An A-Z Glossary of Pump & Industry Terms

Have you ever wondered what we meant when we talk about Dead Head, Cavitation or Suction Lift? Perhaps you’ve wondered what the difference is between Water Abstraction and Water Discharge or maybe you’re wondering to remember what C&D stands for?

Bookmark this page and never be stumped again as we feature an A-Z of pump and industry terms and their meanings.

Abrasive Fluids

Abrasive fluids usually refer to liquids that have sharp solids suspended in them such as slurries consisting of sand, bonemeal or grit.  These ‘sharps’ can quickly reduce the life and performance of handling equipment due to their abrasive nature. Consideration of pump, valve and pipe linings & materials is important for achieving a good service life.  Pump manufacturers will often use rubber-type parts or hard metal alloys for abrasion resistance.

AC Induction Motor

These electrical motors are powered by Alternating Current (AC), which generates rotational force out of the torque produced by the electromagnetic induction from the magnetic field of the stator winding. 

After Use Of Quarries

Land use following the extraction of mineral is an important factor when granting quarry licenses and planning permissions.  Ex-quarries often make good recreational parks or new wildlife lakes and wetlands.  The cost of land restoration and remediation needs factoring into the cost of the minerals extracted. Some quarry operators pay into a mutual funding programme such as those run by the Mineral Products Association or the British Aggregates Association Restoration Guarantee Fund, to guarantee the long term funding availability.

Aggregate Minerals

Aggregate is the broad term for sand, gravel, crushed rock, and other naturally occurring hard mineral materials used for making construction materials and in building work.  The properties of the aggregate is determined by its mineral composition and particle shape and size.

Primary aggregates are those that have been quarried for the first time.  Secondary aggregates are those recycled from demolition work. Geosynthetic aggregates are natural aggregates mixed with polymers as a binder that produces desired qualities, such as strength, flexibility, porosity, etc.

Aggregate Screening

The separation of aggregate by size. Material is then either used as screened or passed on for further processing.

Wash plants are an example of screening that uses water to improve the process.

Aggressive Fluids

A subjective term often used to describe fluids that have chemical or physical properties that can wear down or attack the lining of pumping equipment, pipes and vessels.

Fluids with extreme pH (acidic or base) are typically called ‘aggressive’. See also “Abrasive Fluids”

Agricultural Land Classification

A UK planning consideration to weigh the benefits of new quarries (and other developments) against the loss of potential agricultural land.  Both farming and the primary aggregate industry are vital to the national and regional economy.

Air-Operated Pump

These use compressed air to provide the drive for the pump’s action, instead of an electrical or diesel motor.  Such pumps might be used where the presence of electricity or diesel fuel is not suitable, i.e. explosive atmospheres. 

Air operated diaphragm (AOD) pumps are popular in this category, as their ‘on/off’ valve action suits compressed air technology.

Air Pocket Formation

Air pockets can form inside a pump through faulty setup or operational parameters.  They lead to in-efficiency and possible damage to pumps.

Alkaline Correction

See pH correction

Anaerobic Digestion

Anaerobic Digestion (AD) plants help produce renewable electricity by generating methane biogas from the breakdown of organic matter such as biomass crop or food waste.  Microorganisms break down the waste in the absence of oxygen, the methane gas is captured from this and used to generate electricity and heat in CHP (Combined Heat & Power) plants.  The digestate left at the end of the AD process is used as pasteurized fertiliser.  Atlantic Pumps are used in various AD processes, from keeping the organic matter moving at the right speed to pumping away the fertilizer slurry digestate.  

Anti-Syphon Valve

An anti-syphon valve is inserted into a pipeline to prevent back-flow due to air-pressure differentials (when the pump stops).  See also Check Valve

Asphalt

A combination of bituminous pitch with gravel or sand, used for roads and hard-surfacing as an adaptable alternative to tarmac.

Back Pressure

The pressure of the fluid acting against the pump from the discharge side.  The hydraulic force generated by the pump has to overcome this back-pressure for successful pumping operations.  Back-pressure is increased by friction, head or blockages.

