How many microns of pressure are in a system when a compound gauge reads 29" Hg?

To determine how many microns of pressure correspond to a reading of 29 inches of mercury (Hg) on a compound gauge, it's important to understand the relationship between inches of mercury and microns.

One inch of mercury is equivalent to 25,400 microns. Therefore, if the gauge reads 29 inches of mercury, we can convert this measurement to microns by multiplying the number of inches by the conversion factor.

The calculation would be as follows:

29 inches of Hg x 25,400 microns/inch = 737,600 microns.

This means that when a compound gauge indicates 29 inches of mercury, it reflects a pressure of 737,600 microns.

The confusion may arise from common practice or rounding used in the industry, but the straightforward conversion using the exact number of microns per inch yields a clear numerical value that aligns with standard pressure measurements.

The other options do not accurately reflect the correct calculations based on the conversion formula and would lead to incorrect interpretations of pressure in terms of microns. Only the choice that reflects the correct mathematical conversion aligns with the expected understanding for pressure readings in the context of refrigeration and air conditioning systems.