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Tags: Pump Hydraulic Motor

Pumps are mechanical devices that are used to move fluids (liquids or gases) from one location to another.  They come in many different types and sizes, depending on the specific application and requirements and work by creating a pressure difference that forces the fluid to flow in a specific direction.  Pumps can be powered by various sources, such as electric motors, internal combustion engines, or steam turbines.  They can also be designed for different levels of pressure, flow rate, and viscosity, depending on the specific application.

The specific function of a pump depends on the type and design of the pump, as well as the specific application.  For example, centrifugal pumps are commonly used in industrial applications and HVAC systems to circulate water or other fluids, while positive displacement pumps are often used in chemical processing or oil and gas production to move viscous or abrasive fluids.

Pumps play a critical role in many industries and applications, such as in water and wastewater treatment, oil and gas production, and food and beverage processing.  Regardless of the type or application, pumps are essential for many industrial processes and infrastructure systems.  They must be designed, installed, and maintained properly to ensure their safe and efficient operation.


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Pump Index


Pump Design Classification

  • Gas and Vapor Movers
    • Kinetically Driven Pump  -  Energy is continuously added to increase the fluid velocities within the pump to values greater than those occurring at the discharge, so subsequent velocity reduction within or beyond the pump produces a pressure increase.
      • Rotary
        • Axial Fan  -  These fans usually have three to five blades that have a slight curve to them in order to direct the moving air forward. They pull air from directly behind the blades and push it forward, allowing users to pull air out of one location and push it into another.
        • Centrifugal Fan and Blower
        • Mixed-flow Fan and Blower
      • Nonrotary
        • Ejector or Recompressor
    • Positive Displacement Pump -  Fluid moves by trapping a fixed amount and displacing that trapped volume into the discharge pipe.  Some pumps use an expanding cavity on the suction side and a decreasing cavity on the discharge side.  The volume of liquid is constant for each operational cycle.
      • Rotary
        • Liquid Ring Vacuum Pump
        • Lobe Compressor and Vacuum Pump
        • Vane Compressor and Vacuum Pump
        • Screw Compressor
      • Nonrotary
        • Reciprocating Compressor  -  Compressors are mechanical devices used to intentionally increase the pressure of a air.  This compressor consist of a piston driven by a crankshaft enclosed within a cylinder.  The typical reciprocating air compressor is also comprised of suction and discharge valves.  These type of compressors operate by drawing fluid into a fixed-volume chamber by a mechanical component which physically displaces the air.
  • Liquid Movers
    • Kinetically Driven Pump  -  Energy is continuously added to increase the fluid velocities within the pump to values greater than those occurring at the discharge, so subsequent velocity reduction within or beyond the pump produces a pressure increase.
      • Rotary
        • Axial Pump  -  A pump where a case is split parallel to pump shaft.  These pumps are used in high flow and low head applications.  They are suitable for both low and high pressure, and are specially designed to handle severe pumping conditions.
        • Centrifugal Pump  -  A very basic piece of equipment in the oil field.  This type of hydraulic pump is used to transform the mechanical energy of a propeller or turbine into kinetic energy or pressure to an uncompressible fluid.  The centrifugal pump thus converts the energy with which it is worked, in this case mechanical, into hydraulic energy.
        • Mixed-flow Pump  -  Since the shape of the impeller of the mixed flow pump is between the centrifugal pump impeller and the axial flow pump impeller, the working principle of the mixed flow pump has both centrifugal force and lift.  The impeller sits within the pipe and turns, but the turning mechanism is essentially diagonal, using centrifugal force to move the water along while accelerating it further with the push from the axial direction of the impeller.  This creates enough force to generate high rates of flow.
      • Nonrotary
        • Jet Eductor  -  This pump works by pumping pressurized fluid through a nozzle in the eductor, creating a partial vacuum on the suction side of the eductor.  Liquid or vapor is then pulled up into suction tube that is attached to the suction side of each eductor.  The recovered liquid or vapor is carried along by the pressurized fluid, and the mixture is discharged through the eductor to discharge piping.
