What is the friction loss in 100 feet of 2 ½ inch hose flowing 400 gpm?

What is the friction loss in 100 feet of 2 ½ inch hose flowing 400 gpm?

• A. 16 PSI
• B. 32 PSI
• C. 48 PSI
• D. 64 PSI

Answer: (B)

Friction loss is the pressure drop caused by moving water through hose, and it grows with how much water you’re sending and how long the hose is. In firefighting practice we use friction loss values from tables or calculators that show how many psi are lost per 100 feet for a given hose size and flow. For a 2 1/2 inch hose, delivering 400 gpm, the friction loss is about 32 psi per 100 feet. Since the problem specifies 100 feet, the friction loss is 32 psi. If the hose were longer, you’d add more psi proportionally; and since friction loss increases with the square of the flow, increasing gpm would raise the loss quickly.

Friction loss is the pressure drop caused by moving water through hose, and it grows with how much water you’re sending and how long the hose is. In firefighting practice we use friction loss values from tables or calculators that show how many psi are lost per 100 feet for a given hose size and flow.

For a 2 1/2 inch hose, delivering 400 gpm, the friction loss is about 32 psi per 100 feet. Since the problem specifies 100 feet, the friction loss is 32 psi. If the hose were longer, you’d add more psi proportionally; and since friction loss increases with the square of the flow, increasing gpm would raise the loss quickly.