Going deeper than the IP, will it flood?

jaap · 25th September 2006, 14:50

I was wondering if anyone has first hand experiemce of this scenario:

Take a reglator with a fixt IP on the first stage, say 3 bar. A normal second stage is fitted to it.

Would it flood if it was taken to say 60m depth? The regulator is not used at depth but it is pressurized.

I realise that the water pressure is much higher than the IP so there is a strong chance it will. If it floods how far would the water probably go. All the way into the LP-compartment or just some distance up the hose? Impossible to answer I guess...

Anyway, does anyone know if there is any arrangement that has a somtimes lower than ambient IP and a risk of flooding and some means to protect the regulator from flooding (like a non return valve)?

And now the follow up question:
Does anyone know if the O2-regulators on the "constant"-pO2 SCR are protected from flooding in any way? Like by having a sturdy non return valve fitted? Since the gas goes into the loop I would guess that some system that prevents (humid) gas or water (if flooded) going the wrong way into the regulator is perhaps not strictly necessary.

Examples of "constant"-pO2 SCR are Dräger SM1 and Siva+ (I believe).

Marc T · 25th September 2006, 17:05

Quote: (Originally Posted by jaap)

I was wondering if anyone has first hand experiemce of this scenario:

Take a reglator with a fixt IP on the first stage, say 3 bar. A normal second stage is fitted to it.

Would it flood if it was taken to say 60m depth? The regulator is not used at depth but it is pressurized.

I realise that the water pressure is much higher than the IP so there is a strong chance it will. If it floods how far would the water probably go. All the way into the LP-compartment or just some distance up the hose? Impossible to answer I guess...

Anyway, does anyone know if there is any arrangement that has a somtimes lower than ambient IP and a risk of flooding and some means to protect the regulator from flooding (like a non return valve)?

And now the follow up question:
Does anyone know if the O2-regulators on the "constant"-pO2 SCR are protected from flooding in any way? Like by having a sturdy non return valve fitted? Since the gas goes into the loop I would guess that some system that prevents (humid) gas or water (if flooded) going the wrong way into the regulator is perhaps not strictly necessary.

Examples of "constant"-pO2 SCR are Dräger SM1 and Siva+ (I believe).

Can't answer actually but I know a diver that sometimes go deeper than his IP and realted that
Ive see him only one time on this forum ( Xavier Menniscus ), if ou have no direct answer from him I shall ask to him and then share the info

Drager SM1

have some green for (re ) discovering the real ancestor of the KISS, God ! every Rebreather system has been discovered at least two time!!

Cheers

Marc

jaap · 25th September 2006, 18:35

Quote: (Originally Posted by Marc T)

Can't answer actually but I know a diver that sometimes go deeper than his IP and realted that
Ive see him only one time on this forum ( Xavier Menniscus ), if ou have no direct answer from him I shall ask to him and then share the info

Drager SM1

have some green for (re ) discovering the real ancestor of the KISS, God ! every Rebreather system has been discovered at least two time!!

Cheers

Marc

Merci!

Will drop him a message.

Its really not that tricky to build something simliar to that if one already has a Rebreather with two tanks on it... Or even better with a overcompensating diluent regulator (ratio regulator?) like on the Siva+ (I belive).

Had a wild idea a few years ago about building such a Rebreather using a Aqualung Legend as dilregulator (slightly overcompensated) simply dropping all the the parts into an FGT.

But then its a rather odd form of Rebreather, maybe it should be done just because it can be done...

EDIT: Just to make things clear, my questions have nothing to do with the possible making of a SM1 or similar sort of clone. That was just some mumblings I slipped in.

johnv · 25th September 2006, 19:29

Ok, as nobody else wants to help:

briefly, no, it won't flood, I've done this with my kiss valve, but obviously I have to go semi closed to keep the Po2 at a reasonable level. as the downstream pipe connects to the loop (which hopefully contains gas not water), then dil gets forced up the pipe at ambient pressire. Also, the kiss valve button is very hard to press.

I have no idea about the SCR's you mention, but beware as you may not be able to get fresh gas into the loop. My ADV is depth compensated so I can go semi closed at any depth.