BGS (British Geology Survey)

The BGS is a UK government agency responsible for geological surveys and geoscientific research for the public good. They share knowledge and data to help society use natural resources responsibly, manage environmental change and build resilience to environmental hazards.

Bingham Fluids

This term describes a class of non-Newtonian fluids categorised by their characteristic to behave as a solid when at rest and as a fluid when under shear stress. In other words, the fluid’s yield strength prevents flow until a certain amount of stress is applied. Fluids that became solid, or semi-solid at rest are known as Bingham plastics.

Biogas Plant

Methane is a biogas given off when organic matter breaks down in the absence of oxygen.  Methane released into the atmosphere is a pollutant that contributes to global warming.  Capture it however, and it is a great replacement for fossil fuels, generating renewable energy in the form of ‘green’ heat and electricity.

Bitumen

Bitumen is a liquid that can be quarried naturally or extracted from petrol or coal. It is used in the production of asphalt used for surfacing roads and for waterproofing.

C&D

C & D stands for Construction and Demolition.  These two activities are vital industries, as we build more sustainable homes and resilient infrastructure.  Construction relies on aggregates and consumes nearly all the extracted volumes, whilst demolition waste provides recoverable aggregate that can be recycled back into usable building materials.

Cavitation

Cavitation is caused when the fluid’s pressure suddenly decreases and increases, causing air vapour bubbles to form, then violently collapse. The force of this causes pitting damage and corrosion inside the pump, disrupts efficient flow and makes the pump sound like its ‘pumping marbles’.  Cavitation is to be avoided by ensuring the volume/head pressure of the fluid supply is sufficient for the pump’s capacity whenever it is running.  This is referred to as the NPSHa (Net Positive Suction Head available) being at or above the NPSHr (Net Positive Suction Head required).

This is caused by the fluid’s pressure dropping too low as it accelerates into the pump, creating vapour pockets which collapse rapidly as the pressure increases again. (Cavitation alt description)

This is where air bubbles form and collapse as the fluid changes pressure, causing pitting and damage to the impeller rotor and volute linings. Another cause of cavitation is when a valve or pipe bend restricts the flow, again causing pressure to fluctuate

This is caused by the fluid’s pressure dropping too low as it accelerates into the pump, creating vapour pockets which collapse rapidly as the pressure increases again. (Cavitation alt description)

Pictured below is cavitation damage on a metal propeller

(Erik Axdahl via Creative Commons license)

Cementitious Water

This is water that has been contaminated with cement powder, often from being used to washout concrete trucks and chutes.  Cementitious water has a high pH value (highly alkaline) and can lead to pollution of waterways and ground water, if not treated.  It can also block drains as the cement solids settle.  Various ways to treat cementitious water and prevent pollution are wedge pits, lamina settlement tanks and inline water treatment methods like EnviroHub

Centrifugal Pump

The centrifugal pump has an impeller that spins inside a circular casing. This rotary action generates centrifugal force on the fluid, forcing it against the wall of the volute casing and out of the discharge outlet.   Centrifugal pumps are commonly used where flow volume capacity is more important than pressure per se.  Centrifugal pumps deliver a more steady constant flow compared to peristaltic or diaphragm pumps

Characteristic Curve

The volume and head height of any pump can be charted on a graph to enable easier pump selection.  The head height and volume potential of a pump are inversely related, which creates the performance curve that can be said to be ‘characteristic’ of that pump size and model.

Check Valve

A check valve is installed in a pipeline to prevent backflow when the outlet pressure increases beyond the inlet pressure. i.e., when the pump is off, the gravity pressure of the water closes the check-valve and stops the water flowing back.

Closed Impeller

These impellers have their vanes sandwiched between two discs.  This gives a closed impeller better efficiency than an open impeller pump as there is less pressure loss.  They make efficient pumps for solids-free water but can get clogged easily by sludge or slurry that contains debris or other solid pieces. 

Coal

Mined extensively in the UK from Roman times, it’s use in the UK peaked in the 1960s. Higher grades are required for steel making, whilst the cheaper lignite (brown coal) was used for steam-generation of electricity until 2024.

