How much pressure is needed to achieve a flow rate of 266 GPM with a 2 ½" 200' Pre-Connect and a 1 1/8" SB nozzle?

To determine the pressure needed to achieve a flow rate of 266 gallons per minute (GPM) through a 2 ½" 200' pre-connect line with a 1 1/8" smooth bore (SB) nozzle, it's essential to apply the principles of the friction loss in hoses and the nozzle pressure requirements.

The 1 1/8" SB nozzle typically has a nozzle pressure requirement of around 50 psi for optimal performance. This pressure is crucial for achieving the desired flow rate of 266 GPM, which corresponds with the standard friction loss calculations.

In addition, when calculating the friction loss in a 2 ½" hose, the friction loss is approximately 2 psi per 100 feet for that diameter. The total length of the hose is 200 feet, leading to a friction loss of around 4 psi (2 psi x 2).

When these values are added together (the nozzle pressure plus the hose friction loss), the required pump discharge pressure can be calculated. Therefore, the total pressure needed to achieve this flow rate would be approximately:

Nozzle Pressure (50 psi) + Friction Loss (4 psi) = 54 psi

However, there may be additional factors considered in practical firefighting