Passive Scr Superiority?

decoweenie · 16th October 2006, 13:12

Quote: (Originally Posted by Mike)

One way valve in the bellows?

Only on the small bellow which is the one that is doing the SCR work - forces a fraction of gas out from the loop per breath.

Marc T · 16th October 2006, 13:28

Quote: (Originally Posted by Mark Chase)

I think they could be. However the limited benefits of SCR over OC for OW diving make it a very expensive toy. IF they sorted out the WOB issues with a RB80 type unit It would be worth considering but with fixed PP02 problems, the possibility for error on a gas switching block and the need for multiple drive gases AND bailout on OW dives I still don't see it as being that good a choice.

If i dived one Id dive it the equivalent of Alpinist in that i do two or three big dives on the unit with the same tins of gas. So by dive 3 ill probably not have enough reserve gas to bailout OC

It also reintroduces the best mix issue into diving. These days i dive 18/45 on everything down to 60 and 14/55 past that. The thought of doing a 30m dive on 18/45 doesn't appeal to me. I have a tin of 18/45 and a tin of 14/55 and a booster to fill the little 3ltr tins. Life is good.

I still think the KISS with a HUD is the way to go to achieve the balance of safety and practical advantages of CCR.

ATB

Mark Chase

The usual and realtively easy way to dive securely a passive SCR ( for deep or long dive ) is to fit it with larges backmounted tanks who are here just for bailout. You feed your SCR with small alu tanks and to secure the whole thing you need some OC deco bailout.
So pSCR is a great tool for cave diving BUT its more intersting if you dive several time the same profile and more if you dive sveral time in the same place, you just have to fill again your small tanks ( and your sorb yes

) because you dont touch bailout nor deco gas.
Somes says th pSCR is just a gase saver, thats true.
But the question was is it safe... I do think so, but you can kill yourself with that.
I dont say its an easy way nor thats the future of Rebreather, just safe

Mark Chase · 16th October 2006, 13:43

Quote: (Originally Posted by Marc T)

The usual and realtively easy way to dive securely a passive SCR ( for deep or long dive ) is to fit it with larges backmounted tanks who are here just for bailout. You feed your SCR with small alu tanks and to secure the whole thing you need some OC deco bailout.
So pSCR is a great tool for cave diving BUT its more intersting if you dive several time the same profile and more if you dive sveral time in the same place, you just have to fill again your small tanks ( and your sorb yes

) because you dont touch bailout nor deco gas.
Somes says th pSCR is just a gase saver, thats true.
But the question was is it safe... I do think so, but you can kill yourself with that.
I dont say its an easy way nor thats the future of Rebreather, just safe

I seem to remember GI3 saying the RB80 is a dangerous piece of kit and the YBOD is a dangerous piece of shit.

So he thaught the SCR RB80 design was risky.

IMHO if safety is the primary concern, dont dive any form of SCR CCR. Stick to OC and avoid situations where the gas limitations of OC could cause a problem.

ATB

Mark Chase

Marc T · 16th October 2006, 14:04

Quote: (Originally Posted by Mark Chase)

IMHO if safety is the primary concern, dont dive any form of SCR CCR. Stick to OC and avoid situations where the gas limitations of OC could cause a problem.

ATB

Mark Chase

thats honest and I must admit that speaking about MY personnal cave diving practice I feel that the greatest danger now come from the Rebreather itself ( its no more a p SCR ).
So many hours watching to my PO2 and trying to foresee what the next Rebreather joke will be.
Yes I am seriously thinking on going back OC.
But its just MY feeling

lizardland · 16th October 2006, 14:15

Quote:

So he thaught the SCR RB80 design was risky

The quote I always remember from Techdiver was "I'd rather have a flask of ebola virus in my house than any rebreather".

I think he is right, there is no inherently safe rebreather. Anyone who thinks breathing into a plastic bag through a filter bed of caustic soda in a wet environment which you can't survive unsupported needs their bumps feeling. There are easy rebreathers to use and there are complicated ones, I think it is hard to generalise any further than that.

gtzavelas · 16th October 2006, 14:18

Quote: (Originally Posted by Mike)

One way valve in the bellows?
Mike

see a pSRC tear down
http://www.rebreatherworld.com/semi-...tear-down.html
or directly see the one way valve picture inside the inner:
http://www.rebreatherworld.com/photo...28/Bellows.jpg

if this one way valve stops working no gas is forced out so no gas comes in so PO2 goes to zero...

gtzavelas · 16th October 2006, 14:22

Quote: (Originally Posted by Marc T)

thats honest and I must admit that speaking about MY personnal cave diving practice I feel that the greatest danger now come from the Rebreather itself ( its no more a p SCR ).
So many hours watching to my PO2 and trying to foresee what the next Rebreather joke will be.
Yes I am seriously thinking on going back OC.
But its just MY feeling

can you elaborate? what modifications did you do? and in what way is it more dangerous?