As at 2014, over 26 million tons of permitted reserves remained untapped in the then operational UK coal mines, even while some was still being imported. Much more lies below, and will likely remain there to preserve our clean air.

Coal use remains prevalent in some countries. China, the world’s largest producer mined 4.66 billion tons in 2023, topping it up with imports at the rate of 500 million tons per annum.

Crushing

The grinding, breaking or pounding of ore or stone into small pieces or powder, sometime undertaken over a number of stages in powerful crusher cones. Large rocks are crushed to either produce size-graded aggregate or to enable separation of valuable minerals and metals

Dead Head

A ‘dead-head’ in pumping terminology means that fluid cannot flow out of the system, for example, if a valve or other blockage occurs on the outflow piping.  In a centrifugal pump, this causes the same water to recirculate around the pump’s chamber, increasing the temperature, pressure and load.  For these reasons, dead heading situations should be avoided, flow or temperature sensors are sometimes used to monitor pump operational performance.

DEFRA

Department for Environment Food & Rural Affairs (DEFRA) is a government department responsible for protecting and promoting a sustainable and healthy environment and the communities who depend on it. They monitor and control the interface between human activity and the natural ecosystem.

Delta Starting / Star-Delta

A method of starting up three-pahse electrical motors without excessive, sudden demands on the power current supply.  An alternative Soft-Start may be better for pumps that start up under an existing load.

DfE (Department For The Economy)

Previously part of the Northern Ireland Executive, the DfE had responsibility for mineral planning in Northern Ireland until April 2015.  Since then, planning responsibility for minerals extraction is shared between the Dept of Infrastructure, the Department of the Environment, and the local Council.  A similar function is carried out by MPAs across England, Scotland and Wales.

Dewatering

Dewatering means removing the water from something; this could be dewatering a quarry or mine by pumping the ground water away for instance, or dewatering a slurry by separating the water and solids.

Dirty Water

This term can be applied to any water that is non-potable (non-drinking).  In the quarry and mining industry, this usually refers to storm-water or ground water that has become contaminated with mud, but its viscosity has not reached the level of being a slurry.  Quarry pumps for dirty water often have several design and construction features not usually found in standard ‘puddle suckers’ or ‘clear water’ pumps.

Discharge

Discharge can mean the deliberate action of releasing water out of the site (dewatering), or it can refer to the liquid itself (discharge water).  Water that is discharged from quarries is done so after filtering or settling out suspended solids (typically minerals such as sand or clay), under license and control by, in the UK, the Environment Agency.

Displacement

Displacement in pumping is to move a fluid along though the outlet by introducing more into the inlet. With ‘Positive displacement’ pumps such as as progressive cavity and peristaltic types, the fluid is mechanically pushed along in dynamically moving closed chambers.  In submersibles and other pumps using rotatory impellers, the displacement is caused by centrifugal force.

Down-Time

Down-time refers to a system, operational site or particular machine not being able to work due to a constraint, typically mechanical failure of a critical component, maintenance needs or a power cut. Down-time can be disproportionally disruptive and expensive in lost time and resources.

Dredging

There are two main reasons for dredging, one being to deepen harbors and rivers for navigation and the other for extraction of sand, ores and minerals. The slurry that dredging produces requires specialist pump systems that can keep the silt in suspension and resist the abrasiveness of the slurry.

Dry Install / Dry pump

These terms refer to pumps that are situated above the fluid supply (or beside in the case of silo tanks), as opposed to submersible pumps which sit in the fluid being pumped.

Dry Running Pump

Running most pumps without fluid flowing through causes damage and rapid wear, through over-heating leading to friction and the binding of moving parts. Some ways to avoid dry-running involve installing back-check valves, automatic switch off, and/or self-priming pumps. Certain pumps such as LSM peristaltic pumps can safely run dry from time to time.

Dual Stage Pump

To produce an increase of pressure using the same flow, pumps can be built up in series. Dual stage means two pump chambers are installed inline, multi-stage pumps can include more. The entire system of pumps, pipes and valves should be safety rated for the achievable pressure.

