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2dive
18-05-2013, 08:04 PM
If i was going to do a 40m dive say for an hour in total in water around 18deg on a fresh packed scubber could i continue to use that the next week for up to a total of 3 hours, not exceeding 40m and using air as diluent.

Paulo
18-05-2013, 08:06 PM
Is that not something you would have learned on MOD 1?

Pete Bullen
18-05-2013, 08:08 PM
Are you worried about the cost of a can of slime or the effort involved in changing it?

flyingfisheye
18-05-2013, 08:26 PM
A slightly different point; I have a half a tub of Sorb in the garage since September last year, not used due to weather and unit being away. Used it last week and this week found it to be very very dusty compared to when i used it before. I remember a post saying that if the Sorb freezes in the cold weather that we have had this winter it can cause the water in the sorb to expand and damage the structure. So i have decided to bin the half tub and buy a new one for 60. following the advice "if in doubt tip it out"

BTS
18-05-2013, 08:58 PM
If i was going to do a 40m dive say for an hour in total in water around 18deg on a fresh packed scubber could i continue to use that the next week for up to a total of 3 hours, not exceeding 40m and using air as diluent.

I would but it is your decision...

Major Clanger
18-05-2013, 10:40 PM
If i was going to do a 40m dive say for an hour in total in water around 18deg on a fresh packed scubber could i continue to use that the next week for up to a total of 3 hours, not exceeding 40m and using air as diluent.

The general rule is no deeper than 40m after 100 minutes and no deeper than 20m after 140 minutes up to 180 mins use. I would use it again but clumped lime is an unknown quantity.

Major Clanger
18-05-2013, 10:43 PM
Is that not something you would have learned on MOD 1?

Not necessarily, different users have different ideas. No right answer. Number of variables.

deepunderground
19-05-2013, 06:34 AM
Yes go for it



Sent from my BlackBerry 9900 using Tapatalk

gordyp
19-05-2013, 07:00 AM
I always err on the side of caution when it comes to lime, it's not that expensive. To me it seems that trying to save pennies is a silly way to die.

JPTaylor
19-05-2013, 09:10 AM
If i was going to do a 40m dive say for an hour in total in water around 18deg on a fresh packed scubber could i continue to use that the next week for up to a total of 3 hours, not exceeding 40m and using air as diluent.


The general rule is no deeper than 40m after 100 minutes and no deeper than 20m after 140 minutes up to 180 mins use. I would use it again but clumped lime is an unknown quantity.

I would, Canadian Military tested reusing scrubber (only over several weeks) & found it worked fine as long as scrubber left sealed.

So in your example the 2nd dive one week later to max. 40m shouldn't exceed 40 mins BT & be above 20m after 80 mins. So depends what bottom time you have planned.

Now a real world example:

49m (max), 57 min bottom time, 117 min total in water time. Dived 3 days later with same scrubber, dived max 29m runtime of 65 mins.

[For the benefit of "Scuba Woman" in this months BSAC Scuba rag, dived +30yrs, 9yrs on RB, BSAC Advanced/OWSI, member of 4 branches & been on committee!! :middlefinger:]

notdeadyet
19-05-2013, 09:24 AM
I had the winter off to rest a shoulder injury. Last dive was 40m max for an hour total run, that was in September. I used the same fill at the end of April.

But as said, lime is cheap. If you doubt the scrubber then change the lime. Whether it will be alright or not is irrelevant, you don't need the nagging doubt on your next dive. Things that can prejudice your thinking on a rebreather are often worse than the thing itself that goes wrong.

Major Clanger
19-05-2013, 10:00 AM
So in your example the 2nd dive one week later to max. 40m shouldn't exceed 40 mins BT & be above 20m after 80 mins. So depends what bottom time you have planned.

:]

Not quite

RTF(AP)M

No deeper than 20m between 140 and 180 minutes use. Bin after that. If doing multiple dives fits that profile, I'm happy to re- use.

Just a guide.

JPTaylor
19-05-2013, 10:25 AM
No deeper than 20m between 140 and 180 minutes use. Bin after that. If doing multiple dives fits that profile, I'm happy to re- use.

Yes, I broke the guidelines :)

Major Clanger
19-05-2013, 10:31 AM
Yes, I broke the guidelines :)

:angel: me.

Iain3
19-05-2013, 02:45 PM
The guidelines in the user manual are pretty clear, same as the use-by dates on food. Whether you stick to them is your call.

I have used a scrubber upto 7 hours once, and picked one up that was lying around for over a month and used it with no ill effects.

I know somone regularly pushes Inspo scrubbers to 10 or more hours, not sure if he still does that as he recently had a CO2 hit due to breakthrough.

My answer is, you are given a conservative estimate of what you can safely do on a scrubber. Anything beyond that is your call, just remember how little a refill costs before you start stretching them out to 5 or 6 hours.

And if you can't remember when you last filled it or the hours done on it probably best to change it.

2dive
19-05-2013, 04:00 PM
Thanks guys for your imput will change the scrubber, only had 10 hours on CCr so it is a big learning curve and one I dont want to get wrong it was not about saving money on the lime.
On the course I was diving Friday and Sunday so change the scrubber on the end of the Sunday dive.

