What is the term used to describe the pressure when the nozzle is open and water is flowing?

The term that refers to the pressure present when the nozzle is open and water is actively flowing is dynamic pressure. When water is flowing through a fire suppression system, it experiences changes in pressure due to movement and friction as it travels through pipes and out of the nozzle. Dynamic pressure is a measure of this flow-related pressure, and it reflects the force exerted by the moving water at that moment.

Static pressure, on the other hand, refers to the pressure in the system when water is not moving; residual pressure pertains to the pressure that remains in the system while water is flowing, particularly in relation to the static pressure. Supplied pressure typically refers to the pressure provided by the water source, which can vary due to factors like elevation or supply dynamics. Understanding these distinctions is critical for firefighters in assessing water supply and pressure during operations.