Comprehensive reference guide to wastewater pump terminology, technical definitions, and industry-specific terms for professionals and engineers.
Mathematical relationships that describe how pump performance characteristics (flow, head, and power) change with impeller diameter or rotational speed. Used for pump performance prediction and scaling calculations.
Pump design where fluid flows parallel to the shaft axis. Also called propeller pumps, these are used for high-flow, low-head applications such as large lift stations and flood control.
The absolute pressure at the pump suction minus the vapor pressure of the fluid being pumped, expressed in feet of fluid. Must exceed required NPSH to prevent cavitation.
The operating point on a pump curve where the pump operates at maximum efficiency. Pumps should be selected to operate at or near BEP for optimal performance and longevity.
The actual power required to drive a pump, measured at the pump shaft. Calculated by dividing water horsepower by pump efficiency.
A measure of the amount of oxygen required by microorganisms to decompose organic matter in wastewater. Important parameter for treatment plant design and pump selection.
Formation and collapse of vapor bubbles in a pump due to insufficient NPSH. Causes noise, vibration, performance degradation, and potential damage to pump components.
A rotodynamic pump that uses a rotating impeller to increase the velocity of a fluid. Kinetic energy is converted to pressure energy in the volute or diffuser.
Specialized wastewater pump with cutting blades that mechanically reduce solids and debris before pumping. Prevents clogging and protects downstream equipment.
Pump configuration where the impeller is mounted directly on the motor shaft, eliminating the need for a separate coupling. Common in smaller pumps.
The vertical distance from pump centerline to the point of free discharge, plus any additional pressure requirements in the discharge system.
Non-submersible pump installed in a dry chamber with flooded suction from a wet well. Offers superior efficiency and maintenance access compared to submersible pumps.
The pressure energy of a moving fluid, including velocity head and pressure head. Component of total dynamic head calculation.
The ratio of useful hydraulic power output to mechanical power input, expressed as a percentage. Higher efficiency pumps consume less energy for the same work.
Pump designed for clear water or low-solids wastewater applications, typically used for septic tank effluent or clarified wastewater.
Centrifugal pump configuration where fluid enters axially through the suction nozzle and exits radially through the discharge nozzle.
Level control device that automatically starts and stops pumps based on liquid level in wet wells or tanks. Essential for automatic pump operation.
Suction condition where the liquid level is above the pump centerline, providing positive suction head. Required for most centrifugal pumps.
Volume of fluid pumped per unit time, typically expressed in gallons per minute (GPM) or cubic meters per hour (m³/h).
Head loss due to friction between moving fluid and pipe walls. Calculated using Darcy-Weisbach or Hazen-Williams equations.
Submersible pump with cutting mechanism that grinds solids into small particles before pumping. Used in pressure sewer systems and residential applications.
Measure of water usage per person per day. Used in municipal system design to estimate wastewater generation rates.
Energy per unit weight of fluid, expressed in feet of fluid. Represents the energy that a pump must add to move fluid through a system.
Empirical factor used in the Hazen-Williams equation to calculate friction losses in pipes. Varies with pipe material and condition.
Trade association that develops pump industry standards, test procedures, and performance guidelines widely used in pump selection and specification.
Rotating component of a centrifugal pump that imparts kinetic energy to the fluid. Design variations include open, semi-open, and closed types.
Extraneous water entering sewer systems through direct connections (inflow) or soil infiltration through defective pipes and joints.
Pump configuration where suction and discharge nozzles are in line, allowing installation directly in the piping system without additional fittings.
Small pump that maintains system pressure and handles minor flows, allowing larger main pumps to cycle less frequently.
Unit of electrical power equal to 1,000 watts. Used to measure pump motor power consumption and calculate energy costs.
Pumping station that lifts wastewater from a lower to higher elevation in collection systems where gravity flow is not possible.
Total cost of ownership including initial purchase, installation, energy, maintenance, and disposal costs over the equipment's useful life.
Sealing device that prevents leakage along the pump shaft. Consists of rotating and stationary faces with springs to maintain contact.
Pump design with characteristics between centrifugal and axial flow pumps. Fluid exits the impeller with both radial and axial velocity components.
Power rating of the electric motor driving the pump. Must be sufficient to handle maximum expected brake horsepower plus safety margin.
Measure of energy available at the pump suction to prevent cavitation. NPSH Available must exceed NPSH Required for proper operation.
Impeller design with large passages and minimal restrictions to allow solids and debris to pass through without jamming.
Impeller design without shrouds, allowing easy inspection and adjustment of clearances. Common in wastewater applications for solids handling.
Intersection of pump curve and system curve, representing actual flow and head conditions during operation.
Graphical representation of pump performance showing relationships between flow rate, head, efficiency, power, and NPSH.
Pump that moves fluid by trapping fixed amounts and forcing them through the discharge. Examples include progressive cavity and diaphragm pumps.
Positive displacement pump using a helical rotor and stator to move fluid. Excellent for high-viscosity fluids and sludges.
Maximum head that a pump can develop at zero flow. Represented by the y-intercept of the pump curve.
Sludge returned from secondary clarifiers to aeration tanks in activated sludge treatment process. Requires gentle pumping to preserve floc structure.
Flow pattern in centrifugal pumps where fluid enters axially and exits radially. Most common design for wastewater applications.
Dimensionless parameter that characterizes pump geometry and performance. Used to classify pump types and predict characteristics.
Vertical distance between suction and discharge liquid levels. Does not include friction or minor losses.
Pump designed to operate completely submerged in the fluid being pumped. Motor and pump are in sealed enclosure.
Vertical distance that a pump must lift fluid from suction source to pump centerline. Limited by atmospheric pressure and NPSH requirements.
Graphical representation of system head requirements versus flow rate. Intersection with pump curve determines operating point.
Total energy that a pump must add to move fluid through a system. Includes static head, friction losses, and minor losses.
Measure of solid particles suspended in wastewater. Important parameter for pump selection and treatment process design.
Ratio of maximum to minimum flow rates at which a pump can operate efficiently. Important for variable flow applications.
Vertical hydraulic force acting on pump impeller due to pressure differences. Must be considered in bearing and thrust bearing design.
Electronic device that controls motor speed by varying electrical frequency. Used for energy savings and flow control.
Kinetic energy of moving fluid, calculated as V²/2g. Usually small component of total dynamic head in pump systems.
Multi-stage centrifugal pump with vertical shaft configuration. Used for high-head applications and deep well pumping.
Spiral-shaped pump casing that collects fluid from impeller and converts velocity energy to pressure energy.
Specialized pump design where impeller is recessed from main flow path, allowing large solids to pass through with minimal contact.
Theoretical minimum power required to pump fluid, assuming 100% efficiency. Calculated as (Q × TDH × SG) ÷ 3960.
Excess sludge removed from activated sludge treatment process to maintain desired solids retention time.
Replaceable component that provides close clearance between impeller and casing, minimizing internal recirculation.
Underground chamber that collects wastewater before pumping. Sized to provide adequate storage and prevent short cycling.
Overall efficiency of pumping system from electrical input to hydraulic output. Includes pump, motor, and drive efficiencies.
There are currently no wastewater pump terms beginning with the letter X in this glossary.
Minimum stress required to initiate flow in non-Newtonian fluids such as sludges. Important consideration for sludge pumping applications.
Area around a pump intake where flow patterns may affect pump performance. Important for wet well design and multiple pump installations.