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.
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.
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 effects to a slight degree the efficiency of distillation processes.
SEDIMENT
Very small debris, such as sand, rust, or silt.
SEDIMENTATION
The process by which solids are separated from water by gravity and deposited on the bottom of a container or basin.
SELF PRIMING
A pump designed to have the ability to prime itself automatically, after being initially filled, when operating under a suction lift; to free itself of entrained gas without losing prime; and to continue normal pumping operation without attention.
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.
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.
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.
SERVICE PRESSURE
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
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.
SHUT-OFF HEAD
The head created by a pump that is running against a closed discharge.
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 PROTEIN
A solution containing silver ions, such as Argyrol, used as a germicide.
SKIMMER WEIR
The horizontal surface over which the water flows to the circulating system (usually self-adjusting for water level changes).
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.
SLURRY
A suspension of diatomaceous earth in water used for body feeding in D.E. filters.
SLURRY FEEDER
A device to feed a variable amount of filter aid during the filter cycle.
SODIUM BISULFATE
A dry chemical commonly used to lower pH in water. Also called soda ash.
SODIUM CARBONATE
A dry chemical commonly used to raise pH in water.
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
SOLUTE
Dissolved particles in a solvent
SORBENT
See adsorption.
SPA
A hydrotherapy unit of irregular or geometric shell design. (SEE “HYDROTHERAPY SPA” OR “HOT TUB”)
SPA - INGROUND
A Spa whose sides reside partially or fully below the natural ground level.
SPIRAL WOUND MEMBRANE
The most common practical configuration of membranes for RO systems.
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.
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).
STATIC HEAD
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 OR STANDING WATER LEVEL
The undisturbed level of water in the well before pumping.
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).
SUBMERGENCE
The vertical distance between PUMPING LEVEL and the bottom of the pump or jet assembly. Submergence must be sufficient to insure that the suction opening of the pump or jet assembly is always covered with water, while maintaining enough clearance from the bottom of the well to keep it out of sediment (at least 10 feet clearance is recommended).
SUCTION
Where the water enters the pump
SUCTION HEAD
The total head on the suction side of the pump, including suction lift and friction head.
SUCTION LEAK
An escape of liquid from, or insertion of air into, the piping system going into a pump.
SUCTION PIPING
That part of the pool, spa or hot tub piping through which water passes from the vessel to the pump.
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 SKIMMER
Sometimes called a Recirculating Overflow. A deviced 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.
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 SOLIDS
Includes settle-able particles less than one micron in diameter.
SWIMMING AREA
That area of a pool in excess of 3 feet in depth which is devoted to swimming.