    • Positive Displacement Pump  -  Fluid moves by trapping a fixed amount and displacing that trapped volume into the discharge pipe.  Some pumps use an expanding cavity on the suction side and a decreasing cavity on the discharge side.  The volume of liquid is constant for each operational cycle.
      • Rotary
        • Gear Pump  -  This pump uses the meshing of gears to pump fluid by displacement. Due to their simplicity, versatility and their high reliability they are one of the most common types of pumps for hydraulic fluid power applications.  External gear pumps include two external gears (inside the pump housing), one being a drive gear and the other being an idler gear.  Internal gear pumps include one external gear and one internal gear located inside the external gear (both inside the pump housing).
        • Peristaltic Pump  -  They are typically used for pumping caustic, abrasive, or sensitive fluids and are ideal for long runs with continuous flow.  This pump can be used to deliver a precisely measured volume, specific load of liquid material.  Variable speed peristaltic pumps are used for continuous pumping at a variety of motor speeds.  The flexible tube is compressed between the pump housing and the rollers.  The rollers are housed within the pump head.  The compressed portion of the tube forces the liquid material through the tube, which delivers the desired dose of fluid.
        • Progressive Cavity Pump  -  It features a suction inlet which feeds into an elongated casing.  Within this casing sits a helical worm rotor and stator assembly.  The rotor helix is shaped off-set to the stator creating cavity spaces in the assembly which are formed by temporary seals as the rotor contacts the surface of the stator.  As the rotor begins to move in an eccentric fashion, the cavities form, draw in product and are progressed along the assembly and the product is expelled through the discharge port.    
        • Screw Pump  -  These pumps are rotary, positive displacement pumps that use one or more screws to transfer fluids along an axis.
          • Single Screw Pump  -  Has a single pumping element (screw) that rotates within a stationary.  The individual turns of the screw seal a set volume of fluid by direct contact, with the stator.  The stator has a shape that corresponds to the outside surface of the screw.  The interference fit between the screw or pumping element and the flexible stator create a unique pump design that can handle a variety of fluid characteristics, including high levels of solids and variable viscosities.
          • Two Screw Pump  -  This pump has two shafts.  However, a two screw pump can also be considered a four screw pump if it is a double suction design (two opposing sets of screws pumping towards the discharge).  The pumping element of a two screw pump consists of two intermeshing screws rotating within a stationary housing that is shaped like a figure eight.
        • Vane Pump  -  This pump delivers a constant flow rate under different pressure conditions because it pressurizes the fluid due to the impact of the vanes.  It has a different number of vanes installed on a rotor that moves in the cavity.  Sometimes, these vanes can be of variable length and tensioned to uphold contact with the wall as the pump derives.  The pump also has a pressure relief valve that stops pressure build-up inside the pump that could break the pump.
      • Nonrotary
        • Reciprocating Pump
          • Diaphragm Pump  -  It is a pump that uses a combination of the reciprocating action of a diaphragm and a series of check valves to pump a fluid.  The membrane is mechanically pushed and pulled in and out of a pumping chamber.  When the diaphragm is collapsed all of the air is forced out of the diaphragm chamber.  When the diaphragm is extended the slurry, or whatever is being pumped, is sucked into the diaphragm chamber through the intake line.  The slurry will be discharged out of the discharge line.
          • Piston Pump  -  It is one of the oldest styles of pumps that is still in use.  Its design is very simple.  A piston moves in and out of a cylinder.  This type of pump is often used for high pressure applications and hydraulic systems.  It is capable of pumping high viscosity fluids and fluids which contain solids.
          • Plunger Pump  -  Used at wastewater treatment plants, car washes, food processing plants, and in the oil and gas industry to regulate the flow of fluids.  It consists of two valves mounted in a pumping chamber that controls the action of a plunger into a suction force or discharge force.  The design of the machine allows solids to flow freely without clogging the system.


