What is the realistic minimum usable residual pressure for firefighting?

The realistic minimum usable residual pressure for firefighting is generally considered to be 20 psi. This figure is important because it represents the pressure required to ensure that adequate water flow is available through fire hoses when fire suppression efforts are underway.

When firefighters engage in battling a fire, it's not just about the pressure in the lines; a minimum pressure ensures that water can effectively reach the nozzle and achieve a proper flow rate for extinguishing flames. At 20 psi or higher, firefighters can typically maintain effective operations, allowing sufficient water to be delivered to the fire scene while ensuring the line remains effective and manageable.

If the pressure falls below this threshold, there may be challenges with achieving the necessary water flow, potentially compromising safety and effectiveness during firefighting operations. Hence, maintaining a residual pressure of at least 20 psi is crucial for ensuring that firefighters can operate effectively in emergency situations.