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Sacrificial Anode: In a system is composed of 316 SS (a 300 series stainless steel; it is a very noble alloy meaning it is quite resistant to corrosion and has a high potential) and a mild steel (a very active metal with lower potential). The mild steel will corrode in the presence of an electrolyte such as salt water.  The sacrificial anode (such as a zinc alloy, aluminum alloy, or magnesium),  will corrode, protecting the other metal. This is a common practice in the marine industry to protect ship equipment. Boats and vessels that are in salt water use either zinc alloy or aluminum alloy. If boats are only in fresh water, a magnesium alloy is used. Magnesium has one of the highest galvanic potentials of any metal. If it is used in a salt water application on a steel or aluminum hull boat, hydrogen bubbles will form under the paint, causing blistering and peeling.



Sacrificial Zinc Anode:  Metals are ranked on a Noble Scale as to how well they resist corrosion. If two types of metals are present (Stainless Steel & Zinc for example), the metal that resists corrosion the least (Zinc) will deteriorate before the metal that resists corrosion the best (Stainless Steel). Therefore, the Sacrificial Zinc Anode is designed to protect a unit from corrosion because the Zinc will deteriorate before the Stainless Steel.   It is crucial to inspect the unit and Sacrificial Zinc Anode routinely, and if the Sacrificial Zinc Anode is corroded or deteriorated to half of its original size or less, it should be replaced. The more minerals, such as salt content, the quicker the corrosion will occur, therefore, the Sacrificial Zinc Anode must be checked more often. In areas of high mineral content, it is suggested to check the Anode every couple months. The Sacrificial Zinc Anode does offer some protection against electrolysis. However, a Sacrificial Zinc Anode can be completely deteriorated and damage to the unit can occur in as little as a couple weeks or less. This is largely dependent on the amount of electrical current in the water and how well the current travels through the water. Electricity uses particles in the water to travel, not the water itself, so the more minerals, such as salt, the further and quicker electricity can travel through the water to attack the unit. There are basically two options to protect your equipment from electrolysis. One is to keep replacing the Sacrificial Zinc Anode as often as needed. Two is to contact a qualified electrician to find the source of the stray voltage and eliminate it. Option two is a much more effective and reliable option than option one since damage can occur before an Anode can be changed and it becomes costly to continually change the Anode.



Safety Line: A continuous line not less than 1/4 inch in diameter, which is supported by buoys and attached to opposite sides of a pool which is supported by buoys and attached to opposite sides of a pool to separate the deep and shallow ends.



Saline water: Water that contains significant amounts of dissolved solids. Here are our parameters for saline water: Fresh water - Less than 1,000 parts per million (ppm) Slightly saline water - From 1,000 ppm to 3,000 ppm Moderately saline water - From 3,000 ppm to 10,000 ppm Highly saline water - From 10,000 ppm to 35,000 ppm



Salt Passage Rate: A measurement of the passage of salts through a reverse osmosis membrane. Salt passage is related to rejection by: % Salt passage = 100- % Rejection.



Sample: The water that is analyzed for the presence of EPA-regulated drinking water contaminants. Depending on the regulation, EPA requires water systems and states to take samples from source water, from water leaving the treatment facility, or from the taps of selected consumers.



Sand Filter: A filter tank, usually fiberglass or ABS plastic, filled with sand and gravel. The pump diffuses water over the top of the sand bed, and forces it through the sand and into the laterals on the bottom.



Sanitary Survey: An on-site review of the water sources, facilities, equipment, operation, and maintenance of a public water systems for the purpose of evaluating the adequacy of the facilities for producing and distributing safe drinking water.



Sanitizer: A chemical agent used to remove unwanted contaminants.



Santoprene: Is a thermoplastic rubber designed to offer chemical resistance equivalent to neoprene. It is resistant to a wide variety of solvents and chemicals. Fluids such as alcohols, ketones, glycols, esters, and aqueous solutions of acids, salts, and bases have little effect upon Santoprene rubber. The elastomer itself is a mixture of EPDM rubber and polypropylene. Santoprene elastomer possesses the same levels of flexibility and durability that are commonly found with natural rubber compounds. Because of the longer life of Santoprene elastomer in both extreme hot and cold environments, the material is often preferred over the use of rubber. Environmental aging resistance, electrical properties, and liquid resistance are about the same as EPDM and it can replace EPDM in certain applications.



Santoprene-1-: Santoprene is a thermoplastic elastomer   (TPE). Santoprene is a registered trade mark of Exxon Mobil. It is the mixture EPDM rubber EPDM and Polypropylene (PP). It is supplied as pre-compound material which is able to process by conventional thermoplastic tools. Santoprene is a thermoplastic compound that is processed in much the same way as any type of plastic. The difference is that Santoprene possesses the same levels of flexibility and durability that are commonly found with natural rubber compounds. Because of the longer life of Santoprene in both extreme hot and cold environments, the material is often preferred over the use of rubber.  EPDM and Santoprene have similar chemical characteristics. Where data is not shown for Santoprene, the data for EPDM may be used as a guide.



Saturated Zone: The underground area below the water table where all open spaces are filled with water. A well placed in this zone will be able to pump ground water.



Scale Deposits: Corrosion and Scale Deposits add up to a reduction in flow area, an increase of the velocity of the liquid, and an increase in head loss due to friction.



Scale: Usually whitish in color, scale forms on pool surfaces and equipment when mineral salts are forced out of solution. A scaling condition is one in which calcium hardness, pH and/or alkalinity levels are out of balance.



Scaling: Usually used in reference to distillation or reverse osmosis equipment, scaling is the precipitation of sparingly soluble salts, such as calcium carbonate, onto the surface of a distiller boiler or reverse osmosis membrane. Scaling is associated with decreased flux and reduced reverse osmosis rejection rates. Scaling also affects to a slight degree the efficiency of distillation processes.



Screw impeller: The screw centrifugal impeller is shaped like a tapered Archimedes screw. Originally developped for pumping live fish, the screw centrifugal pump has become popular for  many solids handling applications.



Scrubbing or Scouring Velocity: A velocity of water moving fast enough to remove particles trying to cling to the pipe and keep the solids moving in the pipe. Minimum of 2 feet per second.



Seal faces: The lapped faces that provide the primary seal in a mechanical seal.



Seal life: Seals should run leak free until the sacrificial face (usually carbon/ graphite) is worn away. More than 85% of the mechanical seals in use today fail prematurely.



Seal only pump: The pump does not have a conventional stuffing box so it could not be supplied with soft packing.