Dust Control

Any airborne dust can present a hazard to health if it enters the lungs. Dust can also reduce visibility to dangerous levels. Construction sites and quarries can mitigate dust hazards through dust suppression systems such as water mist cannons and sprinklers, enclosing machinery and using air filters on silos and processing structures.

EA (Environment Agency)

The Environment Agency (or the Northern Ireland Environment Agency, NIEA) regulates the abstraction and discharge of water to and from natural sources.  This is just one part of its work to manage flood risk, protect nature from industrial pollution and protect people and their liviehoods.  In essence, their role is manage the impact of human activity and the natural environment on each other.

Eel Safe Pump

Certain sizes of large peristaltic pumps can safely transport eels and fish. Otherwise, pump inlets should be shrouded by filters to prevent wildlife from getting caught in them. Eels and other aquatic life are protected when river works are necessary, ensuring that the volume, quality, temperature and upstream access is maintained.

Efficiency Rating of Pumps

Any transfer of power from one state to another involves some loss of energy. Pump, motor and engine designers aim to reduce these losses as much as possible to increase the energy efficiency of the process. The efficiency is of a system is determined from the energy consumed (input) and the useful power delivered (output), expressed as a percentage. Efficiency = (output/input)x100

Feed Box

Situated at the feed end of the screen, the purpose of the feed box is to regulate the inflow of material and to spread it across the full width of the screen.

Fines

Very fine silt and clay articles finer than 63µm (some say up to 75µm) are usually classed as a byproduct/mining waste that is ‘cleaned’ from larger aggregate. Techniques for removing fines include washing, screening, vibration, hydro-cyclone, and spiral separation (using gravity and centrifugal forces).

Whilst some fines have commercial value, using them as a product attracts the aggregate-levy tax, making them less viable as a commodity.

Float Switch

A simple mechanical arm which triggers a switch on or off at a pre-set float/surface level. Often used to automatically operate a dewatering pump and help prevent dry-running.

Flocculation

Coalescence of minute particles into small clumps (flocs) to accelerate settlement or floatation as part of water treatment, dewatering mineral slurries, or thickening of a pulp. Polymer-based flocculants promote adhesion between the very fine, suspended particles (colloids). Some instances require pre-treat with a coagulant, to neutralise the charges that prevent the dispersed particles from bonding.

Flooded Suction Pump

A flooded end pump is one that has its inlet below the supply water’s surface level, allowing gravity to produce a positive pressure. This increases the efficiency of pumping, when compared to suction lift pumps. Submersible pumps are an example of flooded end pumps, as are ‘dry-sited’ centrifugal pumps when fed from a elevated tank.

Flow Rate (Q)

Often expressed in either cubic metres an hour, or litres per second, this is the volume of fluid moving through a system in relation to time. Expressed as “q” in engineering formulas

Glass Making and Recycling

The principal ingredient of glass is silica sand. The sustainability of glass is helped by its ease of recycling and continual reuse. Glass for recycling is washed, sorted by colour, then either melted (for re-moulding) or crushed for use in aggregate production.

Clear glass requires high-purity silica sand, whereas coloured glass contains various trace contents of metallic ions.

Gravel

Granular material in the size range 2mm to 60mm, generally arising in the form of sand and gravel deposits allied to river/ water activity. Used as an aggregate in concrete and in the building of roads.

Grit

Small hard fragments of mineral aggregate with angular facets. Useful for application to road surfaces, it’s abrasiveness is often a costly burden for wastewater treatment works, aggregate processors and fluid-handling equipment.

Gritstone

A hard, coarse-grained, siliceous sandstone

Grizzly

A type of screen, robust in build and used for coarse or primary removal of large rock and oversized items in mixed loads. A grizzly is constructed of parallel tapered steel bars held apart by distance pieces.

Gypsum

A soft sulphate mineral composed of calcium sulphate dihydrate, with the chemical formula CaSO4·2H2O. Mined for the manufacture of plaster-board, Portland cement, fertilizer etc.

