If the barometric pressure reads 28 in Hg, what would that be in psia?

To convert barometric pressure from inches of mercury (in Hg) to pounds per square inch absolute (psia), one must understand the relationship between these two measurement units. Standard atmospheric pressure at sea level is typically around 29.92 in Hg, which equates to approximately 14.7 psia.

When the barometric pressure reads 28 in Hg, you need to recognize that this number represents the pressure exerted by the atmosphere, not absolute pressure. Therefore, you need to convert the indicated barometric pressure into psia by first determining the amount of pressure it represents compared to the standard atmospheric pressure.

Each inch of mercury contributes approximately 0.491 psi. Thus, to convert 28 in Hg to psi:

1. Calculate the pressure in psi:

• 28 in Hg × 0.491 psi/in Hg = 13.748 psi.

2. Since psi does not account for atmospheric pressure, to find psia, simply add the atmospheric pressure:

• 14.7 psi (atmospheric pressure) - 13.748 psi = approximately 0.952 psi.

This calculation implies that regarding absolute pressure, the reading is still more or less aligned when considering common atmospheric adjustments, leading to