Why is a refrigerant gauge referred to as a compound gauge?

A refrigerant gauge is referred to as a compound gauge because it is capable of measuring both positive pressure and vacuum. This dual functionality is essential in HVAC and refrigeration applications, where technicians often need to assess the pressure of refrigerants in both standard operating conditions (positive pressure) and when the system is in a low-pressure state (vacuum). By measuring within this range, the compound gauge provides a comprehensive understanding of the refrigerant's status, allowing for accurate diagnostics and system maintenance.

The ability to read both types of pressure enables technicians to evaluate system performance effectively. When a system is under a vacuum, it is crucial to ensure that there are no leaks and that all components are functioning correctly. The gauge can often be calibrated to give readings in different units, providing versatility in measurement. This essential feature sets compound gauges apart from standard gauges, which may only measure high pressure without the capacity to register vacuum levels.