Effect of Depth on Scrubber

dive2dive2000 · 24th August 2006, 05:04

Quote: (Originally Posted by schford)

To be honest I truly believe that the single biggest factor (subject to the gas flow ensuring all the sorb is used) is amount of scrubber material.

11 Hours out of 6 pounds - sure no probs just liked Cedric did umpteen hours on his axial scrubber...and I know people who have done 9 hours plus on their inspiration visions poodling round in the red sea - or hanging motionless with no CO2 production on a shot line at shallow depths waiting for deco to clear.

But none of them would hit those figures with CE testing - you just can not throw around use figures and have them mean anything without us knowing what the temp was, depth was and how much CO2 was producded.

I truly would like to get every unit fill em with the same scrubber material and whack em in a breathing machine at oh say 40m or 5 ata and see when break through occured - I bet that the single biggest factor would be amount of sorb in there....

Hi Stuart,

Not to get off track, depth does not, or should not??? matter IMHO, if does please explain

***schford*** · 24th August 2006, 21:01

Quote: (Originally Posted by dive2dive2000)

Hi Stuart,

Not to get off track, depth does not, or should not??? matter IMHO, if does please explain

Depth affects the run time of a scrubber significantly by affecting the depth of the reaction front.

The bigger the reaction front the sooner break through will occur.

dive2dive2000 · 27th August 2006, 18:47

Quote: (Originally Posted by schford)

Depth affects the run time of a scrubber significantly by affecting the depth of the reaction front.

The bigger the reaction front the sooner break through will occur.

Stuart, are you saying the deeper you are the more CO2 you produce? I do not understand "reaction front" or "depth of reaction front" I have never heard that terminology before?

RonMicjan · 27th August 2006, 18:52

I also dont know this mechanism, but have heard it referred to repeatedly, scrubber time is very limited deep, but will afford more "headroom" as the dive becomes shallow. In testing there is a "deep" capacity and then a reserve, you can use up all the available deep capacity, then gain room as you come shallow, i dont think I am explaining this as well as I would have liked to. I have a call in to Doug Mckenna at micropore, on an unrelated issue, think I will bring this up when I get a call back.

dive2dive2000 · 27th August 2006, 19:06

Hi Ron,

Thanks, I will make some calls too and we can compare answers

***schford*** · 27th August 2006, 19:59

Quote: (Originally Posted by dive2dive2000)

Stuart, are you saying the deeper you are the more CO2 you produce? I do not understand "reaction front" or "depth of reaction front" I have never heard that terminology before?

No but the deeper you are the more scrubber material is needed to absorb the CO2.

Think of it this way - Lets just imagine there are 1000 molecules of gas in the loop at the surface and when you breath you produce 10 molecules of CO2. To remove the 10 molecules of CO2 you use, lets say 1cm 'depth' of scrubber material when at the surface.

eg 1 cm of scrubber material is enough to filter our 10 molecules of CO2 per 1000 molecules of gas. You need that much because not every molecule that bumps into your scrubber material is CO2 and if you only had .5mm then some molecules of CO2 would sneak through along with some of the normal gas molecules.

Now lets Image we were are 40m or 5ata - so this time there will be 5 times more molecules of gas in the loop - eg 5000.

Now for your scrubber material to be able to ensure that those 10 CO2 molecules are absorbed then 5cm of material is needed. If you only had 1cm of material then a bunch of CO2 would sneak through with so many molecules of normal gas. So the depth of the reacion front needs to be so much more.

That is why the deeper you are the shorter the run time of your scrubber - so lets just say a scrubber was 10cm tall - after lets just say 30 mins on the bottom you had used the first 5cm. Then at any moment you would start getting breakthrough at 40m as the reaction front or the total amount of scrubber material being used was 5cm - eg the total that was remaining after using the first 5cm.

But when you come shallower then the reaction front gets smaller eg lets say at 20m it would only be 3cm, now you have 2 cm left of scrubber material that isn't being used.

Hope that helps.