Seal: A device mounted in the pump housing and/ or on the pump shaft, to prevent leakage of liquid from the pump. There are two types: Mechanical: Has a rotating part and stationary part with highly polished touching surfaces. Has excellent sealing capability and life, but can be damaged by dirt or grit in the liquid. Lip: A flexible ring (usually rubber or similar material) with the inner edge held closely against the rotating shaft by a spring.



Seal-1-: The structural part of a galvanic cell that restricts the escape of solvent or electrolyte from the cell and limits the ingress of air into the cell (the air may dry out the electrolyte or interfere with the chemical reactions).



Sealed Dry Battery: A cell or battery where the case can be effectively sealed to allow operation in any position without leakage of the chemical electrolyte.



Seal-less: (Magnetic drive). No seal is used, power is transmitted from motor to pump impeller by magnetic force, through a wall that completely separates motor from impeller.



Seal-less: No seal is used, power is transmitted from the motor to the pump impeller by magnetic force. An example is Magnetic Drive Aquarium Pumps.



Seal-less-1-: No seal is used; power is transmitted from the motor to pump impeller by magnetic force. Example is Magnetic Drive Aquarium Pumps and Wet rotor pumps. Example : Little Giant aquarium pumps, PES Wet Rotor.



Seals: Devices mounted in the pump housing and/or on the pump shaft that prevent leakage of liquid from the pump.



Second Affinity Law: With the same impeller, the head generated by the impeller is related to the square of the liquid exit velocity; if you increase the speed of the water the head will increase by the square of the change.



Secondary Battery: An electrochemical cell or battery which can be recharged.



Secondary Drinking Water Standards: Non-enforceable federal guidelines regarding cosmetic effects (such as tooth or skin discoloration) or aesthetic effects (such as taste, odor, or color) of drinking water.



Secondary wastewater treatment: Treatment (following primary wastewater treatment) involving the biological process of reducing suspended, colloidal, and dissolved organic matter in effluent from primary treatment systems and which generally removes 80 to 95 percent of the Biochemical Oxygen Demand (BOD) and suspended matter. Secondary wastewater treatment may be accomplished by biological or chemical-physical methods. Activated sludge and trickling filters are two of the most common means of secondary treatment. It is accomplished by bringing together waste, bacteria, and oxygen in trickling filters or in the activated sludge process. This treatment removes floating and settleable solids and about 90 percent of the oxygen-demanding substances and suspended solids. Disinfection is the final stage of secondary treatment.



Sediment: Usually applied to material in suspension in water or recently deposited from suspension. In the plural the word is applied to all kinds of deposits from the waters of streams, lakes, or seas.



Sediment-1-: Very small debris, such as sand, rust, or silt, that settles to the bottom of a tank or vessel.



Sedimentary rock: Rock formed of sediment, and specifically: (1) sandstone and shale, formed of fragments of other rock transported from their sources and deposited in water; and (2) rocks formed by or from secretions of organisms, such as most limestone. Many sedimentary rocks show distinct layering, which is the result of different types of sediment being deposited in succession.



Sedimentation tanks: Wastewater tanks in which floating wastes are skimmed off and settled solids are removed for disposal.



Sedimentation: The process by which solids are separated from water by gravity and deposited on the bottom of a container or basin.



Seepage:  The rate at which the fluid being pumped accumulates at the point of suction. Slow seepage allows air into the pump suction, which causes some types of pump to lose their prime.



Seepage-1-: (1) The slow movement of water through small cracks, pores, Interstices, etc., of a material into or out of a body of surface or subsurface water. (2) The loss of water by infiltration into the soil from a canal, ditches, laterals, watercourse, reservoir, storage facilities, or other body of water, or from a field.



Self align: A method of keeping both mechanical seal faces square to the rotating shaft.



Self Discharge: Discharge that takes place while the battery is in an open-circuit condition. All batteries tend to discharge themselves even when not supplying energy, as a result of internal losses. The self-discharge rate describes this effect in terms of a percentage



Self Priming Pump: A centrifugal pump having the capability of dispersing a certain amount of air from its pump body, assuming the pump has been primed initially, when operating under a suction lift; to free itself of entrained gas without losing prime; and to continue normal pumping operation without attention.



Self Priming: Most centrifugal pumps require the pump casing to be filled with water before starting. Self-priming is a term often used to describe pumps that have the ability to purge air from the case and create a partial vacuum, allowing water begin flowing through the suction hose.



Self-priming pump: A pump that does not require priming or a initial filling with liquid. The pump casing carries a reserve of water that helps create a vacuum that will lift the fluid from a low source.



Self-priming: The ability of a pump to purge air from its casing and suction hose, creating a partial vacuum and allowing water to flow freely into the pump.  Pumps that draw liquid up from below pump inlet (suction lift), as opposed to pumps requiring flooded suction.



Self-supplied water: Water withdrawn from a surface- or ground-water source by a user rather than being obtained from a public supply. An example would be homeowners getting their water from their own well.



Semi-Open Impeller: Also know as a vane impeller, it has only one shroud. The other side of the impeller is in close contact with the pump volute case. The vanes of the impeller are spaced far enough apart to pass solids.



Semipermeable: Descriptive of a material, such as a reverse osmosis or ultrafiltration membrane, which allows the passage of some molecules and prevents the passage of others.



Separation Tank: A tank used with a DE filter during the backwash cycle of the filter. It collects backwashed DE and debris, allowing the water to return to the pool.



Separator: The permeable membrane that allows the passage of ions, but prevents electrical contact between the anode and the cathode.



Septic tank: A container used to collect wastewater from a house. Generally they have two compartments and are watertight. The larger compartment is for the raw sewage and the second compartment for effluent water. The second compartment can also be used as a pump chamber.



Septic tank-1-: A tank used to detain domestic wastes to allow the settling of solids prior to distribution to a leach field for soil absorption. Septic tanks are used when a sewer line is not available to carry them to a treatment plant. A settling tank in which settled sludge is in immediate contact with sewage flowing through the tank, and wherein solids are decomposed by anaerobic bacterial action.



Septum: That part of the filter element consisting of cloth, wire screen or other porous material on which the filter medium or aid is deposited.



Sequestering Agent: A chemical that ties-up minerals tightly in solution, preventing their precipitation, which colors the water and/or stains the pool. Synonymous to chelators, these are commonly called stain & scale chemicals.



Series  Parallel Circuit: A circuit that contains some loads connected in series and other loads connected to form multiple paths for electricity.



