Which gauge measures both pressure and vacuum in a system?

The compound gauge is designed to measure both pressure and vacuum, which makes it unique among the listed options. This gauge can indicate pressures above atmospheric pressure, typically in psi (pounds per square inch), and can also measure negative pressures (or vacuums) below atmospheric pressure, which is essential in various applications that require monitoring of systems where either pressure or vacuum conditions may exist.

For instance, in many boiler systems or industrial applications, there are scenarios where it's crucial to monitor pressure to prevent over-pressurization, while also being able to detect when there is a vacuum that needs to be maintained, such as in condensate recovery systems. Thus, the compound gauge's ability to read both types of measurements provides valuable insights into the operational status of the system, enhancing safety and efficiency.

In contrast, a pressure gauge exclusively measures pressures but not vacuums, while a vacuum gauge is solely for measuring negative pressures. A temperature gauge does not measure pressure or vacuum at all, focusing only on thermal conditions. This makes the compound gauge the most suitable choice for applications that require dual-function measurement of both pressure and vacuum.