Gyratory Crusher

A compression crusher consisting of a moving member, known as the head, in the form of an erect truncated cone rotating eccentrically within the fixed member (the outer shell), which is in the form of a frustum of an inverted cone.

Gyratory crushers are larger than Cone crushers, typically used for larger volumes and preliminary crushing of rocks above 300mm size.

Head Pressure

The Head is the measurement of the height differential between the surface of the fluid at one level and another level. Typically this is water being pumped from a lower location to a higher one, or the distance it will free fall if released. Head pressure is often called just “head” in the context of pumps and stored fluids. This vertical distance is measured from any particular location to the surface of the water body, regardless of depth.  is the pressure the pump needs to exert to transfer the fluid to this height. The “total head pressure” requirements for a pump is the head pressure plus the force needed to overcome the pipe system’s resistance. Thus, if the elevation required (head) is 17 metres, and the friction loss (from the pipe’s distance, surface material, bends and valves) is equivalent to 3m, it would need a pump capable of producing 20m of head pressure.

Heated Jacket

These insulated jackets have heating elements in and are wrapped around a fluid storage vessel. They are used to keep the liquid above a certain temperature, for example to stop it from freezing during cold weather.

Heterogeneous Slurry

A heterogeneous fluid is one which has a varying density range from one point to another. This usually occurs as a result of settling/sedimentation of solid particles in a still body of slurry. Slurries that tend to keep their particles in an even suspension are known as homogeneous.

IBA

This stands for Incinerator Bottom Ash. This is the residual solid material after municipal waste is burnt in an incinerator.

Recycled IBA is useful for making ‘clinker’ blocks and other cementitious construction materials. Being a pozzolanic material, it can partially replace virgin cement in concrete, thus reducing CO2 emissions.

Impact Crushers

Impact crushers involve the use of impact rather than pressure to crush material. The material is contained within a cage and fragmented by a rotating mass (the rotor.) The cage has openings on the bottom, end, or side at the desired size to allow the pulverized material to escape.

Impeller

An impeller consists of vanes attached perpendicular to a spinning shaft or plate.  This exerts force on the gas or fluid within the chamber and is a central feature in centrifugal pumps.

Industrial Slurry Types

A slurry is a liquid (i.e. water) that is thickened by the presence of suspended solids.  These slurries could be an ingredient in a larger process, or waste as a by-product.  Slurry waste from factories, farms, quarries and concrete plants will contain different particles, some of which are likely to cause pollution or be hazardous if they are not processed or handled correctly.

Inert Material

Inert material (such as sand or soil) is anything that doesn’t react or breakdown in the environment.

Jaw Crusher

A jaw crusher uses force to break the material. A plate moves forwards and backwards against a fixed plate, crushing the material in-between.

Lagoon

Lagoons, sometimes known as settlement ponds are created on quarries and large construction developments to capture run-off storm water.  The benefits of these lagoons include flash-flood prevention, containment of water for on-site recycling, or gradual treatment and controlled discharge to local natural watercourses.

Lignite

Low grade coal that contains volatile matter and high moisture, often prevalent in alluvial sand deposits, such as the Trent Valley. It is a contaminant in some concrete sand products its traditional use in the UK as a fuel for steam-electric power generation is waning.

Log-Washer

A long log-shaped cage-like structure that rotates, acting like a tubular washing screen. As the mixed-sized material is fed in, the tumbling action encourages the fines to fall through the mesh onto the collecting conveyor below.

They are set at a slope to allow the larger particles to exit at the bottom end of the ‘log’. Some log washers have paddles that break up the conglomerated material and increase the tumbling action which cleans the aggregate.

Materials Recovery Facility

In the waste management industry, a Materials Recovery Facility (MRF) is a specialised plant that receives, separates and prepares recyclable materials for marketing to end-user manufacturers.