Marc T · 16th October 2006, 15:12

Quote: (Originally Posted by gtzavelas)

can you elaborate? what modifications did you do? and in what way is it more dangerous?

Turned my EDO 04 into a mCCR, add a complete second backup loop ( also mCCR ) and choose to dive without any bailout except the 7 liters backmounted tanks.
Now have a sidemounted third loop but not yet O2 display on it so only as O2 Rebreather.
That way you really have to think about what reliability of Rebreather is.

Faceless · 16th October 2006, 16:13

There is a very good explanation with Flash animation on how pSCR works.

http://www.golemrebreathers.com/SCR/SCRteardown.htm

Faceless · 16th October 2006, 17:22

Quote: (Originally Posted by AD_ward9)

There are a lot of things not fixed on popular rebreathers: critical failure points that are likely to cause fatalities. If any manufacturer wants the list for their unit, see me at DEMA. I will see if I can pack in a few tools to demo the failures in a quiet room off the exhibition.

Alex

(Signs) I wish I be there ...

16th October 2006, 13:12	#21 (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: Passive Scr Superiority? Quote: (Originally Posted by Mike) One way valve in the bellows? Only on the small bellow which is the one that is doing the SCR work - forces a fraction of gas out from the loop per breath. __________________ "...after a while you get bored offering advice to a bull that like to keep butting the fence with its head rather than walking through the open gate..." - Rebreather World PM
(Offline)

16th October 2006, 13:28	#22 (permalink)
Marc T hell is in the details Current Rebreather/s: RB80 / Clone Home Build Other Rebreather/s: Not Bought Yet RB80 / Clone Home Build Join Date: Sep 2005 Location: FRANCE Carcassonne Posts: 485	Re: Passive Scr Superiority? Quote: (Originally Posted by Mark Chase) I think they could be. However the limited benefits of SCR over OC for OW diving make it a very expensive toy. IF they sorted out the WOB issues with a RB80 type unit It would be worth considering but with fixed PP02 problems, the possibility for error on a gas switching block and the need for multiple drive gases AND bailout on OW dives I still don't see it as being that good a choice. If i dived one Id dive it the equivalent of Alpinist in that i do two or three big dives on the unit with the same tins of gas. So by dive 3 ill probably not have enough reserve gas to bailout OC It also reintroduces the best mix issue into diving. These days i dive 18/45 on everything down to 60 and 14/55 past that. The thought of doing a 30m dive on 18/45 doesn't appeal to me. I have a tin of 18/45 and a tin of 14/55 and a booster to fill the little 3ltr tins. Life is good. I still think the KISS with a HUD is the way to go to achieve the balance of safety and practical advantages of CCR. ATB Mark Chase The usual and realtively easy way to dive securely a passive SCR ( for deep or long dive ) is to fit it with larges backmounted tanks who are here just for bailout. You feed your SCR with small alu tanks and to secure the whole thing you need some OC deco bailout. So pSCR is a great tool for cave diving BUT its more intersting if you dive several time the same profile and more if you dive sveral time in the same place, you just have to fill again your small tanks ( and your sorb yes ) because you dont touch bailout nor deco gas. Somes says th pSCR is just a gase saver, thats true. But the question was is it safe... I do think so, but you can kill yourself with that. I dont say its an easy way nor thats the future of Rebreather, just safe
(Offline)

16th October 2006, 13:43	#23 (permalink)
Mark Chase I go down for ages Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Jan 2005 Location: Kent Posts: 2,693	Re: Passive Scr Superiority? Quote: (Originally Posted by Marc T) The usual and realtively easy way to dive securely a passive SCR ( for deep or long dive ) is to fit it with larges backmounted tanks who are here just for bailout. You feed your SCR with small alu tanks and to secure the whole thing you need some OC deco bailout. So pSCR is a great tool for cave diving BUT its more intersting if you dive several time the same profile and more if you dive sveral time in the same place, you just have to fill again your small tanks ( and your sorb yes ) because you dont touch bailout nor deco gas. Somes says th pSCR is just a gase saver, thats true. But the question was is it safe... I do think so, but you can kill yourself with that. I dont say its an easy way nor thats the future of Rebreather, just safe I seem to remember GI3 saying the RB80 is a dangerous piece of kit and the YBOD is a dangerous piece of shit. So he thaught the SCR RB80 design was risky. IMHO if safety is the primary concern, dont dive any form of SCR CCR. Stick to OC and avoid situations where the gas limitations of OC could cause a problem. ATB Mark Chase __________________ Is it supposed to make that noise ? I took my unit to the dive shop and demanded they bolt on every thing that would fit. Join my elite diving teem and get a Tshirt "Doing It Chasey"Hammerhead Eccr Advanced Diving System
(Online)

