Hydrophobic membrane in loop?

zbskii · 25th May 2006, 20:55

A thought struck me on the way to lunch today:
Has anybody tried sticking some kind of hydrophobic membranes over the loop mushroom valves? Seems like this would be a simple way to prevent loop floods, however you'd still need a way to clear the mouthpiece. if you didn't have a BOV. Or am I missing something here - is the WOB to high? I know some breathers use 'em over the scrubber so I can't imagine it's too much of an issue.

colinicky · 25th May 2006, 21:11

Interesting question .The only problem I can come up with is that the surface area of a hydrophobic membrane on the scrubber would be a hell of a lot more than the area on mushroom valves therefore as you say it would probably increase the WOB .I expect some body with far more technical knowledge will give us the correct answer though .

decoweenie · 25th May 2006, 21:43

Quote: (Originally Posted by zbskii)

Has anybody tried sticking some kind of hydrophobic membranes over the loop mushroom valves?

Yes, done it for the SK since it is the easier to test.

Used the same material in the rod pod (i.e. 1.5" diameter) and on top of the scrubber entrance (i.e. 4" diameter).

The WOB difference between the 2 locations was exponential. I can't even able to pull a breath comfortably with the smaller diameter in 1-meter of pool water.

When changed to the larger location, the WOB was much less but still noticeable. At the end, I used neither.

If you are going to use any kind of hydrophobic membrane in the unit, I would suggest fitting it in the largest diameter location to give as much surface for the air to go thru as possible.

Mdemon · 25th May 2006, 21:46

Suck it and see...

zbskii · 25th May 2006, 21:55

What were the specs on the membrane you were using? I'm not sure what's needed for diving, but there's serveral different membranes on GE's site:
http://www.osmolabstore.com/OsmoLabP...ldPage&1&1&200
Note the 10 micron membrane has like 400% more flow than most of the others.

Quote: (Originally Posted by decoweenie)

Yes, done it for the SK since it is the easier to test.

Used the same material in the rod pod (i.e. 1.5" diameter) and on top of the scrubber entrance (i.e. 4" diameter).

The WOB difference between the 2 locations was exponential. I can't even able to pull a breath comfortably with the smaller diameter in 1-meter of pool water.

When changed to the larger location, the WOB was much less but still noticeable. At the end, I used neither.

If you are going to use any kind of hydrophobic membrane in the unit, I would suggest fitting it in the largest diameter location to give as much surface for the air to go thru as possible.

decoweenie · 25th May 2006, 22:07

Quote: (Originally Posted by zbskii)

What were the specs on the membrane you were using?

I simply used the Porex found on the MK units since I had them readily available.

25th May 2006, 20:55	#1 (permalink)
zbskii I have a diving problem. Current Rebreather/s: Sport Kiss Other Rebreather/s: Join Date: Dec 2005 Location: Portland, OR Posts: 134	Hydrophobic membrane in loop? A thought struck me on the way to lunch today: Has anybody tried sticking some kind of hydrophobic membranes over the loop mushroom valves? Seems like this would be a simple way to prevent loop floods, however you'd still need a way to clear the mouthpiece. if you didn't have a BOV. Or am I missing something here - is the WOB to high? I know some breathers use 'em over the scrubber so I can't imagine it's too much of an issue.
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25th May 2006, 21:11	#2 (permalink)
colinicky Custom Title Allowed! Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Classic Join Date: Mar 2005 Location: uk Posts: 661	Re: Hydrophobic membrane in loop? Interesting question .The only problem I can come up with is that the surface area of a hydrophobic membrane on the scrubber would be a hell of a lot more than the area on mushroom valves therefore as you say it would probably increase the WOB .I expect some body with far more technical knowledge will give us the correct answer though . __________________ Colin I trust my rebreather completely , I just don't trust the user onwards & downwards
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25th May 2006, 21:43	#3 (permalink)
decoweenie Crash Test Dummy Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2005 Location: Cairo Posts: 5,510	Re: Hydrophobic membrane in loop? Quote: (Originally Posted by zbskii) Has anybody tried sticking some kind of hydrophobic membranes over the loop mushroom valves? Yes, done it for the SK since it is the easier to test. Used the same material in the rod pod (i.e. 1.5" diameter) and on top of the scrubber entrance (i.e. 4" diameter). The WOB difference between the 2 locations was exponential. I can't even able to pull a breath comfortably with the smaller diameter in 1-meter of pool water. When changed to the larger location, the WOB was much less but still noticeable. At the end, I used neither. If you are going to use any kind of hydrophobic membrane in the unit, I would suggest fitting it in the largest diameter location to give as much surface for the air to go thru as possible.
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25th May 2006, 21:46	#4 (permalink)
Mdemon SiegeEngine II Current Rebreather/s: Inspiration Classic Home Build Other Rebreather/s: Inspiration Classic Home Build Join Date: Feb 2007 Location: SWUK Posts: 1,888	Re: Hydrophobic membrane in loop? Suck it and see... __________________ www.southwestmafia.com It's as easy as abc; a) "Carry adequate bailout" b) "If in doubt, bail out" c) "Always know your PO2" If you find that hard, stick to crochet. "Once the agenda-monkeys and perfect-worlders have moved on, perhaps we can do some diving?"
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25th May 2006, 21:55	#5 (permalink)
zbskii I have a diving problem. Current Rebreather/s: Sport Kiss Other Rebreather/s: Join Date: Dec 2005 Location: Portland, OR Posts: 134	Re: Hydrophobic membrane in loop? What were the specs on the membrane you were using? I'm not sure what's needed for diving, but there's serveral different membranes on GE's site: http://www.osmolabstore.com/OsmoLabP...ldPage&1&1&200 Note the 10 micron membrane has like 400% more flow than most of the others. Quote: (Originally Posted by decoweenie) Yes, done it for the SK since it is the easier to test. Used the same material in the rod pod (i.e. 1.5" diameter) and on top of the scrubber entrance (i.e. 4" diameter). The WOB difference between the 2 locations was exponential. I can't even able to pull a breath comfortably with the smaller diameter in 1-meter of pool water. When changed to the larger location, the WOB was much less but still noticeable. At the end, I used neither. If you are going to use any kind of hydrophobic membrane in the unit, I would suggest fitting it in the largest diameter location to give as much surface for the air to go thru as possible.
(Offline)

25th May 2006, 22:07	#6 (permalink)
decoweenie Crash Test Dummy Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2005 Location: Cairo Posts: 5,510	Re: Hydrophobic membrane in loop? Quote: (Originally Posted by zbskii) What were the specs on the membrane you were using? I simply used the Porex found on the MK units since I had them readily available.
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