Tempstik Readings

Chaos

I notice during dives that I have a large portion of my scubber is active, when comparred to my friends inspiration.I am worried because a have read only a small section of scrubber should be active and this should progess through the canister.Does this mean I am susceptable to CO2 breakthough, am I packing the canister wrongly etc ?

Regards - Andy

...Chaos just happens, don't fight it

grahamsp

Andy,

The first question (just to eliminate one of the variables) is whether or not the scrubber is being packed properly. Go to Scrubber Packing Thread for a good discussion on this.

Assuming then that the scrubber is packed properly, I don't think there is an issue. To quote Tino de Rijk:

. . . the tempstik measures the progressing warmth front that travels through the scrubber bed as the Sofnolime progressively gets spent, causing an exothermic reaction in the process. The measurement is done by a number of serially placed temperature sensors in the central pole of the scrubber container.

So, it follows that the tempstik will show a cool portion - the exhaled gas passing through used sofnolime before it gets to the reaction front - followed by a hot portion that starts at the reaction front where the CO2 gets absorbed. In my experience, the heat is then carried through the scrubber by the flow of gas causing the tempstik to show most, and in my experience, quite often all of the rest of the scrubber to be hot.

All of which is a long winded way of saying that I don't think there's any problem - provided your scrubber is properly packed properly in the first place!

However, that does beg the question why your mate's tempstik should show something different. Level of fitness? Size? Work rate? Different approach to scrubber packing? Breathing rate? Not sure - maybe there's a medico out there who could comment?

G

nigelh

It doesn't read active it only reads warm.
When it starts up only the active part is warm but the heat carries through with the gas in the loop and soon it is warm from the active part right up to the top.

Slap your friend round the head and tell him he doesn't have to skip breath a rebreather. A warm scrubber is a happy scrubber.

__________________
nigelh

diver15

Also worth noting is that the Tempstik readout varies with depth. I can't recall the technical reasons as I've been without the unit a few months now but it was obviously linked to gas density.

My experiences where that on shallower dives I found the whole tempstick would get hot and the majority of the indicator bar would be black, whereas on deeper dives the hot active front would compress and activate a smaller part of the indicator bar. This would work its way across as the scrubber was used. Then, on the 6 metre stop and on surfacing, the black indicator bar would grow larger, indicating that more of the scrubber became warm again.

It gave me the willies when I first started using the unit after paying too much attention to the stories banded about by some non-YBOD divers, then I just accepted it as the behaviour of the unit.

Remember, it is merely an aid - it is not a calibrated guage!

And you can't beat a happy scrubber!

Dan

__________________

Dave Faye

I would watch the scrubber packing video on the AP website. Packing the Inspo/Evo scrubber is really a very simple process that is made overly complicated by some. Don't overpack and crush the granules.

__________________
Dave

http://www.Bostondeepwrecks.com

http://www.Fayelaw.com