Series circuit: A circuit that contains multiple loads but only one path for the flow of current.



Series Connection: The arrangement of cells in a battery configured by connecting the positive terminal of each successive cell to the negative terminal of the next adjacent cell so that their voltages are cumulative.



Series operation: The pumps are connected with the discharge of the first pump discharging to the suction of the other. The speed and impeller widths must be the same or the difference in capacities could cause cavitation or over heating problems.



Service Factor: A factor indicating the degree to which an electric motor can be operated over the specified horsepower without danger of overloading or failure. In other words, it is the actual horsepower of the motor.



Service Factor-1-: The service factor (SF) is a measure of continuous overload capacity at which a motor can operate without overload or damage, provided the other design parameters such as rated voltage, frequency and ambient temperature are within norms. Example: a 3/4 HP motor with a 1.15 SF can operate at .86 HP, (.75 HP x 1.15 = 862 HP) without overheating or otherwise damaging the motor if rated voltage and frequency are supplied at the motor's leads. Some motors , have higher service factors than the NEMA standard. It is not uncommon for the original equipment manufacturer (OEM) to load the motor to its maximum load capability (service factor). For this reason, do not replace a motor with one of the same nameplate horsepower but with a lower service factor. Always make certain that the replacement motor has a maximum HP rating (rated HP x SF) equal to or higher than that which it replaces. Multiply the horsepower by the service factor for determining maximum potential loading.



Service line:  The line that supplies water to the home. It will also be the source of water of the sprinkler system.



Service pressure: The pressure required at the outlets. (Expressed in PSI.) The most commonly used discharge pessure is 30/50 PSI.



Service Pressure-1-: The range of pressure in the pressure tank during the pumping cycle, usually expressed in pounds per square inch gauge (P.S.I.G.).



Setting for Pumps: Vertical distance in feet from the top of the well to the top of the pump.



Setting: The vertical distance from the level at which the discharge pipe leaves the well to the bottom of the pump or jet assembly in the well.



Settings for Foot valve or strainer: Vertical distance in feet from the top of the well to the top of the foot valve or strainer.



Settling pond (water quality): An open lagoon into which wastewater contaminated with solid pollutants is placed and allowed to stand. The solid pollutants suspended in the water sink to the bottom of the lagoon and the liquid is allowed to overflow out of the enclosure.



Sewage Pump: A pump designed to pump black water (effluent).



Sewage treatment plant: A facility designed to receive the wastewater from domestic sources and to remove materials that damage water quality and threaten public health and safety when discharged into receiving streams or bodies of water. The substances removed are classified into four basic areas: [1] greases and fats; [2] solids from human waste and other sources; [3] dissolved pollutants from human waste and decomposition products; and [4] dangerous microorganisms. Most facilities employ a combination of mechanical removal steps and bacterial decomposition to achieve the desired results. Chlorine is often added to discharges from the plants to reduce the danger of spreading disease by the release of pathogenic bacteria.



Sewage: Raw wastewater from residential, commercial or industrial sites. Sewage from residential sites is generally defined as 2” or less solids and commercial sites are 3” or 4” solids.



Sewer: A system of underground pipes that collect and deliver wastewater to treatment facilities or streams.



Shaft packing: The soft packing supplied by pump manufacturers. Mechanical seals are replacing most of these leaking packing.



Shallow cycling: Repeatedly discharging a secondary battery by only a small proportion of its capacity before recharging again. Some types of battery prefer it, some don’t.



Shallow Well: A type of jet pump OR a well having less than 25' of lift.



Shallow-Well Jet Pump: A dedicated pump that will work to a maximum depth of about 25 feet. The jet is either attached or pre-cast into the pump body.



Shape Memory: Some alloys remember their original shape and will return to it after being deformed. This is done by just applying heat.



Shelf Life: For a dry cell, the period of time (measured from date of manufacture), at a storage temperature of 21 degrees C (69 degrees F), after which the cell retains a specified percentage (usually 90%) of its original energy content.



Shelf life-1-: Usually refers to the seal elastomer. Buna "N" is the biggest problem because of Ozone attack.



Shock Mounts: Rubber mounts used to dampen vibration from the engine and help prevent the pump from "walking away".



Shock: As a noun it loosely describes the products used in shocking, such as hypochlorites, potassium permonysulfate or hydrogen peroxide. As a verb it describes the act of bringing the sanitizer level up so high that breakpoint chlorination is reached. When breakpoint is reached, a "shock" or perhaps a "lightning bolt" is a better analogy, is sent through the water, tearing apart molecules and slashing through cell walls. Ultimate purification, man.



Short-Circuit Current: That current delivered when a cell is short-circuited (i.e., the positive and negative terminals are directly connected with a low-resistance conductor).



Short-Cycling: The water pump turns on and off too rapidly or too frequently.



Shotcrete: A different type of application of the concrete and sand mix which is used to "shoot the shell". Gunite is pumped dry and mixed with water at the gun, whereas Shotcrete is pumped wet.



Shroud: See >end-suction pump.



Shut off head: The maximum head that the pump can generate with a given impeller outside diameter and horsepower driver.



Shut-off head-1-: The total head created by a pump that is running against a closed discharge.



Shut-off head-2-: The Total Head corresponding to zero flow on the pump performance curve. The shut-off head is the Total Head that the pump can deliver at zero flow (See next Figure). In certain systems (admittedly unusual), the pump discharge line may have to run at a much higher elevation than the final discharge point. The fluid must first reach the higher elevation in the system.  If the shut-off head is smaller than the static head corresponding to the high point, then flow will not be established in the system.  During start-up and checkout of the pump, a quick way to determine if the pump has the potential capacity to deliver the head and flow required, is to measure the shut-off head. This value can be compared to the shut-off head predicted by the performance curve of the pump.



Shut-off valve: They are used to shut off the water supply to the sprinkler and are installed between the service line and the valve manifold. Gate valve or ball valves are two types of shut-off valves.



Shutoff: Point in which pump will not push water passed the listed feet in a vertical column. No flow past the listed vertical feet. This does not affect the horizontal run but if the run is very long say 50 or 100 ft. then friction comes into play.



Side channel pump: Is a pump that provides high head at low flows with the added benefit of being able to handle gases.



Silicon Controlled Rectifier (SCR): A solid state device containing a gate that acts as the "turn-on" switch that allows the device to fully conduct voltage.



Silicone bronze:  Has the ductility of copper but much more strength. The corrosion resistance of silicon bronze is equal to or greater than that of copper. Commonly used as stem material in pressure-rated valves, silicon bronze has greater resistance to stress corrosion cracking than common brasses.



Silicone bronze-1-: Silicone bronze has the ductility of copper but much more strength. The corrosion resistance of silicon bronze is equal to or greater than that of copper. Commonly used as stem material in pressure-rated valves, silicon bronze has greater resistance to stress corrosion cracking than common brasses.



Silt Density Index: A measurement of the rate at which a 0.45 ~m filter disc is plugged under standardized test conditions. Silt density index (SDI) determinations are used to estimate the rate at which various water supplies will cause fouling or plugging of reverse osmosis or ultrafiltration membranes.



Silver Oxide Cell: The silver oxide-zinc cell is an alkaline primary type. It uses silver oxide as the positive electrode and zinc as the negative electrode, with an electrolyte of either sodium or potassium hydroxide. They are mainly used in low-drain applications. Slow or Trickle Charging: Recharging a secondary battery at a rate of between 0.05C and 0.2C — i.e., over a period between 7 and 28 hours (charging 140% of nominal capacity).



Silver Protein: A solution containing silver ions, such as Argyrol, used as a germicide.



Silver:  A silvery white metal that has the highest electrical conductivity of all metals. Silver is also fairly expensive.



Simplex Sewage System: A sewage or effluent system that uses a single pump to control the water level in the storage chamber. Most residential systems are simplex systems. Most simplex systems use an automatic pump with a piggy–back float to turn them on and off, some use a panel.



Single Or Double Pipe System: Refers to the well size and how the well can be entered.



Single Phase Protection (SPP) Device: Senses the power factor as heat builds up in the motor and shuts it down when the preset limit is reached.



Single Pipe: In a jet pump application means there is only one pipe going down into the well. The jet is attached to it and has leathers above the intake. These leathers act as a seal to ensure that well water will only enter through the suction.



Single-Phase Motor Designs: motors that are most common to centrifugal pumps.



Sinkhole: A depression in the Earth's surface caused by dissolving of underlying limestone, salt, or gypsum. Drainage is provided through underground channels that may be enlarged by the collapse of a cavern roof.



Sintered material: Formed from a powder as opposed to being melted and poured into a mold.



Siphon: A system of piping or tubing where the exit point is lower than the entry point and where some part of the piping is above the free surface of the fluid source.



Siphon-1-:  is a system of piping or tubing where the exit point is lower than the entry point.



Skid Mount:  Pump and engine mounting mounted on a base.



Skimmer Basket: Beneath the lid, the basket strains debris, as the first line of defense in filtering the water.



Skimmer Net: Attached to a telescopic pole, a leaf rake is a very useful tool in keeping the pool clean. Also called a skimmer net are the flat, "dip and flip" nets, which aren't so useful.



Skimmer Weir: The horizontal surface over which the water flows to the circulating system (usually self-adjusting for water level changes).



Skimmer: A box set into the edge of the pool with mouth open to the pool, just at water level. It connects to the main circulating pump suction pipe. It both channels water to the pump and skims leaves, debris, etc., off the pool surface. A removable deck cover allows for cleaning.



Sleeve bearing: A non-precision bearing. Usually manufactured from carbon, Teflon. brass etc. Allows too much axial and radial movement for most mechanical seal applications.



Sleeve Bearings: A type of bearing with no rolling elements, where the motor shaft rides on a film of oil.



Slide base: An adjustable frame on which the motor sets. Used for belt drives to adjust belt



Slip Resisting: A surface that has been so treated or constructed as to significantly reduce the chance of a bather from slipping. The surface should not be an abrasion hazard.



Slip stick: An alternating slipping and sticking of the seal faces caused by a poor lubricant between the faces. Will cause vibration problems at the seal face unless the vibration is dampened.



Slip: the difference between the rotor speed and the rotating magnetic field in the stator. Slip is what allows a motor to turn.



Slow Seepage: Water that drains slowly into a trench or work area from the surrouding area. Possibly caused from run off or high water tables.



Sludge pump: Certain types of sludges tend to settle very quickly and are hard to keep in suspension. The Lawrence pump company has solved this problem by putting an agitator in front of the pump suction.



Slurry Feeder: A device to feed a variable amount of filter aid during the filter cycle.



Slurry pump: A rugged heavy duty pump intended for aggressive or abrasive slurry solutions typically found in the mining industry with particles of various sizes. It achieves this by lining the inside of the pump casing as well as the impeller with rubber.



Slurry: A suspension of diatomaceous earth in water used for body feeding in D.E. filters.



Slurry-1-: Solids in liquid. It is impossible to define when the quantity and size of the particles becomes too much for the mechanical seal.



Snifter Valve: A valve in a water system that allows air to enter or escape, and accumulated water to be released.



Snowbelt: The northern half of the United States where freezing temperatures are particularly common.



Soda Ash: A base, used to counteract an acidic condition by raising pH.



Sodium Bicarbonate (baking soda): Another base, however its properties will increase alkalinity more than pH. Used to raise Total Alkalinity levels.



Sodium Bisulfate: A dry chemical commonly used to lower pH in water. Also called soda ash.



Sodium Bisulfate-1-: An granular form of acid, used to counteract a scaling condition by lowering pH and/or alkalinity.



Sodium Carbonate: A dry chemical commonly used to raise pH in water.



Sodium Dichlor: A granular form of chlorine that is stabilized with cyanuric acid. Used for shocking and super-chlorination.



Sodium Hypochlorite: Liquid chlorine used in pools, identical yet stronger than Clorox bleach.



Sodium Tetraborate: New technology that renders algae incapable of processing carbon dioxide, which they need to live.



Soft Start: Bringing a motor up slowly to its full running amps instead of starting the motor with locked-rotor in-rush current.



Soft Water: Water containing less than 1 grain per gallon dissolved calcium and magnesium salts. Definition of where “softness” starts may vary depending on individual viewpoints



Soft Water-1-: Water that has low calcium and/or magnesium content. Soap lathers easily in soft water.



Solar System: Black mats of miniature plastic tubes through which water is pumped, absorbing the heat as it passes through. These mats are roof mounted with up & down plumbing connecting it.



Sole Source Aquifer: An aquifer that supplies 50 percent or more of the drinking water of an area.



Solids Concentration: The ratio of solids to liquid in the overall volume of the material being pumped, which is helpful in determining the proper pump for the application. Hydraulic submersible pumps handle higher solids concentrations than diesel-driven trash pumps.



Solids Size: Average diameter of individual particles in the material being pumped, which is important to know when specifying a pump. Large solids can be filtered with strainers or rock guards.