John

paulraymaekers · 25th September 2006, 19:35

Quote: (Originally Posted by jaap)

Merci!

Will drop him a message.

Its really not that tricky to build something simliar to that if one already has a Rebreather with two tanks on it... Or even better with a overcompensating diluent regulator (ratio regulator?) like on the Siva+ (I belive).

Had a wild idea a few years ago about building such a Rebreather using a Aqualung Legend as dilregulator (slightly overcompensated) simply dropping all the the parts into an FGT.

But then its a rather odd form of Rebreather, maybe it should be done just because it can be done...

why would it flood?? I mean when used in a rebreather
it can only flood if there is an opening from waterside to the internal of the regulater
normally there is no such opening, only the internal side of the breather is in connection with the first stage. the opening is there when you push the manual add valve (gas could go from lung to regulator), and trought the orifice. to prevent gas with moister going backwards trough the orifice, and blocking it, on the rEvo's there is always a one-way valve mounted after the orifice.

we have more than once used our breathers deeper than the IP, (for short time), never a problem

regards
paul

Genesis · 25th September 2006, 20:00

It would "back up" but the O2 feed is not open to the water (you hope!) so it should not "flood" per-se.

However, it obviously wouldn't inject any O2, which, if not noticed, could get kinda bad......

sven · 26th September 2006, 01:27

Now, correct me if I am wrong, but I always thought that the IP is the pressure the 1st stage delivers ABOVE ambient pressure.
For a 60m dive, with an IP of 3bar, that would make it 10bar at the LP port of the 1st stage (7bar ambient plus 3 bar IP). The question is obviously what happens to the higher pressure when you descent to 60m and then ascent. There is no problem with OC for apparent reasons - you breathe constantly from the regulator. With a rebreather, where the ADV is normally not active during ascent, the addition of an over pressure valve to the 1st stage is important. This is what the Inspiration Air2 does as a secondary function. People who replace it, need to add an OPV to the first stage. On the O2 side there is already an OPV on the 1st stage.

In my opinion, the problem with water ingress can only occur if the tank pressure is below ambient pressure, i.e. less then 7 bar (in your example for a dive to 60m). Water can then be forced back into the line if you push the purge button on the 2nd stage. I don't know whether regulators usually have a one way valve built in. I very much doubt that this is the case.

Can someone please check my thinking and correct me if I am wrong (I'll then go back hiding behind my computer screen

).

***ScubaDadMiami*** · 26th September 2006, 02:32

Quote: (Originally Posted by sven)

Now, correct me if I am wrong, but I always thought that the IP is the pressure the 1st stage delivers ABOVE ambient pressure.
For a 60m dive, with an IP of 3bar, that would make it 10bar at the LP port of the 1st stage (7bar ambient plus 3 bar IP). The question is obviously what happens to the higher pressure when you descent to 60m and then ascent. There is no problem with OC for apparent reasons - you breathe constantly from the regulator. With a rebreather, where the ADV is normally not active during ascent, the addition of an over pressure valve to the 1st stage is important. This is what the Inspiration Air2 does as a secondary function. People who replace it, need to add an OPV to the first stage. On the O2 side there is already an OPV on the 1st stage.

In my opinion, the problem with water ingress can only occur if the tank pressure is below ambient pressure, i.e. less then 7 bar (in your example for a dive to 60m). Water can then be forced back into the line if you push the purge button on the 2nd stage. I don't know whether regulators usually have a one way valve built in. I very much doubt that this is the case.

Can someone please check my thinking and correct me if I am wrong (I'll then go back hiding behind my computer screen

).

Bingo (unless I am not clear on the scenario)! My thought exactly.

jdz · 26th September 2006, 02:49

The original question was "fixed IP"...

In a KISS system, the IP is fixed to deliver a constant flow eg ~.8lts/min and this can be achieved by blanking off the regulator from external/ambient pressure thus ensuring that the first stage will deliver a fixed line pressure (IP) regardless of depth (up to the IP pressure).. that is, if the IP is fixed to = 10bar, then the IP will stay constant at 10Bar and you will have flow though a valve to a depth of 90meters. Once you exceed 90 meters, the flow will stop as the pressure external will be greater than the IP.