Mechanical Seal

These seals are an upgrade from the traditional gland seal and are an even better option than expeller seals for pump situations that require no leakage and/or minimal maintenance.  Like their predecessor basic seals, they are inserted on the shaft where it rotates inside the pump casing.  The main function of the mechanical seal is to make a closer seal that prevents any fluid leaking from the wet end, whilst allowing for exceptionally low-friction rotation.  Read more about the comparison of different pump seals

Mineral Planning Authority (MPA)

These are local authority bodies across England, Scotland and Wales responsible for safeguarding the UK’s mineral resources for future extraction needs. They guide local planning authorities on applications for new quarry and mining developments, and work to ensure non-extraction developments don’t impede (“sterilise”) valuable unextracted mineral stocks.

Noise From Pumps

Diesel-powered pumps are the most noisy type in normal operation, electrically-driven pumps are much quieter.  Pumps shouldn’t generally create a lot of noise, if a pump makes a lot of noise it is an indication that it needs attention.  Loud rattling or gurgling sounds (like it is pumping marbles) indicates cavitation is occurring; knocking and/or vibration is likely caused by worn bearings or damage to the impeller or pump shaft.  In either case, turn off the pump and inspect/repair before more damage occurs.

Open Impeller

Thicker slurry and water containing solids is best handled by a centrifugal pump that uses an open impeller.  These are less likely than closed-impeller pumps to get fouled or blocked by solids coming through with the fluid.  

Peristaltic Pump

This type of positive displacement pump consists of paddles that rotate inside a hoop of pipe that holds the fluid being pumped.  Peristaltic pumps are sometimes called ‘Tube pumps’ or ‘roller pumps’.  This versatile and simple concept has resulted in it being used in small laboratory equipment to large industrial slurry pumps.

pH Correction

pH correction is necessary for water that is too alkaline (pH value above 7) or too acidic (pH value less than 7).  For example, washout water from concrete production is highly alkaline and must be corrected to the correct pH value before being re-used or released. 

Picking Station

Picking stations are used when manual sorting of the feedstock is required. Picking stations are horizontal conveyor belts configured to allow operatives to pick out particular items by hand.

Polyurethane

A plastic material that ranges from semi-rigid to flexible. It is used in the lining of pipes, vessels and other parts subject to wear, where its smooth and durable surface helps absorb impact damage and reduce friction. Its properties also lend itself to the manufacture of screen panels in wash plants.

Pontoon

A floating platform used for holding heavy equipment either out of the water or at the desired depth.  Submersible dewatering pumps are often suspended from a pontoon in quarry lagoons.

PPC

PPC is an acronym for Pollution Prevention and Control.  It is a legal requirement for regulated activities and industries which could cause pollution through their processes if not controlled.

Pressure

Pressure is a measurement of the amount of force acting on an area.  Pumps need to transfer enough energy to the liquid to overcome the opposing pressure and create sufficient flow.  In an aggregate filter press, a very high pressure needs to be created as an essential element of the process.  In other common scenarios, a pump is usually required to simply move a volume of water to a higher level.  As fluid (and air) moves from a high pressure to a low pressure area, the pressure differential is the key consideration in many pumping requirements.  The term used for this in fluid mechanics is Pressure Head (or Head Pressure).   back pressure

See also Back Pressure, Dynamic pressure, Hydrodynamic pressure

Primary Crushing

The first stage of the crushing process; primary crushing sees material of 300mm to 1.5m reduced in size.

Sand

A naturally occurring granular material in the size range 0.06mm to 2mm, often containing a high proportion of quartz. Its shape varies from ‘soft’ round sand to ‘sharp’ angular grains. It’s many different types are used in thousands of products; building materials, filter media, glass, silicon chips and abrasives.

Scalping

The process of removing low-grade top rock and clay from the main feed and transferring it to a mineral processing plant.

Screen Deck

A surface provided with apertures of specified size for carrying out the operation of screening out small particles and fines.

Screening

The separation of aggregate by size. The aggregate is then either used immediate or passed on for additional processing

Scrubbers

Scrubbers are designed to break up alluvial gravels, clay and sand. They can handle stone washing, feeds with high clay content and difficult ore. This is done through rotation and the force of particles hitting each other. As the scrubber rotates slowly, the fines are churned along with the oversize and water. As a result, the soil matrix is broken down and the target material is liberated.