Stuart

RonMicjan · 27th August 2006, 20:15

good explanation, so the other gas molecules are "cushioning" the CO2 molecules from hitting the absorbment medium.

dive2dive2000 · 27th August 2006, 21:26

Quote: (Originally Posted by schford)

No but the deeper you are the more scrubber material is needed to absorb the CO2.

Think of it this way - Lets just imagine there are 1000 molecules of gas in the loop at the surface and when you breath you produce 10 molecules of CO2. To remove the 10 molecules of CO2 you use, lets say 1cm 'depth' of scrubber material when at the surface.

eg 1 cm of scrubber material is enough to filter our 10 molecules of CO2 per 1000 molecules of gas. You need that much because not every molecule that bumps into your scrubber material is CO2 and if you only had .5mm then some molecules of CO2 would sneak through along with some of the normal gas molecules.

Now lets Image we were are 40m or 5ata - so this time there will be 5 times more molecules of gas in the loop - eg 5000.

Now for your scrubber material to be able to ensure that those 10 CO2 molecules are absorbed then 5cm of material is needed. If you only had 1cm of material then a bunch of CO2 would sneak through with so many molecules of normal gas. So the depth of the reacion front needs to be so much more.

That is why the deeper you are the shorter the run time of your scrubber - so lets just say a scrubber was 10cm tall - after lets just say 30 mins on the bottom you had used the first 5cm. Then at any moment you would start getting breakthrough at 40m as the reaction front or the total amount of scrubber material being used was 5cm - eg the total that was remaining after using the first 5cm.

But when you come shallower then the reaction front gets smaller eg lets say at 20m it would only be 3cm, now you have 2 cm left of scrubber material that isn't being used.

Hope that helps.

Stuart

Yes very much, thanks.

plazma · 28th August 2006, 08:59

Quote: (Originally Posted by schford)

No but the deeper you are the more scrubber material is needed to absorb the CO2.

Think of it this way - Lets just imagine there are 1000 molecules of gas in the loop at the surface and when you breath you produce 10 molecules of CO2. To remove the 10 molecules of CO2 you use, lets say 1cm 'depth' of scrubber material when at the surface.

eg 1 cm of scrubber material is enough to filter our 10 molecules of CO2 per 1000 molecules of gas. You need that much because not every molecule that bumps into your scrubber material is CO2 and if you only had .5mm then some molecules of CO2 would sneak through along with some of the normal gas molecules.

Now lets Image we were are 40m or 5ata - so this time there will be 5 times more molecules of gas in the loop - eg 5000.

Now for your scrubber material to be able to ensure that those 10 CO2 molecules are absorbed then 5cm of material is needed. If you only had 1cm of material then a bunch of CO2 would sneak through with so many molecules of normal gas. So the depth of the reacion front needs to be so much more.

That is why the deeper you are the shorter the run time of your scrubber - so lets just say a scrubber was 10cm tall - after lets just say 30 mins on the bottom you had used the first 5cm. Then at any moment you would start getting breakthrough at 40m as the reaction front or the total amount of scrubber material being used was 5cm - eg the total that was remaining after using the first 5cm.

But when you come shallower then the reaction front gets smaller eg lets say at 20m it would only be 3cm, now you have 2 cm left of scrubber material that isn't being used.

Hope that helps.

Stuart

If other than CO2 molecules has an effect on lime why doesn't other than O2 molecyles have an effect on O2 cells?

If your theory was correct O2 cells should show less at depth even if the same amount of O2 molecyles was present.

-Pasi

***schford*** · 28th August 2006, 10:26

Quote: (Originally Posted by plazma)

If other than CO2 molecules has an effect on lime why doesn't other than O2 molecyles have an effect on O2 cells?

If your theory was correct O2 cells should show less at depth even if the same amount of O2 molecyles was present.

-Pasi

It's not a theory - it is the reason why depth has a significant effect on Scrubber Duration. Go talk to your Rebreather manufacturer if you doubt my word.