Nomenclature & Symbols for Engineering, Mathematics, and Science

Pump Glossary


  • Affinity Laws  -   The mathematical relationship between the several variables involved in pump performance.  They apply to all types of centrifugal and axial flow pumps.
  • Alignment  -  The centerline of the pump is perfectly aligned with the centerline of the driver.
  • Anti-friction Bearing  -  Usually referring to a ball or roller bearing.
  • Anti-rotation Device  -  A device that prevents one rotating piece from rotating with respect to a second adjacent part. Usually designed as a pin or key.
  • Anti vortex Plate  -  It prevents the formation of a vortex at intake suction points by increasing the path length.  Vortexes can cause disturbances at vertical intakes by allowing air to enter the system along with the fluid being pumped.
  • Axial Split Casing  -  A casing for a pump that is manufactured in two halves and joined. The join runs along the axis of the pump.
  • Axial Thrust  -  The resultant of all axial forces, in direction of the pump shaft, acting in the pump rotor.
  • Axial Thrust Balancing  -  An impeller wants to move in an axial direction with a lot of force.  This is a method by which the axial thrust is balanced to minimize bearing loads.


  • Back Plate  -  Used in some centrifugal pumps to position the stuffing box and provide an impeller wear surface.
  • Back Vane  -  A radial narrow vane located on the back shroud of an impeller and is designed to balance axial thrust.
  • Balance Holes  -  Holes in the back shroud of an impeller designed to balance axial thrust.
  • Balance Seal  -  A design in which the seal face closing area is reduced to lower the closing force, and reduce the heat generation between the faces.
  • Base Plate  -  The plate on which the pump and motor are mounted.
  • Bearing  -  Supports the rotating shaft and allows it to turn with a minimum amount of friction.
  • Bernoulli's Equation  -  A way of describing the conservation of energy principle in an incompressible fluid.
  • Bowl  -  In multi-stage vertical turbine pumps, the bowl is the casing of one of the stages.
  • Buffer Fluid  -  The fluid used between the two mechanical seals of a double seal (see barrier fluid).
  • Buffer Seal  -  The low pressure fluid that is circulated between dual mechanical seals.
  • Bushing  -  A close fitting support device is used to restrict flow between two liquids, thermally isolate a hot liquid, support the rotating shaft, break down pressure, etc.


  • Cartridge Seal  -  A self contained assembly containing the seal, gland, sleeve, and both stationary and rotating seal faces.  Usually needs no installation measurement.  Must be used in a pump with impeller clearance adjustments are made.
  • Cavitation  -  The creation and collapse of bubbles in a liquid.  Localized cavities of vapor form on the low pressure side of the pump (suction) and collapse on themselves as energy is added to the fluid.

  • Cavitation Number  -  The relationship between the difference of a local absolute pressure from the vapor pressure and the kinetic energy per volume.
  • Centrifugal Force  -  When a force pushes away from the center of a circle, but this does not really exist.  When an object travels in a circle, the object always wants to go straight, but the centripetal force keeps the object traveling along an axis of rotation.
  • Closed Impeller  -  An impeller whose vanes are completely enclosed by two shrouds, one on the front and one on the back.
  • Composite  -  In the context of mechanical seals, it refers to either a non-metallic material or a combination of a non-metallic face inserted into a metallic base material.
  • Concentricity  -  The motor shaft and the pump shaft share the same centerline they are concentric to each other.


  • Discharge Pipe  -  The pipe that exits the wet well or valve box.
  • Drawdown  -  The distance that the water level in the well is lowered by pumping.  It is the difference between the static water level and the pumping level.
  • Dry Running  -  In the absence of liquid, flow parts running.
  • Dual Seal  -  Two seals running in various configurations: back to back, tandem, face to face, or concentric.
  • Dynamic Elastomer  -  The elastic components of the seal that must compensate for seal face wear or shaft movement. Usually made of rubber or other elastic polymer.
  • Dynamic Head  -  The dynamic head is the component of the total dynamic head caused by friction in the system, due to interaction of the process fluid with the pipe walls.
  • Dynamic Unbalance  -  A situation where the axis of inertia of a rotor or impeller, is not coincident with its geometric axis.


