i like the spreadsheet.
to do this in your head i will use dfx's example of lp85 2600 psi at 32% nitrox desired fill.
32% is 68% nitrogen
nitrogen comes from air and it has o2 with it
68 *25% =17 (there is an error in this as it is actually 21/79 not 25%)
68+17=85 ( the % of the tank filled with air)
100-85=15 ( the % of tank presure of pure o2 needed to get 32%)
here is the voodoo. take tank psi and subtract 100 psi to comp for the error above 2600-100-2500
15% of 2500 is 375psi ( amount of o2 in psi to make 32% nitrox.)
now for the venting stuff tank the o2 tank psi and subtract 2 times the o2 needed if the o2 ank has 1100 in it then 1100-375-375= 350
vent scuba tank to 350psi and transfer 375 from o2 tank to scuba tank, let cool and top off to 2600 with air.
to do this in your head i will use dfx's example of lp85 2600 psi at 32% nitrox desired fill.
32% is 68% nitrogen
nitrogen comes from air and it has o2 with it
68 *25% =17 (there is an error in this as it is actually 21/79 not 25%)
68+17=85 ( the % of the tank filled with air)
100-85=15 ( the % of tank presure of pure o2 needed to get 32%)
here is the voodoo. take tank psi and subtract 100 psi to comp for the error above 2600-100-2500
15% of 2500 is 375psi ( amount of o2 in psi to make 32% nitrox.)
now for the venting stuff tank the o2 tank psi and subtract 2 times the o2 needed if the o2 ank has 1100 in it then 1100-375-375= 350
vent scuba tank to 350psi and transfer 375 from o2 tank to scuba tank, let cool and top off to 2600 with air.
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