For more immediate proof just go look up the CE test results for the Boris and Inspiration. You will see scrubber run time at 100m is significantly less than the shallowest test.

In terms of cells & scrubber, they are doing totally different things using totally different chemical reactions - I am sure you will agree that cells are not trying to remove all the O2 molecules - would be a might tricky for us if they were

24th August 2006, 05:04	#1 (permalink)
dive2dive2000 PRISM DIVER & LUVIN IT! Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Feb 2005 Location: Long Island, NY Posts: 776	Re: Meg Radial Scrubber Test report Quote: (Originally Posted by schford) To be honest I truly believe that the single biggest factor (subject to the gas flow ensuring all the sorb is used) is amount of scrubber material. 11 Hours out of 6 pounds - sure no probs just liked Cedric did umpteen hours on his axial scrubber...and I know people who have done 9 hours plus on their inspiration visions poodling round in the red sea - or hanging motionless with no CO2 production on a shot line at shallow depths waiting for deco to clear. But none of them would hit those figures with CE testing - you just can not throw around use figures and have them mean anything without us knowing what the temp was, depth was and how much CO2 was producded. I truly would like to get every unit fill em with the same scrubber material and whack em in a breathing machine at oh say 40m or 5 ata and see when break through occured - I bet that the single biggest factor would be amount of sorb in there.... Hi Stuart, Not to get off track, depth does not, or should not??? matter IMHO, if does please explain __________________ Safe Diving, Martin "but what's the fun of getting what you need, instead of what you want?"
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24th August 2006, 21:01	#2 (permalink)
*schford* Despotic Overlord Current Rebreather/s: Megalodon Sport Kiss Other Rebreather/s: Join Date: Jan 2005 Location: London, UK Posts: 3,661	Re: Meg Radial Scrubber Test report Quote: (Originally Posted by dive2dive2000) Hi Stuart, Not to get off track, depth does not, or should not??? matter IMHO, if does please explain Depth affects the run time of a scrubber significantly by affecting the depth of the reaction front. The bigger the reaction front the sooner break through will occur. __________________ Bailout and Kit Management account for Murphy's Law The only bad question is one you did not ask and later wish you had. Use of Rebreather World is subject to the Rebreather World Terms & Conditions of Use
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27th August 2006, 18:47	#3 (permalink)
dive2dive2000 PRISM DIVER & LUVIN IT! Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Feb 2005 Location: Long Island, NY Posts: 776	Re: Meg Radial Scrubber Test report Quote: (Originally Posted by schford) Depth affects the run time of a scrubber significantly by affecting the depth of the reaction front. The bigger the reaction front the sooner break through will occur. Stuart, are you saying the deeper you are the more CO2 you produce? I do not understand "reaction front" or "depth of reaction front" I have never heard that terminology before? __________________ Safe Diving, Martin "but what's the fun of getting what you need, instead of what you want?"
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27th August 2006, 18:52	#4 (permalink)
RonMicjan Cap Ron scourge of the NW Current Rebreather/s: Megalodon Dolphin Home Build Other Rebreather/s: Sport Kiss Classic Kiss Dolphin Home Build Join Date: Feb 2005 Location: Cape Disapointment, The Graveyard of the Pacific Posts: 1,081	Re: Meg Radial Scrubber Test report I also dont know this mechanism, but have heard it referred to repeatedly, scrubber time is very limited deep, but will afford more "headroom" as the dive becomes shallow. In testing there is a "deep" capacity and then a reserve, you can use up all the available deep capacity, then gain room as you come shallow, i dont think I am explaining this as well as I would have liked to. I have a call in to Doug Mckenna at micropore, on an unrelated issue, think I will bring this up when I get a call back. __________________ Ron "Life is pain princess, anyone who tells you different, is selling something", The Dread Pirate Wesley. www.tmishop.com Diving bits etc.
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27th August 2006, 19:06	#5 (permalink)
