How long will you let the scrubber sit

[barrygoss]

No science.

There is no science behind the topic of this thread.

My least conservative instructor set an 11 hour limit for the scrubber. It worked for him and he had done it regularly.

I have set a 6 hour limit open water and 4 hour limit overhead (but after 3.5 hours I am really not happy... so!).

Done it plenty of times no problem.

Back home I pull out the scrubber from the can. Dry the can and replace the little absorbent pad at the bottom. Put the scrubber back in. Seal the scrubber in the can overnight with a top. Let the head dry overnight before recalibrating the next day.

There are many variables we are dealing with and there is no science behind it.

mmm What unit are you diving? it's either a pelagian, a prism, a hammerhead or a nautlius? anything else and you're outside of the tested limits of the scrubber and putting the CO2 hit down to storing the can for more than 3 days, and not exceeding the tested limits (i.e. you're attributing it to teaching error not user error)
The science is the chemical reaction of the lime, (those CE tests people bang on about for durations of use at depth at certain times) the duration above and beyond that is unknown....

But hell, what do I know, I read a load of stuff on the internet and grabbed a rebreather and went diving.

Regards,
B

 

[gianaameri]

mmm What unit are you diving? it's either a pelagian, a prism, a hammerhead or a nautlius? anything else and you're outside of the tested limits of the scrubber and putting the CO2 hit down to storing the can for more than 3 days, and not exceeding the tested limits (i.e. you're attributing it to teaching error not user error)
The science is the chemical reaction of the lime, (those CE tests people bang on about for durations of use at depth at certain times) the duration above and beyond that is unknown....

But hell, what do I know, I read a load of stuff on the internet and grabbed a rebreather and went diving.

Regards,
B

The EN14143:2003 tested limit of my scrubber is 3:30 hours at 0.5% CO2 breakthrough and 4:45 hours at 2% CO2.

No one taught me to dive it 11 hours, but that is what my instructor did (how he dived it).

At 96 meters he penetrated a wreck with no reel (I was buddying with somebody else), and after the dive I told him, "...but you did not use a reel..." and he said, "Do you always do what you are taught to do?"

There is the theory, and there is the practice. Two different things.

 

[barrygoss]

The EN14143:2003 tested limit of my scrubber is 3:30 hours at 0.5% CO2 breakthrough and 4:45 hours at 2% CO2.

No one taught me to dive it 11 hours, but that is what my instructor did.

At 96 meters he penetrated a wreck with no reel (I was buddying with somebody else), and after the dive I told him, "...but you did not use a reel..." and he said, "Do you always do what you are taught to do?"

There is the theory, and there is the practice. Two different things.

Correct, but when the practice is outside the theory, you can't moan like a bitch when it bites you in the arse.

;-D

Regards
B

 

[gianaameri]

Correct, but when the practice is outside the theory, you can't moan like a bitch when it bites you in the arse.

Regards
B

In the context of this thread (the title), there is no exact science.

No theory. We do not know.

When I was little the experts believed that breathold divers' lungs would implode at much much shallower depths than people are actually diving now breathold.

The "experts" do not know "how long to let the scrubber sit."

We read in this thread 14 days, 1 year, to Sofnolime expiration date...

So, I would err on the side of prudence and I felt making this post to rebalance things a bit towards that end.

3 days maximum after initial use.

 

[barrygoss]

In the context of this thread (the title), there is no exact science.

No theory. We do not know.

When I was little the experts believed that breathold divers' lungs would implode at much much shallower depths than people are actually diving now.

The "experts" do not know "how long to let the scrubber sit."

We read in this thread 14 days, 1 year, to Sofnolime expiration date...

So, I would err on the side of prudence and I felt making this post to rebalance things a bit towards that end.

3 days maximum after initial use.

Scrubber duration is a chemical reaction dependant on CO2 and duration.
That chemical reaction requires CO2, without CO2 the chemical reaction does not happen.
Lime requires CO2 to be absorbed to be used up. Once absorbed it is used up.
Until it absorbs CO2 it will not be used up, the CO2 absorbtion limits are set in CE results.
A scrubber is good for x minutes @40m stay inside that envelope and until you've used those minutes you're good. push it past them and you're the guinea pig. (that's the science bit)
I don't do guinea pig.

B

P.s. you've still not said what unit you've set a personal 6hr open water duration on?

