You are supplying Truck 9 directly into their pump with a flow of 1000 GPM. If the hydrant pressure is 50 psi, what is the calculated friction loss?

The correct choice is based on the principles of calculating friction loss in a fireground scenario involving supply lines and hydrant pressures. Friction loss is typically determined using various factors, including the diameter of the hose, the flow rate, and the length of the hose.

In this case, when supplying Truck 9 with a flow of 1000 gallons per minute (GPM) and with a hydrant pressure of 50 psi, the friction loss that occurs in the hose as the water travels from the hydrant to the truck must be factored in.

Typically, for a flow rate of 1000 GPM in a standard diameter hose, there are established charts and formulas (such as the N+E formula) that can be referenced to compute friction loss accurately. It is common to find that at 1000 GPM, depending on the hose diameter and other conditions, the friction loss can add several points to the pressure measured at the hydrant.

In this situation, if the friction loss is calculated to be 20 psi for example, it would mean the pressure available at the nozzle when flow is initiated would be 50 psi - 20 psi = 30 psi. To further ensure a supply at 1000