Prism Scrubber

***caveseeker7*** · 13th October 2005, 17:07

Remember that Stuart's example was pretty far off and a theoretical extreme.

In reality most water enters through the DSV and ends up in the exhalation lung.
In most normal diving postions the water wouldn't enter the rear hose and cannister, instead it can be purged with the valve on the bottom of the CL.

The only practical way water ends up in the inside tube is if you have a leak in the rear hose or the head connector. And those fall into two categories: Slow leaks and fast ones.

A slow leak will have water trickling down the center tube and soak up on the bottom. If water gets in bubbles will come out and depending on the rate you'll adjust your dive.

If it's a fast leak (the equivalent of Stuart's pouring a load of water into the tube) it's more likely than not due to major damage. Cutting the rear breathing hose, doing a Dr.Mike without the cowling and breaking the connector, that sort of situation. That's a catastrophic flood, and you're off the loop. Not because there's water in the tube, but because when that much water gets in as much gas gets out. And you don't need a scrubber if the gas is lost before it. You are now on open circuit, and might as well use a well breathing second stage instead.

silent running · 14th October 2005, 06:56

Quote: (Originally Posted by jradomski)

The designer has to decides whats more important scrubber run time or some additional survivability.. Neither format is wrong, everyone has their own priorities..

Dave T pointed out nicely that an out to in design slows down the gas velocity as it passes through the scrubber this will increase dwell time as the gas exits while an out to in does the opposite..

From the types of dives I do, I like options that keep me on the loop as long as possible in the event of some type of problem... Even with the Inspiration stack I have NEVER run into a single dive I had breakthrough on... I have some really long run times but lots of that is deco doing nothing... In case like that I track my oxygen usage which gives a good indication of CO2 production...

I dont recommend others do it without the proper experience, but I Have put well over 6 hours on an inspiration scrubber albeit most of it at rest doing deco where my average o2 use was less than .5lpm

Hi Joe, while I am in total agreement that staying on the loop is a high priority, it's only a priority as long as the loop is still absorbing CO2. It has become clear to me over time that WOB is much more than a mere comfort issue. It is directly related to CO2 production. It seems that the high WOB at the extreme depth of Dave Shaw's dive was a factor, maybe the factor in his probable, fatal CO2 hit. Granted, he had improperly packed his MK scrubber, but it brings home the importance of minimizing WOB and of scrubber efficiency in general. A scrubber which has the longest dwell time and the longest duration IMHO trumps extreme flood tolerance if for no other reason than the higher probability of unplaned exertion over a major loop flood. I like the idea of a hydrophobic membrane, but apparently it significantly increases the WOB, so I wouldn't use a scrubber that had one, especially on a deep, long dive.

The type of diving I most prefer is exploratory and often takes place in the most remote places and comes with certain risks. I like knowing that no matter how strong a current I find at the bottom of a new dive site, I don't have to worry about over breathing my Prism scrubber as I fight my way through it. It's happened at least once every trip and I'm sure it will happen again. The Prism has the lowest WOB and the scrubber is the most thoroughly tested and refined design available. These are 2 big reasons why I bought one. And I'm pretty sure the excellent design of the scrubber is also the reason why it will now be available in the Meg.-Andy

Underwaterbear · 17th October 2005, 01:47

Quote: (Originally Posted by silent running)

The Prism has the lowest WOB and the scrubber is the most thoroughly tested and refined design available. These are 2 big reasons why I bought one. And I'm pretty sure the excellent design of the scrubber is also the reason why it will now be available in the Meg.-Andy

Yeah, exactly.

But those would be refitters of the Prism scrubber to the Meg would do well to realise that the strength of the Prism scrubber is related to the wholistic design of the total product as a result of the analysis of gas flow throughout the unit - not just the scrubber itself.

It's been said before that one could not expect Prism performance figures from a Meg with prism scrubber...maybe there is an improvement but has anyone tested it? I guess if SMI are supplying ISC with the baskets someone has done the figures, or have they?

Cheers
Andrew

dive2dive2000 · 17th October 2005, 03:55

It is my understanding that PRISM is not supplying Meg with the scrubbers, Meg will make you the adapter you have to buy the Scrubber on your own.

