CMF - Understanding Constant Mass Flow

[paulraymaekers]

Hi all,
during courses, and discussions with rebreather divers, I often notice that there is quite some misconception about constant mass flow. Even during instructor courses I notice that people have difficulties explaining how it works.
So I took some time and wrote a short article about CMF: you can download it from the english pages of our website. Please notice the text is still a draft, if anyone want's to take the time to make nice drawings, he/she is free to do so, his/her name will be in the article when we use it
The text can be used for personal use by anyone, please respect copy-right rules if you reproduce parts/whole of the text

paul

ps will follow later
'understanding oxygen sensors, and why NOT changing them all at the same time'
'understanding sorb'

CMF - Understanding Constant Mass Flow by Paul Raymaekers This editorial is a simplified explanation of the CMF principle, and is only written to assist with the understanding of CMF rebreathers. The author of this article does not accept any responsibility for the use of this information for building or modifying existing rebreathers.

Click above image to read editorial

[spirotechnique]

very interesting reading Paul, thank you very much

[RogerioWagner]

Thanks for the paper Paul

I've been looking for some additional information about that subject, let me explain why.

I'm wondering, if a mCCR make me a less complacent rebreather diver, and the eCCR is nice tool to keep the ppo2 when you are doing some work, the hCCR can be a great choice, but all literature that i have access did not drill down on the subjcet of CMF.

Regards,
Roger

[Hyper-limits]

Thanks for sharing Paul, looking forward to the paper on cell and sorb.

Cheers

Al

[depth]

Hi Paul

Thank you for taking the time to do the write-up, much appriciated...

/Christian

[depth]

What program have you used to make the graphs and equations by the way? Looks awsome ;)

Safe diving Paul....

/Christian

[Paul S]

Nice.

My only comment would be that you seem to avoid talking about mass, preferring to talk about volume at surface pressure. That seems a little odd when trying to explain constant mass flow.

... or have you found that people find the concept of "a gram of gas" difficult to understand when you've been training them?

Hi all,
if anyone want's to take the time to make nice drawings, he/she is free to do

I'm about to send you a PM with some diagrams in if I can work out how to attach them.

[seasick]

Thanks Paul!!

Very informative and much appreciated.

Best regards,
SS

[scubadoc]

Paul,

As a new rebreather diver, I appreciate your efforts. I look forward to your other discussions.

Thanks
Joe

[paulraymaekers]

Nice.

My only comment would be that you seem to avoid talking about mass, preferring to talk about volume at surface pressure. That seems a little odd when trying to explain constant mass flow.

... or have you found that people find the concept of "a gram of gas" difficult to understand when you've been training them?



I'm about to send you a PM with some diagrams in if I can work out how to attach them.

Thanks for diagrams, (all of you that send, I'll have to make a selection
(so no more diagrams needed !!!!

as for talking about volume at surface pressure: indeed it is easier for people to understand than mass: as everybody seems to understand that 1.35 liter at surface is to much, and 0.75 is +/- correct
1.15 gr/min, or 1.55gr/min.... nobody seems to know what is the best

paul