A plumber is performing a pipe sizing calculation for a residential dwelling. The total developed length of the main cold water line from the municipal connection to the furthest fixture is 30 metres, and this includes 5 elbows and 2 tees. If the flow rate required is 0.5 L/s, what specific factor contributes most significantly to the overall pressure loss in the pipe?

Question: A plumber is performing a pipe sizing calculation for a residential dwelling. The total developed length of the main cold water line from the municipal connection to the furthest fixture is 30 metres, and this includes 5 elbows and 2 tees. If the flow rate required is 0.5 L/s, what specific factor contributes most significantly to the overall pressure loss in the pipe?

Answer options:

• The friction loss due to the length of the straight pipe. ✅ The friction loss due to the fittings (elbows and tees).
• The static pressure difference between the municipal connection and the fixture.
• The velocity head at the fixture outlet.

Correct answer: The friction loss due to the fittings (elbows and tees).

Explanation: While straight pipe length contributes to pressure loss, fittings like elbows and tees introduce significant turbulent flow and often account for a substantial portion of the total friction loss in a pipe system, especially in systems with many changes in direction. Static pressure difference influences terminal pressure, and velocity head is energy used for flow, not friction loss.