jepuskar:
Stefan, next time can you go into a little more detail?
Sure thing, let me get a cup of coffee and expand a little bit.
Just kidding. :mooner:
Of course each maker has their reasons why they designed it that way....im sure there are arguments to be made for each.
Well, I remember asking about some of the design decisions like batteries in the loop and all I got was a skunk eye.
But for most part that's probably true, just as there are people that will agree with them or not. Important thing I believe is that one understands and ponder the differences and their implications before making a decision.
What do you two think of the AP's temperature stick in the scrubber?
A great tool within its limits in my opinion. Can only be implemented (reasonably anyway) in axial scrubbers but there they all should have them.
There are a several things that can lead to CO2 poisoning. A scrubber monitor can warn of some, a CO2 monitor of others. Yet neither can warn of the possibility of the diver not properly venting his lungs, retaining CO2 that never goes through the scrubbers and sensors and have a CO2 hit. Something to keep in mind while diving.
The TempStick responds to the cooling down of the absorbant that has been spend, and deletes the bars in the graph from the bottom of the srubber on up. You know how much of your absorbant has been spent and isn't scrubbing anymore. But a scrubber can be "overbreathed", meaning that too much CO2 flows through it at to high a velocity for all the CO2 to get bound. Iain from HSM did some testing under pressure and high exhaustion where CO2 broke through rather quickly, and a temperature sensor build by his company didn't give much warning of it. How could it, it just shows which parts are active (and they were, past the limit) and which aren't. That's something to consider with or without any sort of monitoring.
You got the maximum amount of CO2 the absorbant can bind, under ideal condition in the lab. You got the scrubber duration and physical capacity, so you can calculate the amount of CO2 that can be removed under the conditions of the test protocol. You can monitor your O2 consumption and get an idea of your CO2 production. So if the temperature and ambient pressure match the test condition you have a pretty good idea how long your scrubber will last. Problem is when those two variables change, as they both influence the duration. That's where test data is lacking, unfortunately. There is some out for the Drägers, MK series and Optima, but not much and not enough. More numbers are needed, different temps and depths.
Anyway, that's overall capacity.
But the two I mentioned above, RMV and high CO2 production rate, worry me. Will the scrubber be able to handle high excertion, even if just for a few minutes? Not a lot of data available. The 1.6 lpm used for CE is high for the entire duration of a dive. The 1.35 lpm CO2 addition the Navy uses, too, but closer. But under high excertion I for one have used up to 2.2 lpm O2, so CO2 production was probably close to 2 lpm. Will a scrubber be able to handle that, and handle it at the end of the dive?
Lots of people take cheap shots at the Azimuth and its ss can. But that thing was tested up to 5 lpm CO2 addition! And lasted longer than any human being could ever sustain at that rate. I wish that sort of testing was done on all scrubbers and published. So add different loop gas velocities and CO2 injection rates to the test regimen. Aside from possible embarrasment due to failure, such extensive testing is financially not feasible for most if not all companies.
Has any other manufacturer come up with any other sort of scrubber monitor?
The Navy has some patent or other for a temp sensor that they've been trying to sell for a few years.
AFAIK the elusive Infinito is the only unit that has a working CO2 sensor, actually warning the diver that there is CO2 in the inhalation side of the loop. While the technology should be available, the cost so far have been restrictive. About a year ago it would have doubled the price of current units like the PRISM or Classic Inspo. There woould be few takers I'm afraid.
But several companies are working on it, and sooner or later it will be available.