Solids:  Any particulate that passes through the pump: mud, sand, rock or other debris.



Soluble: When one liquid dissolves or mixes with another liquid.



Solute: A substance that is dissolved in another substance, thus forming a solution.



Solute-1-: Dissolved particles in a solvent.



Solution: A mixture of a solvent and a solute. In some solutions, such as sugar water, the substances mix so thoroughly that the solute cannot be seen. But in other solutions, such as water mixed with dye, the solution is visibly changed.



Solvent: A substance that dissolves other substances, thus forming a solution. Water dissolves more substances than any other, and is known as the "universal solvent".



Sorbent: See adsorption.



Source Water: Water in its natural state, prior to any treatment for drinking.



Source: The device that supplies the current that flows throughout a circuit. Examples of sources include batteries and generators.



Source-1-: Refers to the origination of electrical power. The source for your filter pump (load) is probably a timer clock.



Sp or Specific Gravity of Liquid: The ratio of the mass of a solid or liquid to the mass of an equal volume of distilled water at 4°C (39°F) or of a gas to an equal volume of air or hydrogen under prescribed conditions of temperature and pressure. Also called relative density.



Spa - Inground: A Spa whose sides reside partially or fully below the natural ground level.



Spa: A filtered, hot water vessel with hydrotherapy jets and air induction. Can be portable or installed permanently. Jacuzzi is a brand name.



Spa-1-: A hydrotherapy unit of irregular or geometric shell design. (SEE “HYDROTHERAPY SPA” OR “HOT TUB”)



Space Heaters: Small resistance heater units mounted in a motor that are energized during motor shutdown to prevent condensation of moisture in the motor windings.



Specific conductance: A measure of the ability of water to conduct an electrical current as measured using a 1-cm cell and expressed in units of electrical conductance, i.e., Siemens per centimeter at 25 degrees Celsius. Specific conductance can be used for approximating the total dissolved solids content of water by testing its capacity to carry an electrical current. In water quality, specific conductance is used in ground water monitoring as an indication of the presence of ions of chemical substances that may have been released by a leaking landfill or other waste storage or disposal facility. A higher specific conductance in water drawn from downgradient wells when compared to upgradient wells indicates possible contamination from the facility.



Specific gravity (SG): The ratio of the density of a fluid to that of water at standard conditions. If the SG is 1 then the density is the same as water, if it is less than 1 then the fluid is less dense than water and heavier than water if the SG is bigger than 1. Mercury has an SG of 14, gasoline has an SG of 0.8. The usefulness of specific gravity is that it has no units since it is a comparative measure of density or a ratio of densities therefore specific gravity will have the same value no matter what system of units we are using, Imperial or metric.



Specific gravity: The ratio of the weight of a given volume of a liquid to the same volume of pure water. Power requirement increases for liquids with specific gravities greater than 1.0.



Specific Gravity-1-:  A measure of the weight of a liquid. Fresh water at 4?C (39?F) is given a value of one. If the liquid you are questioning will float on water the specific gravity is less than one. If it sinks, it is higher than one. Density is a better term.



Specific Gravity-2-:  The ratio of the weight of a given volume of liquid to pure water. Pumping heavy liquids (specific gravity greater than 1.0) will require more drive horsepower.



Specific Gravity-3-:  The ratio of the weight of agiven volume of liquid to the same volume of pure water.



Specific heat: Refers to the amount of calories or BTUs required to raise a quantity of a liquid one-degree.



Specific speed: A formula that describes the shape of a pump impeller. The higher the specific speed the less N.P.S.H. required.



Specific speed-1-:  A number that provides an indication what type of pump (for example radial, mixed flow or axial) is suitable for the application.



Spiral Casing or Volute: A pump component that has a gradually expanding water passageway from the tongue or cut water of the volute to the discharge.



Spiral Wound Membrane: The most common practical configuration of membranes for RO systems.



Split Phase Motor: A type of electric motor that has a start winding and a run or main winding separated by 90 degrees and the windings are wired in parallel. The split phase motor is a low cost design and is available from 1/20 to 1-1/2 HP and is usually found on low-end centrifugal pumps. It produces low starting torque (100-175% of run torque) and requires a very high starting current (700-1000% of run current).



Split Phase Start: Motors, which employ a main winding and an auxiliary winding, called the starting winding. The windings are unlike and thereby "split" the single phase of the power supply by causing a phase displacement between the currents of the two windings thus producing a rotating field. After the motor has attained approximately 75% of rated speed, the starting winding is automatically disconnected by means of a centrifugal switch or by a relay. The motor then continues to run on a single oscillating field, which in conjunction with the rotation of the rotor, results in a rotating field effect. Since there is no rotating field, after the starting winding is deenergized, the rotation cannot be changed until the motor has come to rest or at least slowed down to the speed at which the automatic switch closes. Special starting switches are available as well as special reversing switches which have a means for shunting the open contracts of the automatic switch while the motor is running and thus permits the split phase motor to be reversed while rotating. This type of starting is found typically on single phase fractional motors.



Spray irrigation: An common irrigation method where water is shot from high-pressure sprayers onto crops. Because water is shot high into the air onto crops, some water is lost to evaporation.



Spray Rinse, Mechanical: A fixed or mechanically movable spray system which directs a stream of water against the filter surface, causing the filter aid and accumulated dirt to dislodge into the empty tank.



Spring: A water body formed when the side of a hill, a valley bottom or other excavation intersects a flowing body of groundwater at or below the local water table, below which the subsurface material is saturated with water.



Springboard: A board especially designed to produce diver spring action when properly installed on an anchor (base) and fulcrum. (The term diving board includes non-spring types).



Sprinkler valves:  Automatic or manual valves that turn the water on and off to different zones in a system. Automatic valves are the most common type used today and are controlled by a timer. Used in underground sprinkler systems.



Squirrel Cage Induction Type Electric Motor: A motor whose name is derived from the similarity between the motor windings (which may use conductive bars connected together at both ends by shorting rings forming a cage-like shape) and a squirrel cage/hamster wheel. These are the most common type of industrial AC electric motors, being rugged and requiring neither a separate DC power source nor ship-rings. They are constant speed devices when energized by a constant frequency AC supply.



SSE: Sump, Sewage and Effluent pumps.



Stabilizer: See Cyanuric Acid. Stabilizers, also called conditioners, can be added directly to your pool to extend your chlorine efficacy. Cyanuric acid is already added to certain "stabilized" products such as Trichlor tablets and Sodium Dichlor.



Stainless steel: Alloy steels containing a high percentage of chromium.



Standard volute pump close coupled: The volute is the casing which has a spiral shape. The motor shaft is connected to the impeller without an intermediate coupling providing a compact arrangement. The flow range is typically less than 300 gpm.



Standard volute pump separately coupled-1-:  The volute is the casing which has a spiral shape. The motor shaft is connected to the impeller with an intermediate shaft with two couplings.



Standing water level: The distance from the top of the well to the top of the water when the pump is not running.



Standpipe: Vertical pipe that carries water from the hub and lateral assembly to or from the multiport valve on a top mount sand filter.



Start Winding: A second set of coils connected in series with a capacitor.



Starting Switch or Governor or Relay: A device designed to open its contacts when the motor reaches a critical speed, removing the start capacitor from the circuit.



Starting-Lighting-Ignition (SLI) Battery: A battery designed to start internal combustion engines and to power the electrical systems in automobiles when the engine is not running. SLI batteries can be used in emergency lighting situations.



State of Charge (SOC): Condition of a cell in terms of the capacity remaining in the cell.



Static Discharge Head:  The vertical distance between the pump’s discharge port and the point of discharge, which is the liquid surface if the hose is submerged or pumping into the bottom of a tank.



Static Discharge Head-1-: Another name for elevation. It is the distance between the datum plane and the highest point you are pumping to.



Static Discharge Head-2-: The vertical distance from the centerline of the pump impeller to the point of discharge. (See definition for dynamic discharge head). Maximum vertical distance (in feet) from pump to point of discharge with no flow.



Static discharge head-3-: The vertical distance from the pump to the highest outlet in the water system.



Static Discharge Head-4-: Vertical Distance (in Feet) from pump to point of discharge.



Static Electricity: An imbalance of protons (positive charged particles) and electrons (negative charged particles); a separation of negative and positive charges, caused by the intimate contact and then separation of two dissimilar insulating materials.



Static head: The maximum height the liquid is being pumped as long as you take into consideration the siphon affect in some piping systems.



Static Head-1-: The vertical distance between the free level of the source of the supply and the point of free discharge, or to the level of the free surface of the discharged water.



Static Height is the maximum height reached by the pipe after the pump (also known as the 'discharge head').



Static Lift: Is the height the water will rise before arriving at the pump (also known as the suction head).



Static Or Standing Water Level: The undisturbed level of water in the well before pumping.



Static Suction Head- Is located on the suction side of the pump and is the distance between the datum plane and the water. It can be expressed as a positive or negative number depending if the pump has to lift the water.



Static Suction Head: The vertical distance between the pump impeller and the surface of the liquid on the suction side of the pump.



Static Suction Lift: The vertical distance from the lowest suction point to the centerline of the pump impeller. This distance should be kept to a minimum for maximum pump performance. (See definitions for theoretical and maximum suction lift.).



Static water level: Vertical distance from the top of the well to the standing natural water level. Also known as "standing water level" and as "the water table".



Station: Each station on a timer controls a separate valve.



Stationary Battery: A secondary battery designed for use in a fixed location.



Stationary seal: The spring loaded or moveable portion of the seal does not rotate with the shaft. Must be used when the seal surface speed exceeds 5000 fpm. or 25 meters per second.



Stator Slots: Slots in the stator for the coils of wire that will cause the magnetic field that rotate the rotor.



Stator: The part of the motor that does not move. It consists of a stack of metal stampings called "laminations" that are bound together with a series of slots that contain the windings of the motor. Stator also includes the starting windings in a single phase motor.



Stellite: Cobalt base alloy, one of the best all-purpose hard facing alloys. Stellite is very resistant to heat, abrasion, corrosion, impact, galling, oxidation, thermal shock and erosion. Stellite takes a high polish and is used in steel valve seat rings. Normally applied with transfer plasma-arc; Stellite hardness is not affected by heat treatment. STELLITE is a registered trademark of the Cabott Company



STELLITE®:  Cobalt base alloy, one of the best all-purpose hard facing alloys. Very resistant to heat, abrasion, corrosion, impact, galling, oxidation, thermal shock and erosion. Stellite takes a high polish and is used in steel valve seat rings. Normally applied with transfer plasma-arc; Stellite hardness is not affected by heat treatment. STELLITE is a registered trademark of the Cabott Company.



STEP Pump (Septic Tank Effluent Pump): A pump designed to pump gray or effluent water.



STEP System (Septic Tank Effluent Pump)-1-: An effluent pump transfers septic tank effluent, collected in the pump chamber to a distribution box or manifold for gravity flow to an absorption field or sewer line. The advantage of this method compared to other gravity systems is that the absorption field or sewer line can be located at a higher elevation than the septic tank. Disadvantages are common with all gravity systems, i.e. progressive plugging of the drain holes and absorption areas, and minimal effectiveness in hard soils or high water tables.



Steps: Riser/tread or series of risers/treads extending down from into the deck with the bottom riser/tread terminating at the pool



Sterilization: A physical or chemical process that reduces the number of organisms to a safe predetermined level (see also disinfection).



Storage Battery: An assembly of identical cells in which the electrochemical action is reversible so that the battery may be recharged by passing a current through the cells in the opposite direction to that of discharge. While many non-storage batteries have a reversible process, only those that are economically rechargeable are classified as storage batteries. Synonym: Accumulator; Secondary Battery. See Secondary Cell.



Storage Cell: An electrolytic cell for the generation of electric energy in which the cell after being discharged may be restored to a charged condition by an electric current flowing in a direction opposite the flow of current when the cell discharges. Synonym: Secondary Cell. See Storage Battery.



Storm sewer: A sewer that carries only surface runoff, street wash, and snow melt from the land. In a separate sewer system, storm sewers are completely separate from those that carry domestic and commercial wastewater (sanitary sewers).



Straight Centrifugal Pump: The common name for non self-priming pumps. When air enters the eye of the impeller and voids the low pressure area in the impeller, this type of pump immediately loses its prime and must be manually re-primed.



Strain: The ratio between the absolute displacement of a reference point within a body to a characteristic length of the body.



Strainer Basket: The second line of defense is a basket at the pump. The holes in this are smaller than those in a skimmer basket, and prevent the pump impeller from clogging up.



Strainer:  A fitting at the end of the suction hose that prevents solids larger than the pump is capable of passing from entering.



Strainer-1-: A device installed in the inlet of the pump to prevent foreign particles from damaging the internal parts of the pump.



