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

Scuba_Vixen · 12th June 2006, 14:04

Quote: (Originally Posted by Freef)

With an ideal dive, you would be able to work out the vO2 based purely on O2 consumption, ie if you use 20 bar out of a 3L cylinder [60 bar in total] on an hour long dive your vO2 would be 1 l/min.

But with CCR you would also have to work out the dilutent use as it too contains oxygen. With air and 20 bar of dilutent used [from a 3L] you then have [20 x 3] + [0.21 x 20 x 3], a total of 72.6L, 1.21 L/min.

Of course, if you had a dilutent with no O2 present that would help, but it would be more than slightly unsafe!

When you add in factors such as different set points during the dive things get more complex, but with a known flow rate you should still be able to work out the vO2 using my formula, or if you did a 20 min fixed depth dive and noted the start and end pressures of O2 and knew the flow rate [while keeping the pO2 contstant] you would be able to work it out fom there.

David.

I think you're adding needless complexity to my original post.

If I have to exhale thru my nose and cause the adv to fire on inhale to bring down a slowly rising PO2 on a regular basis during a dive, it's a fact then, that my O2 metabolic rate has to be below the orifice flow rate for that IP. ... This wastes a gas needlessly.

Nothing more needs be computed. .....

1) I adjust the IP until the PO2 stays stable.
2) I measure the flow rate on the flowmeter. .... that's my O2 consumption rate
3) I measure the IP on the IP check gage for a reference point.

Everything is now known.

In practice,
I can lower the IP to bring down the flow rate, but there are two downsides to that solution, .... neither particularly acceptable.... :

1) The depth at which the O2 addition rate remains constant is significantly reduced, and I'll be hitting the button more and sooner.

2) The depth at which O2 will no longer flow at all is significantly reduced, limiting the usable depth.

A slightly smaller orifice would be the proper solution the problem.

The real issue is how to find one.

Darlene

John J. Jones, IV · 13th June 2006, 06:30

Darlene:

I have a question for you. I am in the process of converting my SCR Dolphin to mCCR. Martin from Tecme has been helping assemble the various piece parts, including two new regs, 3 cell ppo2 display and housing, and O2 injection in a new ADV. I will be using my VR3 with a ppo2 sensor as well.

My current unit consists of his SS Hydrogom shell, SS backplate, a VR3 plumbed into the inhale bag, and a single cell ppo2 stick in a 90 degree housing. I have also added a DSV/BOC from Divematics and an Extend Air canister. Everything works fine, no problems, no questions.

My question revolves around what PPo2 settings are you looking at when you are at the surface, and what level should normally be maintained while diving. Our diving here is very shallow, 30-40ft, and from what I have read thus far, independent of depth, is to maintain a level between 1.0-1.2. Any reason for not a lesser level, .50-.90 as to avoid CNS buildup?

Best regards,

John

abowie · 13th June 2006, 07:50

Quote: (Originally Posted by Scuba_Vixen)

A slightly smaller orifice would be the proper solution the problem.

The real issue is how to find one.

Darlene

Darlene, maybe I'm missing the point here (it has happened before) but why not just buy a couple of orifi(ces) from Lenoxlaser ( or whoever) and try them and see what happens.

You should be able to do perfectly safe "dry land" bench testing with your unit, and with your monitoring you should then be able to do equally safe in water testing.

PS aren't I good; I let all of the Benny Hill double entendre go right on by.

Scuba_Vixen · 13th June 2006, 13:30

Quote: (Originally Posted by abowie)

Darlene, maybe I'm missing the point here (it has happened before) but why not just buy a couple of orifi(ces) from Lenoxlaser ( or whoever) and try them and see what happens.

You should be able to do perfectly safe "dry land" bench testing with your unit, and with your monitoring you should then be able to do equally safe in water testing.

PS aren't I good; I let all of the Benny Hill double entendre go right on by.

The one in my kiss valve looks like a brass hex head on a short screw. ... I didn't take it out of the ss plunger, so I don't know the threrad size.