  • Elevation  -  A vertical distance up or down from a fixed point.
  • Enthalpy  -  The sum of internal energy changes in heat under constant pressure of the system.
  • Expeller  -  A type of gland seal that reduces the bypass pressure from the pump into the gland or rotary sealing area of the pump.
  • Eye of the Impeller  -  The center of the impeller, where the fluid enters.


  • Face-to-face Seals  -  Two seals running against a common seal face.  The barrier fluid pressure is always lower than stuffing box pressure.
  • Face Lubrication  -  The fluid or vapor that exists between lapped mechanical seal faces.
  • Flooded Suction  -  The liquid flows to the pump inlet from an elevated source by means of gravity.  This is generally recommended for centrifugal pumps.
  • Friction  -  The mechanical resistance to the relative movement of two surfaces.  The frictional force on each body is in an opposite direcrion to the motion of the other body.
  • Friction Loss  -  How much loss of flow through a pipe is due to the viscosity, the measure of the internal friction/resistance to the flow of a liquid near the surface of the pipe.   


  • Galling  -  A situation where two moving parts that are in close contact, seize and are bonded together.
  • Gland  -  A component of a mechanical seal that attaches to the stuffing box.
  • Gland Packing  -  A dynamic sealing device that generates a compression force between the packing and the rotating part and the fixed part through the self-tightening effect of pre-tightening or medium pressure.


  • Head Loss  -  A pressure loss due to the resistance of the fluid and obstructions along the way in a pipe.
  • Head Pressure  -  The pressure at a specific point to the vertical distance at another specific point.
  • Heating Jacket  -  Used to maintain a constant product temperature or temperature range while the fluid flows through the pump.
  • Hydraulic Balance  -  A method of reducing mechanical seal face loading by reducing the seal face closing area.
  • Hydraulic Gradient Flow Rate  -  Measure the amount of fluid that flows in a given time past a specific.


  • Impeller  -  The portion of a centrifugal pump that does the work.  Water enters the impeller and is accelerated across the vanes.
  • Impeller Eye  -  The centre of the impeller or the point where fluid enters the impeller.
  • Impeller Shroud  -  The plates located on one or both sides of the impeller vanes.  Prevents solids from penetrating behind the vanes.
  • Impeller Vane  -  Located between the eye and the discharge side of the impeller.  Directs the flow of the liquid to the outside diameter of the impeller.


  • Journal  -  The proportion of the main shaft that is supported by a plain bearing.
  • Journal Bearing  -  A plain, sleeve or sleeve-shaped bearing used to support a shaft.
  • Journal Box  -  A casing or housing that contains the journal and the journal bearing.



  • Lag Pump  -  A succeeding or backup pump in a pump system.
  • Lead Pump  -  The first pump to start in a pump cycle.
  • Liquid End  -  A term referring to the side or parts of the pump that come into contact with the process fluid.  This applies to any air operated pump including air operated diaphragm pumps, air operated piston pumps and air operated drum pumps.


  • Magnetic Drive  -  This is a method of connecting the motive force to the pump which uses a series of magnets coupled together, with a containment chamber separating them. Magnetic drives keep the fluid sealed from atmosphere and other environmental factors and eliminate the need for seals and seal maintenance.
  • Mechanical Efficiency  -  The ratio of theoretical power the pump needs to operate to the actual power delivered to the pump itself.
  • Mechanical Seal  -  Mechanical assembly that forms a leak proof barrier between flat, rotating surfaces to prevent high-pressure leakage.


  • Net Positive Suction Head  -  Total suction head in meters (feet) of liquid absolute determined at suction nozzle and referred to datum elevation, minus the vapor pressure of liquid in meters (feet) absolute.


  • Open Impeller  -  Impellers designed without front, outer, shrouds.
  • Operating Box  -  Measured after the seal has been compressed the proper amount.  The measurement is usually made from the face of the stuffing box.
  • Overall Efficiency  -  The ratio of the output of actual power to the input of actual power.  It determines the amount of energy lost overall.
  • Overload Protection  -  The effect of a device operative on excessive current, but not necessarily on short circuit, to cause and maintain the interruption of current flow to the device being governed.
  • Overload Relay  -  A relay that responds to electric load and operates at a preset value of overload. The unit senses the current in each line to the motor and is either bimetallic, melting alloy or solid state actuated. It may be of the non-compensated or ambient-compensated type, and of a standard or fast-trip design.


