What is the recommended dynamic pressure for a system using four lengths of 2½-inch hose and a 1¼-inch shutoff pipe?

The recommended dynamic pressure for a system using four lengths of 2½-inch hose and a 1¼-inch shutoff pipe is established based on hydraulic calculations that consider friction loss and required nozzle pressure for effective fire fighting operations.

In this scenario, utilizing four sections of 2½-inch hose typically leads to a higher friction loss, necessitating a dynamic pressure that compensates for that loss while also providing sufficient pressure at the nozzle for effective operation. The choice of 70 psi effectively balances the requirements, ensuring that firefighters have adequate water flow delivered at the nozzle while minimizing the risks of inadequate pressure that could lead to disruptions in firefighting efforts.

This value allows for the proper operation of the nozzle under the conditions expected with the setup described. It is also essential to consider that dynamic pressures are influenced by factors such as the length of hose, the diameter of the hose, and the type of shutoff valve used. Other pressures suggested may not provide the optimal balance needed for efficiency and safety in firefighting operations for the given configuration.