Anyway, I didn't see anything like it out of all the Lenox Laser items on the website, so I thought maybe some one else has had this experience and found out if there's a direct replacement. .... maybe a special order.

Does anyone know the thread size even?

I was just trying to "do the homework" in advance, so when I call them, I don't sound too stupid. When I call anyplace about anything technical, I loose about 50 IQ points for being female as it is.

They list orifices in increments of 25 microns. The kiss orifice at .0035" is about 90 microns, .0030" would be about 80, neither an increment of 25.

I don't have to be in to work 'till late today, guess I'll be calling them and Kim.

Darlene

jeff h · 13th June 2006, 14:55

Quote: (Originally Posted by Scuba_Vixen)

Does anyone know the thread size even?

The orifice is a Norgren restrictor part number 4LR-010-D04 with 10-32
threads.

-Jeff

gibbogeo · 13th June 2006, 15:53

Quote: (Originally Posted by decoweenie)

The 0.0035" has been supplied as the standard orifice for a few years now. Optional item is the 0.004" if specifically requested. So I am sure they are the same size/shape.

Argh, i have the images of the two orifices side by side. Unless there is some srt of adapter, the two are different in lenght.

I tried to attach it t this mesage, maybe i successed.

Quote:

Our conditions aren't as wonderful as the Carribean, but it is fairly warm as well.

Lived in Lybian desert for three years, wonderful beaches, full of clear sand and not crowded, but the sea is usually quite far...

Quote:

And geologists should find job easily.

Interesting...

Quote:

As for Environmental Engineers, we just leave them in the desert along with the environmental hazards...

It's perfect for my wife (she is the engineer!).

Scuba_Vixen · 13th June 2006, 16:38

Quote: (Originally Posted by gibbogeo)

Argh, i have the images of the two orifices side by side. Unless there is some srt of adapter, the two are different in lenght.

I tried to attach it t this mesage, maybe i successed.

Lived in Lybian desert for three years, wonderful beaches, full of clear sand and not crowded, but the sea is usually quite far...

Interesting...

It's perfect for my wife (she is the engineer!).

Mine is exactly like the one on the right designated as Lenox Laser.

Does it use the 10-32 thread as well?

Does anyone have a website for Norgren?

I tried Google, but it turns up thousands of urls, with no way to know the right one if I see it.

Darlene

jeff h · 13th June 2006, 18:15

Quote: (Originally Posted by Scuba_Vixen)

Mine is exactly like the one on the right designated as Lenox Laser.

If you have Lenox one then it looks like they make the same part in several sizes.

Link to Lenox (down to 1 micron)
http://www.lenoxlaser.com/flowproducts/hex_screws.html

I believe the 0.004" (100 micron) is the smallest Norgren makes.

Scuba_Vixen · 13th June 2006, 20:32

Hey Guys,

Looks like we are barking up the wrong tree with Lenox Laser.

The KISS orifices come from Bird Precision.

http://www.birdprecision.com/orifices/index.shtml

This info comes directly from Kim. She says the ones in the MAV are made just for them, and she buys them in lots of 250 or so.

I spent some time searching the website, and it seems there are a couple alternatives available that could be made to work.

Jetsam also has plugs, essentially undrilled orificies, that depending on cost, I could have laser drilled by Lenox, as opposed to the ruby insert of the Bird.

I'll be calling the folks at Bird for more details.

Darlene

gibbogeo · 13th June 2006, 20:42

Quote: (Originally Posted by Scuba_Vixen)

Looks like we are barking up the wrong tree with Lenox Laser.

Sorry, my fault, i was quite sure.

Quote:

This info comes directly from Kim. She says the ones in the MAV are made just for them, and she buys them in lots of 250 or so.

I have bought my spares allways from jetsam.

Quote:

Jetsam also has plugs

This is really interesting for me.