In a non fixed IP, ie a normal regulator first stage, the IP will be fixed ABOVE ambient pressure. That is, if the regulator is set a IP=10bar, then the IP will rise to 12 bar at 20meters. (This will obviously affect the flow rate of gas through a valve hence the IP is fixed in KISS valve systems...)

I hope this helps, otherwise I will link you to other articles to explain more fully.... good luck!

Cheers, JDZ

Edit: Sorry guys, I think I missed the original point of the thread...

The reversal of flow, apart from depressing the purge, will depend on whether the valve is upstream or downsteam...

jakelost · 26th September 2006, 04:28

Hello JAAP !!

Dont you think that the only problem with this is only the design of the
second stage , i would make a second stage with a piston design rather
than using a membran.

// Jakob

25th September 2006, 14:50	#1 (permalink)
jaap Normal people worry me Current Rebreather/s: Classic Kiss Other CCR RB80 / Clone Ray Other SCR Home Build Other Rebreather/s: Other CCR RB80 / Clone Ray Other SCR Home Build Join Date: Jun 2005 Location: Stockholm Sweden Posts: 437	Going deeper than the IP, will it flood? I was wondering if anyone has first hand experiemce of this scenario: Take a reglator with a fixt IP on the first stage, say 3 bar. A normal second stage is fitted to it. Would it flood if it was taken to say 60m depth? The regulator is not used at depth but it is pressurized. I realise that the water pressure is much higher than the IP so there is a strong chance it will. If it floods how far would the water probably go. All the way into the LP-compartment or just some distance up the hose? Impossible to answer I guess... Anyway, does anyone know if there is any arrangement that has a somtimes lower than ambient IP and a risk of flooding and some means to protect the regulator from flooding (like a non return valve)? And now the follow up question: Does anyone know if the O2-regulators on the "constant"-pO2 SCR are protected from flooding in any way? Like by having a sturdy non return valve fitted? Since the gas goes into the loop I would guess that some system that prevents (humid) gas or water (if flooded) going the wrong way into the regulator is perhaps not strictly necessary. Examples of "constant"-pO2 SCR are Dräger SM1 and Siva+ (I believe). Last edited by jaap : 25th September 2006 at 14:54. Reason: Added more to the question
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25th September 2006, 17:05	#2 (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: 433	Re: Going deeper than the IP, will it flood? Quote: (Originally Posted by jaap) I was wondering if anyone has first hand experiemce of this scenario: Take a reglator with a fixt IP on the first stage, say 3 bar. A normal second stage is fitted to it. Would it flood if it was taken to say 60m depth? The regulator is not used at depth but it is pressurized. I realise that the water pressure is much higher than the IP so there is a strong chance it will. If it floods how far would the water probably go. All the way into the LP-compartment or just some distance up the hose? Impossible to answer I guess... Anyway, does anyone know if there is any arrangement that has a somtimes lower than ambient IP and a risk of flooding and some means to protect the regulator from flooding (like a non return valve)? And now the follow up question: Does anyone know if the O2-regulators on the "constant"-pO2 SCR are protected from flooding in any way? Like by having a sturdy non return valve fitted? Since the gas goes into the loop I would guess that some system that prevents (humid) gas or water (if flooded) going the wrong way into the regulator is perhaps not strictly necessary. Examples of "constant"-pO2 SCR are Dräger SM1 and Siva+ (I believe). Can't answer actually but I know a diver that sometimes go deeper than his IP and realted that Ive see him only one time on this forum ( Xavier Menniscus ), if ou have no direct answer from him I shall ask to him and then share the info Drager SM1 have some green for (re ) discovering the real ancestor of the KISS, God ! every Rebreather system has been discovered at least two time!! Cheers Marc
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25th September 2006, 18:35	#3 (permalink)
