Before calculating total friction loss, should hoses (except 5 inch) be converted to 2 1/2 inch?

Before calculating total friction loss, should hoses (except 5 inch) be converted to 2 1/2 inch?

• A. False
• B. True
• C. Not applicable
• D. Depends on system

Answer: (B)

Friction loss is tied to hose diameter, so you must express all portions of the attack line in a single reference size to add them up correctly. The standard practice is to convert all hose segments (except the 5 inch) to the equivalent length of 2 1/2 inch hose and use a single friction loss table for that size. This lets you sum the losses along the entire line consistently and then add any nozzle friction to determine the required pump discharge pressure. The 5 inch segment is left unconverted because its friction characteristics are handled differently in many procedures, and it’s typically treated with its own considerations.

Friction loss is tied to hose diameter, so you must express all portions of the attack line in a single reference size to add them up correctly. The standard practice is to convert all hose segments (except the 5 inch) to the equivalent length of 2 1/2 inch hose and use a single friction loss table for that size. This lets you sum the losses along the entire line consistently and then add any nozzle friction to determine the required pump discharge pressure. The 5 inch segment is left unconverted because its friction characteristics are handled differently in many procedures, and it’s typically treated with its own considerations.