12th June 2006, 14:04	#31 (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 Freef) With an ideal dive, you would be able to work out the vO2 based purely on O2 consumption, ie if you use 20 bar out of a 3L cylinder [60 bar in total] on an hour long dive your vO2 would be 1 l/min. But with CCR you would also have to work out the dilutent use as it too contains oxygen. With air and 20 bar of dilutent used [from a 3L] you then have [20 x 3] + [0.21 x 20 x 3], a total of 72.6L, 1.21 L/min. Of course, if you had a dilutent with no O2 present that would help, but it would be more than slightly unsafe! When you add in factors such as different set points during the dive things get more complex, but with a known flow rate you should still be able to work out the vO2 using my formula, or if you did a 20 min fixed depth dive and noted the start and end pressures of O2 and knew the flow rate [while keeping the pO2 contstant] you would be able to work it out fom there. David. I think you're adding needless complexity to my original post. If I have to exhale thru my nose and cause the adv to fire on inhale to bring down a slowly rising PO2 on a regular basis during a dive, it's a fact then, that my O2 metabolic rate has to be below the orifice flow rate for that IP. ... This wastes a gas needlessly. Nothing more needs be computed. ..... 1) I adjust the IP until the PO2 stays stable. 2) I measure the flow rate on the flowmeter. .... that's my O2 consumption rate 3) I measure the IP on the IP check gage for a reference point. Everything is now known. In practice, I can lower the IP to bring down the flow rate, but there are two downsides to that solution, .... neither particularly acceptable.... : 1) The depth at which the O2 addition rate remains constant is significantly reduced, and I'll be hitting the button more and sooner. 2) The depth at which O2 will no longer flow at all is significantly reduced, limiting the usable depth. A slightly smaller orifice would be the proper solution the problem. The real issue is how to find one. Darlene Last edited by Scuba_Vixen : 12th June 2006 at 14:15.
(Offline)

13th June 2006, 06:30	#32 (permalink)
John J. Jones, IV New Member Current Rebreather/s: Dolphin Other Rebreather/s: Dolphin Join Date: Mar 2006 Location: Hong Kong Posts: 34	Re: O2 Metabolic Rates, Oriffice Sizes, ..... Questions... Darlene: I have a question for you. I am in the process of converting my SCR Dolphin to mCCR. Martin from Tecme has been helping assemble the various piece parts, including two new regs, 3 cell ppo2 display and housing, and O2 injection in a new ADV. I will be using my VR3 with a ppo2 sensor as well. My current unit consists of his SS Hydrogom shell, SS backplate, a VR3 plumbed into the inhale bag, and a single cell ppo2 stick in a 90 degree housing. I have also added a DSV/BOC from Divematics and an Extend Air canister. Everything works fine, no problems, no questions. My question revolves around what PPo2 settings are you looking at when you are at the surface, and what level should normally be maintained while diving. Our diving here is very shallow, 30-40ft, and from what I have read thus far, independent of depth, is to maintain a level between 1.0-1.2. Any reason for not a lesser level, .50-.90 as to avoid CNS buildup? Best regards, John
(Offline)

13th June 2006, 07:50	#33 (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... Quote: (Originally Posted by Scuba_Vixen) A slightly smaller orifice would be the proper solution the problem. The real issue is how to find one. Darlene Darlene, maybe I'm missing the point here (it has happened before) but why not just buy a couple of orifi(ces) from Lenoxlaser ( or whoever) and try them and see what happens. You should be able to do perfectly safe "dry land" bench testing with your unit, and with your monitoring you should then be able to do equally safe in water testing. PS aren't I good; I let all of the Benny Hill double entendre go right on by. __________________ Andrew Bowie Rebreather-friendly Buddy
(Offline)

