Question 1

Is TDH the same as static head?

Accepted Answer

No. Static head is just the elevation difference. TDH adds friction, velocity, and pressure heads — the actual work the pump must do.

Question 2

Do I include suction lift in TDH?

Accepted Answer

Yes — suction lift adds to static head. Suction head (positive flooded suction) subtracts.

Question 3

What's a typical velocity head?

Accepted Answer

At 5 ft/s, only 0.4 ft. At 10 ft/s, 1.6 ft. Usually negligible except for very high-velocity lines and discharge calculations.

Question 4

Why convert psi to ft?

Accepted Answer

Pump curves are plotted in ft of head, not psi. Multiplying psi × 2.31 (= 1 psi/0.433) puts everything in consistent units.

Total Dynamic Head (TDH) Calculator