Secondary Aggregates

These are aggregates that are sourced from recycling demolition material and construction waste.  The secondary aggregate market is important as naturally occurring mineral such as rock and sand is a finite resource.

Secondary Crushing

A second reduction in size of a material by means of crushing. The material is reduced to 50-60mm or even 40mm in some plants.

Service Water

Sometimes used interchangeably with ‘process water’, service water means it is not suitable for drinking (non-potable).  It may however need to be of a certain quality for its particular use so is often tested and treated accordingly.  An example of service water is that used for concrete production or irrigation in agriculture.

Settlement Pond

Often storm or ground water in a quarry becomes turbid due to suspended solids such as sand, minerals or mud.  Diverting this cloudy water into a settlement pond allows for the suspended solids to settle out naturally over time.  The clear water can then be pumped off the surface and returned to use.

Settlement Tank

Like Settlement ponds, these tanks are made for separating out suspended solids such as minerals, sand or soil from turbid water, allowing cleaner water to be drawn off the top.  Lamella tanks are designed to increase the settlement process capacity by increasing the amount of surface that silt can settle on. Typically, a thickener underflow takes the bottom sludge away for further treatment and dewatering.

Sieve Analysis

A practice used to assess the particle size distribution of a granular material. Knowing this helps in specifying and designing material handling systems and slurry pumping equipment. It is also used to measure the consistency and quality of fine aggregates in manufacturing mortars, screeds etc.

An often used measure of particle size is the “D50” which means the mean average size (50% being below this and 50% above).

Slag

This is the stony waste matter separated from metals during the smelting or refining of ore. This by-product of the steel industry is added to asphalt roads and high-performance concrete to improve durability and other factors.

Slurry

A suspension of solid particles in water, such as mineral silt or organic matter.

Stormwater

During peak rain periods, the excess water can result in flooding, erosion, turbid or polluted rivers and debris blocking watercourses and drains. 

Silt Pump

Silt pump is another name for a slurry pump, however the slurry term has a broader meaning.  Silt is sand or soil fines suspended in water which makes for a challenging slurry to move.  The abrasiveness of the fluid can quickly wear down an inferior made pump and the sand is apt to settle into a densely packed semi-solid like state.  Silt pumps need to be able to made more robust than normal water pumps. 

Soft Start

A method of starting three-phase motors which reduces the power draw surge, it is most commonly used in larger (11kWh and more) industrial electric pumps.  Unlike the Star Delta method it replaced, it works even when the motor is under load so is ideal for pumps.

Split-Casing Pumps

To make inspection, servicing and replacement of inner pump parts and lining quicker and easier, the main chamber of these pumps is made as two parts that bolt together.  On larger pumps, this is made easier and safer still with the addition of a sliding base to the pump casing.

Stuffing Box

A stuffing box holds the gland that prevents fluid from leaking out of the wet chamber where the shaft runs through the casing.  Another name for the stuffing box is a gland package.

Submersible Pump

A pump that is designed to be fully immersed in the fluid that it is pumping. Advantages include no need to prime before use, space-saving, and the pump is cooled by the surrounding water.

Suction Lift

This refers to either the application of a pump used to lift water from a reservoir sited below the pump (opposite of a flooded end), or the distance between the water level supply and centre line of the pump chamber. The lower-level water supply creates a negative pressure, requiring the creation of a (partial) vacuum by the pump. If the lift distance is too great, it can cause damaging cavitation. This can be overcome by a priming device/priming pump or shortening the suction lift height.

Sustainability

Sustainability means using resources in such a way as not to deplete them faster than they are being renewed. 

Tertiary Crushing

Typically the third stage of the crushing process involving reducing the particle size of material to under 20mm.

Thickener

Also known as a Clarifier. This is a large round tank, in which solids settle out from slurry over time. The thickened slurry (thickener underflow) is pumped out of the base of the thickener while clarified water overflows the top into an outer catchment ring.

Trommel

Also known as a rotary screen, a trommel is used for washing and sorting different sized pieces of mixed waste, ore or aggregate. It consists of a cylindrical shell of perforated plate or wire cloth, mounted on a central shaft inclined at a small angle to the horizontal. It may also be fitted to the discharge end of a washing barrel or scrubber.

