Which pressure is needed at the inlet when flowing 1500 GPM's to Truck 3 through 100' of 5" hose with a hydrant pressure of 55 psi?

To determine the necessary inlet pressure when flowing 1500 GPM through 100 feet of 5-inch hose, it’s essential to account for both the friction loss within the hose and any additional pressure required to maintain the desired flow rate at the truck's intake.

First, for a flow of 1500 GPM through a 5-inch diameter hose, you can use a friction loss formula or reference a friction loss chart specific to that hose size and flow rate. Typically, the friction loss for a 5-inch hose is calculated to be approximately 0.1 psi per 100 feet at this flow rate. Therefore, for 100 feet, the friction loss would equate to around 10 psi.

Next, the addition of the flow’s required pressure starts from the hydrant pressure, which is given as 55 psi. Thus, you would calculate the total pressure needed at the truck inlet by adding the hydrant pressure to the friction loss.

This results in: Hydrant Pressure (55 psi) + Friction Loss (10 psi) = 65 psi.

However, the question likely involves an additional factor not covered solely by the friction loss and hydrant pressure. Often, as a part of the fireground operations, a pumping