If a barometer shows a pressure reading of 29.40" Hg, what will it read when it increases to 34.4" Hg in pounds absolute?

To determine the pressure reading in pounds absolute (PSIA) when the barometer reading increases from 29.40 inches of mercury (Hg) to 34.4 inches of Hg, it's important to understand the concept of atmospheric pressure and how to convert inches of mercury to pounds per square inch absolute.

First, you can start by recognizing that 1 inch of mercury corresponds to approximately 0.491 psi. Therefore, to convert a reading in inches of mercury to psi, you multiply the height in inches of mercury by this conversion factor.

Given the initial pressure reading of 29.40 inches of Hg:

• The conversion to psi would be:

29.40 inches Hg × 0.491 psi/inch Hg ≈ 14.48 psi (approximately 14.5 psi)

Next, for the new pressure reading of 34.4 inches of Hg:

• The conversion would be:

34.4 inches Hg × 0.491 psi/inch Hg ≈ 16.91 psi (approximately 16.9 psi)

When you look for the absolute pressure in pounds per square inch (PSIA), you would add the atmospheric pressure at the baseline (which is around 14.5 psi, noted previously