What term describes the pressure remaining in the system once water starts flowing from a hydrant?

The term that describes the pressure remaining in the system once water starts flowing from a hydrant is known as residual pressure. When water is drawn from a hydrant, it disrupts the overall system pressure, resulting in a reduction from the static pressure that was present before flow commenced. The residual pressure is crucial because it indicates how much pressure remains available in the system to push water through hoses and equipment during firefighting operations. A clearer understanding of residual pressure is essential for firefighters to ensure that adequate water supply and pressure are maintained during emergencies. Static pressure refers to the pressure in the system when no water is flowing, while dynamic pressure reflects the pressure when water is flowing through the system, typically lower than the static pressure. Effective pressure is not a standard term used in this context. Thus, residual pressure is the appropriate term describing the pressure left in the system after flow begins.