What does "residual pressure" indicate in a firefighting system?

Residual pressure is an important concept in a firefighting system as it refers to the amount of pressure that remains in the system while water is actively flowing. This pressure is critical for ensuring that there is enough force behind the water to reach the firefighting teams and effectively suppress the fire.

When firefighters engage a hydrant and flow water, the residual pressure provides insight into the system's performance, such as the ability to maintain adequate pressure during firefighting operations. It is particularly relevant when considering the capability of hoses and nozzles to deliver water where it is needed most.

Understanding residual pressure helps firefighters assess whether additional water supply or resources might be needed in a given situation to maintain effective firefighting capabilities.