  • Peak Factor  -  A variable multiplier used with average flow to determine required pump capacity for wastewater lift stations or potable water booster stations.  Variation is determined by the size and type of facility.
  • Performance Curve  -  A graph depicting the plot of total head vs flow rate for a specific pump, with a specific impeller and set of characteristics
  • Potential Energy  -  The possessed energy by a body due to its relative position in a gravitational field.  As the elevation of the body decreases the less potential energy.
  • Power Factor  -  The ratio between the amount of consumed power and the amount of absorbed or returned power.
  • Pressure  -  The force exerted perpendicular to the surface of an object and is expressed as force per unit area.
  • Pulsation  -  In principle, every diaphragm pump generates a continuous sequence of individual pump pulses.  The pressure fluctuations in the pumped medium caused by these cyclical diaphragm movements.


  • Quill Shaft  -  A shaft that is hollow, containing another shaft inside of it.


  • Reynolds Number  -  The ratio of inertial forces (forces that remain at rest or in uniform motion) to viscosity forces (the resistance to flow).


  • Scum  -  Floating matter which rises to the surface of a liquid and forms a layer or film.
  • Sealing Flange  -  The connection between the pump discharge and force main when used with guide rail systems.
  • Shaft Packing  -  Shaft packing is a kind of friction seal or stuffing box to prevent leakage between the pump shaft and the casing.  Commonly used shaft seal types include packing seal, mechanical seal, and power seal.
  • Shut-off Head  -  The total head corresponding to zero flow on the pump performance curve.
  • Specific Gravity  -  The density or ratio of any substance to another substance.
  • Strain  -  The deformation, stretched or compressed, of a material compared to its original length.
  • Stress  -  The force per unit area of cross-section.
  • Stroke  -  The stroke of a pump describes the length of the distance that is necessary for the complete deflection of the diaphragm ,top dead center to bottom dead center.  With our eccentric diaphragm pumps, the stroke is defined by the size of the rotating eccentric.
  • Stuffing Box  -  That portion of the pump that held the packing and now holds the mechanical seal.
  • Submergence  -  The vertical distance between pumping level and the bottom of the pump or jet assembly.  Submergence must be sufficient to insure that the suction opening of the pump or jet assembly is always covered with water, while maintaining enough clearance from the bottom of the well to keep it out of sediment.
  • Suction Head Coefficient  -  The angular velocity of the turbomachine shaft and the turbomachine impeller diameter.
  • Surge Arrestor  -  A protective device typically connected to the input power for limiting surge voltages on equipment by discharging or bypassing surge current.


  • Total Discharge Head  -  The total of the friction, pressure, and static discharge.
  • Total Suction Head  -  The total of the friction, pressure, and static discharge.



  • Vane  - The vanes, rotary vanes or vane cell plates, are part of the pump head of a rotary vane pump.  The vanes move in the guide slots of the revolving rotor and are responsible for transporting the medium.
  • Viscosity  -  The measure of the internal friction/resistance to the flow of a liquid.  Lower viscosity fluids flow easily in pipes where high viscosity fluids have a have a higher pressure drop
  • Volumetric Efficiency  -  This is for the volumetric efficiency for an internal combustion engine.  For a thermal engine, the combustion process depends on the air-fuel ratio inside the cylinder.  The more air inside the combustion chamber, the more fuel that can be burned and the higher the output engine torque and power.
  • Volute  -  The casing of a centrifugal pump made in the form of a spiral or volute as an aid to the partial conversion of the velocity energy into pressure head as the water leaves the impeller.


  • Water Hammer  -  It occurs when a valve is suddenly opened or closed.  This can creates a repeating pressure wave of the liquid in the pipe that could cause a rupture to the pipe or even damage equipment.
  • Work  -  The action done or applied force on an object that displaces the object.





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Cavitation Number Vapor Pressure
Centrifugal Pump
Centrifugal Pump Installation

Tags: Pump Hydraulic Motor