How do I get friction head Hf from piping?

Run the Pressure Drop & Friction calculator for suction + discharge ΔP, then convert Hf = ΔP / (ρ g). Include fittings and strainers.

What does HI 14.3 cover here?

ANSI/HI 14.3 is the Hydraulic Institute standard for rotodynamic pump hydraulic performance acceptance. This app uses the same power/η language for field screening, not a formal witness test.

How is motor size chosen?

Motor input ≈ brake power / η_m. The app multiplies by service factor SF (default 1.15), then picks the next IEC kW (metric) or NEMA HP (imperial) ≥ that sizing basis.

Total Dynamic Head (TDH) & Pump Power — Seawater 100 m³/h · Hs 20 m · Hf 6 m | FieldEngineersKit

Parameter	Value
Service fluid	Seawater

Engineering Reference & ASME Code Basis

1. Core Formula & Variable Definitions

Hydraulic Institute ANSI/HI 14.3 — Rotodynamic Pumps for Hydraulic Performance Acceptance Tests · Affinity / classical BHP sizing practice (US customary & SI) · IEC 60034 motor kW ratings · common NEMA HP frames (recommendation only)

TDH = Hs + Hf + Hp

BHP = Q·TDH·SG / (3960·η_p) · P = ρ·g·Q·TDH / η_p

Hydraulic Institute ANSI/HI 14.3 · affinity / duty sizing (screening)

Standard HI 14.3Hero TDHPower BHP / kWMotor IEC · NEMA · SF

TDH is the total head the pump must develop: static elevation Hs (may be negative downhill), friction Hf (from Darcy ΔP → head), and pressure head Hp = (Pd−Ps)/(ρg). Brake power divides hydraulic power by pump efficiency η_p. Motor input divides brake power by motor efficiency η_m; the app multiplies by motor service factor SF (default 1.15) then recommends the next IEC kW or NEMA HP rating. HI 14.3 is the hydraulic performance acceptance context — not a guaranteed datasheet.

Hs (Static head) — Discharge elevation − suction elevation (negative if downhill / gravity-assisted).
Hf (Friction head) — Pipe + fittings + strainer losses (convert ΔP/(ρg) from Pressure Drop tool).
Hp (Pressure head) — (Pd − Ps)/(ρ g). Often ≈ 0 for open tanks at atmosphere.
TDH (Total dynamic head) — Hs + Hf + Hp — head the pump must develop at the duty flow.
η_p (Pump efficiency) — Hydraulic efficiency at the operating capacity from the OEM curve.
BHP (Brake horsepower) — Shaft power = Q·TDH·SG/(3960·η_p) (gpm·ft) or ρ·g·Q·H/η_p (SI).
SF (Motor service factor) — Multiplier on estimated motor input before IEC/NEMA pick (typical field default 1.15).

2. Allowances, Tolerances & Standards

Use OEM η_p at the actual duty point. Motor recommendation = next standard rating ≥ (brake/η_m)×SF.

Friction HfFrom ΔP/(ρ g)

Estimate piping ΔP with the Pressure Drop calculator, convert to head, include fittings.

Pump η_pCurve at Q

Do not use BEP efficiency if the duty is far off BEP — power rises when η drops.

Motor pickNext standard ≥ input×SF

IEC kW or NEMA HP ≥ estimated motor input × service factor (default SF 1.15).

ViscosityNo HI derate here

Viscous services need HI / OEM viscosity correction charts — not applied in this app.

Quick Reference Lookup Table

Illustrative water duties (this app, η_p ≈ 0.70–0.75, η_m = 0.92, SF = 1.15)
Case	TDH	Focus
Water 50 m³/h · Hs 20 m · Hf 5 m	25 m	Default metric · ~7.5 kW IEC @ SF 1.15
Water 100 m³/h · Hs 40 m · Hf 10 m	50 m	Higher head
Water 100 GPM · Hs 60 ft · Hf 15 ft	75 ft	Default imperial case
Seawater 50 m³/h · Hs 15 m · Hf 5 m	20 m	Higher SG → more BHP
Light HC 40 m³/h · Hs 30 m · Hf 6 m	36 m	Lower SG → less BHP

3. Material & Code Limitations

Clean liquid centrifugal / rotodynamic screening. Not for positive-displacement volumetric power models or multiphase flow.

Material Group	Temperature Range	Allowable Stress / Limit	Engineering Notes
Water / seawater / condensate	Ambient screening densities	N/A — hydraulic power	Use project fluid properties when temperature shifts density significantly.
Light hydrocarbon	Screening SG	Lower BHP vs water	Confirm vapor pressure / NPSH separately — TDH does not check cavitation.
Viscous liquids	μ ≫ 1 cP	HI derate required	This tool does not apply HI viscosity correction charts.

Code Applicability & Safety Boundaries

Field screening only — not HI 14.3 acceptance test documentation.
Motor recommendation applies the entered service factor (default 1.15); set SF = 1.0 to size on raw motor input.
Velocity head differences and complex control-valve losses must be folded into Hf/Hp by the user.
Export / PDF is a duty sizing sheet — not a stamped pump datasheet.

4. Step-by-Step Worked Example

Field VerificationShow

Step-by-Step Worked Example: Water 50 m³/h · Hs 20 m · Hf 5 m

Screen TDH and brake power for a fresh-water centrifugal pump at 50 m³/h, static elevation 20 m, friction 5 m, open tanks (Hp = 0), η_p = 70%, η_m = 92%, motor SF = 1.15 (HI 14.3 / affinity screening).

Flow Q:50 m³/hFluid:Water · ρ ≈ 998 kg/m³ · SG ≈ 0.998 (ref 1000)Hs / Hf / Hp:20 m / 5 m / 0 mη_p / η_m / SF:70% / 92% / 1.15

Form TDH

TDH = H_{s} + H_{f} + H_{p}

TDH = 20 + 5 + 0 = 25 m.

Result:TDH = 25 m

Hydraulic & brake power

P_{hyd} = ρ g Q H, P_{brake} = P_{hyd} / η_{p}

Q = 50/3600 m³/s · ρgQH ≈ 3.40 kW hydraulic · /0.70 ≈ 4.86 kW brake (≈ 6.5 HP).

Result:Brake ≈ 4.9 kW (≈ 6.5 HP)

Motor input × SF & standard rating

P_{sized} = (P_{brake} / η_{m}) \cdot SF

4.86 / 0.92 ≈ 5.3 kW input · ×1.15 ≈ 6.1 kW sizing basis → next IEC rating 7.5 kW.

Result:Recommend 7.5 kW (IEC)

Open /water-50m3h-hs-20m-hf-5m for the live default case. Pair with Pressure Drop for Hf and NPSH for suction margin.

Conclusion: For 50 m³/h water against 25 m TDH at 70% pump efficiency, expect roughly 5 kW shaft power and a 7.5 kW IEC motor screen at SF 1.15 — confirm on the OEM curve and project motor SF.

5. Frequently Asked Questions & Technical References

Show

Total Dynamic Head is the head the pump must develop at the duty flow: TDH = Hs + Hf + Hp (static + friction + pressure head).