+ Reply to Thread
Page 1 of 3 1 2 3 LastLast
Results 1 to 10 of 23

Thread: CMF - Understanding Constant Mass Flow

  1. #1
    rEvo's daddy
    paulraymaekers has a reputation beyond repute paulraymaekers has a reputation beyond repute paulraymaekers has a reputation beyond repute paulraymaekers has a reputation beyond repute paulraymaekers has a reputation beyond repute paulraymaekers has a reputation beyond repute paulraymaekers has a reputation beyond repute paulraymaekers has a reputation beyond repute paulraymaekers has a reputation beyond repute paulraymaekers has a reputation beyond repute paulraymaekers has a reputation beyond repute paulraymaekers's Avatar
    Join Date
    May 2005
    Location
    belgium
    Posts
    4,073
    rEvo

    CMF - Understanding Constant Mass Flow

    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
    Attached Files
    Last edited by Curt Bowen; 30th August 2010 at 19:18.
    www.rEvo-rebreathers.com
    ...."Yes you have to pre-breathe to activate the scrubber sorb, anyone who says different doesn't know what they are talking about!"...
    .... to get more accurate CO2 injection in the breathing machine we put 2 mass flow controllers in series ...
    .... The noise is a few tens of nano-volts, so DL were able to reduce the output voltage ...
    .... radial scrubbers give longer dwell time than axials...
    .... the earth is flat and ...

  2. #2
    RBW Member spirotechnique has a little shameless behaviour in the past spirotechnique's Avatar
    Join Date
    Jun 2010
    Location
    France
    Posts
    9
    ISC Pathfinder

    Oxygers 57 / Caimano / FGT.1D

    Re: Understanding Constant Mass Flow

    very interesting reading Paul, thank you very much

  3. #3
    RBW Member RogerioWagner has a spectacular aura about RogerioWagner has a spectacular aura about RogerioWagner has a spectacular aura about RogerioWagner has a spectacular aura about RogerioWagner has a spectacular aura about RogerioWagner has a spectacular aura about RogerioWagner's Avatar
    Join Date
    May 2010
    Location
    Brazil
    Posts
    221
    Megalodon APECS 2.7/Predator

    CUDA 650

    Re: Understanding Constant Mass Flow

    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

  4. #4
    Prince of darkness Hyper-limits is just really nice Hyper-limits is just really nice Hyper-limits is just really nice Hyper-limits is just really nice Hyper-limits is just really nice Hyper-limits is just really nice Hyper-limits is just really nice Hyper-limits is just really nice Hyper-limits is just really nice Hyper-limits is just really nice Hyper-limits's Avatar
    Join Date
    Apr 2006
    Location
    Ottawa, Ontario
    Posts
    472
    Megalodon

    Re: Understanding Constant Mass Flow

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

    Cheers

    Al

  5. #5
    Christian Rasmussen depth is just really nice depth is just really nice depth is just really nice depth is just really nice depth is just really nice depth is just really nice depth is just really nice depth is just really nice depth is just really nice depth's Avatar
    Join Date
    Aug 2006
    Location
    Denmark
    Posts
    1,020

    Re: Understanding Constant Mass Flow

    Hi Paul

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

    /Christian

  6. #6
    Christian Rasmussen depth is just really nice depth is just really nice depth is just really nice depth is just really nice depth is just really nice depth is just really nice depth is just really nice depth is just really nice depth is just really nice depth's Avatar
    Join Date
    Aug 2006
    Location
    Denmark
    Posts
    1,020

    Re: Understanding Constant Mass Flow

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

    Safe diving Paul....

    /Christian

  7. #7
    RBW Member Paul S is on a distinguished road Paul S is on a distinguished road Paul S's Avatar
    Join Date
    Sep 2008
    Location
    UK, Twickenham
    Posts
    147
    rEvo III Mini hCCR

    Re: Understanding Constant Mass Flow

    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?

    Quote Originally Posted by paulraymaekers  View Original Post
    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.

  8. #8
    lEEbo lEEblEEdErs seasick has a spectacular aura about seasick has a spectacular aura about seasick has a spectacular aura about seasick has a spectacular aura about seasick has a spectacular aura about seasick's Avatar
    Join Date
    Mar 2006
    Location
    Singapore
    Posts
    631
    rEvo II Micro FT mCCR

    Shearwater Meg DCCCR

    Re: Understanding Constant Mass Flow

    Thanks Paul!!

    Very informative and much appreciated.

    Best regards,
    SS

  9. #9
    RBW Member scubadoc is an unknown quantity at this point scubadoc's Avatar
    Join Date
    Aug 2008
    Location
    Va
    Posts
    21
    rEvo III Micro FT

    Re: Understanding Constant Mass Flow

    Paul,

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

    Thanks
    Joe

  10. #10
    rEvo's daddy
    paulraymaekers has a reputation beyond repute paulraymaekers has a reputation beyond repute paulraymaekers has a reputation beyond repute paulraymaekers has a reputation beyond repute paulraymaekers has a reputation beyond repute paulraymaekers has a reputation beyond repute paulraymaekers has a reputation beyond repute paulraymaekers has a reputation beyond repute paulraymaekers has a reputation beyond repute paulraymaekers has a reputation beyond repute paulraymaekers has a reputation beyond repute paulraymaekers's Avatar
    Join Date
    May 2005
    Location
    belgium
    Posts
    4,073
    rEvo

    Re: Understanding Constant Mass Flow

    Quote Originally Posted by Paul S  View Original Post
    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
    www.rEvo-rebreathers.com
    ...."Yes you have to pre-breathe to activate the scrubber sorb, anyone who says different doesn't know what they are talking about!"...
    .... to get more accurate CO2 injection in the breathing machine we put 2 mass flow controllers in series ...
    .... The noise is a few tens of nano-volts, so DL were able to reduce the output voltage ...
    .... radial scrubbers give longer dwell time than axials...
    .... the earth is flat and ...

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts