O2 Manual Add Options

Lancer4545 · 24th December 2007, 08:28

I have been having a bit of trouble with my PO2 monitoring with the 4th cell and VR3 when manually adding O2. I nearly always fly my Meg with a slightly lower setpoint to what I want and manually add O2 to maintain my PO2. I don't have to anticipate the solenoid firing O2 and I can maintain much better neutral buoyancy, specially when diving in a wreck where it's paramount to have perfect trim.

Having the 4th cell and the manual add valve both located in the inhale CL causes it to spike my PO2 readings on the VR3 and causes it to have a heart attack. Lately I have been changing it to monitor a preset setpoint and not worry about the 4th cell monitoring, but it defeats the point in having the 4th cell at all.

I have been thinking of moving my O2 manual add hose to the Mixed Gas Bypass and manually add O2 into the exhale CL. This seems to make sense to me as the O2 would have time to better mix with the gas in the loop and would pass the cells in the head before passing the 4th cell and then being inhaled.

Has anyone already tried this and got any feedback before I try it for myself?

Regards,

Lance

divingabe · 24th December 2007, 12:10

Hi Lance,
I have been adding O2 on the exhale lung from the beginning. It just made more sense to me to add the additional O2 in the exahale lung and give it a chance to properly mix with the loop prior to reaching the sensors and then my lungs. I do not have the extra sensor attached to my unit, but it seems to me that by rearranging your feed, the read out on your vr3 will be therefore be more accurate, and your controllers be giving you a more accurate reading of what you are actually breathing.
I also dive manually operating the O2 injection using the apecs as a backup to maintain PP, since in do not have the fourth sensor hook up I just dive using the vr3 set at a point of minus .1 of my pre set PP on my apecs to give a slight additional safety margin.
You will find that by switching your O2 add to the other lung will take a few dives to have your muscle memory readjusted but not very long. It will stop your vr3 from going nuts on you everytime you add.

Hey Lance I like the manifold you have shown on previous posts for the dill side. Where was it available from, I presently am using one from M & J but it does not have the four outlets that yours has on top for the BOV, ADV, Wing and offboard supply I like your set up and would be interested in that manifold to eliminate 2 swivels which I have to use on the one I currently have.

***jradomski*** · 24th December 2007, 12:25

Quote: (Originally Posted by Lancer4545)

I have been having a bit of trouble with my PO2 monitoring with the 4th cell and VR3 when manually adding O2. I nearly always fly my Meg with a slightly lower setpoint to what I want and manually add O2 to maintain my PO2. I don't have to anticipate the solenoid firing O2 and I can maintain much better neutral buoyancy, specially when diving in a wreck where it's paramount to have perfect trim.

Having the 4th cell and the manual add valve both located in the inhale CL causes it to spike my PO2 readings on the VR3 and causes it to have a heart attack. Lately I have been changing it to monitor a preset setpoint and not worry about the 4th cell monitoring, but it defeats the point in having the 4th cell at all.

I have been thinking of moving my O2 manual add hose to the Mixed Gas Bypass and manually add O2 into the exhale CL. This seems to make sense to me as the O2 would have time to better mix with the gas in the loop and would pass the cells in the head before passing the 4th cell and then being inhaled.

Has anyone already tried this and got any feedback before I try it for myself?

Regards,

Lance

Well Those "spikes" should be telling you what you are actually inhalling! granted it will drop quickly, but it is showing you the probable inspired gas..

Lancer4545 · 24th December 2007, 23:40

Quote: (Originally Posted by divingabe)

Hi Lance,
I have been adding O2 on the exhale lung from the beginning. It just made more sense to me to add the additional O2 in the exahale lung and give it a chance to properly mix with the loop prior to reaching the sensors and then my lungs. I do not have the extra sensor attached to my unit, but it seems to me that by rearranging your feed, the read out on your vr3 will be therefore be more accurate, and your controllers be giving you a more accurate reading of what you are actually breathing.
I also dive manually operating the O2 injection using the apecs as a backup to maintain PP, since in do not have the fourth sensor hook up I just dive using the vr3 set at a point of minus .1 of my pre set PP on my apecs to give a slight additional safety margin.
You will find that by switching your O2 add to the other lung will take a few dives to have your muscle memory readjusted but not very long. It will stop your vr3 from going nuts on you everytime you add.

Hey Lance I like the manifold you have shown on previous posts for the dill side. Where was it available from, I presently am using one from M & J but it does not have the four outlets that yours has on top for the BOV, ADV, Wing and offboard supply I like your set up and would be interested in that manifold to eliminate 2 swivels which I have to use on the one I currently have.

Hi Abe,

That's exactally what I already do now with the manual add and the PO2 setpoint and VR3 setpoint.

It make a lot more sense to inject the O2 before the sensors in the head and the VR3.....Gives the gas more time to better mix with the breathing loop gas and has to give a more accurate reading of the inspired gasses.

The other way has the breathing gas pass the sensors giving you a PO2 reading and then you add to the mixture and inhale it, with the elevated PO2. By the time it gets back to the sensors the Po2 has dropped due to part of the O2 being metabilised. The reading is inaccurate and there is a much higher possibility of having an O2 hit.

I guess if you totally rely on the electronics to manitain your PO2 and don't ever use the O2 manual add then you don't have a problem........

Regards,

Lance

Lancer4545 · 24th December 2007, 23:50

Quote: (Originally Posted by jradomski)

Well Those "spikes" should be telling you what you are actually inhalling! granted it will drop quickly, but it is showing you the probable inspired gas..

Thanks for the reply.

I spoke to my instructor about this when I was setting up the 4th cell and it made sense at the time.......But if you read my previous post......it would appear NOT to be the best method when you consider you're breathing a higher PO2 than what you think you are and your sensors are showing. I am not convinced the VR3 is reading accurately either as it's being flooded with O2 every time you manually inject O2 directly onto the 4th cell.

Combine that with an electronics package that monitors your O2 injection/deco and the problem gets even worse.....

Regards,

Lance

**Dsix36** · 25th December 2007, 00:04

This is a little off track, but it falls along a similar line of PO2 spikes.

On my Optima there is a tube in the center of the canister that directs O2 from the solenoid to the far end of the cartridge. Without the tube there is a PO2 spike at every injection but it settles very quickly. With the tube in place there is no spike. My instructor told me that it made no difference in what I was actually inhaling just that it was injecting closer to the cells.

My manual add is in the exhale CL and effects the PO2 readings a little slower than the solenoid without the tube and faster than the solenoid with the tube.

I don't have a VR3 and a 4th cell.

Lancer4545 · 25th December 2007, 00:36

Quote: (Originally Posted by Dsix36)

This is a little off track, but it falls along a similar line of PO2 spikes.

On my Optima there is a tube in the center of the canister that directs O2 from the solenoid to the far end of the cartridge. Without the tube there is a PO2 spike at every injection but it settles very quickly. With the tube in place there is no spike. My instructor told me that it made no difference in what I was actually inhaling just that it was injecting closer to the cells.

My manual add is in the exhale CL and effects the PO2 readings a little slower than the solenoid without the tube and faster than the solenoid with the tube.

I don't have a VR3 and a 4th cell.

YES......YOURE RIGHT!!

It is off track!!

Hahaha....Have a good Christmas.

Lance

**Dsix36** · 25th December 2007, 00:54

Quote: (Originally Posted by Lancer4545)

YES......YOURE RIGHT!!

It is off track!!

Hahaha....Have a good Christmas.

Lance

The point is this: the manual add is in the exhale CL just before the head/sensors and there is not a PO2 spike when flying manually. My unit is designed this way and seems to work just fine.

like you said """It make a lot more sense to inject the O2 before the sensors in the head and the VR3.....Gives the gas more time to better mix with the breathing loop gas and has to give a more accurate reading of the inspired gasses.

The other way has the breathing gas pass the sensors giving you a PO2 reading and then you add to the mixture and inhale it, with the elevated PO2. By the time it gets back to the sensors the Po2 has dropped due to part of the O2 being metabilised. The reading is inaccurate and there is a much higher possibility of having an O2 hit."""

Lancer4545 · 25th December 2007, 02:13

Quote: (Originally Posted by Dsix36)

The point is this: the manual add is in the exhale CL just before the head/sensors and there is not a PO2 spike when flying manually. My unit is designed this way and seems to work just fine.

like you said """It make a lot more sense to inject the O2 before the sensors in the head and the VR3.....Gives the gas more time to better mix with the breathing loop gas and has to give a more accurate reading of the inspired gasses.

The other way has the breathing gas pass the sensors giving you a PO2 reading and then you add to the mixture and inhale it, with the elevated PO2. By the time it gets back to the sensors the Po2 has dropped due to part of the O2 being metabilised. The reading is inaccurate and there is a much higher possibility of having an O2 hit."""

Oops.....I was having a dig at you.

But "Exactally my point"......

Lance

Gilles · 25th December 2007, 05:24

Similiar post here

http://www.rebreatherworld.com/offic...-readings.html

By plugging your man-ad to the left lung, you will only find advantages (listed therein).

The only disadvantage is a slight compromise to the "right is rich" rule.

24th December 2007, 08:28	#1 (permalink)
Lancer4545 Closed Circuit Divers Aus Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Jun 2007 Location: Cairns QLD Australia Posts: 529	O2 Manual Add Options I have been having a bit of trouble with my PO2 monitoring with the 4th cell and VR3 when manually adding O2. I nearly always fly my Meg with a slightly lower setpoint to what I want and manually add O2 to maintain my PO2. I don't have to anticipate the solenoid firing O2 and I can maintain much better neutral buoyancy, specially when diving in a wreck where it's paramount to have perfect trim. Having the 4th cell and the manual add valve both located in the inhale CL causes it to spike my PO2 readings on the VR3 and causes it to have a heart attack. Lately I have been changing it to monitor a preset setpoint and not worry about the 4th cell monitoring, but it defeats the point in having the 4th cell at all. I have been thinking of moving my O2 manual add hose to the Mixed Gas Bypass and manually add O2 into the exhale CL. This seems to make sense to me as the O2 would have time to better mix with the gas in the loop and would pass the cells in the head before passing the 4th cell and then being inhaled. Has anyone already tried this and got any feedback before I try it for myself? Regards, Lance __________________ You can run but you can't hide! ISC Appointed Megalodon Dealer for East Australia http://www.closedcircuitdivers.com.au info@closedcircuitdivers.com.au
(Online)

24th December 2007, 12:10	#2 (permalink)
divingabe New Member Current Rebreather/s: Megalodon Other Rebreather/s: Sport Kiss Join Date: Oct 2005 Location: Sag Harbor Posts: 72	Re: O2 Manual Add Options Hi Lance, I have been adding O2 on the exhale lung from the beginning. It just made more sense to me to add the additional O2 in the exahale lung and give it a chance to properly mix with the loop prior to reaching the sensors and then my lungs. I do not have the extra sensor attached to my unit, but it seems to me that by rearranging your feed, the read out on your vr3 will be therefore be more accurate, and your controllers be giving you a more accurate reading of what you are actually breathing. I also dive manually operating the O2 injection using the apecs as a backup to maintain PP, since in do not have the fourth sensor hook up I just dive using the vr3 set at a point of minus .1 of my pre set PP on my apecs to give a slight additional safety margin. You will find that by switching your O2 add to the other lung will take a few dives to have your muscle memory readjusted but not very long. It will stop your vr3 from going nuts on you everytime you add. Hey Lance I like the manifold you have shown on previous posts for the dill side. Where was it available from, I presently am using one from M & J but it does not have the four outlets that yours has on top for the BOV, ADV, Wing and offboard supply I like your set up and would be interested in that manifold to eliminate 2 swivels which I have to use on the one I currently have. Last edited by divingabe : 24th December 2007 at 22:15. Reason: additional question for the originator of the post
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24th December 2007, 12:25	#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: 2,795	Re: O2 Manual Add Options Quote: (Originally Posted by Lancer4545) I have been having a bit of trouble with my PO2 monitoring with the 4th cell and VR3 when manually adding O2. I nearly always fly my Meg with a slightly lower setpoint to what I want and manually add O2 to maintain my PO2. I don't have to anticipate the solenoid firing O2 and I can maintain much better neutral buoyancy, specially when diving in a wreck where it's paramount to have perfect trim. Having the 4th cell and the manual add valve both located in the inhale CL causes it to spike my PO2 readings on the VR3 and causes it to have a heart attack. Lately I have been changing it to monitor a preset setpoint and not worry about the 4th cell monitoring, but it defeats the point in having the 4th cell at all. I have been thinking of moving my O2 manual add hose to the Mixed Gas Bypass and manually add O2 into the exhale CL. This seems to make sense to me as the O2 would have time to better mix with the gas in the loop and would pass the cells in the head before passing the 4th cell and then being inhaled. Has anyone already tried this and got any feedback before I try it for myself? Regards, Lance Well Those "spikes" should be telling you what you are actually inhalling! granted it will drop quickly, but it is showing you the probable inspired gas.. __________________ 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.
(Online)

24th December 2007, 23:40	#4 (permalink)
Lancer4545 Closed Circuit Divers Aus Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Jun 2007 Location: Cairns QLD Australia Posts: 529	Re: O2 Manual Add Options Quote: (Originally Posted by divingabe) Hi Lance, I have been adding O2 on the exhale lung from the beginning. It just made more sense to me to add the additional O2 in the exahale lung and give it a chance to properly mix with the loop prior to reaching the sensors and then my lungs. I do not have the extra sensor attached to my unit, but it seems to me that by rearranging your feed, the read out on your vr3 will be therefore be more accurate, and your controllers be giving you a more accurate reading of what you are actually breathing. I also dive manually operating the O2 injection using the apecs as a backup to maintain PP, since in do not have the fourth sensor hook up I just dive using the vr3 set at a point of minus .1 of my pre set PP on my apecs to give a slight additional safety margin. You will find that by switching your O2 add to the other lung will take a few dives to have your muscle memory readjusted but not very long. It will stop your vr3 from going nuts on you everytime you add. Hey Lance I like the manifold you have shown on previous posts for the dill side. Where was it available from, I presently am using one from M & J but it does not have the four outlets that yours has on top for the BOV, ADV, Wing and offboard supply I like your set up and would be interested in that manifold to eliminate 2 swivels which I have to use on the one I currently have. Hi Abe, That's exactally what I already do now with the manual add and the PO2 setpoint and VR3 setpoint. It make a lot more sense to inject the O2 before the sensors in the head and the VR3.....Gives the gas more time to better mix with the breathing loop gas and has to give a more accurate reading of the inspired gasses. The other way has the breathing gas pass the sensors giving you a PO2 reading and then you add to the mixture and inhale it, with the elevated PO2. By the time it gets back to the sensors the Po2 has dropped due to part of the O2 being metabilised. The reading is inaccurate and there is a much higher possibility of having an O2 hit. I guess if you totally rely on the electronics to manitain your PO2 and don't ever use the O2 manual add then you don't have a problem........ Regards, Lance __________________ You can run but you can't hide! ISC Appointed Megalodon Dealer for East Australia http://www.closedcircuitdivers.com.au info@closedcircuitdivers.com.au
(Online)

24th December 2007, 23:50	#5 (permalink)
Lancer4545 Closed Circuit Divers Aus Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Jun 2007 Location: Cairns QLD Australia Posts: 529	Re: O2 Manual Add Options Quote: (Originally Posted by jradomski) Well Those "spikes" should be telling you what you are actually inhalling! granted it will drop quickly, but it is showing you the probable inspired gas.. Thanks for the reply. I spoke to my instructor about this when I was setting up the 4th cell and it made sense at the time.......But if you read my previous post......it would appear NOT to be the best method when you consider you're breathing a higher PO2 than what you think you are and your sensors are showing. I am not convinced the VR3 is reading accurately either as it's being flooded with O2 every time you manually inject O2 directly onto the 4th cell. Combine that with an electronics package that monitors your O2 injection/deco and the problem gets even worse..... Regards, Lance __________________ You can run but you can't hide! ISC Appointed Megalodon Dealer for East Australia http://www.closedcircuitdivers.com.au info@closedcircuitdivers.com.au
(Online)

25th December 2007, 00:04	#6 (permalink)
Dsix36 Going Down? Current Rebreather/s: Optima Other Rebreather/s: Join Date: Aug 2007 Location: florida Posts: 856	Re: O2 Manual Add Options This is a little off track, but it falls along a similar line of PO2 spikes. On my Optima there is a tube in the center of the canister that directs O2 from the solenoid to the far end of the cartridge. Without the tube there is a PO2 spike at every injection but it settles very quickly. With the tube in place there is no spike. My instructor told me that it made no difference in what I was actually inhaling just that it was injecting closer to the cells. My manual add is in the exhale CL and effects the PO2 readings a little slower than the solenoid without the tube and faster than the solenoid with the tube. I don't have a VR3 and a 4th cell. __________________ THE MORE THAT I LEARN, THE MORE THAT I STILL NEED TO LEARN!!!!!!
(Online)

25th December 2007, 00:36	#7 (permalink)
Lancer4545 Closed Circuit Divers Aus Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Jun 2007 Location: Cairns QLD Australia Posts: 529	Re: O2 Manual Add Options Quote: (Originally Posted by Dsix36) This is a little off track, but it falls along a similar line of PO2 spikes. On my Optima there is a tube in the center of the canister that directs O2 from the solenoid to the far end of the cartridge. Without the tube there is a PO2 spike at every injection but it settles very quickly. With the tube in place there is no spike. My instructor told me that it made no difference in what I was actually inhaling just that it was injecting closer to the cells. My manual add is in the exhale CL and effects the PO2 readings a little slower than the solenoid without the tube and faster than the solenoid with the tube. I don't have a VR3 and a 4th cell. YES......YOURE RIGHT!! It is off track!! Hahaha....Have a good Christmas. Lance __________________ You can run but you can't hide! ISC Appointed Megalodon Dealer for East Australia http://www.closedcircuitdivers.com.au info@closedcircuitdivers.com.au
(Online)

25th December 2007, 00:54	#8 (permalink)
Dsix36 Going Down? Current Rebreather/s: Optima Other Rebreather/s: Join Date: Aug 2007 Location: florida Posts: 856	Re: O2 Manual Add Options Quote: (Originally Posted by Lancer4545) YES......YOURE RIGHT!! It is off track!! Hahaha....Have a good Christmas. Lance The point is this: the manual add is in the exhale CL just before the head/sensors and there is not a PO2 spike when flying manually. My unit is designed this way and seems to work just fine. like you said """It make a lot more sense to inject the O2 before the sensors in the head and the VR3.....Gives the gas more time to better mix with the breathing loop gas and has to give a more accurate reading of the inspired gasses. The other way has the breathing gas pass the sensors giving you a PO2 reading and then you add to the mixture and inhale it, with the elevated PO2. By the time it gets back to the sensors the Po2 has dropped due to part of the O2 being metabilised. The reading is inaccurate and there is a much higher possibility of having an O2 hit.""" __________________ THE MORE THAT I LEARN, THE MORE THAT I STILL NEED TO LEARN!!!!!!
(Online)

25th December 2007, 02:13	#9 (permalink)
Lancer4545 Closed Circuit Divers Aus Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Jun 2007 Location: Cairns QLD Australia Posts: 529	Re: O2 Manual Add Options Quote: (Originally Posted by Dsix36) The point is this: the manual add is in the exhale CL just before the head/sensors and there is not a PO2 spike when flying manually. My unit is designed this way and seems to work just fine. like you said """It make a lot more sense to inject the O2 before the sensors in the head and the VR3.....Gives the gas more time to better mix with the breathing loop gas and has to give a more accurate reading of the inspired gasses. The other way has the breathing gas pass the sensors giving you a PO2 reading and then you add to the mixture and inhale it, with the elevated PO2. By the time it gets back to the sensors the Po2 has dropped due to part of the O2 being metabilised. The reading is inaccurate and there is a much higher possibility of having an O2 hit.""" Oops.....I was having a dig at you. But "Exactally my point"...... Lance __________________ You can run but you can't hide! ISC Appointed Megalodon Dealer for East Australia http://www.closedcircuitdivers.com.au info@closedcircuitdivers.com.au
(Online)

25th December 2007, 05:24	#10 (permalink)
Gilles Worship the feminine Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Sep 2005 Location: Den Haag (Netherlands) Posts: 761	Re: O2 Manual Add Options Similiar post here http://www.rebreatherworld.com/offic...-readings.html By plugging your man-ad to the left lung, you will only find advantages (listed therein). The only disadvantage is a slight compromise to the "right is rich" rule. __________________ Gilles http://www.dirrebreather.com
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