ESCO Air Conditioning Practice Exam

A compound pressure gauge is specifically designed to measure both positive pressure and vacuum, making it suitable for applications where the pressure can be below atmospheric levels as well as above. These gauges typically have dual scales, allowing users to easily read values in both positive pressure (above atmospheric) and vacuum (below atmospheric).

This functionality is critical in many air conditioning and refrigeration systems, where both types of pressure measurements are often required for operational diagnostics and system monitoring. Understanding the pressure differential can help technicians assess the overall performance of the system, troubleshoot issues, and ensure optimal operation.

In contrast, gauges that measure absolute pressure do not reference atmospheric pressure, focusing solely on the total pressure exerted. High pressure only does not encompass vacuum measurements, and a gauge measuring pressure and temperature would be an entirely different instrument that leverages additional sensors for temperature readings. Therefore, the capability of a compound pressure gauge to measure both pressure and vacuum makes it a versatile tool essential for HVAC applications.