Sofnolime: 797 Vs 812

[Mark Chase]

What do you mean by stepping outside the manufacturers guidelines? How do you interpret the Temp Stick guidelines?

Matt.

Does the temp stick have guidelines which state you can dive to the temp stick limits/

I had assumed the Inspo was a 3 hour rated scrubber and if you used it past 3 hours on your head be it.

The temp stick is supposed to be there to monitor scrubber errors and breakthrough due to incorrect packing and accidental over use.

PS I am no concerned about people diveing to the temp stick my comments before were ironic and aimed at all those who said I was being reckless.

I chose a scrubber limit based on maths. I calculated I could get about 9 hours out on my scrubber so set a limit of 6

Aparently this is reckless but reliance on a bit of tec is not?? Go figure

[Mark Chase]

If you understand the test conditions giving 3h rating on inspo (and JJ and maybe others) you would know that 3h is very conservative and therefore some extrapolation to longer times is possible. The big question is how far can one extrapolate safely. I know what has worked in the past for my CCR for me but there is some risk to assuming it will be all ok in the future based on that.

C02 = 85% VO2

V02 = 4% RMV

Scrubber calculations are done on a C02 production of 1.6lpm 40RMV at 40m in 4C water


A rough way of doing it would be if your RMV is 10 and the scrubber is rated at 3 hours @ 40RMV you should be able to get 12 hours


4% RMV 10 = 0.4

85% of 0.4 = 0.34

Test level C02 production was 1.6lpm

1.6 divided by 0.35 = 4.7

So in theory you can go to 4.7 X test result because scrubber performance is based on how much C02 it can absorb and this is related to the amount of C02 you put through it


Other issues influencing the result is time at depth and water temp. So if your diving in water warmer than 4c you have an increased margin of error. If your doing dives to 30m not 40m you have an increased margin of error


Personaly I did the calc on 15 SAC (my SAC is around 10) so I get 2.6 X test = 7.8hours and I rounded that down to 6 to give me a max planned duration with a margin of error.


Who needs a temp stick????

[gobfish1]

My C02 production working off o2 used is about .6lpm so im good for noddy diving


RMV SAC lol thats bailout talk ,

[matt]

Does the temp stick have guidelines which state you can dive to the temp stick limits/

There's no time guidelines if that's what you mean. The Temp Stick works by showing you the Sofnolime decay, and when you get to the last block you get a warning (3-5mbar PCO2):



The second warning comes when the Sofnolime is exhausted (5-10mbar PCO2):



I've never seen 1 block, my tests have only ever been to 2 blocks (9h in warm water). I didn't really trust it until I also got the CO2 sensor to test it against.

I had assumed the Inspo was a 3 hour rated scrubber and if you used it past 3 hours on your head be it.

Rated for 3h at CE condition. Can be used longer with Sofnolime 797 and the Temp Stick.

The temp stick is supposed to be there to monitor scrubber errors and breakthrough due to incorrect packing and accidental over use.

That's one of it's uses, but not the primary use.

PS I am no concerned about people diveing to the temp stick my comments before were ironic and aimed at all those who said I was being reckless.

I chose a scrubber limit based on maths. I calculated I could get about 9 hours out on my scrubber so set a limit of 6

Aparently this is reckless but reliance on a bit of tec is not?? Go figure

The only real difference with the maths approach and the bit-of-tech approach is that you don't see the other errors you can see with the Temp Stick (as you pointed out already). And it gives you some real idea what's going on, outside of remembering to set your timer.

If I gave you a used scrubber and a Temp Stick, about 30 mins into a dive you would know how much this scrubber had been used for - it helps stop mistakes.

YMMV.

Matt.

[Alby R]

The temp stick is supposed to be there to monitor scrubber errors and breakthrough due to incorrect packing and accidental over use.

hi matt

i have moved onto a jj from my vision, and i must say i do miss the temp stick.

re this quote i was always under the impression that the temp stick monitored the temperature, not breakthroughs or incorrect packing, these would be for a co2 monitor surely

alby

[matt]

The monitor is for temperature, but it is tested against actual CO2 breakthrough. The limits I posted are from "the list" by the factory. They are also the CE test conditions. For CE marking if you have a device it must be tested and must work.

I agree, though. I decided not to make any scubber endurance trials on myself and stuck to changing the scrubber daily for quite some time.

Then I bought the CO2 sensor and reasoned that if this measures the actual CO2 then I could calibrate (my mind) to understand what the fancy thermometer was telling me.

I've done many many trials in 27c or warmer water. This is where you get the big advantage, and also where you are most likely to find supply issues and high cost. I settled on 2-blocks remaining to give some extra comfort, same as Mark describes in his mathematical calculation.

I have done some limited trials in cold-water, but would not gas dive on a used scrubber as it is not worth any risk with decompression.

I've also done some storage tests of my own invention.

I find the information interesting and helpful; more so than only having the CE test data and some theoretical-math to follow.

Matt.

hi matt

i have moved onto a jj from my vision, and i must say i do miss the temp stick.

re this quote i was always under the impression that the temp stick monitored the temperature, not breakthroughs or incorrect packing, these would be for a co2 monitor surely

alby