dive2dive2000 PRISM DIVER & LUVIN IT! Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Feb 2005 Location: Long Island, NY Posts: 776	Re: Meg Radial Scrubber Test report Hi Ron, Thanks, I will make some calls too and we can compare answers __________________ Safe Diving, Martin "but what's the fun of getting what you need, instead of what you want?"
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27th August 2006, 19:59	#6 (permalink)
*schford* Despotic Overlord Current Rebreather/s: Megalodon Sport Kiss Other Rebreather/s: Join Date: Jan 2005 Location: London, UK Posts: 3,661	Re: Meg Radial Scrubber Test report Quote: (Originally Posted by dive2dive2000) Stuart, are you saying the deeper you are the more CO2 you produce? I do not understand "reaction front" or "depth of reaction front" I have never heard that terminology before? No but the deeper you are the more scrubber material is needed to absorb the CO2. Think of it this way - Lets just imagine there are 1000 molecules of gas in the loop at the surface and when you breath you produce 10 molecules of CO2. To remove the 10 molecules of CO2 you use, lets say 1cm 'depth' of scrubber material when at the surface. eg 1 cm of scrubber material is enough to filter our 10 molecules of CO2 per 1000 molecules of gas. You need that much because not every molecule that bumps into your scrubber material is CO2 and if you only had .5mm then some molecules of CO2 would sneak through along with some of the normal gas molecules. Now lets Image we were are 40m or 5ata - so this time there will be 5 times more molecules of gas in the loop - eg 5000. Now for your scrubber material to be able to ensure that those 10 CO2 molecules are absorbed then 5cm of material is needed. If you only had 1cm of material then a bunch of CO2 would sneak through with so many molecules of normal gas. So the depth of the reacion front needs to be so much more. That is why the deeper you are the shorter the run time of your scrubber - so lets just say a scrubber was 10cm tall - after lets just say 30 mins on the bottom you had used the first 5cm. Then at any moment you would start getting breakthrough at 40m as the reaction front or the total amount of scrubber material being used was 5cm - eg the total that was remaining after using the first 5cm. But when you come shallower then the reaction front gets smaller eg lets say at 20m it would only be 3cm, now you have 2 cm left of scrubber material that isn't being used. Hope that helps. Stuart __________________ Bailout and Kit Management account for Murphy's Law The only bad question is one you did not ask and later wish you had. Use of Rebreather World is subject to the Rebreather World Terms & Conditions of Use
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27th August 2006, 20:15	#7 (permalink)
RonMicjan Cap Ron scourge of the NW Current Rebreather/s: Megalodon Dolphin Home Build Other Rebreather/s: Sport Kiss Classic Kiss Dolphin Home Build Join Date: Feb 2005 Location: Cape Disapointment, The Graveyard of the Pacific Posts: 1,081	Re: Meg Radial Scrubber Test report good explanation, so the other gas molecules are "cushioning" the CO2 molecules from hitting the absorbment medium. __________________ Ron "Life is pain princess, anyone who tells you different, is selling something", The Dread Pirate Wesley. www.tmishop.com Diving bits etc.
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27th August 2006, 21:26	#8 (permalink)
dive2dive2000 PRISM DIVER & LUVIN IT! Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Feb 2005 Location: Long Island, NY Posts: 776	Re: Meg Radial Scrubber Test report Quote: (Originally Posted by schford) No but the deeper you are the more scrubber material is needed to absorb the CO2. Think of it this way - Lets just imagine there are 1000 molecules of gas in the loop at the surface and when you breath you produce 10 molecules of CO2. To remove the 10 molecules of CO2 you use, lets say 1cm 'depth' of scrubber material when at the surface. eg 1 cm of scrubber material is enough to filter our 10 molecules of CO2 per 1000 molecules of gas. You need that much because not every molecule that bumps into your scrubber material is CO2 and if you only had .5mm then some molecules of CO2 would sneak through along with some of the normal gas molecules. Now lets Image we were are 40m or 5ata - so this time there will be 5 times more molecules of gas in the loop - eg 5000. Now for your scrubber material to be able to ensure that those 10 CO2 molecules are absorbed then 5cm of material is