jaap Normal people worry me Current Rebreather/s: Classic Kiss Other CCR RB80 / Clone Ray Other SCR Home Build Other Rebreather/s: Other CCR RB80 / Clone Ray Other SCR Home Build Join Date: Jun 2005 Location: Stockholm Sweden Posts: 437	Re: Going deeper than the IP, will it flood? Quote: (Originally Posted by Marc T) Can't answer actually but I know a diver that sometimes go deeper than his IP and realted that Ive see him only one time on this forum ( Xavier Menniscus ), if ou have no direct answer from him I shall ask to him and then share the info Drager SM1 have some green for (re ) discovering the real ancestor of the KISS, God ! every Rebreather system has been discovered at least two time!! Cheers Marc Merci! Will drop him a message. Its really not that tricky to build something simliar to that if one already has a Rebreather with two tanks on it... Or even better with a overcompensating diluent regulator (ratio regulator?) like on the Siva+ (I belive). Had a wild idea a few years ago about building such a Rebreather using a Aqualung Legend as dilregulator (slightly overcompensated) simply dropping all the the parts into an FGT. But then its a rather odd form of Rebreather, maybe it should be done just because it can be done... EDIT: Just to make things clear, my questions have nothing to do with the possible making of a SM1 or similar sort of clone. That was just some mumblings I slipped in. Last edited by jaap : 26th September 2006 at 08:47. Reason: Clarification
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25th September 2006, 19:29	#4 (permalink)
johnv Custom Title Allowed! Current Rebreather/s: Other CCR Home Build Other Rebreather/s: Other CCR Home Build Join Date: Dec 2005 Location: UK Posts: 125	Re: Going deeper than the IP, will it flood? Ok, as nobody else wants to help: briefly, no, it won't flood, I've done this with my kiss valve, but obviously I have to go semi closed to keep the Po2 at a reasonable level. as the downstream pipe connects to the loop (which hopefully contains gas not water), then dil gets forced up the pipe at ambient pressire. Also, the kiss valve button is very hard to press. I have no idea about the SCR's you mention, but beware as you may not be able to get fresh gas into the loop. My ADV is depth compensated so I can go semi closed at any depth. John
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25th September 2006, 19:35	#5 (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: 1,340	Re: Going deeper than the IP, will it flood? Quote: (Originally Posted by jaap) Merci! Will drop him a message. Its really not that tricky to build something simliar to that if one already has a Rebreather with two tanks on it... Or even better with a overcompensating diluent regulator (ratio regulator?) like on the Siva+ (I belive). Had a wild idea a few years ago about building such a Rebreather using a Aqualung Legend as dilregulator (slightly overcompensated) simply dropping all the the parts into an FGT. But then its a rather odd form of Rebreather, maybe it should be done just because it can be done... why would it flood?? I mean when used in a rebreather it can only flood if there is an opening from waterside to the internal of the regulater normally there is no such opening, only the internal side of the breather is in connection with the first stage. the opening is there when you push the manual add valve (gas could go from lung to regulator), and trought the orifice. to prevent gas with moister going backwards trough the orifice, and blocking it, on the rEvo's there is always a one-way valve mounted after the orifice. we have more than once used our breathers deeper than the IP, (for short time), never a problem regards 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 : 25th September 2006 at 19:38.
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25th September 2006, 20:00	#6 (permalink)
Genesis Bubbless Box of Death Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Oct 2005 Location: Sunny Florida Posts: 1,394	Re: Going deeper than the IP, will it flood? It would "back up" but the O2 feed is not open to the water (you hope!) so it should not "flood" per-se. However, it obviously wouldn't inject any O2, which, if not noticed, could get kinda bad...... __________________ "A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American." http://www.denninger.net http://www.diversunion.org/liability.htm - Fix the Diving Cert racket
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26th September 2006, 01:27	#7 (permalink)
sven Blogs Admin / Forum Mod Current Rebreather/s: Inspiration Classic Other Rebreather/s: Evolution Join Date: Nov 2005 Location: Sydney Posts: 574	Re: Going deeper than the IP, will it flood? Now, correct me if I am wrong, but I always thought that the IP is the pressure the 1st stage delivers ABOVE ambient pressure. For a 60m dive, with an IP of 3bar, that would make it 10bar at the LP port of the 1st stage (7bar ambient plus 3 bar IP). The question is obviously what happens to the higher pressure when you descent to 60m and then ascent. There is no problem with OC for apparent reasons - you breathe constantly from the regulator. With a rebreather, where the ADV is normally not active during ascent, the addition of an