A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

DEIONIZATION - The removal of all ionized minerals and salts (both cationic and anionic) from a solution by a two-phase ion exchange procedure. First, positively charged for a chemically equivalent amount of hydrogen ions. Second, negatively charged ions are removed by an anion exchange resin for a chemically equivalent amount of hydroxide ions. The hydrogen and hydroxide ions introduced in this process unite to form water molecules. The term is often used interchangeably with demineralization.

DEMINERALIZATION - The removal of ionized inorganic minerals and salts (not organic materials) from a solution by a two-phase ion exchange procedure; similar to deionization, and the two terms are often used interchangeably.

D.I. or DI - Abbreviation for "deionization".

DISINFECTION - A process in which pathogenic (disease producing bacteria) are killed; may involve disinfecting agents such as chlorine, or physical processes such as heating.

DISSOLVED SOLIDS - The weight of matter in true solution in a stated volume of water; includes both inorganic and organic matter; usually determined by weighing the residue after evaporation of the water at 105 or 180 Degrees Celcius.

DISTILLATION - The process in which a liquid, such as water, is converted into its vapor state by heating, and the vapor cooled and condensed to the liquid state and collected; used to remove solids and other impurities from water, multiple distillations are required for extreme purity.

EQUIVALENT PER MILLION - A unit of concentration used in chemical calculations, calculated by dividing the concentration in ppm or mg/1 by the equivalent weight.

EXHAUSTION - The state of an ion exchange material in which it is no longer capable of effective function due to the depletion of the initial supply of exchangeable ions; the exhaustion point may be defined in terms of a limiting concentration of matter in the effluent, or in the case of demineralization, in terms of electrical conductivity.

FILTER - Specifically, a device or system for the removal of solid particles (suspended solids); in general, includes mechanical, adsorptive, oxidizing and neutralizing filters.

FLOCCULATION - The agglomeration of finely divided suspended solids into larger, usually gelatinous, particles; the development of a "floc" after treatment with a coagulant by gentle stirring or mixing.

FLOW CONTROL - A device designed to limit the flow of water or regenerant to a predetermined value over a broad range of inlet water pressures.

FLOW RATE - The quantity of water or regenerant which passes a given point in a specified unit of time, often expressed in gallons per minute.

FLUORIDATION - The addition of a fluoride compound to a water supply to produce the concentration desired for the reduction in incidence of dental caries.

FOULING - The process in which undesirable foreign matter accumulates in a bed of filter media or ion exchanger, clogging pores and coating surfaces and thus inhibiting or retarding the proper operation of the bed.

FREEBOARD - The vertical distance between a bed of filter media or ion exchange material and the over flow or collector for backwash water; the height above the bed of granular media available for bed expansion during backwashing; may be expressed either as a linear distance or a percentage of bed depth.

GPG - Abbreviation for "grain per gallon".

GRAIN - (gr.) A unit of weight equal to 1/7000th of a pound, or 0.0648 gram.

GRAIN PER GALLON - (gpg) A common basis for reporting water analyses in the United States and Canada; one grain per U.S. gallon equals 17.12 milligrams per liter (mg/1) or parts per million (ppm).

GRAM - (g) The basic unit of weight (mass) of the metric system, originally intended to be the weight of 1 cubic centimeter of water a 4 DegC.

GREENSAND - A natural mineral, primarily composed of complex silicates, which possess ion exchange properties.