standard axial scrubber duration in shallow warm water?

**Gill Envy** · 13th March 2008, 16:29

This question is really for those that dive tropical:

on a standard Meg scrubber in warm water/140' max depth, how many hours are you comfortable putting on a fill? We are gearing up for another big trip to indonesia and starting to calculate how much sorb to ship and take with us...a radial scrubber would be oh so nice right about now!

When I was using the evolution with the temp stick in warm water, obviosly a much smaller scrubber, I was easily getting 4-5 hours of recreational depth diving with plenty of room to spare.

oli · 14th March 2008, 21:33

for myself , in Egypt, max 4 hours with axial scrubber in 3 dives.
if one dive is running more than 2h30/ 3 h than i change the sofno.
water 28/29°celcius
Regards

Gilles · 15th March 2008, 00:30

Using Spherasorb, in 28degC water easy diving I typically run to 6hrs +. I have pushed it much beyond this on occasion. Finishing off @5-6hrs is safe.

lancsman · 15th March 2008, 07:39

Hi

When I dived in the Red Sea I dived 2 O2 fills per scrubber fill (6 plus hours) on the theory it is based on individual CO2 production that counts not durration.

Mark

Darkwater · 15th March 2008, 10:07

Well you can create a very rough rule of thumb for yourself. Over a series of dives take accurate reading of the O2 you use and from this you can calculate the average O2 you use, (don't worry about accent etc. as this adds to the conservatism). Typically you create 0.9 CO2 for every Ltr of O2 you consume. This will based on your O2 used provide you with a CO2 production rate.
For CE certified Rebreather the duration of the scrubber is calculated on a CO2 production rate of 1.6 ltr minute (this is high). From this you can create a linear prediction on how the scrubber will last with your CO2 production (probably about 1lt

r/m). The fact the CE testing is conducted at 4oc again provide a conservative approach if you are diving in warm water.

I have found this calculation handy to determine scrubber requirements

VIKTOR66 · 3rd April 2008, 03:31

I dive evolution and I did run up to 8 hours and half in shallow water with tempstick still showing 2 bars and water temp 23 to 28 celsius. I pushed it in controlled conditions with OC divers. Usually I consider 5 to 6 hours conservative enough if everything went smooth. If I dive deeper or I had more exercise than expected I change scrubber earlier. For me the problem is when you go up to the limits and something goes wrong and you exercise more than expected and you have not enough area in your scrubber to work properly.

brunospf · 3rd April 2008, 06:21

Here in Brazil (Salvador, BA), 27/28o Celcius degress water, I put five hours in multiply dives on my standart axial Meg scrubber.

I use Atrasorb Subaquática, similar Spherasorb and my VO2 were about 1,17 l/minute.

cheers,

hillbilly · 16th April 2008, 20:19

I've ran my to a max of 6 1/2 hours. There is a picture of it around after that time. Now I cut back to 5 1/2 hours in warm water.

Lorne

paulraymaekers · 16th April 2008, 21:05

Quote: (Originally Posted by Gill Envy)

..a radial scrubber would be oh so nice right about now!

hi gill,
actually in warm water, really warm, there is no advantage in radial (exept perhaps for WOB), but not for scrubber durations

in warm water all that counts is how much kg is in there... and the depth you go, but it does not depend on radial or axial

the difference in radial and axial performance lies in the thermal behaviour of the unit: how good can it keep the sorb warm!

a simple exampe: repeat the CE test between meg and sentinel, but do it at 28°... the meg will last much longer!!

regards
paul

**Gill Envy** · 16th April 2008, 21:32

thanks everyone for the replies. we've been sticking to 4.5 hours in the cold waters here which can get in the 6 C/ 43 F range in the winter. I follow these rules of thumb:
- before a deep dive, fresh sorb (thought I don't really dive deep yet)
- deepish dive, then progressively shallower dives follow
- 4.5 hours in cold water

Only 10 days till our Bali/Alor trip

I'll report back after that... planning on 6.5 total hours per fill.

