The required pump discharge pressure to supply standpipes primarily depends on:

The required pump discharge pressure to supply standpipes primarily depends on friction loss in the standpipe. When water flows through a standpipe system, the pressure is affected by the resistive forces encountered due to friction between the water and the walls of the pipe, as well as any fittings, valves, or bends in the system. This friction loss can vary based on several factors, including the diameter and length of the standpipe, the flow rate, and the specific materials used in the piping.

Although the height of the building and the type of fire present are important considerations in fire suppression operations, they do not directly determine the necessary pump discharge pressure in the way that friction loss does. The height of the building affects the elevation pressure needed, but that is generally calculated in conjunction with friction loss to ascertain the total discharge pressure required. The capacity of the engine can influence the overall system capability, but it does not account for the dynamics of pressure loss within the standpipe itself during operation. Thus, understanding friction loss is crucial for ensuring that the pump discharge pressure is adequate for effective water delivery to the fire in a standpipe system.