Glossary Of Water Treatment
Industry Terms . . ."N"
"nm", a unit of length equal to one thousandth of a micrometer.
Often used to express the wavelength of ultraviolet light and the colors
of visible light in colorimetric analytical procedures.
negative charge - The
electrical charge on an electrode or ion in solution, due to the presence
of an excess of electrons. (See electron, anion.)
negative head - A condition
of negative pressure or partial vacuum.
negative pressure - A
pressure below that of the surrounding atomspheric pressure at a specific
point; a partial vacuum.
nephelometric turbidity unit-
An arbitrary unit of measuring the turbidity in water by the light
scattering effect of fine suspended particles in a light beam (contrast
to "Jackson Turbidity Unit").
neutral - In electrical
systems, the term used to indicate neither an excess nor a lack of electrons;
a condition of balance between positive and negative charges. In chemistry,
the term used to indicate a balance between acids and bases; the neutral
point on the pH scale is 7.0, indicating the presence of equal numbers
of free hydrogen (acidic) and hydroxide (basic) ions.
neutralization - The
addition of either an acid or a base to a solution as required to produce
a neutral solution. The use of alkaline or basic materials to neutralize
the acidity of some waters is a common practice in water conditioning.
neutralizer - A common
designation for alkaline materials such as calcite (calcium carbonate)
or magnesia (magnesium oxide) used in the neutralization of acid waters.
- Water hardness due to the presence of compounds such as calcium
and magnesium chlorides, sulfates or nitrates; the excess of total hardness
over total alkalinity.
normal solution - A solution
containing a gram equivalent weight of a substance in one liter of solution.
(See equivalent weight.)
NTU - Abbreviation for "Nephelometric Turbidity Unit".