13th March 2008, 16:29	#1 (permalink)
Gill Envy Shearwater Copis Diver Current Rebreather/s: Other CCR Other Rebreather/s: Evolution Other CCR Join Date: Nov 2005 Location: seattle Posts: 1,138	standard axial scrubber duration in shallow warm water? This question is really for those that dive tropical: on a standard Meg scrubber in warm water/140' max depth, how many hours are you comfortable putting on a fill? We are gearing up for another big trip to indonesia and starting to calculate how much sorb to ship and take with us...a radial scrubber would be oh so nice right about now! When I was using the evolution with the temp stick in warm water, obviosly a much smaller scrubber, I was easily getting 4-5 hours of recreational depth diving with plenty of room to spare. __________________ Gill Envy ...Because I wasn't born with gills! ><(°>><(°>><(°>><(°>><(°>><(°>><(°>><(°>
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14th March 2008, 21:33	#2 (permalink)
oli New Member Current Rebreather/s: Megalodon Dolphin Other Rebreather/s: Dolphin Join Date: Jun 2006 Location: Belgium Posts: 8	Re: standard axial scrubber duration in shallow warm water? for myself , in Egypt, max 4 hours with axial scrubber in 3 dives. if one dive is running more than 2h30/ 3 h than i change the sofno. water 28/29°celcius Regards
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15th March 2008, 00:30	#3 (permalink)
Gilles Worship the feminine Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Sep 2005 Location: Den Haag (Netherlands) Posts: 747	Re: standard axial scrubber duration in shallow warm water? Using Spherasorb, in 28degC water easy diving I typically run to 6hrs +. I have pushed it much beyond this on occasion. Finishing off @5-6hrs is safe. __________________ Gilles http://www.dirrebreather.com
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15th March 2008, 07:39	#4 (permalink)
lancsman New Member Current Rebreather/s: Not Bought Yet Other Rebreather/s: Megalodon Not Bought Yet Join Date: Oct 2005 Location: UK, Flitwick Posts: 54	Re: standard axial scrubber duration in shallow warm water? Hi When I dived in the Red Sea I dived 2 O2 fills per scrubber fill (6 plus hours) on the theory it is based on individual CO2 production that counts not durration. Mark
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15th March 2008, 10:07	#5 (permalink)
Darkwater New Member Current Rebreather/s: Other CCR Other Rebreather/s: Inspiration Classic Other CCR Join Date: Mar 2008 Location: Australia Posts: 7	Re: standard axial scrubber duration in shallow warm water? Well you can create a very rough rule of thumb for yourself. Over a series of dives take accurate reading of the O2 you use and from this you can calculate the average O2 you use, (don't worry about accent etc. as this adds to the conservatism). Typically you create 0.9 CO2 for every Ltr of O2 you consume. This will based on your O2 used provide you with a CO2 production rate. For CE certified Rebreather the duration of the scrubber is calculated on a CO2 production rate of 1.6 ltr minute (this is high). From this you can create a linear prediction on how the scrubber will last with your CO2 production (probably about 1ltr/m). The fact the CE testing is conducted at 4oc again provide a conservative approach if you are diving in warm water. I have found this calculation handy to determine scrubber requirements
(Offline)

3rd April 2008, 03:31	#6 (permalink)
VIKTOR66 New Member Current Rebreather/s: Evolution Other Rebreather/s: Join Date: May 2007 Location: Playa del Carmen Posts: 5	Re: standard axial scrubber duration in shallow warm water? I dive evolution and I did run up to 8 hours and half in shallow water with tempstick still showing 2 bars and water temp 23 to 28 celsius. I pushed it in controlled conditions with OC divers. Usually I consider 5 to 6 hours conservative enough if everything went smooth. If I dive deeper or I had more exercise than expected I change scrubber earlier. For me the problem is when you go up to the limits and something goes wrong and you exercise more than expected and you have not enough area in your scrubber to work properly.
(Offline)

3rd April 2008, 06:21	#7 (permalink)
brunospf New Member Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Oct 2007 Location: Salvador, BA Posts: 44	Re: standard axial scrubber duration in shallow warm water? Here in Brazil (Salvador, BA), 27/28o Celcius degress water, I put five hours in multiply dives on my standart axial Meg scrubber. I use Atrasorb Subaquática, similar Spherasorb and my VO2 were about 1,17 l/minute. cheers, __________________ Bruno S P Fagundes IANTD Megalodon CCR Diver TDI Extended Range Diver TDI Trimix Diver DSAT Trimix Gas Blender PDIC Divementor
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16th April 2008, 20:19	#8 (permalink)
hillbilly New Member Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Sep 2006 Location: Edmonton Posts: 35	Re: standard axial scrubber duration in shallow warm water? I've ran my to a max of 6 1/2 hours. There is a picture of it around after that time. Now I cut back to 5 1/2 hours in warm water. Lorne
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16th April 2008, 21:05	#9 (permalink)
paulraymaekers rEvo's daddy Current Rebreather/s: rEvo Other CCR Home Build Other Rebreather/s: rEvo Other CCR Home Build Join Date: May 2005 Location: belgium Posts: 1,241	Re: standard axial scrubber duration in shallow warm water? Quote: (Originally Posted by Gill Envy) ..a radial scrubber would be oh so nice right about now! hi gill, actually in warm water, really warm, there is no advantage in radial (exept perhaps for WOB), but not for scrubber durations in warm water all that counts is how much kg is in there... and the depth you go, but it does not depend on radial or axial the difference in radial and axial performance lies in the thermal behaviour of the unit: how good can it keep the sorb warm! a simple exampe: repeat the CE test between meg and sentinel, but do it at 28°... the meg will last much longer!! regards paul __________________ www.rEvo-rebreathers.com
(Online)

16th April 2008, 21:32	#10 (permalink)
Gill Envy Shearwater Copis Diver Current Rebreather/s: Other CCR Other Rebreather/s: Evolution Other CCR Join Date: Nov 2005 Location: seattle Posts: 1,138	Re: standard axial scrubber duration in shallow warm water? thanks everyone for the replies. we've been sticking to 4.5 hours in the cold waters here which can get in the 6 C/ 43 F range in the winter. I follow these rules of thumb: - before a deep dive, fresh sorb (thought I don't really dive deep yet) - deepish dive, then progressively shallower dives follow - 4.5 hours in cold water Only 10 days till our Bali/Alor trip I'll report back after that... planning on 6.5 total hours per fill. __________________ Gill Envy ...Because I wasn't born with gills! ><(°>><(°>><(°>><(°>><(°>><(°>><(°>><(°>
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