Orifices "protection"

TR300 · 21st June 2006, 10:42

I just wondering around, some manufacteurs does the protection of his "life supporting" orifices in the Rebreather.

The best protection I ever seen was the Dolphin, there you have at least two orifices, if one fails (stick) the other does the half flow (enough to survive in deep), also the protection to run dirt or wet ist perfect. on the inlet there is a plasticmesh, on the outlet the orifices is protectect with a rubberpiece. also the 1. Stage reg. has its sinterfilter.

seen on other new SCR Rebreathers on the market, nothing like the dolphin, the orifices can run wet from both side (very unlikely in salt water conditions), the systems have just one orifices, sometimes no sinterfilter in the 1.stage, etc.

I think the orifices are important to support the diver with fresh gas, so if the orifices stick just a bit the flow will decrease and (we know don´t do) if the diver uses not the right orifices for the mix hypoxi will occur.

just thinking

Holger

***jradomski*** · 21st June 2006, 10:48

Quote: (Originally Posted by TR300)

I just wondering around, some manufacteurs does the protection of his "life supporting" orifices in the Rebreather.

The best protection I ever seen was the Dolphin, there you have at least two orifices, if one fails (stick) the other does the half flow (enough to survive in deep), also the protection to run dirt or wet ist perfect. on the inlet there is a plasticmesh, on the outlet the orifices is protectect with a rubberpiece. also the 1. Stage reg. has its sinterfilter.

seen on other new SCR Rebreathers on the market, nothing like the dolphin, the orifices can run wet from both side (very unlikely in salt water conditions), the systems have just one orifices, sometimes no sinterfilter in the 1.stage, etc.

I think the orifices are important to support the diver with fresh gas, so if the orifices stick just a bit the flow will decrease and (we know don´t do) if the diver uses not the right orifices for the mix hypoxi will occur.

just thinking

Holger

Yes but the "two" orifices are now half size each, increasing the liklihood they can get blocked by partilces that wouldnt have blocked the full size orifice..

TR300 · 21st June 2006, 13:33

Quote: (Originally Posted by jradomski)

Yes but the "two" orifices are now half size each, increasing the liklihood they can get blocked by partilces that wouldnt have blocked the full size orifice..

hmm, but the Dolphin has also a filter before the orficies. And if come so a lot of particles then a full size orifices may also be stucked.

Holger

***jradomski*** · 21st June 2006, 13:44

Quote: (Originally Posted by TR300)

hmm, but the Dolphin has also a filter before the orficies. And if come so a lot of particles then a full size orifices may also be stucked.

Holger

Just trying to point out.. just about every possible advantage also has a negative implication..

paulraymaekers · 21st June 2006, 14:40

Quote: (Originally Posted by jradomski)

Just trying to point out.. just about every possible advantage also has a negative implication..

well, the rEvo's have filter before and after orifice, and non-return valve after orifice to prevent water intake from lung-side
works pretty well until now

regards
paul

ps: orifices of dolphins are not to be compared with orifices for CMF: the last ones are much smaller

Stephane · 21st June 2006, 14:52

Quote: (Originally Posted by paulraymaekers)

well, the rEvo's have filter before and after orifice, and non-return valve after orifice to prevent water intake from lung-side
works pretty well until now

regards
paul

I must confess that without the non-return valve, it is not idiot proof. And I am an idiot ...

Scuba_Vixen · 21st June 2006, 17:13

Quote: (Originally Posted by paulraymaekers)

well, the rEvo's have filter before and after orifice, and non-return valve after orifice to prevent water intake from lung-side
works pretty well until now

regards
paul

ps: orifices of dolphins are not to be compared with orifices for CMF: the last ones are much smaller

I'm wondering if where you say CMF, you meant to type CCR, because, ......

If I'm understanding this correctly, you're saying that the Dolphins orifice structure is Not CMF?

That's not correct, it *is* CMF. That's why they use 2 smaller orifices instead of one larger one. With the 245# IP, the gas velocity thru those 2 orifices maintains at the sonic level. If there was a single larger orifice that flowed the same amount, it would require a much higher IP yet.

The difference in size between an SCRs orifice and addition orifices in CCRs is basicaly a function of how much gas they need to flow.

Darlene

paulraymaekers · 21st June 2006, 17:37

hello darlene, I should have written O2 CMF ('KISS-like')
the flow is +/- 0.75l/min, in the dolphin it is between 15 and 3 l/min
(both are CMF, but the O2 orifice is much smaller)

....IF there was a single larger orifice that flowed the same amount, it would require a much higher IP yet. ...

this is not the case: you only need one orifice that is slightly bigger to replace 2 orifices and get the same flow: as flow is proportional to the diameter in the third degree (I think, shoul check it)

one 0.0035 gives +/- the same flow as two 0.0028 at the same pressure

regards
paul

***jradomski*** · 21st June 2006, 17:49

Quote: (Originally Posted by paulraymaekers)

well, the rEvo's have filter before and after orifice, and non-return valve after orifice to prevent water intake from lung-side
works pretty well until now

regards
paul

ps: orifices of dolphins are not to be compared with orifices for CMF: the last ones are much smaller

Filters get clogged which is a given, but the non return valve... Hmmm I'll have to think about that one and what if any possible negatives can be said..