Thickener Underflow

This is the heavy sludge that settles out of slurry and exits the bottom of the thickener tank.

Three Phase Power

Going back to the late 19th century, three-phase electricity supply is a more versatile and efficient way to transmit power over long distances.  The mathematics of the three phases mean the voltage can be stepped up and down effectively as needed through the national grid.  Large-scale electric industrial motors run directly on three-phase for a smoother operation under heavy workloads.  Most industrial water and slurry pumps are powered by three-phase supply, although single phase variants are available on smaller models.

Trommel

A trommel screen or trommel machine separates aggregates and other solids by their various size.  Mixed material such as freshly mined quarry rock, or demolition waste is fed into the top of the trommel.  The material then moves along trommel screens with progressively larger mesh openings, so that the aggregate is separated out from the finest (“trommel fines”) to the largest stones.  Keeping the material moving about by agitation is achieved by a combination of screen vibration and water being continually pumped around the system.

Turbidity

Turbidity is the opposite measure to clarity; it is caused by suspended solids in fluids (eg. silt-laden slurry).

Up-Time

The measurement of time that the machinery, process or entire plant is operational. Opposite of down-time.

Vertical Pumps

Whilst the majority of pumps are considered “horizontal”, vertical pumps have their motor mounted directly above the wet-chamber. This means that the shaft enters the pump chamber beneath the fluid, avoiding the issue of shaft leakage and the need for expensive seals. Vertical pumps can be referred to as ‘semi-submersible’ 

Vibratory Feeders

An instrument that uses vibration to feed material either to a machine or to a process.

Wash Plant

A complete plant used in the aggregate production process to remove clay and silt from sand and gravel. Provides the means to producing higher aggregate specifications which are increasingly necessary due to shortages of natural sand and gravel.

Washing Barrel

A device for washing aggregate. A rotating cylinder featuring lifters inside which lift and move the material along the barrel. The aggregate can be moved either with or against the wash.

Washing Screen

An angled vibrating screen. Water is sprayed from above the screen onto the feed to aid the removal of unwanted content such as dust, loam and clay.

Wastewater

Wastewater usually refers to unwanted water that has been used in an industrial process, or surface water and wash water come via the combined sewer system.  It typically has acquired contamination of some kind and needs to be collected and either taken off-site by a licensed waste carrier or treated onsite to restore it to a clean state.

Water Abstraction

This means to take water from a natural source such as a river, lake or ground source.  Thirsty Industries such as agriculture and energy production rely on water from rivers or boreholes.  In the UK, you almost always need an abstraction licence from the Environment Agency in order to abstract more than 20,000 litres a day.

Water Discharge

The opposite of water abstraction, water is discharged directly (pumped) off-site into a sewer, watercourse or onto the ground. Discharges over a certain daily amount require a licence from the relevant environmental authority and/or in the case of discharge to sewer, the local sewage company.

Wet End

The wet end of a pump is all those parts that come into contact with water/liquid during their normal use.  This includes the impeller, volute casing, shaft, pump inlet and outlet – all the parts that actually handle the water and are responsible for turning the rotary power into effective fluid dynamics.  Conversely, the dry-end of a pump is the motor, power supply and drive transmission.  Seals on the shaft (and cabling entry points on submersibles) prevent water ingress from the wet-end.

Weighbridge

A device for weighing a load carried by road or rail wagons. It is a very heavy duty weighing scale which can weigh the vehicle both empty and loaded and thus calculate the load carried by the vehicle.

Wet Pump

Another name for a submersible pump, i.e. it can sit in the fluid it is pumping.

Wet Screening

The stage at which water is pumped into the material being screened/washed or sprayed on to it as it moves over the screening deck. Wet screening improves screening efficiency and capacity, producing a cleaned product.

WRAP

Waste & Resources Action Programme. A registered charity that works with businesses, individuals and communities to achieve a circular economy through helping them reduce waste, develop sustainable products and use resources in an efficient way