Water Pumping Costs

Overview

Engineering reference data for Water Pumping Costs in pumps.

Key Formulas

Pump Power

$P = \frac{Q \cdot H \cdot \rho \cdot g}{\eta}$

Hydraulic power / efficiency.

NPSH Available

$NPSH_a = \frac{P_s}{\rho g} + \frac{v_s^2}{2g} - \frac{P_v}{\rho g}$

Net Positive Suction Head available.

Affinity Laws

$Q \propto n, \quad H \propto n^2, \quad P \propto n^3$

Flow, head, power vs speed.

Variables

Example Calculation

Given:

• Volume flow (Q): 10 US gpm
• Differential head (h): 10 ft
• Electricity cost rate (c): 0.1 USD/kWh
• Pump efficiency (μp): 0.9 (90%)
• Motor efficiency (μm): 0.9 (90%)

Using the Imperial formula:

$C = \frac{0.746 \cdot Q \cdot h \cdot c}{3960 \cdot \mu_p \cdot \mu_m}$

$C = \frac{0.746 \times 10 \times 10 \times 0.1}{3960 \times 0.9 \times 0.9} = 0.002 \text{ USD/hour}$

Unit Conversions

These conversions allow you to switch between Imperial and Metric calculation methods. When using metric units, ensure density is set to 1000 kg/m³ for water and gravitational acceleration to 9.81 m/s².

References

• Original Source