What is the impact on static pressure once friction loss occurs during a flow?

When friction loss occurs during the flow of water in a piping system, it diminishes the amount of pressure available to overcome resistance in the system. This loss occurs due to the interaction of the flowing water with the internal surfaces of the pipes, fittings, and valves, and results in a reduction of the pressure that can be effectively utilized for delivering water.

As water flows through the system, the initial static pressure experienced becomes what is referred to as residual pressure. This residual pressure is what remains after accounting for the friction losses, and it is critical for understanding the effective pressure available for firefighting or other applications. In this context, the term "static pressure" refers to the pressure when the water is at rest, whereas "residual pressure" specifically indicates the pressure remaining after friction losses have been deducted from the static or total pressure available at the source.

By recognizing this relationship, it becomes clear that friction loss impacts the static pressure by converting it into residual pressure, which is indicative of the reduced force available for operational use after such losses are considered.