13th June 2006, 13:30	#34 (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 abowie) Darlene, maybe I'm missing the point here (it has happened before) but why not just buy a couple of orifi(ces) from Lenoxlaser ( or whoever) and try them and see what happens. You should be able to do perfectly safe "dry land" bench testing with your unit, and with your monitoring you should then be able to do equally safe in water testing. PS aren't I good; I let all of the Benny Hill double entendre go right on by. The one in my kiss valve looks like a brass hex head on a short screw. ... I didn't take it out of the ss plunger, so I don't know the threrad size. Anyway, I didn't see anything like it out of all the Lenox Laser items on the website, so I thought maybe some one else has had this experience and found out if there's a direct replacement. .... maybe a special order. Does anyone know the thread size even? I was just trying to "do the homework" in advance, so when I call them, I don't sound too stupid. When I call anyplace about anything technical, I loose about 50 IQ points for being female as it is. They list orifices in increments of 25 microns. The kiss orifice at .0035" is about 90 microns, .0030" would be about 80, neither an increment of 25. I don't have to be in to work 'till late today, guess I'll be calling them and Kim. Darlene
(Offline)

13th June 2006, 14:55	#35 (permalink)
jeff h New Member Current Rebreather/s: Megalodon Other CCR Home Build Other Rebreather/s: Other CCR Home Build Join Date: Feb 2006 Location: Michigan Posts: 89	Re: O2 Metabolic Rates, Oriffice Sizes, ..... Questions... Quote: (Originally Posted by Scuba_Vixen) Does anyone know the thread size even? The orifice is a Norgren restrictor part number 4LR-010-D04 with 10-32 threads. -Jeff
(Offline)

13th June 2006, 16:38	#37 (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 gibbogeo) Argh, i have the images of the two orifices side by side. Unless there is some srt of adapter, the two are different in lenght. I tried to attach it t this mesage, maybe i successed. Lived in Lybian desert for three years, wonderful beaches, full of clear sand and not crowded, but the sea is usually quite far... Interesting... It's perfect for my wife (she is the engineer!). Mine is exactly like the one on the right designated as Lenox Laser. Does it use the 10-32 thread as well? Does anyone have a website for Norgren? I tried Google, but it turns up thousands of urls, with no way to know the right one if I see it. Darlene Last edited by Scuba_Vixen : 13th June 2006 at 19:02.
(Offline)

13th June 2006, 18:15	#38 (permalink)
jeff h New Member Current Rebreather/s: Megalodon Other CCR Home Build Other Rebreather/s: Other CCR Home Build Join Date: Feb 2006 Location: Michigan Posts: 89	Re: O2 Metabolic Rates, Oriffice Sizes, ..... Questions... Quote: (Originally Posted by Scuba_Vixen) Mine is exactly like the one on the right designated as Lenox Laser. If you have Lenox one then it looks like they make the same part in several sizes. Link to Lenox (down to 1 micron) http://www.lenoxlaser.com/flowproducts/hex_screws.html I believe the 0.004" (100 micron) is the smallest Norgren makes.
(Offline)

13th June 2006, 20:32	#39 (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... Hey Guys, Looks like we are barking up the wrong tree with Lenox Laser. The KISS orifices come from Bird Precision. http://www.birdprecision.com/orifices/index.shtml This info comes directly from Kim. She says the ones in the MAV are made just for them, and she buys them in lots of 250 or so. I spent some time searching the website, and it seems there are a couple alternatives available that could be made to work. Jetsam also has plugs, essentially undrilled orificies, that depending on cost, I could have laser drilled by Lenox, as opposed to the ruby insert of the Bird. I'll be calling the folks at Bird for more details. Darlene
(Offline)

13th June 2006, 20:42	#40 (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: 312	Re: O2 Metabolic Rates, Oriffice Sizes, ..... Questions... Quote: (Originally Posted by Scuba_Vixen) Looks like we are barking up the wrong tree with Lenox Laser. Sorry, my fault, i was quite sure. Quote: This info comes directly from Kim. She says the ones in the MAV are made just for them, and she buys them in lots of 250 or so. I have bought my spares allways from jetsam. Quote: Jetsam also has plugs This is really interesting for me.
(Offline)

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