1. What is Total Dynamic Head (TDH)?

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 represents the actual workload on the pump and is crucial for proper pump selection and system design.

2. Understanding the TDH Components

The TDH formula consists of three main components:

Where:

• Static Head — The vertical distance between the fluid level in the suction tank and the discharge point (ft)
• Friction Loss — The head loss due to friction in pipes, valves, and fittings (ft)
• Pressure Head — Additional pressure required at the discharge point (ft of liquid)

Explanation: TDH accounts for all resistances the pump must overcome to move fluid through the system at the desired flow rate.

3. Importance of TDH Calculation

Details: Accurate TDH calculation is essential for selecting a properly sized pump that can deliver the required flow rate against the system's total resistance. Underestimating TDH can lead to insufficient pump performance, while overestimating can result in oversized, inefficient pumps.

4. Using the Calculator

Tips:

• Measure Static Head as the vertical distance from the source to discharge
• Calculate Friction Loss using pipe size, length, flow rate, and fluid properties
• Include Pressure Head if the discharge is pressurized (e.g., into a pressurized vessel)
• All values must be in feet of liquid

5. Frequently Asked Questions (FAQ)

Q1: How is TDH different from static head?
A: Static head only considers elevation difference, while TDH includes all resistances (friction, pressure) the pump must overcome.

Q2: Why is friction loss important in TDH?
A: Friction loss increases with flow rate and can become the dominant factor in systems with long pipe runs or high velocities.

Q3: When can pressure head be ignored?
A: Pressure head can be omitted when discharging to atmospheric pressure (like an open tank).

Q4: How does fluid density affect TDH?
A: TDH is expressed in feet of liquid, so it's independent of fluid density for the same system. However, the pressure required (psi) will vary with density.

Q5: What's a typical TDH range for water systems?
A: Residential systems might have 50-100 ft TDH, while industrial systems can exceed 300 ft depending on the application.