***schford*** · 17th October 2005, 09:22

Like I posted it is not officially confirmed but word on the street is that Steam Machines will probably supply ISC with scrubbers for them to sell on to customers.

I also totally agree with Underwaterbears post - the whole design of the PRISM scrubber and the exhaustive testing Pete has done has been focussed around an In---> Out flow, as far I know no testing has been done using it in a Meg with an Out ---> In flow.

Although I don't think it unreasonable to assume one would see an increase in run times....

Wouldn't it be good if we could get access to an ANSI machine and a few other bits and bobs for us to run a series of tests on different scrubber architectures, flows and absorbant materials!

Stuart

***caveseeker7*** · 17th October 2005, 17:47

Quote: (Originally Posted by Underwaterbear)

...maybe there is an improvement but has anyone tested it? I guess if SMI are supplying ISC with the baskets someone has done the figures, or have they?

Has anyone ever done any formal testing on any other scrubber configuration that is being used in Megs?

Standard and Mini axial, Cis-Lunar radial and ExtendAir cartridge have been used in the past and I'm not aware of any formal testing of any of these configurations ... which would be a requirement to see an improvement.

Hasn't kept people from buying them in the past ...

***schford*** · 18th October 2005, 21:00

My biggest bug bear with the Meg Scrubbers but at least it will be resolved with CE testing...

13th October 2005, 17:07	#21 (permalink)
*caveseeker7* Who loves ya, baby Current Rebreather/s: Sport Kiss Other Rebreather/s: Prism Topaz Join Date: Jan 2005 Location: Too far from Neverland Posts: 5,555	Remember that Stuart's example was pretty far off and a theoretical extreme. In reality most water enters through the DSV and ends up in the exhalation lung. In most normal diving postions the water wouldn't enter the rear hose and cannister, instead it can be purged with the valve on the bottom of the CL. The only practical way water ends up in the inside tube is if you have a leak in the rear hose or the head connector. And those fall into two categories: Slow leaks and fast ones. A slow leak will have water trickling down the center tube and soak up on the bottom. If water gets in bubbles will come out and depending on the rate you'll adjust your dive. If it's a fast leak (the equivalent of Stuart's pouring a load of water into the tube) it's more likely than not due to major damage. Cutting the rear breathing hose, doing a Dr.Mike without the cowling and breaking the connector, that sort of situation. That's a catastrophic flood, and you're off the loop. Not because there's water in the tube, but because when that much water gets in as much gas gets out. And you don't need a scrubber if the gas is lost before it. You are now on open circuit, and might as well use a well breathing second stage instead. __________________ Cheers Stefan "Political Correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.!"
(Offline)

14th October 2005, 06:56	#22 (permalink)
silent running Mature mouth breather Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Jun 2005 Location: U.S.A. Brooklyn, New York Posts: 1,873	Quote: (Originally Posted by jradomski) The designer has to decides whats more important scrubber run time or some additional survivability.. Neither format is wrong, everyone has their own priorities.. Dave T pointed out nicely that an out to in design slows down the gas velocity as it passes through the scrubber this will increase dwell time as the gas exits while an out to in does the opposite.. From the types of dives I do, I like options that keep me on the loop as long as possible in the event of some type of problem... Even with the Inspiration stack I have NEVER run into a single dive I had breakthrough on... I have some really long run times but lots of that is deco doing nothing... In case like that I track my oxygen usage which gives a good indication of CO2 production... I dont recommend others do it without the proper experience, but I Have put well over 6 hours on an inspiration scrubber albeit most of it at rest doing deco where my average o2 use was less than .5lpm Hi Joe, while I am in total agreement that staying on the loop is a high priority, it's only a priority as long as the loop is still absorbing CO2. It has become clear to me over time that WOB is much more than a mere comfort issue. It is directly related to CO2 production. It seems that the high WOB at the extreme depth of Dave Shaw's dive was a factor, maybe the factor in his probable, fatal CO2 hit. Granted, he had improperly packed his MK scrubber, but it brings home the importance of minimizing WOB and of scrubber efficiency in general. A scrubber which has the longest dwell time and the longest duration IMHO trumps extreme flood tolerance if for no other reason than the higher probability of unplaned exertion over a major loop flood. I like the idea of a hydrophobic membrane, but apparently it significantly increases the WOB, so I wouldn't use a scrubber that had one, especially on a deep, long dive. The type of diving I most prefer is exploratory and often takes place in the most remote places and comes with certain risks. I like knowing that no matter how strong a current I find at the bottom of a new dive site, I don't have to worry about over breathing my Prism scrubber as I fight my way through it. It's happened at least once every trip and I'm sure it will happen again. The Prism has the lowest WOB and the scrubber is the most thoroughly tested and refined design available. These are 2 big reasons why I bought one. And I'm pretty sure the excellent design of the scrubber is also the reason why it will now be available in the Meg.-Andy
(Offline)

