What type of indicator is a fuel pressure gauge?

A fuel pressure gauge is primarily a differential pressure indicator. This type of gauge measures the difference between the fuel pressure inside the aircraft's fuel system and the atmospheric pressure. It displays the fuel system's pressure levels relative to a reference point, which is usually atmospheric pressure.

In aircraft fuel systems, maintaining an appropriate fuel pressure is crucial for ensuring proper engine performance and fuel delivery. The differential pressure reading helps the pilot or technician assess whether the fuel is being delivered at the correct pressure and can indicate potential issues such as blockages or pump failures, making it a vital tool for fuel system monitoring.

Other types of indicators, like constant pressure monitors, would provide a specific pressure reading without regard to atmospheric conditions, while absolute pressure gauges measure pressure relative to a perfect vacuum. Flow rate indicators, on the other hand, show the volume of fuel flowing through the system over time and do not convey pressure information. Therefore, the classification of the fuel pressure gauge as a differential pressure indicator supports its essential role in monitoring fuel system health and performance.