New Meg Radial Scrubber

paulraymaekers · 17th May 2008, 19:36

Quote: (Originally Posted by Steve)

Paul, This is your opinion, it isn't a fact, and I for one don't share it. I believe the following to be the case.

A rebreather's scrubber's dwell time is due "primarily" to 2 things. The ratio between the divers lung size and the loop volume, and the length of the gas path in the scrubber. Your way of looking at dwell time ignores these 2 key factors and looks at a simplistic linear gas path which ignores the reality of the system as a whole.

What you say is of course very true if the gas flow is constant and the scrubber isn't in a rebreather, but that isn't how we use rebreathers and is therefore of passing simplistic interest.

The gas moves through a CCR in steps directly related to the breaths of the diver. There is some further gas movement due to pressure equalisation but it is a smaller amount. The length of these steps and the length of the sorb bed are very important in determining dwell time. I find it usefull to focus on a single molecule of CO2. It is moving through the system and can only be scrubbed when in the sorb bed. A smaller tidal volume to scrubber bed length increase the dwell time and ovbiously the converse is true.

Steve, seems w're discussing 2 different things: I speak about a scrubber on itself, isolated from the breather: meaning: if you want to compare scubbers, and not rebreathers as a whole, you isolate the scrubber and put it on a 'standardised rebreather', and this way you can study and compare scrubbers.

You speak about scrubber performance as part of the whole system, and offcourse in that case dwell time varies by the system around the scrubber. (as i stated in my other mail: it is function of the 'flowcurve': the graph that gives you the flow (liters/min) as function of time: it is clear that the ideal curve would be a constant flow with no peaks and no lows (stops), but unfortunately humans can't breath that way..

The ratio between the divers lung size and the loop volume,

euh, can you explain how this influences dwell-time??
please do the mats and see for your self :-)

problem is that people try to imagine 'dwell time', to have a 'feeling' about it and what would influence it
dwell time is expressed in seconds, and nothing else, and for a given flow-curve, and a given scrubber form, you can calculate mathematically those seconds, and when you do that, you will see that for a given flow-curve, the shape of the cannister is not part of the equation, only the total volume of the scrubber

paul

Pelagian · 17th May 2008, 23:55

Hello

I was wondering how short fat radials compare to tall skinny ones in terms of duration and breakthrough?

I remember Kevin Gurr saying something to me once about the advantages of the short fat radial he had in his Boris over the tall skinny Cis radial, but we didn't have time to go into details. It was something about grain boundries

Anyone have any insight?

Cheers

Seb

**Steve** · 18th May 2008, 04:58

Quote: (Originally Posted by paulraymaekers)

The ratio between the divers lung size and the loop volume,

euh, can you explain how this influences dwell-time??
please do the mats and see for your self :-)
paul

Small tidal volume coupled with a large loop volume and a long scrubber bed increases dwell time. The molecules of CO2 only move in short steps with each breath cycle and as a result stay in contact with the scrubber bed longer. Many pause in the bed with each breath. This set up is great for removing CO2 but not as nice to dive as min loop volume. Swings and roundabouts.

I would suggest you check this via testing rather than just maths

. You will of course need a rebreather that can make use of an axial and a radial of the same volume of sorb. Please get back to me when you have done this and we can compare notes.

mempilot · 18th May 2008, 05:38

I always find it amusing when someone starts a thread about a new product offering from the manufacturer of their rebreather, and other manufacturers have to jump in on the thread, start a debate that has nothing to do with the original post, and otherwise just hijack the thread.

So, is this about the new ISC radial, or rEVO's knack of joining every thread that has nothing to do with their Rebreather?

paulraymaekers · 18th May 2008, 07:23

Quote: (Originally Posted by mempilot)

I always find it amusing when someone starts a thread about a new product offering from the manufacturer of their rebreather, and other manufacturers have to jump in on the thread, start a debate that has nothing to do with the original post, and otherwise just hijack the thread.

