What is the discharge pressure (DP) for Engine 3 when deploying two 2 1/2" sections to the standpipe?

The correct answer for the discharge pressure (DP) for Engine 3 when deploying two 2 1/2" sections to the standpipe is based on the factors influencing the calculation of pressure in fire suppression systems.

When deploying hose lines, especially in a standpipe scenario, several components are considered, including the friction loss in the hose, the elevation gain to the standpipe outlet, and any additional factors that may affect the overall pressure required to ensure adequate flow.

For two 2 1/2" sections of hose, there is a set friction loss per 100 feet of hose, typically calculated from established charts or guidelines. The pressure must also take into account the height of the building and the necessary pressure to overcome this elevation.

By establishing a base discharge pressure and adding the friction loss from the total length of hose deployed, the appropriate pressure needed at the pump to effectively deliver water through the hose lines to the standpipe outlet can be determined. The selected answer takes into account both the friction loss for the two sections of hose and any applicable factors related to the water delivery system and elevation, making it an appropriate solution given the context.

Hence, the answer of 390 + FL is correct as it reflects the total discharge pressure