over pressure valve to the 1st stage is important. This is what the Inspiration Air2 does as a secondary function. People who replace it, need to add an OPV to the first stage. On the O2 side there is already an OPV on the 1st stage. In my opinion, the problem with water ingress can only occur if the tank pressure is below ambient pressure, i.e. less then 7 bar (in your example for a dive to 60m). Water can then be forced back into the line if you push the purge button on the 2nd stage. I don't know whether regulators usually have a one way valve built in. I very much doubt that this is the case. Can someone please check my thinking and correct me if I am wrong (I'll then go back hiding behind my computer screen ). __________________ Regards, Sven [SIZE=1]The Sydney Project website: [URL]http://www.sydneyproject.com[/URL] My Blog: [URL]http://sven.rebreatherworld.com[/URL] "Whenever you find yourself on the side of the majority, it's time to pause and reflect." Mark Twain[/SIZE]
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26th September 2006, 02:32	#8 (permalink)
*ScubaDadMiami* Moderator Current Rebreather/s: Optima Other Rebreather/s: Join Date: Sep 2005 Location: Florida, USA Posts: 1,887	Re: Going deeper than the IP, will it flood? Quote: (Originally Posted by sven) Now, correct me if I am wrong, but I always thought that the IP is the pressure the 1st stage delivers ABOVE ambient pressure. For a 60m dive, with an IP of 3bar, that would make it 10bar at the LP port of the 1st stage (7bar ambient plus 3 bar IP). The question is obviously what happens to the higher pressure when you descent to 60m and then ascent. There is no problem with OC for apparent reasons - you breathe constantly from the regulator. With a rebreather, where the ADV is normally not active during ascent, the addition of an over pressure valve to the 1st stage is important. This is what the Inspiration Air2 does as a secondary function. People who replace it, need to add an OPV to the first stage. On the O2 side there is already an OPV on the 1st stage. In my opinion, the problem with water ingress can only occur if the tank pressure is below ambient pressure, i.e. less then 7 bar (in your example for a dive to 60m). Water can then be forced back into the line if you push the purge button on the 2nd stage. I don't know whether regulators usually have a one way valve built in. I very much doubt that this is the case. Can someone please check my thinking and correct me if I am wrong (I'll then go back hiding behind my computer screen ). Bingo (unless I am not clear on the scenario)! My thought exactly. __________________ Howard Packer IANTD CCR Instructor Miami Beach, Florida CCRDiveTraining.com
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26th September 2006, 02:49	#9 (permalink)
jdz Prism Cave Diver Current Rebreather/s: Prism Topaz Dolphin Home Build Other Rebreather/s: Dolphin Home Build Join Date: Feb 2005 Location: Melbourne Australia Posts: 212	Re: Going deeper than the IP, will it flood? The original question was "fixed IP"... In a KISS system, the IP is fixed to deliver a constant flow eg ~.8lts/min and this can be achieved by blanking off the regulator from external/ambient pressure thus ensuring that the first stage will deliver a fixed line pressure (IP) regardless of depth (up to the IP pressure).. that is, if the IP is fixed to = 10bar, then the IP will stay constant at 10Bar and you will have flow though a valve to a depth of 90meters. Once you exceed 90 meters, the flow will stop as the pressure external will be greater than the IP. In a non fixed IP, ie a normal regulator first stage, the IP will be fixed ABOVE ambient pressure. That is, if the regulator is set a IP=10bar, then the IP will rise to 12 bar at 20meters. (This will obviously affect the flow rate of gas through a valve hence the IP is fixed in KISS valve systems...) I hope this helps, otherwise I will link you to other articles to explain more fully.... good luck! Cheers, JDZ Edit: Sorry guys, I think I missed the original point of the thread... The reversal of flow, apart from depressing the purge, will depend on whether the valve is upstream or downsteam... Last edited by jdz : 26th September 2006 at 02:58. Reason: misread..
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26th September 2006, 04:28	#10 (permalink)
jakelost New Member Current Rebreather/s: Sport Kiss Other SCR Other Rebreather/s: Other SCR Join Date: Feb 2006 Location: Sweden Posts: 20	Re: Going deeper than the IP, will it flood? Hello JAAP !! Dont you think that the only problem with this is only the design of the second stage , i would make a second stage with a piston design rather than using a membran. // Jakob
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