Quote: (Originally Posted by
lamont)
Isn't this as easy as just taking off the helium %age from the service pressure.
So, over in the states, 1950 psi of EAN32 ~= 3000 psi of 21/35:
(1.00 - .35) * 3000 = 1950
You can go the extra mile to treat N2 and O2 differently and correct for the weight of helium, but doesn't that work closely enough?
Hi
Sorry for the delay - forgot to reply to this. I guess your method would be approximate enough, especially if you’re dealing with same salinity conversions. Trying to guess between these and/or when using higher helium percentages then the errors get larger. For instance with same-salinity and converting from 200 bar of 21/35 the equivalent air pressure difference is 11 bar when using your shortcut, rising to 20 bar for 10/70. Where you’re crossing salinities it doesn’t really work at all and you get some huge differences.
Joe