UFC 3-240-13FN
25 May 2005
Backwash -- The reversal of flow through a filter or an ion exchanger to wash clogging
material out of the filtering medium and reduce conditions causing loss of head.
Backflow preventer -- A device for a water supply pipe to prevent the backflow of
water into the water supply system from the system which it supplies.
Bacteria -- Simple single-cell microscopic organisms generally free of pigment. They
do not require light for their life processes.
Base -- An alkali or hydroxide of alkali metals and ammonia. They can neutralize acids
to form salts and water. A base will ionize to form hydroxyl ions (OH-).
Biocides -- Material typically used to destroy microorganisms (also called
"microbiocides").
processes. Biological deposits may be composed of microscopic organisms, as in
slimes, or of macroscopic organisms such as barnacles or mussels.
Blowdown -- Draining a portion of water from a system to reduce the concentration of
dissolved solids or to discharge accumulations of materials carried by the water.
British Thermal Unit (BTU) -- The amount of heat necessary to raise the temperature
of one pound of water one degree Fahrenheit (oF).
Brine -- A saturated solution for ion exchange regeneration, refrigeration, or cooling
processes. It is usually a sodium chloride water solution for ion exchange regeneration.
It may be sodium chloride water solution or calcium chloride water solution for
refrigeration.
Causticity -- A common term that describes hydroxyl alkalinity or the alkalinity resulting
from the presence of the hydroxyl ion (OH-).
Concentration -- A measure of the amount of dissolved substances contained per unit
volume of solution. This may be expressed as grains per gallon, pounds per million
gallons, milligrams per liter, ppm, or percent.
Condensate -- The material formed when vapor returns to the liquid state. In steam
heating systems, the water condensed from steam. In air conditioning, water extracted
from air by condensation on the cooling coil of a refrigeration machine.
measured between opposite faces of a centimeter cube of an aqueous solution at a
specified temperature. Electrical conductivity is expressed in micromhos (mhos), the
reciprocal of megohms. This is used as a measure of total dissolved solids (TDS).
Corrosion -- The destruction of a substance, usually a metal, or its properties because
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