 

[gianaameri]

Scrubber duration is a chemical reaction dependant on CO2 and duration.
That chemical reaction requires CO2, without CO2 the chemical reaction does not happen.
Lime requires CO2 to be absorbed to be used up. Once absorbed it is used up.
Until it absorbs CO2 it will not be used up, the CO2 absorbtion limits are set in CE results.
A scrubber is good for x minutes @40m stay inside that envelope and until you've used those minutes you're good. push it past them and you're the guinea pig. (that's the science bit)
I don't do guinea pig.

B

P.s. you've still not said what unit you've set a personal 6hr open water duration on?

You are talking about a different thing now which is CO2 endurance at a given depth than the thread topic (scrubber storage after use), but we can discuss that as well.

EN14143:2003 CO2 endurance is a good benchmark or point of reference, but I do not dive in such cold water, at that constant depth, for that long, producing those levels of CO2.

The limits I gave are the manufacturer calculated limits for my scrubber at "constant depth" of 40 meters based on EN14143:2003.

Now, some manufacturer quote the EN14143 number based on "constant depth" of 40 meters, while other manufacturers instead quote a different number based on a Qinetiq variant to the standard which is more relaxed (and often it is not clear which of the two is applied, the true EN14143:2003 as stated, or the Qinetiq variant).

So, the same scrubber I use if it were tested to the QinetiQ variant would last a lot longer than the number I gave below.

So, which is right... which is the theoretically correct one and the theoretically incorrect one: a. "constant depth," or b. "QinetiQ variant?"

My point is that even when it comes to CO2 endurance, the "experts" do not know.

There are many variables to take into account which is why in an overhead environment I follow the more prudent guideline (4 hours), and in an open water environment I follow a less prudent one (6 hours) - but I take care to keep the WOB low all the time no matter what, and add safety margin depending on actual conditions of use.

 

[barrygoss]

You are talking about a different thing now which is CO2 endurance at a given depth than the thread topic (scrubber storage after use), but we can discuss that as well.

EN14143:2003 CO2 endurance is a good benchmark or point of reference, but I do not dive in such cold water, at that constant depth, for that long, producing those levels of CO2.

The limits I gave are the manufacturer calculated limits for my scrubber at "constant depth" of 40 meters based on EN14143:2003.

Now, some manufacturer quote the EN14143 number based on "constant depth" of 40 meters, while other manufacturers instead quote a different number based on a Qinetiq variant to the standard which is more relaxed (and often it is not clear which of the two is applied, the true EN14143:2003 as stated, or the Qinetiq variant).

So, the same scrubber I use if it were tested to the QinetiQ variant would last a lot longer than the number I gave below.

So, which is right... which is the theoretically correct one and the theoretically incorrect one: a. "constant depth," or b. "QinetiQ variant?"

My point is that even when it comes to CO2 endurance, the "experts" do not know.

There are many variables to take into account which is why in an overhead environment I follow the more prudent guideline (4 hours), and in an open water environment I follow a less prudent one (6 hours) - but I take care to keep the WOB low all the time no matter what, and add safety margin depending on actual conditions of use.

Gian,

back to the subject (and the scrubber duration / endurance is not different, in fact it is the same thing) how many Litres of Co2 can your scrubber "scrub"?
anything outside that is user error not unit/information error
substitute Litres for MOLS or grams or the CE results?

ok, In plain english. my scrubber can deal with 1256litres of CO2 before it is expired, it doesn't care if it gets that in one, two, three or ten hits. 1256L is what it can take.(and that's the storage bit covered)

As I said, go outside that and it's user error, not anything else.

My point to start with, there is science behind the scrubber duration, stay inside that, don't let the scrubber dryout and it will think it's on one loooong dive, just not absorbing CO2 for a chunk of it.

Regards,
B

 

[gianaameri]

Gian,

back to the subject (and the scrubber duration / endurance is not different, in fact it is the same thing) how many Litres of Co2 can your scrubber "scrub"?
anything outside that is user error not unit/information error
substitute Litres for MOLS or grams or the CE results?

ok, In plain english. my scrubber can deal with 251litres of CO2 before it is expired, it doesn't care if it gets that in one, two, three or ten hits. 251L is what it can take.(and that's the storage bit covered)

As I said, go outside that and it's user error, not anything else.

