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Pump and Dredge Common Terms Defined

Need to know terms of dredging and pump talk. Education Series and Common Terms Clients Use.
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Pump Terminology

Keywords you should know when you talk pumps and dredges with your friends BBQing this weekend.

Atmospheric PressureThe pressure exerted by the weight of the atmosphere, sea level has an average value of 101,325 pascals which is equal to roughly 14.6959 pounds per square inch.

Best Efficiency Point (BEP)An operating region or point along with the PPC at which the rate of flow of a pump operates at the highest or optimum efficiency for a given speed and impeller diameter.

Brake HorsePower (BHP)The measure of the force needed to brake the engine, the available power of an engine.

Booster PumpSurface pump used to increase or boost the pressure in a liquid pipeline.

Cavitation – The formation of air pockets or cavities in a liquid, occurs in areas of relatively low pressure around the impeller.

Close Coupled – A pump in which the impeller mounts directly to the pump drive shaft.

Concentration By Volume (Cv) – The volume of solids divided by the total volume of the solution. Alternatively, these can be measured by weight, sometimes called the percentage of solids.

Critical Line Velocity – The minimum rate of flow needed to keep material turbulent enough to prevent material from settling at the bottom of the discharge pipeline, potentially leading to clogging.

Cutter Hydraulic Pump Temperature – This is temperature of the hydraulic pump case temperature.

Density – The density of a liquid is defined as its mass per a set unit of volume, usually pounds per gallon. Different liquids have different densities: a gallon of water weighs more than a gallon of gasoline.

DewateringThe act of removing or displacing groundwater or surface water from a worksite, most often by directly pumping or utilizing gravity.

Discharge Head – The discharge head consists of the discharge velocity head, discharge friction head and discharge static lift.

Discharge Pressure – The discharge pressure is measured by pounds per square inch (PSI) It is an indicator of pressure in the discharge line, as the pressure changes the discharge head changes.

Effective Particle DiameterThe single or average particle size found in a slurry mixture of various sizes of particles. This figure is used to calculate pump system requirements and overall pump performance.

Elevation – The measured angle of the pipeline connected to the dredge pump. Steep elevation increases material friction and decreases velocity. Many times this measurement starts from the water level and measures to the highest point along the discharge line.

Flooded SuctionSuction pump chamber that is full of liquid because of the liquid level and pressure in the suction tank.

Flow – The measured liquid volume capacity of a pump, often expressed in gallons per minute(GPM).

Friction Loss – Friction Loss is the loss of pressure or “head” that occurs in pipe or duct flow due to the effect of the fluid’s viscosity near the surface of the pipe or duct.

Gear Temperature – Peak operating temperature should be 160° F. High temperatures can lead to premature wear/tear and part failures.

Head – The measured height at which a pump can raise water. Specifically the head discharge. The energy of a liquid in reference to an arbitrary datum that is expressed in units of energy per unit weight of liquid.

Hydraulic Oil Temperature – Measured temperature of hydraulic oil, maximum hydraulic oil should be set to between 160° F and 180° F. While the minimum oil temperature should be set to 70° F.

Hydraulic Pump Charge Pressure – The hydraulic charge pump is in charge of supplying coolant to the system while maintaining positive pressure in the main system loop. The normal operating pressure range is 350 psi and 380 psi. Pressures outside this range will not cause the pump control to operate incorrectly.

HPU (Hydraulic Power Unit)The main driving component of any hydraulic system. Comprised of a motor, a hydraulic pump, and a reservoir. Capable of producing immense power for industrial pumps and dredges.

Impeller – The rotor located inside the case of a pump. This has the purpose of increasing or decreasing the pressure and flow rate of a fluid. The recessed impeller and unique design of the EDDY Pump is what makes our pump excel while moving solids/slurry.

NPSH (Net Positive Suction Head) – Made up of two components. NPSH is available: The absolute pressure at the suction port of the pump. NPSH required: The minimum pressure required at the suction port to prevent the pump from cavitating.

Pipe Friction Loss – The loss of pressure or head that occurs in a pipe. This is due to the effect of the fluid’s viscosity near the surface of the pipe.

PLC (Programmable Logic Controller) – Ruggedized computer used for pump control. The PLC receives information from connected sensors or input devices installed on the pump, processes the data, and triggers outputs based on pre-programmed parameters.

Pressure – The force a liquid exerted on the walls of a container, such as a tank or a pump pipe. The pressure is typically measured as PSI (pounds per square inch) in the USA. The metric system, however, measures the pressure in bars, where one bar equals a standard atmosphere.

Pressure Drop – A difference in pressure due to a pressure decrease. Also, it is the loss of potential energy where typically there is friction(‘heat’) of the fluid due to flow disturbance.

Priming – The act of removing air from the volute by filling it with liquid.

Pump Curve – Typically a plot such as total head vs. flow rate. The plot is used to determine the total head of a pump when given the flow rate of the pump.

Pump Speed – The rate of speed that the impellers spin to suck the water and material into the pipeline. The speed must be increased to maintain optimal slurry velocity the farther away from the original dredging point. Pump speed refers to the Motor RPM. The RPM will vary depending on the type of material pumped. Some electric motors are fixed RPM and others can be adjusted by using a VFD.

Radial Flow – Where the fluid being pumped by a centrifugal pump is discharged radially or at right angles to the pump shaft.

Self-priming PumpA centrifugal pump that integrates a vacuum-based priming unit that removes the air from the pipeline and volute. This allows the pump to fully operate without manually priming the pump.

Service Water Pressure – The service water is measured in pounds per square inch. The service water is required to be less than the dredge discharge pressure and optimally higher than it.

Sediment – Fragmented, naturally occurring material such as silt, sand, and gravel found settled at the bottom of a body of water or other liquid.

