one caveat.. 12 psi over ambient at sea level is not the same as 12 psi

over ambient at altitude. Keep that in mind when plotting.

 

Dave

 

Not sure what you mean, Dave.  At any altitude it is ambient plus cap pressure. At sea level the system pressure is 14.7 + 12 = 26.7 psi(absolute); and at 15000 ft it is 8.3 + 12 = 20.3 psia.  Or am I missing the point?

Al G