The pressure gauges we use are calibrated or set to a value of zero psi. What are pressures measured with these gauges called?

When pressure gauges are calibrated to a value of zero psi, the pressures measured with these gauges are referred to as gauge pressures. This means that the gauge readings reflect the pressure relative to the atmospheric pressure. Essentially, gauge pressure measures how much pressure exists above atmospheric pressure, which is why the gauge is set to zero at ambient conditions.

In contrast, absolute pressure measures the total pressure exerted, including atmospheric pressure. Static pressure refers to the pressure of a fluid at rest within a system or storage tank. Dynamic pressure, on the other hand, relates to the pressure associated with the motion of the fluid and is often assessed in applications involving fluid flow. Understanding these distinctions highlights that gauge pressures specifically indicate the difference between the pressure within a system and the surrounding atmospheric pressure, making gauge pressures the correct term in this context.