How long will you let the scrubber sit

matthewoutram said:
Interesting, do you have a reference for that data, Gian?

Matt.
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The reference is quoted in my prior post.

There have been "issues" relating to my linking to my own server in respect of pictures, videos, documents, data... where I store everything methodically, so I suggest a Google search for any document I may reference as a suitable alternative.
 
ccrdave said:
clumping is also exacerbated by overpacking scrubbers
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Yes, I've noticed that. Since I stopped "hard packing" and moved to "loose packing" (i.e. proper packing) I've noticed I have less clumping and I get 1 extra fill from a keg :-)

Matt.
 
matthewoutram said:
Which post? I googled "CIS Lunar has a 2.66 j/l WOB at 300 feet and 75 RMV" and get nothing, nor anything relevant for NEDU research.

Matt.
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This one:

gianaameri said:
I am confused by some of the numbers quoted, but it is interesting how the longer the scrubber is used, based on manufacturer tests, the greater becomes the WOB.

This confirms my hypothesis that clumping increases WOB. We also know that clumping reduces Sofnolime ability to absorb CO2. I suspect clumping may also cause channelling and CO2 to bypass the scrubber.

It would be prudent until manufacturers actually test in a scientific and documented way not to store a used scrubber for any significant period of time, and then re-use it.

To put some numbers and documented facts (not opinion) behind my hypothesis:

1. Under EN14143, the max. WOB is 2.75 j/l. This based on 75 RMV, which is what is required under EN14143 (and not 40 or 25 RMV as others appear to suggest).
2. EN14143 is not science, but a "minimum" requirement (an unscientific politically acceptable consensus), and according to the best science, the max. WOB should not be 2.75 j/l, but it should be a lot lower - 1.5 to 2.0 j/l in the ventilation range 30 to 75 l/m (Warkander 1992).
3. As an example, from the NEDU research (WORK OF BREATHING LIMITS FOR HELIOX BREATHING, Nov. 2010) few rebreathers meet the EN14143 and/or the Warkander limits (some exceed both, the higher the WOB, the more risky the rebreather):

CIS Lunar has a 2.66 j/l WOB at 300 feet and 75 RMV
AP Diving Inspiration has a 2.98 j/l WOB at 300 feet and 75 RMV
MK16 has a 1.85 j/l at 300 feet and 75 RMV
MK16 Mod 2 has a 2.08 j/l at 300 feet and 75 RMV
Stealth MOD has a 1.71 j/l at 300 feet and 75 RMV
Viper E Stealth MOD has a 1.82 j/l at 300 feet and 75 RMV

So, considering the already very high WOB (above "best science" limits and in some cases also EN14143 limits), and that clumping increases WOB (or to the least that as the scrubber gets used the WOB increases as shown by manufacturer tests), it would be very very unwise to reuse, store, and extend scrubber duration over multiple dives, until manufacturers provide some hard data to support that such use is safe.

Of course, as a Homebuilder I am not suggesting people should not be free to experiment at their own risk, but the available evidence already suggest it would not be prudent to do so over multiple dives and over multiple days after extended storage of a used scrubber.

I would welcome the opinion and comments to the above from the "experts" (as I am not one).
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gianaameri said:
CIS Lunar has a 2.66 j/l WOB at 300 feet and 75 RMV
AP Diving Inspiration has a 2.98 j/l WOB at 300 feet and 75 RMV
MK16 has a 1.85 j/l at 300 feet and 75 RMV
MK16 Mod 2 has a 2.08 j/l at 300 feet and 75 RMV
Stealth MOD has a 1.71 j/l at 300 feet and 75 RMV
Viper E Stealth MOD has a 1.82 j/l at 300 feet and 75 RMV
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How does using Sofnolime (Intersorb?) 812 affect these results, if at all?

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA550047 said:
NEDU.png
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Not sure why that was so hard to find.

Matt.
 
matthewoutram said:
How does using Sofnolime (Intersorb?) 812 affect these results, if at all?



Not sure why that was so hard to find.

Matt.
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Sofnolime with a size of 8 - 12 is what is normally recommended on many rebreathers by most manufacturers and I like it.

I suspect using a larger size grain would reduce WOB, but Sofnolime with a grain size of 8 - 12 if anything validates results (not that I would or could question NEDU results anyway).
 
gianaameri said:
. . .

So, considering the already very high WOB (above "best science" limits and in some cases also EN14143 limits), and that clumping increases WOB (or to the least that as the scrubber gets used the WOB increases as shown by manufacturer tests), it would be very very unwise to reuse, store, and extend scrubber duration over multiple dives, until manufacturers provide some hard data to support that such use is safe.

. . .
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Eh ? That does not follow.

The tests simply show that WOB increases as the scrubber is consumed (during what appears to be a single continuous test session).

There is nothing to suggest that the WOB during a 3rd 1 hour dive is any worse than the WOB during the 3rd hour of a single dive.

The test results are very interesting, but they tell you absolutely nothing about the merits of single-use vs multi-use.

Mike
 
I am not sure what work the HSL has done in the UK looking at this subject and, if they have done anything, whether it can be released to the public.

I am not sure if the diving public are aware of the cost and time requirements in conducting duration/performance tests. I think the number quoted from NEDU for 27 (3^4) combinations (depth, pressure, workload, temperature) for each CCR and sorb combination would be something like 6+ months worth of effort. Are the user community going to pay for that?