So, is this about the new ISC radial, or rEVO's knack of joining every thread that has nothing to do with their Rebreather?

I just replied to what was said in this thread, and got 'carried away'.. :-)
you'e right, moved to other thread, sorry

paul

Mike448 · 18th May 2008, 08:50

well said Erik. Back to the original topic, are the new radials now available to purchase?

johanvanlyl · 18th May 2008, 11:29

Spyros,

send Tom an email at tom@trimix.net to check out prices and availability.

as i understood it, his alu cylinders come in black off the shelf.

btw is diving the zenobia possible throughout the whole year or is there a preferred period ?

johan

mempilot · 18th May 2008, 14:36

Quote: (Originally Posted by Mike448)

well said Erik. Back to the original topic, are the new radials now available to purchase?

When Mark gets back from Innerspace in Cayman, I'm going to ask him if Dive Rite Express, aka Fill Express, aka Rebreather Express is going to stock the ISC radial since he is the local ISC dealer. Mark has done a great job of stocking the full inventory of Meg parts for us local guys and his online clientele. I'd like to take a look at the ISC radial in person and see the dynamics of it mated with my Cave Meg. I'd also like to see the Tetradon wing again, but fitted to my Cave can, since the last time I saw it was at DEMA on a FRM canister.

Having the shop locally for the touchy feely before order is a great asset.

Mike448 · 18th May 2008, 15:28

Erik, ounds like you are stil a dedicated Meg pilot - good to hear. I bought my Meg from Tony at FE, and my VR3, and all my spares, and yes most of my OC stuff too over the past few years

They should offer a "valued customer" type of deal for those that spend more than half their annual income with them...

Anyway, back on topic, I would be keen on a radial as soon as they have stock.

mempilot · 18th May 2008, 15:39

Quote: (Originally Posted by Mike448)

Erik, ounds like you are stil a dedicated Meg pilot - good to hear. I bought my Meg from Tony at FE, and my VR3, and all my spares, and yes most of my OC stuff too over the past few years

They should offer a "valued customer" type of deal for those that spend more than half their annual income with them...

Anyway, back on topic, I would be keen on a radial as soon as they have stock.

FE is very loyal to their very loyal customers.

I couldn't be more happy with the service I get every time I walk in there. It doesn't hurt that they are all dive buddies as well, but I think they treat everyone in the same manor.

I hope they continue to support ISC's customers into the future, as I think there are great things ahead for the Meg. And while I get kidded by the Optima Army on a regular basis, there is no truth in the rumors of a crossover for me. Black through and through here.

17th May 2008, 19:36	#31 (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: 1,511	Re: New Meg Radial Scrubber Quote: (Originally Posted by Steve) Paul, This is your opinion, it isn't a fact, and I for one don't share it. I believe the following to be the case. A rebreather's scrubber's dwell time is due "primarily" to 2 things. The ratio between the divers lung size and the loop volume, and the length of the gas path in the scrubber. Your way of looking at dwell time ignores these 2 key factors and looks at a simplistic linear gas path which ignores the reality of the system as a whole. What you say is of course very true if the gas flow is constant and the scrubber isn't in a rebreather, but that isn't how we use rebreathers and is therefore of passing simplistic interest. The gas moves through a CCR in steps directly related to the breaths of the diver. There is some further gas movement due to pressure equalisation but it is a smaller amount. The length of these steps and the length of the sorb bed are very important in determining dwell time. I find it usefull to focus on a single molecule of CO2. It is moving through the system and can only be scrubbed when in the sorb bed. A smaller tidal volume to scrubber bed length increase the dwell time and ovbiously the converse is true. Steve, seems w're discussing 2 different things: I speak about a scrubber on itself, isolated from the breather: meaning: if you want to compare scubbers, and not rebreathers as a whole, you isolate the scrubber and put it on a 'standardised rebreather', and this way you can study and compare scrubbers. You speak about scrubber performance as part of the whole system, and offcourse in that case dwell time varies by the system around the scrubber. (as i stated in my other mail: it is function of the 'flowcurve': the graph that gives you the flow (liters/min) as function of time: it is clear that the ideal curve would be a constant flow with no peaks and no lows (stops), but unfortunately humans can't breath that way.. The ratio between the divers lung size and the loop volume, euh, can you explain how this influences dwell-time?? please do the mats and see for your self :-) problem is that people try to imagine 'dwell time', to have a 'feeling' about it and what would influence it dwell time is expressed in seconds, and nothing else, and for a given flow-curve, and a given scrubber form, you can calculate mathematically those seconds, and when you do that, you will see that for a given flow-curve, the shape of the cannister is not part of the equation, only the total volume of the scrubber paul __________________ www.rEvo-rebreathers.com .... the earth is flat, Elvis is alive, and radial scrubbers give longer dwell time than axials...
(Offline)

