O2 Metabolic Rates, Oriffice Sizes, ..... Questions...

Scuba_Vixen · 11th June 2006, 00:08

Hi guys,

Been doing some tweaks and tests on the Dolphin conversion before taking the new leccies for some real dives.

I'm most curious about what would be the normal range of O2 metabolized while breathing the loop, sitting on the bed next to the unit with no other physical activity. I wear my mask, so there's no chance of nose breathing.

If I don't set the IP down to ~7.5 bar, (just a bit over 0.4 l/m on the flowmeter) The PO2 will slowly climb. The dill isn't even turned on, so there's no chance of adv leaking by.

On 30m to 40m dives, I have to keep the IP down between 8 to 9 bar, or the PO2 climbs a bit. .... This is going to be an issue with significantly deeper dives that require a higher IP.

Do I just seem to metabolize an unusually small amount of O2?

I've been playing with the numbers in this oriffice size calculator, and it seems like 0.003 to 0.00325" would be about right.

http://www.lenoxlaser.com/calculator/orifice.asp

Any chance that Jetsam has a 0.003" oriffice?

Darlene

abowie · 11th June 2006, 04:34

The magic number for basal O2 consumption in anaesthesia is about 250ml per minute. Awake, sitting on the couch 400ml might well be a reasonable number. Activity will increase this to some degree.

The Rebreather manufacturers usually work on about a litre per minute. My KISS delivers about 820ml/min and drops slowly with low exertion diving.

Body size (more related to lean muscle mass than weight) and gender (females use less per kg than males) will also affect basal O2 consumption.

***jradomski*** · 11th June 2006, 04:43

Quote: (Originally Posted by Scuba_Vixen)

Hi guys,

Been doing some tweaks and tests on the Dolphin conversion before taking the new leccies for some real dives.

I'm most curious about what would be the normal range of O2 metabolized while breathing the loop, sitting on the bed next to the unit with no other physical activity. I wear my mask, so there's no chance of nose breathing.

If I don't set the IP down to ~7.5 bar, (just a bit over 0.4 l/m on the flowmeter) The PO2 will slowly climb. The dill isn't even turned on, so there's no chance of adv leaking by.

On 30m to 40m dives, I have to keep the IP down between 8 to 9 bar, or the PO2 climbs a bit. .... This is going to be an issue with significantly deeper dives that require a higher IP.

Do I just seem to metabolize an unusually small amount of O2?

I've been playing with the numbers in this oriffice size calculator, and it seems like 0.003 to 0.00325" would be about right.

http://www.lenoxlaser.com/calculator/orifice.asp

Any chance that Jetsam has a 0.003" oriffice?

Darlene

This kiss orifice is .0035

Scuba_Vixen · 11th June 2006, 05:40

Quote: (Originally Posted by jradomski)

This kiss orifice is .0035

Yes, That's the size I have. ..... the latter model.

What I was hoping for was a slightly smaller one, .003" so I could run a ~12bar IP, but have a bit less than the normal .8 l/m flow rate.

Darlene

**Freef** · 11th June 2006, 07:22

http://www.rebreatherworld.com/semi-...culations.html

Hi Darlene,

I found the thread after emailing you, Sec 3 should be useful.

Any comments on the thread should be posted there not on this one!

David.

decoweenie · 11th June 2006, 08:55

Quote: (Originally Posted by Freef)

http://www.rebreatherworld.com/semi-...culations.html

Sec 3 should be useful.

David,

Unless I miscalculate, when plugging in CCR relevant data (i.e. PO2 is constant at all depth), your SCR equation will simply be:

Rate(out) (1 - loopFiO2) = Rate(in) (1 - loopFiO2), or

Out = In

decoweenie · 11th June 2006, 10:04

Quote: (Originally Posted by Scuba_Vixen)

Any chance that Jetsam has a 0.003" oriffice?

AFAIK, I think not. However, the orifices come with an after-manufactured tolerance range stated on the label. I don't think you will get one down to 0.003" but check if:

a) yours has higher + tolerance range
b) swap with a lower - tolerance range

Otherwise, you will have to:

a) use a lower IP, and switch to a variable flow valve when diving deeper than the IP allowed.
b) get more muscle mass which metabolize more O2

Scuba_Vixen · 11th June 2006, 10:19

Quote: (Originally Posted by decoweenie)

AFAIK, I think not. However, the orifices come with an after-manufactured tolerance range stated on the label. I don't think you will get one down to 0.003" but check if:

a) yours has higher + tolerance range
b) swap with a lower - tolerance range

Otherwise, you will have to:

a) use a lower IP, and switch to a variable flow valve when diving deeper than the IP allowed.
b) get more muscle mass which metabolize more O2

If only these thoracic bouyancy reserves could metabolize O2!

On the other hand, maybe the electronic control for a solenoid idea may have to come off the back burner.