I have seen non return valves that have coroded stuck shut, but I am assuming you are using SS on all components in the valve so That really shouldn't be an issue..

I may have to put this one on the side of a no brainer...

shell-back · 21st June 2006, 21:59

Quote: (Originally Posted by jradomski)

Filters get clogged which is a given, but the non return valve... Hmmm I'll have to think about that one and what if any possible negatives can be said..

I have seen non return valves that have coroded stuck shut, but I am assuming you are using SS on all components in the valve so That really shouldn't be an issue..

I may have to put this one on the side of a no brainer...

sinter filters get clogged ?? sure they pick some of the particulates but it does not change the porosity of the filter and or its flow rate. If so would it not change the flow rate of the orifice.

21st June 2006, 10:42	#1 (permalink)
TR300 Holger Berghäuser Current Rebreather/s: Other CCR Dolphin Other SCR Home Build Other Rebreather/s: Not Bought Yet Other CCR Dolphin Other SCR Home Build Join Date: Jan 2005 Location: Weinheim, Germany Posts: 208	Orifices "protection" I just wondering around, some manufacteurs does the protection of his "life supporting" orifices in the Rebreather. The best protection I ever seen was the Dolphin, there you have at least two orifices, if one fails (stick) the other does the half flow (enough to survive in deep), also the protection to run dirt or wet ist perfect. on the inlet there is a plasticmesh, on the outlet the orifices is protectect with a rubberpiece. also the 1. Stage reg. has its sinterfilter. seen on other new SCR Rebreathers on the market, nothing like the dolphin, the orifices can run wet from both side (very unlikely in salt water conditions), the systems have just one orifices, sometimes no sinterfilter in the 1.stage, etc. I think the orifices are important to support the diver with fresh gas, so if the orifices stick just a bit the flow will decrease and (we know don´t do) if the diver uses not the right orifices for the mix hypoxi will occur. just thinking Holger __________________ If it makes bubbles it means its brocken Visit: www.tr300.com, Missions: www.rebreatherteam.de
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21st June 2006, 10:48	#2 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Home Build Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Home Build Join Date: Mar 2005 Location: "Da" Bronx Posts: 2,998	Re: Orifices "protection" Quote: (Originally Posted by TR300) I just wondering around, some manufacteurs does the protection of his "life supporting" orifices in the Rebreather. The best protection I ever seen was the Dolphin, there you have at least two orifices, if one fails (stick) the other does the half flow (enough to survive in deep), also the protection to run dirt or wet ist perfect. on the inlet there is a plasticmesh, on the outlet the orifices is protectect with a rubberpiece. also the 1. Stage reg. has its sinterfilter. seen on other new SCR Rebreathers on the market, nothing like the dolphin, the orifices can run wet from both side (very unlikely in salt water conditions), the systems have just one orifices, sometimes no sinterfilter in the 1.stage, etc. I think the orifices are important to support the diver with fresh gas, so if the orifices stick just a bit the flow will decrease and (we know don´t do) if the diver uses not the right orifices for the mix hypoxi will occur. just thinking Holger Yes but the "two" orifices are now half size each, increasing the liklihood they can get blocked by partilces that wouldnt have blocked the full size orifice.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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21st June 2006, 13:33	#3 (permalink)
TR300 Holger Berghäuser Current Rebreather/s: Other CCR Dolphin Other SCR Home Build Other Rebreather/s: Not Bought Yet Other CCR Dolphin Other SCR Home Build Join Date: Jan 2005 Location: Weinheim, Germany Posts: 208	Re: Orifices "protection" Quote: (Originally Posted by jradomski) Yes but the "two" orifices are now half size each, increasing the liklihood they can get blocked by partilces that wouldnt have blocked the full size orifice.. hmm, but the Dolphin has also a filter before the orficies. And if come so a lot of particles then a full size orifices may also be stucked. Holger __________________ If it makes bubbles it means its brocken Visit: www.tr300.com, Missions: www.rebreatherteam.de
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21st June 2006, 13:44	#4 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Home Build Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Home Build Join Date: Mar 2005 Location: "Da" Bronx Posts: 2,998	Re: Orifices "protection" Quote: (Originally Posted by TR300) hmm, but the Dolphin has also a filter before the orficies. And if come so a lot of particles then a full size orifices may also be stucked. Holger Just trying to point out.. just about every possible advantage also has a negative implication.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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21st June 2006, 14:40	#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: 1,498	Re: Orifices "protection" Quote: (Originally Posted by jradomski) Just trying to point out.. just about every possible advantage also has a negative implication.. well, the rEvo's have filter before and after orifice, and non-return valve after orifice to prevent water intake from lung-side works pretty well until now regards paul ps: orifices of dolphins are not to be compared with orifices for CMF: the last ones are much smaller __________________ www.rEvo-rebreathers.com .... the earth is flat, Elvis is alive, and radial scrubbers give longer dwell time than axials...
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21st June 2006, 14:52	#6 (permalink)
Stephane Stéphane Acounis Current Rebreather/s: rEvo Other Rebreather/s: rEvo Join Date: Nov 2005 Location: Nantes - France Posts: 773	Re: Orifices "protection" Quote: (Originally Posted by paulraymaekers) well, the rEvo's have filter before and after orifice, and non-return valve after orifice to prevent water intake from lung-side works pretty well until now regards paul I must confess that without the non-return valve, it is not idiot proof. And I am an idiot ... __________________ Stéphane
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21st June 2006, 17:13	#7 (permalink)
Scuba_Vixen e/mCCR Dolphin Pilot Current Rebreather/s: Other CCR Home Build Other Rebreather/s: Other CCR Home Build Join Date: May 2005 Location: St. Croix USVI Posts: 557	Re: Orifices "protection" Quote: (Originally Posted by paulraymaekers) well, the rEvo's have filter before and after orifice, and non-return valve after orifice to prevent water intake from lung-side works pretty well until now regards paul ps: orifices of dolphins are not to be compared with orifices for CMF: the last ones are much smaller I'm wondering if where you say CMF, you meant to type CCR, because, ...... If I'm understanding this correctly, you're saying that the Dolphins orifice structure is Not CMF? That's not correct, it is CMF. That's why they use 2 smaller orifices instead of one larger one. With the 245# IP, the gas velocity thru those 2 orifices maintains at the sonic level. If there was a single larger orifice that flowed the same amount, it would require a much higher IP yet. The difference in size between an SCRs orifice and addition orifices in CCRs is basicaly a function of how much gas they need to flow. Darlene
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21st June 2006, 17:37	#8 (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: 1,498	Re: Orifices "protection" hello darlene, I should have written O2 CMF ('KISS-like') the flow is +/- 0.75l/min, in the dolphin it is between 15 and 3 l/min (both are CMF, but the O2 orifice is much smaller) ....IF there was a single larger orifice that flowed the same amount, it would require a much higher IP yet. ... this is not the case: you only need one orifice that is slightly bigger to replace 2 orifices and get the same flow: as flow is proportional to the diameter in the third degree (I think, shoul check it) one 0.0035 gives +/- the same flow as two 0.0028 at the same pressure regards paul __________________ www.rEvo-rebreathers.com .... the earth is flat, Elvis is alive, and radial scrubbers give longer dwell time than axials...
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21st June 2006, 17:49	#9 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Home Build Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Home Build Join Date: Mar 2005 Location: "Da" Bronx Posts: 2,998	Re: Orifices "protection" Quote: (Originally Posted by paulraymaekers) well, the rEvo's have filter before and after orifice, and non-return valve after orifice to prevent water intake from lung-side works pretty well until now regards paul ps: orifices of dolphins are not to be compared with orifices for CMF: the last ones are much smaller Filters get clogged which is a given, but the non return valve... Hmmm I'll have to think about that one and what if any possible negatives can be said.. I have seen non return valves that have coroded stuck shut, but I am assuming you are using SS on all components in the valve so That really shouldn't be an issue.. I may have to put this one on the side of a no brainer... __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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21st June 2006, 21:59	#10 (permalink)
shell-back I do all my own stunts Current Rebreather/s: Other CCR Dolphin Ray Azimuth Other SCR Home Build Other Rebreather/s: Other CCR Dolphin Ray Azimuth Other SCR Home Build Join Date: Jul 2005 Location: middle of US Posts: 481	Re: Orifices "protection" Quote: (Originally Posted by jradomski) Filters get clogged which is a given, but the non return valve... Hmmm I'll have to think about that one and what if any possible negatives can be said.. I have seen non return valves that have coroded stuck shut, but I am assuming you are using SS on all components in the valve so That really shouldn't be an issue.. I may have to put this one on the side of a no brainer... sinter filters get clogged ?? sure they pick some of the particulates but it does not change the porosity of the filter and or its flow rate. If so would it not change the flow rate of the orifice. __________________ The greatest obstacle to discovery is not ignorance -- it is the illusion of knowledge. ----Daniel Boorstin Billy Beal SDITDI IT #3507 Rebreather World FIGJAM commitee member
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