Using the subtract 10 method, what is the calculated pump discharge pressure for 300 ft of 2.5 inch hose with a nozzle pressure of 50 psi?

To determine the pump discharge pressure using the subtract 10 method, you start by understanding the factors involved in calculating the pressure needed to achieve a specific nozzle pressure through a given length of hose.

In this scenario, the nozzle pressure is given as 50 psi. The subtract 10 method is commonly used in firefighting to account for the pressure loss associated with the friction as water travels through the hose. The general principle is that for every 100 feet of 2.5-inch hose, you lose approximately 10 psi due to friction.

Since you have 300 feet of hose, you would calculate the total friction loss as follows:

• This is 3 segments of 100 feet, each contributing a 10 psi loss, resulting in a total friction loss of 30 psi (10 psi per 100 feet × 3).

Now, to find the calculated pump discharge pressure, you start with the nozzle pressure and add the friction loss to it. Therefore, the calculation will look like this:

• 50 psi (nozzle pressure) + 30 psi (friction loss) = 80 psi.

However, the given answer of 145 psi indicates there might be other content in the problem statement not provided here, or an additional