Strainer-2-: A fitting at the end of a suction hose that prevents solids larger than its solids handling capability from entering the pump. A device installed in the inlet of a pump to prevent foreign particles from damaging the internal parts.



Stratosphere: The second layer of Earth's atmosphere, just above the troposphere, and below the mesosphere. It is stratified in temperature, with warmer layers higher up and cooler layers farther down. This is in contrast to the troposphere near the Earth's surface, which is cooler higher up and warmer farther down.



Stream flow: The water discharge that occurs in a natural channel. A more general term than runoff, stream flow may be applied to discharge whether or not it is affected by diversion or regulation.



Stream: A general term for a body of flowing water; natural water course containing water at least part of the year. In hydrology, it is generally applied to the water flowing in a natural channel as distinct from a canal.



Stress: in this case refers to tangential stress or the force between the layers of fluid divided by the surface area between the layers.



Stuffing box pressure: Between suction and discharge pressure but closer to suction pressure.



Stuffing box: The joint that seals the fluid in the pump stopping it from coming out between the casing and the pump shaft. The following image (source: the Pump Handbook by McGraw-Hill) shows a typical stuffing box with gland packing. The function of packing is to control leakage and not to eliminate it completely. The packing must be lubricated, and a flow from 40 to 60 drops per minute out of the stuffing box must be maintained for proper lubrication. This makes this type of seal unfit for situations where leakage is unacceptable but they are very common in large primary sector industries such a mining and pulp and paper.



Stuffing box-1-: The portion of the pump that held the packing and now holds the mechanical seal.



Sub Turbine: The driver is close coupled to the pump end and submerged with it, eliminating the need for a long line shaft extending down from the surface. A sub turbine can be installed in any position, from vertical to horizontal.



Submergence: The distance the ejector, foot valve or submersible pump is installed below the pumping level.



Submergence-1-: 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 (at least 10 feet clearance is recommended).



Submersible Pump: A multi-stage centrifugal pump with a waterproof electric motor mounted below the pump end.



Submersible pump-1-: A pump that operates only when totally submersed in the fluid which is being pumped, with waterproof electrical connections, using a motor that is cooled by the liquid.



Submersible Pump-2-: A submersible pump is a centrifugal pump designed to operate within the water source being pumped, thereby eliminating the suction lift limitations common to other types. Submersible pumps, as the name implies, are placed below the water level. They are used mostly for pumping groundwater from wells. The pump is basically a multi-stage centrifugal pump. The impellers of the pump are mounted on a vertical shaft. Each impeller passes water to the next stage through a diffuser shaped so that the water flows vertically to the next diffuser. Each impeller and diffuser is called a stage. The desired output pressure determines the number of stages. The pump is driven by an electric motor bolted  to the pump and is constructed for submerged operation. The wiring of the electric motor is such that it is waterproof. The motors are manufactured to ensure water does not cause it to fail by grounding or shorting out. However, most failures of submersible pumps are due to electrical problems with the motors.



Submersible Turbine Pump Stage: Consists of an impeller, a multi-vane diffuser, a common shaft for all the stages, and fasteners and spacers (depending on the exact style of construction).



Submersible Turbine Pump: A number of centrifugal pumps plumbed together. The discharge on one pump is plumbed directly into the suction of the next pump. That adds pressure energy to the liquid.



Submersible Well Pump – A multi-stage pump with a waterproof electric motor mounted below the pump end.



Submersible well pump ( 4"): A submersible pump consists of two components, a pump end and a submersible motor. The motor end consists of several impellers and diffusers (called stages) that spin on a common shaft. The number of stages determines the head (or pressure) the pump will develop. 4" indicates that the pump will fit a minimum 4" inside diameter well casing.



Submersible: A pump which operates only when totally submersed in the fluid which is being pumped, with water-proof electrical connections or cord, using a motor which is cooled by liquid.



Submersion: Submersion as used here is the height between the free surface of a suction tank and the pump intake pipe.



Subsidence: A dropping of the land surface as a result of ground water being pumped. Cracks and fissures can appear in the land. Subsidence is virtually an irreversible process.



Suction flow splitter: A rib of metal across the pump suction that is installed on certain pumps. It's purpose is to remove large scale vortexes so that the stream lines are as parallel as possible as the fluid enters the impeller eye.



Suction guide: A device that helps straighten the flow ahead of a pump that has a 90 degree elbow immediately ahead of it.



Suction head: Exists when the liquid source is above the centerline of the pump.



Suction head-1-: The total head on the suction side of the pump, including suction lift and friction head.



Suction Hose:  A reinforced hose through which water flows into the suction end of a pump.



Suction Inducer Sleeve: A sleeve surrounding a pump that forces the air or gas to rise in the well, allowing only water to enter the pump suction.



Suction Leak: An escape of liquid from, or insertion of air into, the piping system going into a pump.



Suction lift: Exists when the liquid source is below the centerline of the pump.



Suction Lift-1-: The condition where the water supply is below the pump.



Suction Outlet: Any fitting that allows water to go back from the pool to the main circulating pump (in other words, any pool fitting on the end of the pump’s suction line).



Suction Piping: That part of the pool, spa or hot tub piping through which water passes from the vessel to the pump.



Suction Port:  Same as the inlet. The point where the suction hose or pipe is connected to the pump.



Suction recirculation: Piping from the bottom of the stuffing box back to the suction side of the pump. Used to lower pressure and circulate liquid in the stuffing box.



Suction Side: The plumbing prior to and carrying water to the pump. This side is under vacuum pressure.



Suction specific speed: A formula that will predict one of the types of cavitation. Pumps should be purchased with a number below 8500 (10,000 metric)



Suction specific speed-1-: A number that indicates whether the suction conditions are sufficient to prevent cavitation. According to the Hydraulic Institute the suction specific speed should be less than 8500. Other experiments have shown that the suction specific speed could be as high as 11000. When a pump has a high suction specific speed value, it will also mean that the impeller inlet area has to be large to reduce the inlet velocity which is needed to enable a low NPSHR. However, if you continue to increase the impeller inlet area (to reduce NPSHR), you will reach a point where the inlet area is too large resulting in suction recirculation (hydraulically unstable causing vibration, cavitation, erosion etc..). The recommended maximum suction specifc speed value is to avoid reaching that point.  Keeping the suction specific speed below 8500 is also a way of determining the maximum speed of a pump and avoiding cavitation.



Suction Static Head: the difference in elevation between the liquid level of the source of supply and the centerline of the pump. This head also includes any additional head that may be present at the suction tank fluid surface.



