What two factors must be considered when calculating friction loss in the supply line to the Siamese connection of the sprinkler/standpipe system?

The calculation of friction loss in the supply line to the Siamese connection of a sprinkler or standpipe system is critical for ensuring adequate water flow and pressure. The correct factors to consider are the total GPM (Gallons Per Minute) flow and the length of hose from the engine to the connection.

When water flows through a hose, friction with the inner walls creates resistance, which affects pressure. The longer the hose, the greater the friction loss due to increased surface area contact between the water and the hose. Additionally, the flow rate (GPM) directly influences how much friction loss occurs; higher flow rates increase the velocity of the water, which in turn leads to greater friction losses. Understanding both of these factors allows operators to calculate the necessary pressure needed at the pump to ensure that the sprinkler or standpipe system functions properly, especially during emergencies.

The other options introduce factors that are either not directly involved in friction loss calculations or are secondary considerations. For example, pump model might influence pumping capacity but does not affect friction loss directly. Similarly, while nozzle size can impact pressure after the connection, it is not a direct factor when calculating friction loss prior to the connection. Focusing on GPM flow and hose length provides the most accurate assessment for