Calculate theoretical friction loss for a 65 mm hose line 60 m long operating at 950 l/min.

Calculate theoretical friction loss for a 65 mm hose line 60 m long operating at 950 l/min.

• A. 100.00 kPa
• B. 171.65 kPa
• C. 200.50 kPa
• D. 150.75 kPa

Answer: (B)

Friction loss in a fire hose is the pressure drop caused by the water rubbing along the hose walls as it flows. For a given hose size, this loss is typically looked up from standard tables or a nomogram at the operating flow, and then scaled by the hose length. The idea is that, for a 65 mm hose at 950 L/min, the friction loss is about 286 kPa per 100 meters of hose. Using that per-100-meter value and the actual length of 60 meters, you scale by length: 60/100 × 286 kPa ≈ 171.6 kPa. So the theoretical friction loss is about 171.65 kPa. In short, the tested concept is applying standard friction-loss data for the hose size and flow and scaling by the actual length to get the total friction loss.

Friction loss in a fire hose is the pressure drop caused by the water rubbing along the hose walls as it flows. For a given hose size, this loss is typically looked up from standard tables or a nomogram at the operating flow, and then scaled by the hose length. The idea is that, for a 65 mm hose at 950 L/min, the friction loss is about 286 kPa per 100 meters of hose.

Using that per-100-meter value and the actual length of 60 meters, you scale by length: 60/100 × 286 kPa ≈ 171.6 kPa. So the theoretical friction loss is about 171.65 kPa.

In short, the tested concept is applying standard friction-loss data for the hose size and flow and scaling by the actual length to get the total friction loss.