What is residual pressure?

Residual pressure refers to the pressure that remains in a fire suppression system while water is actively flowing through it. This measurement is essential for understanding the system's ability to deliver sufficient water to the fire scene and ensuring that there is adequate pressure available for effective firefighting operations.

When water flows through a system, it experiences losses due to friction and other factors, which is why measuring the residual pressure during flow is crucial. It helps in assessing how much pressure is still available for fire suppression after accounting for these loses, thus allowing operators to make informed decisions about pump settings and adjust flow rates as needed. Understanding residual pressure is also vital for ensuring that fire hydrants and other supply sources are functioning as intended under working conditions.

In contrast, the other options represent different aspects of pressure in a fire service context. For example, pressure in a pump's reservoir refers to static conditions and does not typically reflect the system's ability to perform during operations. The condition when no water is flowing relates to static pressure, which is important for understanding the maximum potential pressure but does not provide practical insights during firefighting activities. Lastly, pressure at the pump inlet pertains to the feed side of the pump, which is important for pump operation but is not the same as residual pressure in the