17th May 2008, 23:55	#32 (permalink)
Pelagian Multi-Circuit Meg Monkey! Current Rebreather/s: Megalodon Other Rebreather/s: Inspiration Classic Inspiration Vision Evolution Sport Kiss Optima Join Date: Feb 2005 Location: Leeds, England Posts: 284	Re: New Meg Radial Scrubber Hello I was wondering how short fat radials compare to tall skinny ones in terms of duration and breakthrough? I remember Kevin Gurr saying something to me once about the advantages of the short fat radial he had in his Boris over the tall skinny Cis radial, but we didn't have time to go into details. It was something about grain boundries Anyone have any insight? Cheers Seb __________________ 'Because... I was Inverted!'
(Offline)

18th May 2008, 04:58	#33 (permalink)
Steve Ladies bring a plate Current Rebreather/s: Megalodon Home Build Other Rebreather/s: Not Bought Yet Inspiration Classic Sport Kiss Classic Kiss MK 15.X Home Build Join Date: Feb 2005 Location: Perth - Australia Posts: 1,117	Re: New Meg Radial Scrubber Quote: (Originally Posted by paulraymaekers) The ratio between the divers lung size and the loop volume, euh, can you explain how this influences dwell-time?? please do the mats and see for your self :-) paul Small tidal volume coupled with a large loop volume and a long scrubber bed increases dwell time. The molecules of CO2 only move in short steps with each breath cycle and as a result stay in contact with the scrubber bed longer. Many pause in the bed with each breath. This set up is great for removing CO2 but not as nice to dive as min loop volume. Swings and roundabouts. I would suggest you check this via testing rather than just maths . You will of course need a rebreather that can make use of an axial and a radial of the same volume of sorb. Please get back to me when you have done this and we can compare notes. __________________ WARNING: I contain occasional coarse language, extreme sexual references, nudity, and adult themes, which may offend some people - Usually churchy types.
(Online)

18th May 2008, 05:38	#34 (permalink)
mempilot Eric Stadtmueller Current Rebreather/s: Megalodon Other Rebreather/s: Megalodon Join Date: Aug 2006 Location: Ft. Lauderdale Posts: 1,522	Re: New Meg Radial Scrubber I always find it amusing when someone starts a thread about a new product offering from the manufacturer of their rebreather, and other manufacturers have to jump in on the thread, start a debate that has nothing to do with the original post, and otherwise just hijack the thread. So, is this about the new ISC radial, or rEVO's knack of joining every thread that has nothing to do with their Rebreather? __________________ Eric Stadtmueller, otherwise known as, MEM "Da Pilot"
(Online)

18th May 2008, 07:23	#35 (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: 1,511	Re: New Meg Radial Scrubber Quote: (Originally Posted by mempilot) I always find it amusing when someone starts a thread about a new product offering from the manufacturer of their rebreather, and other manufacturers have to jump in on the thread, start a debate that has nothing to do with the original post, and otherwise just hijack the thread. So, is this about the new ISC radial, or rEVO's knack of joining every thread that has nothing to do with their Rebreather? I just replied to what was said in this thread, and got 'carried away'.. :-) you'e right, moved to other thread, sorry paul __________________ www.rEvo-rebreathers.com .... the earth is flat, Elvis is alive, and radial scrubbers give longer dwell time than axials... Last edited by paulraymaekers : 18th May 2008 at 07:49.
(Offline)