Slurry – A semiliquid mixture, often composed of abrasives like cement, sand, or coal ash suspended in a liquid such as oil or water.

Slurry Transport – hydraulic conveying, conventional lean slurry and high concentration slurry disposal

Smart PumpA smart pump can connect to other devices to both operate the pumps and to receive diagnostic information related to the performance of the pump.

Soft Start – A device used with electrical motors to temporarily reduce the load and torque in the powertrain and electric current surge of the motor during start-up to help extend the life of the motor.

Specific Gravity(Liquid) – The ratio of the density of a liquid to the density of water at 4°C.

Static Lift/Terminal Elevation – Static lift is defined as the vertical difference between the point of discharge and surface of the water.°C.

Suction Head – Suction head is defined as the resistance to slurry flow in the suction system calculated in feet of water.°C.

Surface Feet Per Minute – Measured speed of a point of a surface in correlation to the impeller eye or outside diameter.°C.

Total Dynamic Head – The sum of the discharge head, suction head, and friction loss in a pump. Total head is also defined as the work done by the pump per unit weight, per unit volume of fluid.

Turbulence – Turbulence is produced from velocity and friction within the pipeline. Turbulence assists you in keeping materials suspended allowing for efficient travel throughout the pipeline.

Vacuum – Vacuum is defined as a unit of pressure measured by inches of mercury. Usually measures the pressure of the suction head of the pump.

Variable Frequency Drive (VFD) – A system for controlling the rotational speed of electric motors by regulating the frequency of electrical power supplied to the motor.

Variable Frequency Drive (VFD) – A system for controlling the rotational speed of electric motors by regulating the frequency of electrical power supplied to the motor.

Viscosity – A measure of the response(resistance) to gradual deformation through stress. Liquid viscosity corresponds to the ‘thickness’ of the medium.

Volute – The casing of the centrifugal pump or and EDDY Pump that receives the fluid being pumped by the impeller, and slowing down the fluid’s flow rate.

Water hammer – An increase in pressure due to fluid in motion has a sudden change in momentum(sudden change in direction).

Dredge Terminology

Auger DredgeAuger dredges incorporate an archimedean type screw which is set at 90-degree angles to the suction pipe of a dredge. The auger acts like a wide, low-turbidity cutter head in mechanically breaking up the target material and feeding the pump.

Autonomous Dredge A type of dredge that operates independently using predefined inputs.

Beach RestorationDescribes a process in which sediment is lost through erosion and is replaced with sediment gathered from dredging.

Construction Dredging – Dredging equipment that used to create trenches for tunnels and pipelines for buildings and structures.

Cutterhead – The rotating tool attached to the end of a dredge pump. Equipped with cutting teeth to help agitate and break up densely-packed sediment for feeding the pump.

Cutter Pressure – This is the temperature of the hydraulic pump case temperature.

Dredge Advance – Dredging the removal of sediments and debris from the bottom of water bodies. The sediment is either disposed of at a different location or utilized in other applications. Many times the material is pumped to a beach or marsh for restoration projects.

Dredging – Dredging the removal of sediments and debris from the bottom of water bodies. The sediment is either disposed of at a different location or utilized in other applications. Many times the material is pumped to a beach or marsh for restoration projects.

Dredging Depth – Dredging depth is the total vertical distance between the water surface and the target material.

Dredge Pump – Equipment that pumps slurry into the pipeline. The slurry is pumped from the target material through suction via the turning impellers. With the EDDY Pump we use a large open rotor that is designed to move high solids and rocks found in the dredging process.

Environmental Dredging – The use of a dredge to remove contaminated materials from bodies of water to restore water levels and efficiency by removing unwanted contaminated

Ladder – The boom that extends from the front of the dredge. The ladder is submerged below the water to reach the garget material where it utilizes a suction pipe and cutting device to agitate and pump the material.

Lake / Lagoon Dredging – Over time sediment and sludge accumulate at the bottom of the lake/lagoons causing an unsightly appearance and odor and decreasing water volume. Dredging is used to maintain optimal efficiency by removing excess built-up sediment and restoring the original capacity.

Mining Dredging – Using dredging equipment to excavate gravel, sand, coal, and other mine tailings.

Mechanical Dredging – Process of removing compacted materials such as debris or slurry with a physical agitator to break up clumped up formations. Commonly this is a bucket or clamshell deployed from a crane or boom of an excavator.

Navigational Dredging – Using dredging equipment to deepen waterways and channels. Commonly used to maintain ports, harbors, and shipping channels to maintain waterways allowing large ships and vessels can navigate.

Recreational Dredging – Dredging to maintain, deepen and expand lakes and other bodies of water to be used for recreational swimming and boating. Without maintenance dredging, accumulated sediment will make the water more shallow and disrupt boat travel.

Common Dredge and Pumping Measurements
Acres – a unit of land area equal to 4,840 square yards.

Cubic Meter – m3 a unit of volume equal to a cube one meter long on each side

Cubic Yards – yd3 A unit of volume equal to a cube one yard long on each side

GPM – Stands for gallons per minute, also known as flow rate. GPM is a standard measurement for dredging and pumping applications for the desired flow rate of the material.

Tons of material – A unit of weight equivalent to 2,000 pounds

Cubic Meter (M3) Formula – yd3 x 1.308

Cubic Yard (Y3) Formula – Length (in feet) x Width (in feet) x Depth (in feet) ÷ 27

How Eddy Pump Works


cut-away-view-slurry-pumpA look inside the EDDY Pump

Grit Pump for Wastewater

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Why EDDY Pumps Are Better – Highlights

This video shows how EDDY Pump transports high slurry and abrasive materials. Featured dredge pump equipment includes the Remote Operated Subdredge, Diver Operated Pump and a Excavator Attachment Dredge Pump.