Thanks

JPTaylor
19-05-2013, 04:06 PM
Thanks guys for your imput will change the scrubber, only had 10 hours on CCr so it is a big learning curve and one I dont want to get wrong it was not about saving money on the lime.
On the course I was diving Friday and Sunday so change the scrubber on the end of the Sunday dive.


See your in Spain... water temperature has an impact. I'd push scrubber more in Red Sea as water warmer than UK & lime twice as expensive. In UK where temp. is well below 10c at present, not so much. Duration tests done at 4c (as I understand from standards).

JPTaylor
19-05-2013, 04:41 PM
I would use it again but clumped lime is an unknown quantity.

Like this?
http://i1079.photobucket.com/albums/w504/jptaylor9/IMG-20130407-00041.jpg (http://s1079.photobucket.com/user/jptaylor9/media/IMG-20130407-00041.jpg.html)

Major Clanger
19-05-2013, 04:54 PM
Like this?
http://i1079.photobucket.com/albums/w504/jptaylor9/IMG-20130407-00041.jpg (http://s1079.photobucket.com/user/jptaylor9/media/IMG-20130407-00041.jpg.html)

Indeed. Sometimes I'll empty the lime out and it's all loose, other times it's clumped. Must make breakthrough potentially more likely I'd have thought.

SteveCowley
27-05-2013, 08:10 PM
Whats the problem with my Wife?




I would, Canadian Military tested reusing scrubber (only over several weeks) & found it worked fine as long as scrubber left sealed.

So in your example the 2nd dive one week later to max. 40m shouldn't exceed 40 mins BT & be above 20m after 80 mins. So depends what bottom time you have planned.

Now a real world example:

49m (max), 57 min bottom time, 117 min total in water time. Dived 3 days later with same scrubber, dived max 29m runtime of 65 mins.

[For the benefit of "Scuba Woman" in this months BSAC Scuba rag, dived +30yrs, 9yrs on RB, BSAC Advanced/OWSI, member of 4 branches & been on committee!! :middlefinger:]

matt
27-05-2013, 08:42 PM
Indeed. Sometimes I'll empty the lime out and it's all loose, other times it's clumped. Must make breakthrough potentially more likely I'd have thought.

I thought clumping was more to do with dust and tight-packing?

Why would it make breakthrough more likely? Increased WOB I get.

Matt.

Major Clanger
27-05-2013, 09:30 PM
I thought clumping was more to do with dust and tight-packing?

Why would it make breakthrough more likely? Increased WOB I get.

Matt.

If a clump forms between dive days on same fill as moisture content dries does it then mean that no breath can be drawn through that clump on subsequent dives, therefore the lump, if sizeable, is no longer available to scrub and drawn breath therefore travels around it leading to potentially reduced lime life possibly? Not certain. Does a breath still get drawn through a clump? Summizing here as I thought gas would follow the path of least resistance therefore rest of scrubber is working harder. If gas still passes through the lump of lime then wob could raise but the lump won't be as efficient as when gas passing unhindered. Rambling a bit but that was what I was thinking.

I guess the question is, how is gas flow affected by clumped lime? I'd assumed, the clump resulted in extra strain on the lime around it.

matt
31-05-2013, 06:54 PM
If a clump forms between dive days on same fill as moisture content dries does it then mean that no breath can be drawn through that clump on subsequent dives, therefore the lump, if sizeable, is no longer available to scrub and drawn breath therefore travels around it leading to potentially reduced lime life possibly? Not certain. Does a breath still get drawn through a clump? Summizing here as I thought gas would follow the path of least resistance therefore rest of scrubber is working harder. If gas still passes through the lump of lime then wob could raise but the lump won't be as efficient as when gas passing unhindered. Rambling a bit but that was what I was thinking.

I guess the question is, how is gas flow affected by clumped lime? I'd assumed, the clump resulted in extra strain on the lime around it.

I'd also guess that least resistance path is most likely. But doesn't the gas travel through and not around the lime? Will it not pass through the clump (or are we imagining that the clump has a full-hard-outer (i.e. no way in?).

I assume that the path is changed, and therefore WOB may increase, but I'm not aware if efficacy is reduced (perhaps the path change implies it is?). My only supporting evidence (from the field) is that there seems to me more CO2 incidents on reused scrubbers put down to "out breathing the scrubber" - I've always assumed this is retained CO2 due to increased WOB rather than reduced effectiveness of the material (but this I do not know or understand).

Good topic though.

Matt.

Major Clanger
31-05-2013, 07:03 PM
I'd also guess that least resistance path is most likely. But doesn't the gas travel through and not around the lime? Will it not pass through the clump (or are we imagining that the clump has a full-hard-outer (i.e. no way in?).

I assume that the path is changed, and therefore WOB may increase, but I'm not aware if efficacy is reduced (perhaps the path change implies it is?). My only supporting evidence (from the field) is that there seems to me more CO2 incidents on reused scrubbers put down to "out breathing the scrubber" - I've always assumed this is retained CO2 due to increased WOB rather than reduced effectiveness of the material (but this I do not know or understand).

Good topic though.

Matt.

Seems to be a grey area. Maybe with improved co2 monitoring, a link might be identified between increased levels in the loop, lime lumping and elevated retained co2 levels when problems occur within use limits. Remains to be seen.