Pipe Sizing

Question 1

Name four reasons why engineers pipe size?

Answer 1

• Selection of suitable pipe for system.
• Ensure desired head and flow at outlet.
• Enables sleection of efficient pump.
• Ensure maximum economy (Capex v Opex)

Question 2

What are the three main methods of pipe sizing and their accuracy?

Answer 2

1. Low accuracy - Nomograms
2. Medium accuracy - ME Vol II method
3. High accuracy - CIBSE Guide C and Software (Building Services, civillian infrastructure)

Question 3

What are the three methods of taking into account friction losses through fittings in a pipeline and their relevant accuracy?

Answer 3

1. Low accuracy - 5% for long lines and 20% for short lines
2. Medium accuracy - ME Vol VI method
3. High accuracy - Velocity head method (CIBSE)

Question 4

What are the seven main steps to sizing pipe?

Answer 4

1. Label each leg and select an index circuit (longest usually)
2. Calulate estimates effective lengths (with fitting allowance) and flow rates requred at each leg.
3. Calulate maximum pressure loss over whole length using the index circuit and equation at top of sizing schedule.
4. Determine pipe size from sizing table using max pressure loss.
5. Enter pipe size and actual pressure loses on sizing schedule.
6. Repeat for all legs steps 4 to 5.
7. Check residual head at all outlets is sufficient.