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authorGravatar Rick Walsh <rickmwalsh@gmail.com>2015-08-29 21:43:32 +1000
committerGravatar Dirk Hohndel <dirk@hohndel.org>2015-08-29 20:06:37 -0700
commit7d09f418f85372cdd1e8f8841444a5d8c7eb6f1f (patch)
tree3e59698fa21ee10059f6d1cb0ec08e58272dc73e /planner.c
parentbecc1e6dc417765670fec7d49e955cb0b3edbb23 (diff)
downloadsubsurface-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>
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