Darlene

gibbogeo · 11th June 2006, 11:42

Quote: (Originally Posted by Scuba_Vixen)

On 30m to 40m dives, I have to keep the IP down between 8 to 9 bar, or the PO2 climbs a bit. .... This is going to be an issue with significantly deeper dives that require a higher IP.

On deeper dive you will have other problems with a modified dolphins.

The shell and the original wing are not made to support the bailout bottles you will need. So you will need to fit a bigger wing and a support for the bailout bottles.

From my experience, for a depth of 60-70 m you can use the dolphin with the kiss without the need to change the wing and the shell. And with a IP of 9 you can quite safely dive to this depth.

Deeper it would be better to use a more solid unit or modify the shell and change the wings.

divetheworld · 11th June 2006, 13:27

???

Bail is clipped to the harness.
Darlene already modified it like the rest of us to backplate and harness. Isnt it a DR dual Rec wing your using Darlene?

BTW, Jetsam made two different orafices on there KISS valves. The KISS Valve orifice is 0.09mm for the flat sided steel one, and 0.1mm for the old round style.
Assuming ambient temperature to be 10deg C, with an IP of 12bar to flow 0.75-0.8ltr/min your using a KISS valve with an orifice about 0.09mm (0035).
This means that you will have linear oxygen delivery upto about 50m then it will trail off in an inverse log curve and you will have no flow at 110m.

The orafices are available in almost any size you want, I wish I could find my supplier list. Its not Jetsam I got them from.
If I find the details I will pass them on pet.

Brent.

