What does a pressure gauge measure?

A pressure gauge specifically measures the pressure exerted by gases or liquids within a system. It provides a quantitative reading of how much force the fluid exerts per unit area, which is crucial for maintaining safe operational levels within various equipment and systems, such as pipelines, boilers, and compressors. Proper pressure readings help prevent issues like overpressure conditions, which can lead to equipment failure or unsafe operating conditions.

In contrast, the other options focus on different measurements: the volume of gases or liquids pertains to the amount of fluid present in a space; the flow rate refers to how quickly fluid moves through a system, and the temperature gauges the thermal state of the fluids. Each of these measures serves a specific purpose, but they do not relate to the direct measurement of pressure, which is the primary function of a pressure gauge.