1. What is Total Dynamic Head?

Total Dynamic Head (TDH) is the total equivalent height that a fluid is to be pumped, taking into account friction losses in the pipe. It's the sum of static head, friction head, and pressure head.

2. How to Calculate Pump Head

The TDH formula is:

Where:

• Static Head — Vertical distance from water surface to discharge point (ft)
• Friction Loss — Head loss due to friction in pipes and fittings (ft)
• Pressure Head — Additional pressure required at discharge (converted to ft of head)

Example: For a system with 50 ft static lift, 12 ft friction loss, and needing 20 psi (46.2 ft) at discharge: TDH = 50 + 12 + 46.2 = 108.2 ft

3. Importance of Accurate Head Calculation

Details: Proper pump selection requires accurate TDH calculation to ensure the pump can provide enough pressure to overcome system resistance and deliver required flow.

4. Using the Calculator

Tips:

• Measure static head as vertical distance from lowest to highest point
• Calculate friction loss using pipe size, length, flow rate, and material
• Convert pressure requirements to feet of head (1 psi = 2.31 ft of water)

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between static head and dynamic head?
A: Static head is the vertical distance only, while dynamic head includes friction and pressure components.

Q2: How do I calculate friction loss?
A: Use the Hazen-Williams equation or Darcy-Weisbach equation based on pipe characteristics and flow rate.

Q3: When is pressure head needed?
A: When the discharge point requires pressure (like sprinkler systems) rather than just open discharge.

Q4: What units should I use?
A: All values should be in consistent units (feet for head, psi for pressure which must be converted).

Q5: How does this affect pump selection?
A: The pump curve must show adequate flow rate at your calculated TDH for proper operation.