Calculate Total Dynamic Head (TDH) and required pump power for centrifugal and positive displacement pumps.
Pump head is the energy per unit weight of fluid that a pump must deliver to move flow from the suction reservoir to the discharge, expressed in meters or feet of fluid column. This calculator computes total dynamic head from elevation difference, pressure difference, velocity head, and friction losses using the steady-state energy (Bernoulli) equation, which lets you select a pump curve that meets the system curve at the design operating point.
Bernoulli: H = (P₂ − P₁) / (ρg) + (v₂² − v₁²) / (2g) + (z₂ − z₁) + h_f, where the terms are static (pressure) head, velocity head, elevation head, and friction head. Velocity head is usually negligible in industrial systems unless one side is open to atmosphere. Friction head h_f comes from the Darcy–Weisbach pressure drop converted to head: h_f = ΔP_friction / (ρ × g). The calculator returns head in meters of fluid; convert to bar with H_m × ρ × g / 10⁵ or to psi with H_ft × specific_gravity / 2.31. Pump shaft power P = (Q × H × ρ × g) / η_p where η_p is overall pump efficiency, typically 60–80% for centrifugal pumps.
A facilities engineer sizes a circulating pump for 30 m of vertical lift, 3 bar discharge pressure, and 12 m of friction loss on a 50 m/m³ piping run, totalling 75 m head at 200 m³/h — then matches to a 200 kW vertical inline pump from the catalog.
A process technician verifying a transfer pump from an atmospheric tank to a 6 bar receiver computes 60 m pressure head + 8 m elevation + 5 m friction = 73 m total, and confirms the existing pump still meets the duty with a 10% margin.
A maintenance supervisor estimating sump-pump head requirement for a 7 m vertical discharge applies the energy equation, including pipe friction at 200 lpm, to confirm the in-stock pump curve meets the duty point.
Head is independent of fluid density, so a pump that develops 30 m of head delivers 30 m of water column, 30 m of oil column, or 30 m of glycol column at the same shaft RPM. This makes catalog selection straightforward.
Pressure (bar) = head (m) × specific gravity / 10.2. Or pressure (psi) = head (ft) × specific gravity / 2.31. Water has SG = 1.0; light oil 0.85-0.9; heavy oil 0.95.
Friction head scales as v² (and v scales linearly with flow at fixed pipe size), so doubling flow quadruples friction head. This is the shape of the system curve, which crosses the pump curve at the operating point.