If the friction loss in 90 m of hose is 490 kPa, what is the friction loss in 135 m of the same size hose carrying the same flow?

If the friction loss in 90 m of hose is 490 kPa, what is the friction loss in 135 m of the same size hose carrying the same flow?

• A. 735 kPa
• B. 441 kPa
• C. 490 kPa
• D. 900 kPa

Answer: (A)

Friction loss in a hose of fixed diameter varies directly with the length of hose for the same flow. So, if you know the loss for a certain length, you can scale it by the ratio of the new length to the old length. Here, the length increases from 90 m to 135 m, which is a factor of 135/90 = 1.5. Multiply the known friction loss by this factor: 490 kPa × 1.5 = 735 kPa. So, the friction loss in 135 m of the same size hose carrying the same flow is 735 kPa. (This assumes identical flow and hose diameter; changes in flow or hose size would alter the relationship.)

Friction loss in a hose of fixed diameter varies directly with the length of hose for the same flow. So, if you know the loss for a certain length, you can scale it by the ratio of the new length to the old length.

Here, the length increases from 90 m to 135 m, which is a factor of 135/90 = 1.5. Multiply the known friction loss by this factor: 490 kPa × 1.5 = 735 kPa.

So, the friction loss in 135 m of the same size hose carrying the same flow is 735 kPa. (This assumes identical flow and hose diameter; changes in flow or hose size would alter the relationship.)