17th October 2005, 01:47	#23 (permalink)
Underwaterbear A Prismer in Megland Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: May 2005 Location: Seattle, WA Posts: 198	Quote: (Originally Posted by silent running) The Prism has the lowest WOB and the scrubber is the most thoroughly tested and refined design available. These are 2 big reasons why I bought one. And I'm pretty sure the excellent design of the scrubber is also the reason why it will now be available in the Meg.-Andy Yeah, exactly. But those would be refitters of the Prism scrubber to the Meg would do well to realise that the strength of the Prism scrubber is related to the wholistic design of the total product as a result of the analysis of gas flow throughout the unit - not just the scrubber itself. It's been said before that one could not expect Prism performance figures from a Meg with prism scrubber...maybe there is an improvement but has anyone tested it? I guess if SMI are supplying ISC with the baskets someone has done the figures, or have they? Cheers Andrew
(Offline)

17th October 2005, 03:55	#24 (permalink)
dive2dive2000 PRISM DIVER & LUVIN IT! Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Feb 2005 Location: Long Island, NY Posts: 796	It is my understanding that PRISM is not supplying Meg with the scrubbers, Meg will make you the adapter you have to buy the Scrubber on your own. __________________ Safe Diving, Martin
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17th October 2005, 09:22	#25 (permalink)
*schford* RBW Founder Current Rebreather/s: Megalodon Sport Kiss Other Rebreather/s: Join Date: Jan 2005 Location: UK Posts: 3,564	Like I posted it is not officially confirmed but word on the street is that Steam Machines will probably supply ISC with scrubbers for them to sell on to customers. I also totally agree with Underwaterbears post - the whole design of the PRISM scrubber and the exhaustive testing Pete has done has been focussed around an In---> Out flow, as far I know no testing has been done using it in a Meg with an Out ---> In flow. Although I don't think it unreasonable to assume one would see an increase in run times.... Wouldn't it be good if we could get access to an ANSI machine and a few other bits and bobs for us to run a series of tests on different scrubber architectures, flows and absorbant materials! Stuart
(Offline)

17th October 2005, 17:47	#26 (permalink)
*caveseeker7* Who loves ya, baby Current Rebreather/s: Sport Kiss Other Rebreather/s: Prism Topaz Join Date: Jan 2005 Location: Too far from Neverland Posts: 5,555	Quote: (Originally Posted by Underwaterbear) ...maybe there is an improvement but has anyone tested it? I guess if SMI are supplying ISC with the baskets someone has done the figures, or have they? Has anyone ever done any formal testing on any other scrubber configuration that is being used in Megs? Standard and Mini axial, Cis-Lunar radial and ExtendAir cartridge have been used in the past and I'm not aware of any formal testing of any of these configurations ... which would be a requirement to see an improvement. Hasn't kept people from buying them in the past ... __________________ Cheers Stefan "Political Correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.!"
(Offline)

18th October 2005, 21:00	#27 (permalink)
*schford* RBW Founder Current Rebreather/s: Megalodon Sport Kiss Other Rebreather/s: Join Date: Jan 2005 Location: UK Posts: 3,564	My biggest bug bear with the Meg Scrubbers but at least it will be resolved with CE testing...
(Offline)

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