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author | Rick Walsh <rickmwalsh@gmail.com> | 2015-08-29 21:43:32 +1000 |
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committer | Dirk Hohndel <dirk@hohndel.org> | 2015-08-29 20:06:37 -0700 |
commit | 7d09f418f85372cdd1e8f8841444a5d8c7eb6f1f (patch) | |
tree | 3e59698fa21ee10059f6d1cb0ec08e58272dc73e /planner.c | |
parent | becc1e6dc417765670fec7d49e955cb0b3edbb23 (diff) | |
download | subsurface-7d09f418f85372cdd1e8f8841444a5d8c7eb6f1f.tar.gz |
Use Schreiner water vapour pressure for VPM-B
Inspired gas loading equations depend on the partial pressure of inert gas in
the alveolar.
P_alv = (P_amb - P_H2O + (1 - Rq) / Rq * P_CO2) * f
where:
P_alv alveolar partial pressure of inert gas
P_amb ambient pressure
P_H2O water vapour partial pressure = ~0.0627 bar
P_CO2 carbon dioxide partial pressure = ~0.0534 bar
Rq respiratory quotient (O2 consumption / CO2 production)
f fraction of inert gas
In our calculations, we simplify this to use an effective water vapour pressure
WV = P_H20 - (1 - Rq) / Rq * P_CO2
Buhlmann ignored the contribution of CO2 (i.e. Rq = 1.0), whereas Schreiner
adopted Rq = 0.8.
WV_Buhlmann = PP_H2O = 0.0627 bar
WV_Schreiner = 0.0627 - (1 - 0.8) / Rq * 0.0534 = 0.0493 bar
Buhlmann calculations use the Buhlmann value, VPM-B calculations use the
Schreiner value.
Concept explained here:
http://www.divetable.de/workshop/V1_e.htm
Signed-off-by: Rick Walsh <rickmwalsh@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Diffstat (limited to 'planner.c')
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