Which hose size yields 400.78 kPa friction loss at 75 m and 375 l/min?

Which hose size yields 400.78 kPa friction loss at 75 m and 375 l/min?

• A. 45 mm
• B. 38 mm
• C. 65 mm
• D. 90 mm

Answer: (B)

Friction loss in a hose with a fixed length and flow increases dramatically as the diameter gets smaller. When you push the same flow through a smaller bore, the water velocity goes up, which raises shear losses along the hose and makes the friction head grow quickly. For 375 L/min over 75 meters, reaching about 400 kPa of friction loss requires a high resistance, something that only the smallest diameter in the list provides. The larger diameters would produce much lower friction losses at the same flow and length, so they wouldn’t reach that 400 kPa value. Therefore, the diameter that yields the specified friction loss is the smallest hose size available in the options.

Friction loss in a hose with a fixed length and flow increases dramatically as the diameter gets smaller. When you push the same flow through a smaller bore, the water velocity goes up, which raises shear losses along the hose and makes the friction head grow quickly. For 375 L/min over 75 meters, reaching about 400 kPa of friction loss requires a high resistance, something that only the smallest diameter in the list provides. The larger diameters would produce much lower friction losses at the same flow and length, so they wouldn’t reach that 400 kPa value. Therefore, the diameter that yields the specified friction loss is the smallest hose size available in the options.