11th June 2006, 00:08	#1 (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	O2 Metabolic Rates, Oriffice Sizes, ..... Questions... Hi guys, Been doing some tweaks and tests on the Dolphin conversion before taking the new leccies for some real dives. I'm most curious about what would be the normal range of O2 metabolized while breathing the loop, sitting on the bed next to the unit with no other physical activity. I wear my mask, so there's no chance of nose breathing. If I don't set the IP down to ~7.5 bar, (just a bit over 0.4 l/m on the flowmeter) The PO2 will slowly climb. The dill isn't even turned on, so there's no chance of adv leaking by. On 30m to 40m dives, I have to keep the IP down between 8 to 9 bar, or the PO2 climbs a bit. .... This is going to be an issue with significantly deeper dives that require a higher IP. Do I just seem to metabolize an unusually small amount of O2? I've been playing with the numbers in this oriffice size calculator, and it seems like 0.003 to 0.00325" would be about right. http://www.lenoxlaser.com/calculator/orifice.asp Any chance that Jetsam has a 0.003" oriffice? Darlene Last edited by Scuba_Vixen : 11th June 2006 at 00:31.
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11th June 2006, 04:34	#2 (permalink)
abowie Fighting Girl Current Rebreather/s: Sport Kiss Other Rebreather/s: Join Date: May 2005 Location: Land of Oz Posts: 573	Re: O2 Metabolic Rates, Oriffice Sizes, ..... Questions... The magic number for basal O2 consumption in anaesthesia is about 250ml per minute. Awake, sitting on the couch 400ml might well be a reasonable number. Activity will increase this to some degree. The Rebreather manufacturers usually work on about a litre per minute. My KISS delivers about 820ml/min and drops slowly with low exertion diving. Body size (more related to lean muscle mass than weight) and gender (females use less per kg than males) will also affect basal O2 consumption. __________________ Andrew Bowie Rebreather-friendly Buddy
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11th June 2006, 04:43	#3 (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: 2,817	Re: O2 Metabolic Rates, Oriffice Sizes, ..... Questions... Quote: (Originally Posted by Scuba_Vixen) Hi guys, Been doing some tweaks and tests on the Dolphin conversion before taking the new leccies for some real dives. I'm most curious about what would be the normal range of O2 metabolized while breathing the loop, sitting on the bed next to the unit with no other physical activity. I wear my mask, so there's no chance of nose breathing. If I don't set the IP down to ~7.5 bar, (just a bit over 0.4 l/m on the flowmeter) The PO2 will slowly climb. The dill isn't even turned on, so there's no chance of adv leaking by. On 30m to 40m dives, I have to keep the IP down between 8 to 9 bar, or the PO2 climbs a bit. .... This is going to be an issue with significantly deeper dives that require a higher IP. Do I just seem to metabolize an unusually small amount of O2? I've been playing with the numbers in this oriffice size calculator, and it seems like 0.003 to 0.00325" would be about right. http://www.lenoxlaser.com/calculator/orifice.asp Any chance that Jetsam has a 0.003" oriffice? Darlene This kiss orifice is .0035 __________________ 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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11th June 2006, 05:40	#4 (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: O2 Metabolic Rates, Oriffice Sizes, ..... Questions... Quote: (Originally Posted by jradomski) This kiss orifice is .0035 Yes, That's the size I have. ..... the latter model. What I was hoping for was a slightly smaller one, .003" so I could run a ~12bar IP, but have a bit less than the normal .8 l/m flow rate. Darlene
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11th June 2006, 07:22	#5 (permalink)
Freef Custom Title Disallowed! Current Rebreather/s: Dolphin Other Rebreather/s: Dolphin Join Date: Jan 2006 Location: Land of the Freef, UK. Posts: 1,356	Re: O2 Metabolic Rates, Oriffice Sizes, ..... Questions... http://www.rebreatherworld.com/semi-...culations.html Hi Darlene, I found the thread after emailing you, Sec 3 should be useful. Any comments on the thread should be posted there not on this one! David. __________________ David. Currently owner of two differently sized ankles.
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11th June 2006, 08:55	#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: O2 Metabolic Rates, Oriffice Sizes, ..... Questions... Quote: (Originally Posted by Freef) http://www.rebreatherworld.com/semi-...culations.html Sec 3 should be useful. David, Unless I miscalculate, when plugging in CCR relevant data (i.e. PO2 is constant at all depth), your SCR equation will simply be: Rate(out) (1 - loopFiO2) = Rate(in) (1 - loopFiO2), or Out = In
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11th June 2006, 10:04	#7 (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: O2 Metabolic Rates, Oriffice Sizes, ..... Questions... Quote: (Originally Posted by Scuba_Vixen) Any chance that Jetsam has a 0.003" oriffice? AFAIK, I think not. However, the orifices come with an after-manufactured tolerance range stated on the label. I don't think you will get one down to 0.003" but check if: a) yours has higher + tolerance range b) swap with a lower - tolerance range Otherwise, you will have to: a) use a lower IP, and switch to a variable flow valve when diving deeper than the IP allowed. b) get more muscle mass which metabolize more O2
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11th June 2006, 10:19	#8 (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: O2 Metabolic Rates, Oriffice Sizes, ..... Questions... Quote: (Originally Posted by decoweenie) AFAIK, I think not. However, the orifices come with an after-manufactured tolerance range stated on the label. I don't think you will get one down to 0.003" but check if: a) yours has higher + tolerance range b) swap with a lower - tolerance range Otherwise, you will have to: a) use a lower IP, and switch to a variable flow valve when diving deeper than the IP allowed. b) get more muscle mass which metabolize more O2 If only these thoracic bouyancy reserves could metabolize O2! On the other hand, maybe the electronic control for a solenoid idea may have to come off the back burner. Darlene
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11th June 2006, 11:42	#9 (permalink)
gibbogeo kiss addict Current Rebreather/s: Classic Kiss Dolphin Home Build Other Rebreather/s: Dolphin Home Build Join Date: Sep 2005 Location: italy Posts: 308	Re: O2 Metabolic Rates, Oriffice Sizes, ..... Questions... Quote: (Originally Posted by Scuba_Vixen) On 30m to 40m dives, I have to keep the IP down between 8 to 9 bar, or the PO2 climbs a bit. .... This is going to be an issue with significantly deeper dives that require a higher IP. On deeper dive you will have other problems with a modified dolphins. The shell and the original wing are not made to support the bailout bottles you will need. So you will need to fit a bigger wing and a support for the bailout bottles. From my experience, for a depth of 60-70 m you can use the dolphin with the kiss without the need to change the wing and the shell. And with a IP of 9 you can quite safely dive to this depth. Deeper it would be better to use a more solid unit or modify the shell and change the wings.
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11th June 2006, 13:27	#10 (permalink)
divetheworld Dive porn pimp Current Rebreather/s: Inspiration Classic Other CCR Other Rebreather/s: Not Bought Yet Inspiration Classic Inspiration Vision Classic Kiss Other CCR Join Date: Mar 2005 Location: Leeds, England Posts: 1,535	Re: O2 Metabolic Rates, Oriffice Sizes, ..... Questions... ??? Bail is clipped to the harness. Darlene already modified it like the rest of us to backplate and harness. Isnt it a DR dual Rec wing your using Darlene? BTW, Jetsam made two different orafices on there KISS valves. The KISS Valve orifice is 0.09mm for the flat sided steel one, and 0.1mm for the old round style. Assuming ambient temperature to be 10deg C, with an IP of 12bar to flow 0.75-0.8ltr/min your using a KISS valve with an orifice about 0.09mm (0035). This means that you will have linear oxygen delivery upto about 50m then it will trail off in an inverse log curve and you will have no flow at 110m. The orafices are available in almost any size you want, I wish I could find my supplier list. Its not Jetsam I got them from. If I find the details I will pass them on pet. Brent. __________________ Self praise is no reccomendation. Dont try to be a great man, just be a man and let history be the judge of you. CHECK OUT OUR INTERWEBS FOR CUSTOM REBREATHER UPGRADES *WWW.NARKEDAT90.CO.UK* *http://www.grpservices.com/pursuit/* Supporting Shearwater Research Products in Europe Last edited by divetheworld : 11th June 2006 at 13:39.
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