18th May 2008, 08:50	#36 (permalink)
Mike448 Mike O'Neill Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Apr 2007 Location: Knysna (South Africa) & Florida Posts: 41	Re: New Meg Radial Scrubber well said Erik. Back to the original topic, are the new radials now available to purchase? __________________ Cheers Mike mike448 @ mac.com www.shadowdivers.net
(Offline)

18th May 2008, 11:29	#37 (permalink)
johanvanlyl New Member Current Rebreather/s: Megalodon Other Rebreather/s: Inspiration Vision Join Date: Nov 2005 Location: Belgium Posts: 44	Re: New Meg Radial Scrubber Spyros, send Tom an email at tom@trimix.net to check out prices and availability. as i understood it, his alu cylinders come in black off the shelf. btw is diving the zenobia possible throughout the whole year or is there a preferred period ? johan
(Offline)

18th May 2008, 14:36	#38 (permalink)
mempilot Eric Stadtmueller Current Rebreather/s: Megalodon Other Rebreather/s: Megalodon Join Date: Aug 2006 Location: Ft. Lauderdale Posts: 1,522	Re: New Meg Radial Scrubber Quote: (Originally Posted by Mike448) well said Erik. Back to the original topic, are the new radials now available to purchase? When Mark gets back from Innerspace in Cayman, I'm going to ask him if Dive Rite Express, aka Fill Express, aka Rebreather Express is going to stock the ISC radial since he is the local ISC dealer. Mark has done a great job of stocking the full inventory of Meg parts for us local guys and his online clientele. I'd like to take a look at the ISC radial in person and see the dynamics of it mated with my Cave Meg. I'd also like to see the Tetradon wing again, but fitted to my Cave can, since the last time I saw it was at DEMA on a FRM canister. Having the shop locally for the touchy feely before order is a great asset. __________________ Eric Stadtmueller, otherwise known as, MEM "Da Pilot"
(Online)

18th May 2008, 15:28	#39 (permalink)
Mike448 Mike O'Neill Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Apr 2007 Location: Knysna (South Africa) & Florida Posts: 41	Re: New Meg Radial Scrubber Erik, ounds like you are stil a dedicated Meg pilot - good to hear. I bought my Meg from Tony at FE, and my VR3, and all my spares, and yes most of my OC stuff too over the past few years They should offer a "valued customer" type of deal for those that spend more than half their annual income with them... Anyway, back on topic, I would be keen on a radial as soon as they have stock. __________________ Cheers Mike mike448 @ mac.com www.shadowdivers.net
(Offline)

18th May 2008, 15:39	#40 (permalink)
mempilot Eric Stadtmueller Current Rebreather/s: Megalodon Other Rebreather/s: Megalodon Join Date: Aug 2006 Location: Ft. Lauderdale Posts: 1,522	Re: New Meg Radial Scrubber Quote: (Originally Posted by Mike448) Erik, ounds like you are stil a dedicated Meg pilot - good to hear. I bought my Meg from Tony at FE, and my VR3, and all my spares, and yes most of my OC stuff too over the past few years They should offer a "valued customer" type of deal for those that spend more than half their annual income with them... Anyway, back on topic, I would be keen on a radial as soon as they have stock. FE is very loyal to their very loyal customers. I couldn't be more happy with the service I get every time I walk in there. It doesn't hurt that they are all dive buddies as well, but I think they treat everyone in the same manor. I hope they continue to support ISC's customers into the future, as I think there are great things ahead for the Meg. And while I get kidded by the Optima Army on a regular basis, there is no truth in the rumors of a crossover for me. Black through and through here. __________________ Eric Stadtmueller, otherwise known as, MEM "Da Pilot"
(Online)

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