needed. If you only had 1cm of material then a bunch of CO2 would sneak through with so many molecules of normal gas. So the depth of the reacion front needs to be so much more. That is why the deeper you are the shorter the run time of your scrubber - so lets just say a scrubber was 10cm tall - after lets just say 30 mins on the bottom you had used the first 5cm. Then at any moment you would start getting breakthrough at 40m as the reaction front or the total amount of scrubber material being used was 5cm - eg the total that was remaining after using the first 5cm. But when you come shallower then the reaction front gets smaller eg lets say at 20m it would only be 3cm, now you have 2 cm left of scrubber material that isn't being used. Hope that helps. Stuart Yes very much, thanks. __________________ Safe Diving, Martin "but what's the fun of getting what you need, instead of what you want?"
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28th August 2006, 08:59	#9 (permalink)
plazma New Member Current Rebreather/s: Inspiration Classic Home Build Other Rebreather/s: Home Build Join Date: Feb 2005 Location: Oulu, Finland Posts: 104	Re: Meg Radial Scrubber Test report Quote: (Originally Posted by schford) No but the deeper you are the more scrubber material is needed to absorb the CO2. Think of it this way - Lets just imagine there are 1000 molecules of gas in the loop at the surface and when you breath you produce 10 molecules of CO2. To remove the 10 molecules of CO2 you use, lets say 1cm 'depth' of scrubber material when at the surface. eg 1 cm of scrubber material is enough to filter our 10 molecules of CO2 per 1000 molecules of gas. You need that much because not every molecule that bumps into your scrubber material is CO2 and if you only had .5mm then some molecules of CO2 would sneak through along with some of the normal gas molecules. Now lets Image we were are 40m or 5ata - so this time there will be 5 times more molecules of gas in the loop - eg 5000. Now for your scrubber material to be able to ensure that those 10 CO2 molecules are absorbed then 5cm of material is needed. If you only had 1cm of material then a bunch of CO2 would sneak through with so many molecules of normal gas. So the depth of the reacion front needs to be so much more. That is why the deeper you are the shorter the run time of your scrubber - so lets just say a scrubber was 10cm tall - after lets just say 30 mins on the bottom you had used the first 5cm. Then at any moment you would start getting breakthrough at 40m as the reaction front or the total amount of scrubber material being used was 5cm - eg the total that was remaining after using the first 5cm. But when you come shallower then the reaction front gets smaller eg lets say at 20m it would only be 3cm, now you have 2 cm left of scrubber material that isn't being used. Hope that helps. Stuart If other than CO2 molecules has an effect on lime why doesn't other than O2 molecyles have an effect on O2 cells? If your theory was correct O2 cells should show less at depth even if the same amount of O2 molecyles was present. -Pasi
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28th August 2006, 10:26	#10 (permalink)
*schford* Despotic Overlord Current Rebreather/s: Megalodon Sport Kiss Other Rebreather/s: Join Date: Jan 2005 Location: London, UK Posts: 3,661	Re: Meg Radial Scrubber Test report Quote: (Originally Posted by plazma) If other than CO2 molecules has an effect on lime why doesn't other than O2 molecyles have an effect on O2 cells? If your theory was correct O2 cells should show less at depth even if the same amount of O2 molecyles was present. -Pasi It's not a theory - it is the reason why depth has a significant effect on Scrubber Duration. Go talk to your Rebreather manufacturer if you doubt my word. For more immediate proof just go look up the CE test results for the Boris and Inspiration. You will see scrubber run time at 100m is significantly less than the shallowest test. In terms of cells & scrubber, they are doing totally different things using totally different chemical reactions - I am sure you will agree that cells are not trying to remove all the O2 molecules - would be a might tricky for us if they were __________________ Bailout and Kit Management account for Murphy's Law The only bad question is one you did not ask and later wish you had. Use of Rebreather World is subject to the Rebreather World Terms & Conditions of Use
(Offline)

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