Refer to Figure 2.7. The moveable atmospheric pressure datum is measured relative to the fixed absolute zero pressure datum. Therefore, the variable atmospheric pressure above the fixed absolute zero...

Refer to Figure 2.7. The moveable atmospheric pressure datum is measured relative to the fixed absolute zero pressure datum. Therefore, the variable atmospheric pressure above the fixed absolute zero is reported in absolute pressure units (psi [abs] or psia in the English system, and Pa [abs] in the metric system). How is the absolute pressure of a fluid above the fixed absolute zero computed?