16th October 2006, 14:04	#24 (permalink)
Marc T hell is in the details Current Rebreather/s: RB80 / Clone Home Build Other Rebreather/s: Not Bought Yet RB80 / Clone Home Build Join Date: Sep 2005 Location: FRANCE Carcassonne Posts: 485	Re: Passive Scr Superiority? Quote: (Originally Posted by Mark Chase) IMHO if safety is the primary concern, dont dive any form of SCR CCR. Stick to OC and avoid situations where the gas limitations of OC could cause a problem. ATB Mark Chase thats honest and I must admit that speaking about MY personnal cave diving practice I feel that the greatest danger now come from the Rebreather itself ( its no more a p SCR ). So many hours watching to my PO2 and trying to foresee what the next Rebreather joke will be. Yes I am seriously thinking on going back OC. But its just MY feeling
(Offline)

16th October 2006, 14:15	#25 (permalink)
lizardland Yak Current Rebreather/s: MK 15.X Home Build Other Rebreather/s: Classic Kiss Home Build Join Date: Mar 2005 Location: North... Posts: 1,302	Re: Passive Scr Superiority? Quote: So he thaught the SCR RB80 design was risky The quote I always remember from Techdiver was "I'd rather have a flask of ebola virus in my house than any rebreather". I think he is right, there is no inherently safe rebreather. Anyone who thinks breathing into a plastic bag through a filter bed of caustic soda in a wet environment which you can't survive unsupported needs their bumps feeling. There are easy rebreathers to use and there are complicated ones, I think it is hard to generalise any further than that. __________________ Can you imagine drifting along in the sea with your mouth open and a load of f***ing plankton going in? You'd like it, would you? www.westons-cider.co.uk Azerbaijani Association of Technical Divers Publicity Officer and Goat Wrangler
(Offline)

16th October 2006, 14:18	#26 (permalink)
gtzavelas Rebreather World Writer Current Rebreather/s: Megalodon RB80 / Clone Other Rebreather/s: RB80 / Clone Join Date: Jan 2006 Location: Athens,Greece Posts: 261	Re: Passive Scr Superiority? Quote: (Originally Posted by Mike) One way valve in the bellows? Mike see a pSRC tear down http://www.rebreatherworld.com/semi-...tear-down.html or directly see the one way valve picture inside the inner: http://www.rebreatherworld.com/photo...28/Bellows.jpg if this one way valve stops working no gas is forced out so no gas comes in so PO2 goes to zero...
(Online)

16th October 2006, 14:22	#27 (permalink)
gtzavelas Rebreather World Writer Current Rebreather/s: Megalodon RB80 / Clone Other Rebreather/s: RB80 / Clone Join Date: Jan 2006 Location: Athens,Greece Posts: 261	Re: Passive Scr Superiority? Quote: (Originally Posted by Marc T) thats honest and I must admit that speaking about MY personnal cave diving practice I feel that the greatest danger now come from the Rebreather itself ( its no more a p SCR ). So many hours watching to my PO2 and trying to foresee what the next Rebreather joke will be. Yes I am seriously thinking on going back OC. But its just MY feeling can you elaborate? what modifications did you do? and in what way is it more dangerous?
(Online)

16th October 2006, 15:12	#28 (permalink)
Marc T hell is in the details Current Rebreather/s: RB80 / Clone Home Build Other Rebreather/s: Not Bought Yet RB80 / Clone Home Build Join Date: Sep 2005 Location: FRANCE Carcassonne Posts: 485	Re: Passive Scr Superiority? Quote: (Originally Posted by gtzavelas) can you elaborate? what modifications did you do? and in what way is it more dangerous? Turned my EDO 04 into a mCCR, add a complete second backup loop ( also mCCR ) and choose to dive without any bailout except the 7 liters backmounted tanks. Now have a sidemounted third loop but not yet O2 display on it so only as O2 Rebreather. That way you really have to think about what reliability of Rebreather is.
(Offline)

16th October 2006, 16:13	#29 (permalink)
Faceless alone lurking in wrecks Current Rebreather/s: Other CCR Other Rebreather/s: Not Bought Yet Other CCR Join Date: May 2006 Location: France, Montpellier Posts: 100	Re: Passive Scr Superiority? There is a very good explanation with Flash animation on how pSCR works. http://www.golemrebreathers.com/SCR/SCRteardown.htm Last edited by Faceless : 16th October 2006 at 16:19.
(Offline)

16th October 2006, 17:22	#30 (permalink)
Faceless alone lurking in wrecks Current Rebreather/s: Other CCR Other Rebreather/s: Not Bought Yet Other CCR Join Date: May 2006 Location: France, Montpellier Posts: 100	Re: Passive Scr Superiority? Quote: (Originally Posted by AD_ward9) There are a lot of things not fixed on popular rebreathers: critical failure points that are likely to cause fatalities. If any manufacturer wants the list for their unit, see me at DEMA. I will see if I can pack in a few tools to demo the failures in a quiet room off the exhibition. Alex (Signs) I wish I be there ...
(Offline)

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode