Megalodon Calibration Procedures

hrdubwd · 10th April 2006, 07:25

Quote: (Originally Posted by UWSojourner)

If the water vapor is absent during cell reaction then we can exclude it from our discussion here.

The cell is filled with an aqueous solution (potassium hydroxide - very caustic! - do not open) - it is required for the chemistry. Condensation on the membrane should have little effect except to slow down diffusion a bit and add to the response time. Other solutions (spit, sea, soda-lime) are also not expected to have an effect, but they will destroy the electronics on the pcb inside at the connector end.

FYI: a major source of error is the resistance of the connection from cell pin to meter terminal. Corrosion at contacts (i.e. not soldered) can rapidly raise the resistance, create a voltage divider and give total nonsense at the display even when the cell is working properly. Such contacts can be intermittent, and depending on moisture as well. Flexing a wire excessively can break conductors, water in the cable can corrode the copper. Before blaming cells or displays, if the mV reading directly at the cell is good in air or 100% O2, check the resistance end-to-end. Inspect, clean, replace solder as necessary.

Applies to all rbs.

BWD

ROB DAVIE · 10th April 2006, 09:23

I would like to thank all of the members of this Board who have pitched in with information in this most interesting thread! I would like to particularly thank Joe Radomski for his excellent summary of the pertinent points. Well done as usual, Joe! Have some green!

**wedivebc** · 29th April 2006, 05:14

Quote: (Originally Posted by jradomski)

Yes but did you then go back outside and verify if the meter was still reading 20.9??

Was there a significant temperature change between the two enviroments??

was the door closed where all the additional water vapor in an enclosed enviroment slightly raised the local (room) ambient pressure??

Yes I did in fact and it seemed to make little difference. I admit it was hardly scientific or controlled but I did happen to be heading to the shower when I read Stefan's post so it seems an easy test. Outside temp was about 12C and bathroom temp was more like 25C. I may not have left it out for thermal stability, just the check the air/o2 reading.

***schford*** · 12th May 2006, 09:57

This informaiton is just for people who read through this entire and start worrying about calibrating their Megs.

Kevin has done some extensive testing to ascertain whether there is anything to be concerned about. (The short of it is there is not).

Please see this articles.

http://www.rebreatherworld.com/megal...lodon-ccr.html

Stuart

10th April 2006, 07:25	#121 (permalink)
hrdubwd New Member Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Nov 2005 Posts: 86	Re: Megalodon Calibration Procedures Quote: (Originally Posted by UWSojourner) If the water vapor is absent during cell reaction then we can exclude it from our discussion here. The cell is filled with an aqueous solution (potassium hydroxide - very caustic! - do not open) - it is required for the chemistry. Condensation on the membrane should have little effect except to slow down diffusion a bit and add to the response time. Other solutions (spit, sea, soda-lime) are also not expected to have an effect, but they will destroy the electronics on the pcb inside at the connector end. FYI: a major source of error is the resistance of the connection from cell pin to meter terminal. Corrosion at contacts (i.e. not soldered) can rapidly raise the resistance, create a voltage divider and give total nonsense at the display even when the cell is working properly. Such contacts can be intermittent, and depending on moisture as well. Flexing a wire excessively can break conductors, water in the cable can corrode the copper. Before blaming cells or displays, if the mV reading directly at the cell is good in air or 100% O2, check the resistance end-to-end. Inspect, clean, replace solder as necessary. Applies to all rbs. BWD
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10th April 2006, 09:23	#122 (permalink)
ROB DAVIE Administrator Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: HOUSTON, REPUBLIC OF TEJAS Posts: 1,120	Re: Megalodon Calibration Procedures I would like to thank all of the members of this Board who have pitched in with information in this most interesting thread! I would like to particularly thank Joe Radomski for his excellent summary of the pertinent points. Well done as usual, Joe! Have some green! __________________ "CC Rebreathers will become a viable part of tech diving WHEN PIGS FLY!!"--GI3
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29th April 2006, 05:14	#123 (permalink)
wedivebc Dave Tomblin Current Rebreather/s: Megalodon Other CCR Other Rebreather/s: Not Bought Yet Inspiration Classic Sport Kiss Other CCR Join Date: Feb 2005 Location: Vancouver Island BC Canada Posts: 1,508	Re: Megalodon Calibration Procedures Quote: (Originally Posted by jradomski) Yes but did you then go back outside and verify if the meter was still reading 20.9?? Was there a significant temperature change between the two enviroments?? was the door closed where all the additional water vapor in an enclosed enviroment slightly raised the local (room) ambient pressure?? Yes I did in fact and it seemed to make little difference. I admit it was hardly scientific or controlled but I did happen to be heading to the shower when I read Stefan's post so it seems an easy test. Outside temp was about 12C and bathroom temp was more like 25C. I may not have left it out for thermal stability, just the check the air/o2 reading. __________________ Cheers, Dave.... Man is the only animal burdened with the knowledge he will eventually die
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12th May 2006, 09:57	#124 (permalink)
*schford* RBW Founder Current Rebreather/s: Megalodon Sport Kiss Other Rebreather/s: Join Date: Jan 2005 Location: UK Posts: 3,564	Re: Megalodon Calibration Procedures This informaiton is just for people who read through this entire and start worrying about calibrating their Megs. Kevin has done some extensive testing to ascertain whether there is anything to be concerned about. (The short of it is there is not). Please see this articles. http://www.rebreatherworld.com/megal...lodon-ccr.html Stuart __________________ Bailout and Kit Management account for Murphy's Law The only bad question is one you did not ask and later wish you had. Use of RBW is subject to the Rebreather World Terms & Conditions of Use
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