My point to start with, there is science behind the scrubber duration, stay inside that, don't let the scrubber dryout and it will think it's on one loooong dive, just not absorbing CO2 for a chunk of it.

Regards,
B

There is a chemical reaction and that is scientific, and a maximum amount in liters of CO2 that Sofnolime can absorb, but whether the scrubber can actually remove the CO2 without bypass at any point in time during the dive depends on a fairly large number of variables.

So, no one can put a scientifically certain number to how long you can use a scrubber for and be safe.

You can test time to breakthrough in artificial conditions using specific parameters like EN14143:2003 - but that is only a guideline or benchmark (a good one to know).

If my scrubber is rated for 3:30 minutes under EN14143:2003, but after say 3:00 hours I produce 3.15 liters of CO2 (under heavy exertion), it might still break-through (especially if deeper than 40 meters).

So, unfortunately scrubber duration and sofnolime storage limits after use is a bit of guesswork within an estimated range based on artificial tests (which is why I went through the trouble of building a CO2 Monitor).

 

[Venomguy]

There is a chemical reaction and that is scientific, and a maximum amount in liters of CO2 that Sofnolime can absorb, but whether the scrubber can actually remove the CO2 without bypass at any point in time during the dive depends on a fairly large number of variables.

So, no one can put a scientifically certain number to how long you can use a scrubber for and be safe.

You can test time to breakthrough in artificial conditions using specific parameters like EN14143:2003 - but that is only a guideline or benchmark (a good one to know).

If my scrubber is rated for 3:30 minutes under EN14143:2003, but after say 3:00 hours I produce 3.15 liters of CO2 (under heavy exertion), it might still break-through (especially if deeper than 40 meters).

So, unfortunately scrubber duration and sofnolime storage limits after use is a bit of guesswork within an estimated range based on artificial tests (which is why I went through the trouble of building a CO2 Monitor).

Where I dive the CCR boys have been running for 6 hours as the norm on their scubbers, Kiss, Disco and JJ's, water temp is 30 C, not much science but real life tests, however as sorb is cheap I would not bother storing a part used canister longer than 2 weeks.

 

[Bythesea]

Other than it drying out what are peoples main concerns with using 'sat' scrubber?

AFAIK so long as it doesn't loose its moisture content it will be fine, it doesn't decay as such and is only likely to loose its moisture of sat in arid conditions...

 

[gianaameri]

I'll put some Sofnolime in a glass of fresh water and leave it there for 5 days. Some time at 40C... some time at 20C... some time at 10C. Then, I'll let it dry in the garage in air for 4 days,and top up the drying in an air conditioned room for 1 day.

Then I'll test it, in a rudimentary way, and see if it still works.

If it does, I'll concede that my 3 day limit is probably too conservative, but I'll still stick to it because of the personal experience I went through.

It is a "stress test" (fairly extreme I think), but you can come up with different ones.

The problem with storing part used Sofnolime in a scrubber is that the conditions of storage including ambient temperature will be different, together with many other variables like how long it was used for, how it was used, in what conditions.

Maybe someone could come up with a used Sofnolime storage standard test like there is CO2 Endurance in EN14143:2003 and that would create a benchmark or baseline we could use for reference, but putting down any number at this stage is very much guess work and non-scientific and there is some risk.

Then there is the issue of microbiological growth. Storing a part used scrubber in Thailand or the Maldives is probably very different than in colder climates.

 

[Hanssing]

I nearly died because of posts like this.

3 days maximum storage after initial use, and then bin the sorb.

I dont mind you not storing the scrubber, but saying there is no science behind my post is bullsh@t

However if you do not understand the arguments, the reaction chemistry, or the studies performed and just want to listen to your instructor thats fine.

But my post is not going to kill anyone, and I take offense for you implying so!

You quote your instroctors verbal communication, and clearly have zero understanding.of what they were saying. Please in the future can you refrain from answering my post, unless you have some valid argument, or point?

 

[gianaameri]

I dont mind you not storing the scrubber, but saying there is no science behind my post is bullshit.

However if you do not understand the arguments, the reaction chemistry, or the studies performed and just want to listen to your instructor thats fine.

But my post is not going to kill anyone, and I take offense for you implying so!

You quote your instroctors verbal communication, and clearly have zero understanding.of what they were saying. Please in the future can you refrain from answering my post, unless you have some valid argument, or point?