Regards
 
GLOC said:
I am not sure what work the HSL has done in the UK looking at this subject and, if they have done anything, whether it can be released to the public.

I am not sure if the diving public are aware of the cost and time requirements in conducting duration/performance tests. I think the number quoted from NEDU for 27 (3^4) combinations (depth, pressure, workload, temperature) for each CCR and sorb combination would be something like 6+ months worth of effort. Are the user community going to pay for that?

Regards
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No because what we have works in a very wide range of situations, in a wide range of units and with choices over absorbent.

I'd rather manufacturers invested time elsewhere than on this.

Matt.
 
Mike_123 said:
Eh ? That does not follow.

The tests simply show that WOB increases as the scrubber is consumed (during what appears to be a single continuous test session).

There is nothing to suggest that the WOB during a 3rd 1 hour dive is any worse than the WOB during the 3rd hour of a single dive.

The test results are very interesting, but they tell you absolutely nothing about the merits of single-use vs multi-use.

Mike
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You are right, and we need more testing.

However,my view is "colored" by two events:

1. When I did a rather non-scientific test of mixing Sofnolime with tap water and letting it sit overnight (something which anybody can do) in varying amounts, I was surprised how different it all looked in the morning - it made me understand how the clumps are formed (not immediately, it takes time for them to form).
2. At the end of my Full Cave Course (one week), I saw my instructor empty his experimental 8 lbs. radial scrubber (he had used it for 11 hours and I know since I was supplying the Sofnolime and dived with him and he stayed at my house and we used my garage...). He went to the side of the road, and started just pouring out the Sofnolime, and I remarked watching, "Why is it that with my scrubber [at the time a plastic axial bucket sealed top and bottom with hydrophobic membrane] I get huge lumps after only 2 hours of use, and you after 11 hours the Sofnolime has no lumps and looks like new?"

He looked at me and smiled.
 
gianaameri said:
You are right, and we need more testing.

However,my view is "colored" by two events:

1. When I did a rather non-scientific test of mixing Sofnolime with tap water and letting it sit overnight (something which anybody can do) in varying amounts, I was surprised how different it all looked in the morning - it made me understand how the clumps are formed (not immediately, it takes time for them to form).
2. At the end of my Full Cave Course (one week), I saw my instructor empty his experimental 8 lbs. radial scrubber (he had used it for 11 hours and I know since I was supplying the Sofnolime and dived with him and he stayed at my house and we used my garage...). He went to the side of the road, and started just pouring out the Sofnolime, and I remarked watching, "Why is it that with my scrubber [at the time a plastic axial bucket sealed top and bottom with hydrophobic membrane] I get huge lumps after only 2 hours of use, and you after 11 hours the Sofnolime has no lumps and looks like new?"

He looked at me and smiled.
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And? What's the ending? Some magic? Why you've suddenly gone all riddles and big fonts I don't know.
 
I'd look back, smile, and ask, did you know you were planning on running an 8hr scrubber during 11hrs of teaching me diving in an overhead environment? ;)

Regards
 
GLOC said:
I'd look back, smile, and ask, did you know you were planning on running an 8hr scrubber during 11hrs of teaching me diving in an overhead environment? ;)

Regards
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Bit scary, but it works 11 hours and no clumps (it was 20C water, average depth 14 meters)... that is why I bought one!

I did change my plastic bucket axial every 2 hours (every day) during the course though :amstupid:
 
GLOC said:
I'd look back, smile, and ask, did you know you were planning on running an 8hr scrubber during 11hrs of teaching me diving in an overhead environment? ;)

Regards
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LOL. Is that a CE approved scrubber? Good job most of what is on the internet is rubbish.

Matt.
 
matthewoutram said:
LOL. Is that a CE approved scrubber? Good job most of what is on the internet is rubbish.

Matt.
Click to expand...

Most definitely it is CE tested to EN14143, but only the smaller version (lbs. 5.5) is CE approved.

Having said that, CE is shite and it is devoid of any meaning and significance.

"CE" is the most misleading two letters - taken in isolation.

Anything can be "CE" in the context of rebreathers - even a hoover.

Any manufacturer can make up its own standard and based on that manufactured standard get a "CE" stamp on his kit.

To understand the true risk and quality and dependability of the equipment you are purchasing and using, and to make an informed decision as to what is acceptable risk to yourself, you need to be provided a little more information than just the two letters "CE."

For example, I would not buddy up with anyone using some "CE" rebreathers, while I would have no problem "team diving" and "risk sharing" with Homebuilders using a non-CE rebreather (the latter being safer, better conceived, and in any event the true risk and acceptance thereto being clearer, than the letters "CE").
 
gianaameri said:
To understand the true risk and quality and dependability of the equipment you are purchasing and using, and to make an informed decision ...
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Agreed. That's why I bought the unit I have - 10 years and no missed dives. No doubt others are using the same data for their choices too.

Cheers
Matt.
 
matthewoutram said:
Agreed. That's why I bought the unit I have - 10 years and no missed dives. No doubt others are using the same data for their choices too.

Cheers
Matt.
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Gee... your profile shows 500 - 1000 hours on CCR - you should be put in the Guinness Book of World Records.

I'll go for the reverse record - for the man who has had the most problems on CCR :lol: - some units more than others.

Check this one out as well: Longest nose on a living person - Size - Explore Records - Guinness World Records
 
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