Pump Hydraulic Sizing & Selection - Practical & Proven

Define pump head as the net work on liquid, including static, velocity, and friction heads, and show how atmospheric, gauge, vacuum, and absolute pressures convert to head.

Select the right pump by calculating total head, verifying NPSH to prevent cavitation, and plotting system and pump curves to find the operating point.

Compute static head and total pump head by analyzing suction and discharge elevations, using the pump center point as the datum, and illustrate positive, negative, and zero static head.

Calculate pressure head as the discharge head minus the suction head, converting pressure to head, illustrated with atmospheric references and a 4 psig example.

Learn to calculate velocity head in pump hydraulics by linking flow, area, and velocity to kinetic energy, using Hv = V^2/2g, with a 4-inch sch40 pipe example.

Compute total pump head by decomposing into static, pressure, velocity, and friction heads for a water system, including fittings and equipment losses, via Reynolds number and Moody chart guidance.

Learn how pump efficiency measures energy from the liquid relative to shaft power. Apply the centrifugal pump efficiency formula: flow times head times specific gravity divided by shaft power.

Compute pump power using hydraulic, brake, and motor power steps with imperial formulas for flow, head, and specific gravity, then learn how to size a motor just above the calculation.

Explore net positive suction head concepts, calculate the available NPSH for centrifugal pumps, and compare it to the required NPSH to prevent cavitation.

Compare available NPSH to the pump's required NPSH to prevent cavitation, ensuring NPSHA is at least 10% higher than NPSHR, demonstrated with a 4.5 ft NPSHR example yielding 4.95 ft.

Cavitation occurs when the pump's absolute pressure drops below the liquid's vapor pressure, forming and collapsing vapor bubbles that wear internal parts, degrade efficiency, and cause noise and vibration.

Calculate NPSHA from suction pressure, static head, vapor pressure, and friction losses, then compare to NPSHR to prevent cavitation and explore adjustments to reach 2.75 m.

Understand how pump performance curves reveal head versus flow, efficiency, and NPSHR to avoid cavitation, with standardized flow on the x-axis across HQ, efficiency, BHP, and NPSHR curves.

Explore how the brake horsepower (BHP) curve links flow rate to motor power and why selecting a motor that meets the maximum BHP prevents overload.

Explore variable elevation in a pumping system by plotting two system curves for suction tank levels Hs1 and Hs2, defining the operating range for efficient, safe operation.

Introduce the pump affinity law and its two primary formula sets, showing how changes in speed or impeller diameter affect flow, head, and power for practical pump design.

Learn practical centrifugal pump sizing through benzene transfer, computing total head, NPSH available, interpreting system curves, and determining operating points to judge pump suitability.

Show how a VFD optimizes a centrifugal pump per affinity law, shifting flow from 1000 to 700 m3/h and cutting power from 190 kW to 65.2 kW, delivering energy savings.