In a room you would have a very different set of ambient conditions than in a rebreather loop? Where would the humidity and limited volume come from that you might taste carbon acid?
Tasting the CO2 as it begins to break through the scrubber? Sounds a bit like well 'ard, billy-big-bollox stuff to me, like the person who manfully informing a group of people that if he felt things had gone so wrong on a deep dive that he'd probably not make it back to the surface alive, he'd clip himself onto the wreck so they could find his body easier.
I wouldn't rely on it.
mk15,lar vII, ray
what a crock of shit , I doubt they guy was even certified on a ccr , 10 milliseconds after you get a caustic cocktail ,,THEN YOU KNOW AND TASTE it
Dolphin
This is probably a stupid idea since I thought of it.
Natural gas is odorless, so a chemical is added to the gas that smells foul to alert that there is a gas leak.
Different mechanism, but would it be possible to add something reactive enough to CO2 that would be user noticeable at the higher level of an "acceptable" CO2 level to give some warning of an impending problem? Of course it would have to be non-toxic and breathable. It would be ideal if it were part of the sorb formulation.
I'm not sure that it would be even possible to create a formulation that could do that and even if it was, the price of the lime would be pretty steep. The work alone to qualify such a system would probably make it a non-starter (after all, the amount of the trace material would become critical to safety, so that trace would have to be extremely uniform in distribution and have very tightly controlled dosing levels). All of it assume that everyone has the same sense of taste too, which I think is not the case. I guess we're stuck with trying to measure the actual CO2 content and the old debates about the best method and location to measure it!
Unless you could come up with something that remained inert until some dosage of CO2 and then cascaded in stank levels. Having it mixed through the sorb would be useless, too, as a 3.5% CO2 load at the start of the scrubber is normal compared to less than a tenth of that being acceptable at the other end of the sorb. A doped loose weave cloth at the end of the bed, maybe?
Tricky. But I like the thinking!
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