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D.I. Or Di |
Abbreviation for "deionization". |
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Dechlorination |
The removal of chlorine
residual. |
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Deionization |
The removal of all ionized
minerals and salts from a solution by a two-phase ion exchange process.
First, positively charged ions are removed by a cation exchange resin in
exchange 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,
commonly abbreviated as DI, is often used interchangeably with
demineralization. (See demineralization, ion exchange.) |
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Demineralization |
The removal of ionized
minerals and salts from a solution by a two-phase ion exchange procedure,
similar to deionization, and the two terms are often used interchangeably.
(See deionization, ion exchange.) |
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Density |
The mass of a substance per
specified unit of volume; for example, pounds per cubic foot. True density
is the mass per unit volume excluding pores; apparent density is the mass
per unit volume including pores. (See specific gravity.) |
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Detergent |
Any material with cleaning
powers, including soaps, synthetic detergents, many alkaline materials and
solvents, and abrasives. In popular usage the term is often used to mean
the synthetic detergents such as ABS of LAS. (See alkyl benzene sulfonate,
linear alkyl sulfonate, soap.) |
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Dialysis |
The separation of
components of a solution by diffusion through a semi-permeable membrane
which is capable of passing certain ions or molecules while rejecting
others. (See electrodialysis, semi-permeable membrane.) |
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Diaphragm Pump |
A type of positive
displacement pump in which the reciprocating piston is separated from the
solution by a flexible diaphragm, thus protecting the piston from
corrosion and erosion, and avoiding problems with packing and seals. |
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Diatomaceous Earth |
A processed natural
material, the skeletons of diatoms, used as a filter medium. |
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Diatomite |
Another name for
diatomaceous earth. |
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Dielectric Fitting |
A plumbing fitting made of,
or containing, an electrical nonconductor, such as plastic; used to
separate dissimilar metals in a plumbing system to control galvanic
corrosion. |
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Differential Pressure |
See pressure differential. |
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Digestion |
The process in which
complex materials are broken down into simpler substances; may be due to
chemical, biological or a combination of reactions. (See sterilization.) |
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Disinfectant |
A chemical (commonly
chlorine, chloramine, or ozone) or physical process (e.g., ultraviolet
light) that kills microorganisms such as bacteria, viruses, and protozoa. |
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Disinfection |
A process in which
vegetative bacteria are killed; may involve disinfecting agents such as
chlorine, or physical processes such as heating. (See aerobic, anaerobic.) |
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Dissociation |
The separation of molecules
into positively and negatively charged ions; occurs when salts dissolve in
water. (See ionization.) |
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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 180oC. |
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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. |
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Distribution System |
A network of pipes leading
from a treatment plant to customers' plumbing systems. |
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Distributor |
A device or system designed
to produce even flow through all sections of an ion exchanger or filter
bed, and to retain the media in the tank or vessel; usually installed at
the top and bottom of loose media systems. (See collector.) |
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Dolomite |
A specific form of
limestone containing chemically equivalent concentrations of calcium and
magnesium carbonates; the term is sometimes applied to limestones with
compositions similar to true dolomite. |
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Domestic |
A term sometimes applied to
water conditioning equipment designed for household use. |
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Downflow |
A term designating the
direction (down) in which water or a regenerant flows through an ion
exchanger or filter during any phase of the operating cycle. |
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Drain |
A pipe or conduit in a
building plumbing system which carries liquids to waste by gravity;
sometimes the term is limited to liquids other than sewage. |
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Drain Line |
A tube or pipe from a water
conditioning unit that carries backwash water, regeneration wastes and/or
rinse water to a drain or waste system. |
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Dynamic |
Active, alive, or tending
to produce motion, as opposed to static, resting or fixed. |
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Dynamic System |
A system or process in
which motion occurs, or includes active forces, as opposed to static
conditions with no motion. |
