Vacuum gauges indicate readings in which measurement unit?

Vacuum gauges are primarily designed to measure pressures lower than atmospheric pressure, which is essential in various applications including HVAC systems, scientific experiments, and laboratory processes. The reading in inches of mercury (Hg) is a common unit used in the context of vacuum measurements because it directly relates to how atmospheric pressure is defined and allows easy understanding of how much pressure has been reduced.

Inches of mercury describes how high a column of mercury can be raised by the pressure in the vacuum environment. This is particularly useful in industries and fields where understanding the vacuum levels in relation to atmospheric pressure is critical. The use of this unit provides a clear and practical visualization of vacuum conditions, making it a standard measurement in many engineering and scientific applications.

While other units such as atmospheres, bars, and pascals can technically be used to express pressure, inches of mercury specifically aligns with the standardized measurements typically used in vacuum gauge readings, which makes it the most relevant choice among the options.