Suction Static Head-1-: The difference in elevation between the liquid level of the fluid source and the centerline of the pump.  This head also includes any additional pressure head that may be present at the suction tank fluid surface, for example as in the case of a pressurized suction tank.



Suction Static Lift: The same definition as the Suction Static head. This term is only used when the pump centerline is above the suction tank fluid surface.



Suction vane: See suction guide.



Suction: Where the water enters the pump.



Sump: A well or pit in which liquids collect below floor level, sometimes refers to an oil reservoir.



Sunbelt: The Sun Belt is a region of the United States generally considered to stretch across the geographic southern United States. The main defining feature of the Sun Belt is its warm-temperate climate with extended summers and brief, relatively mild winters.



Super-Chlorination: Applying 7 - 10 times the normal amounts of chlorine to the pool as an added "boost" for contaminant removal. Some refer to super-chlorinating as being less than shocking, in that breakpoint thresholds are not reached, or the terms may be used synonymously.



Superficial Velocity: A quantitative expression of the rate of linear motion with which water passes through a vessel used to house particles, such as ion exchange resin or carbon media.



Surface Attraction: Another form of resistance to flow in any liquid. A liquid will attach itself to any surface and cannot be moved.



Surface Skimmer or Recirculating Overflow: A device designed to continuously remove surface film and water and return it through the filter as part of the recirculation system, usually incorporating a self-adjusting weir, a collection tank and a means to prevent air lock of the pump (sometimes referred to as a “recirculation overflow,” or a “mechanical” or “automatic skimmer”).



Surface Skimmer System: This term encompasses perimeter type overflows, surface skimmers and surface water collection systems of various design and manufacture.



Surface speed: A measure of the feet per minute the seal face or some other component is moving.



Surface Temperature: The temperature of a motor to the "touch". The surface temperature of continuously (and correctly) operating general purpose industrial electric motor will easily be 80° C (176° F) and perhaps as high as 100° C (212° F). You cannot keep your hand on a surface that hot long enough to discern differences, and if you try, you could get a nasty burn. There are no published standards regarding surface temperatures of general purpose motors, though UL does set such standards for explosion-proof motors.



Surface tension: The attraction of molecules to each other on a liquid's surface. Thus, a barrier is created between the air and the liquid.



Surface water: Naturally occurring water from rainfall which creates lakes, rivers and streams.



Surface Water-1-: The water that systems pump and treat from sources open to the atmosphere, such as rivers, lakes, and reservoirs.



Surge Arrester: Another type of pump protection; protects the pump and controller if someone down line shuts off a piece of equipment that uses lots of power.



Surge Chamber: A storage chamber within the pool recirculating system used to absorb the water displaced by bathers.



Surge Tank: A type of pressurized water storage vessel. Surge tanks typically have large areas of stagnation that offer opportunistic bacteria a favorable environment for multiplication. Commonly found in reverse osmosis systems. Requires periodic sanitation to ensure control of bacterial growth.



Suspended sediment: Very fine soil particles that remain in suspension in water for a considerable period of time without contact with the bottom. Such material remains in suspension due to the upward components of turbulence and currents and/or by suspension.



Suspended solids: Solids that are not in true solution and that can be removed by filtration. Such suspended solids usually contribute directly to turbidity. Defined in waste management, these are small particles of solid pollutants that resist separation by conventional methods.



Suspended-sediment concentration: The ratio of the mass of dry sediment in a water-sediment mixture to the mass of the water-sediment mixture. Typically expressed in milligrams of dry sediment per liter of water-sediment mixture.



Suspended-sediment discharge: The quantity of suspended sediment passing a point in a stream over a specified period of time. When expressed in tons per day, it is computed by multiplying water discharge (in cubic feet per second) by the suspended-sediment concentration (in milligrams per liter) and by the factor 0.0027.



Swamee-Jain equation: An equation that can be used as a substitute for the Colebrook equation for calculating the friction factor f.



Swimming Area: That area of a pool in excess of 3 feet in depth which is devoted to swimming.



Swing joint:  A flexible sprinkler connection made by connecting three threaded elbows fittings together.



Switch Frequency: Same as carrier frequency; the higher the frequency, the more resolution each PWM pulse contains OR the smoother the output waveform and the higher the resolution.



Synchronous motor: Runs with out slippage. Used in elevators and compressors frequently, but seldom used in pumping. Pumps mostly use induction or "squirrel cage" motors.



Synchronous Speed Motor: The speed of the rotating magnetic field set up by the stator winding of an induction motor. In a synchronous motor, the rotor locks into step with the rotating magnetic field and the motor is said to run at synchronous speed. Approximately the speed of the motor with no load on it.This is equal to 120 x Frequency = RPM (revolutions per minute) No Poles.



System curve: A description of what the pump is required to perform. The pump will pump where the system curve intersects the pump curve.



System Curve-1-: A graphical representation the pump Total Head vs. flow. Calculations are done for the total head at different flow rates, these points are linked and form a curve called the system curve. It can be used to predict how the pump will perform at different flow rates. The Total head includes the static head which is constant and the friction head and velocity head difference which depends on the flow rate.    The intersection of the system curve with the pump characteristic curve defines the operating point of the pump.  Changes to the system such as opening or closing valves or making the discharge pipe longer or shorter will change the friction head which will change the shape of the system curve and therefore the operating point.



System curve-2-: is a plot of flow vs. Total Head that satisfies the system requirements.



System Equation: The equation for Total Head vs. flow for a specific system.



System Head Demand: A method of evaluating the Total Head requirements of an entire pumping system.



System head: The head caused by friction in the piping valves and fittings.



System requirements: the parameters that determine Total Head, that is: friction and system inlet and outlet conditions (i.e. velocity, elevation and pressure).



System requirements-1-: Those elements that determine Total Head: friction and the system inlet and outlet conditions (for example velocity, elevation and pressure).



System: As in pump system. The system includes all the piping, including the equipment, starting at the inlet point (often the fluid surface of the suction tank) and ending at the outlet point (often the fluid surface of the discharge tank).



System-1-: The system as referred to in this book includes all the piping with or without a pump, starting at the inlet point (often the fluid surface of the suction tank) and ending at the outlet point (often the fluid surface of the discharge tank).



System-2-: The system as referred to in this book includes all the piping with or without a pump, starting at the inlet point (often the fluid surface of the suction tank) and ending at the outlet point (often the fluid surface of the discharge tank).



System Head Demand: A method of evaluating the Total Head requirements of an entire pumping system.