So, you stated:

As long as the material does not dry out - then I let it sit forever.

Show me the science behind that (reminds me of the movie Ali G).

There is NONE.

 

[Bythesea]

I'll put some Sofnolime in a glass of fresh water and leave it there for 5 days.

How does that mirror real life usage?

 

[divingabe]

Depth of the next dive is more of a concern for using a partially used scrubber. Time of storage (for properly stored scrubber) is not a noticeable factor.
I regularly set my stack timer to 480min. average dive time of 90min once a week for average depth of 100 feet range 80feet to 130feet. Scrubber stored in a sealed container between dive days. You can see that under these circumstances one fill lasts me better than a month.
If the plan is for a dive to 180-200 feet I will not use a scrubber that has more than 200 min use, if so it is epmtied and refilled.
By no means should you follow my example, everyone has to follow their own drummer and be comfortable with the state of their equipment for a particular dive and if in doubt fix the concern area prior to submerging.
Gabe

 

[gianaameri]

How does that mirror real life usage?

It does not... but when you want to test a potential carcinogen on a rat, you tend to feed it quite a lot.

Then, if the rat gets cancer, the skeptics will say "Oh, but you fed it more than a human will ever eat in his lifetime."

It is an artificial test. It is extreme. If the Sofnolime passes that test, then I'd be pretty confident it can withstand a lot less.

When I tested in my rudimentary way, but I wanted to touch first-hand the subject, frozen Sofnolime, I froze it to -17C. I could have frozen it to -7C, but chose -17C because if it then worked when defrosted from -17C... well, I do not have to worry about testing it at -7C as well.

It is an extreme test. If it fails, I can relax the test parameters, and test again.

If it passes, I guess it shows (to me, others may disagree) Sofnolime is pretty resilient.

 

[Hanssing]

Groaan!
Firstly, the qoute made was not science, but stated fact of what I do.
Secondly, read through the whole post again, understand it, read the canadian navy report on storing sorb etc.
Then what ever is left that you dont understand, ask someone.

But ask someone else please!

Oh and you are on ignore from now on, so its not that i am rude if i dont reply, i simply dont want to waste time on trolls.

So, you stated:
Show me the science behind that (reminds me of the movie Ali G).

There is NONE.

 

[gianaameri]

Groaan!
Firstly, the qoute made was not science, but stated fact of what I do.
Secondly, read through the whole post again, understand it, read the canadian navy report on storing sorb etc.
Then what ever is left that you dont understand, ask someone.

But ask someone else please!

Oh and you are on ignore from now on, so its not that i am rude if i dont reply, i simply dont want to waste time on trolls.

O.K. we agree then that your statement is NOT SCIENCE, and you can ignore me going forward.

The Canadian report is interesting. I read it before and read it again and without reading it yet again now from what I loosely remember it concluded that it is best to bin the Sofnolime after use, even though for 7 days it does not appear to loose its efficacy under the tested conditions.

"7 DAYS," NOT "FOREVER."

 

[Bythesea]

It does not...

Then I shall soak some in washing up liquid, carry it around in my underwear for a fortnight, mix it with some Moroccan spices and if it still smokes well after all that will dive a fresh fill and put the experimental one in a hookah...

It has as much validity as yours but with extra fun added...


BTW freezing lime is a bad idea, you didn't need to experiment to find that out, it is known....

 

[gianaameri]

Then I shall soak some in washing up liquid, carry it around in my underwear for a fortnight, mix it with some Moroccan spices and if it still smokes well after all that will dive a fresh fill and put the experimental one in a hookah...

It has as much validity as yours but with extra fun added...


BTW freezing lime is a bad idea, you didn't need to experiment to find that out, it is known....

Well, not really.

With my test I am trying to expose the Sofnolime to the same conditions it would be stored after use, but exacerbate the conditions to get some results quicker (without adding phlegm).

Bit like accelerating the aging process of spirits.

So, there is some more logic to it, than you seem to suggest (but I accept it is not science in any way, shape, or form, and its finding would have some significance only if the Sofnolime still appears to be working after enduring those rather extreme and admittedly so conditions).

Science though works in funny ways I seem to remember reading at school about a guy called Fleming (1928)... could be a dum thing to do looking at it now, but might turn into accidental science!