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
IMPINGEMENT: As used in air-sampling, impingement
refers to a process for the collection of particulate
matter in which a particle containing gas is directed
against a wetted glass plate and the particles
are retained by the liquid.
IMPINGEMENT FILTER: Any filter which removes
particulate only when the particles hit (impinge
on) the filter media.
INCH OF WATER (IN. W.G.): A unit of pressure
equal to the pressure exerted by a column of liquid
water 1 inch high at a temperature of 39.2oF.
INCHES OF WATER COLUMN: A unit used in measuring
pressures. One inch of water column equals a pressure
of 0.25 kPa (0.036 lb per sq in.).
INDUCTION: The process of drawing room air into
the projected air stream because of the velocity
of the projected air stream (sometimes called
aspiration).
INFECTION: 1. The invasion of the body by germs
that reproduce and multiply, causing disease by
local cell injury, release of poisons, or germ-antibody
reaction in the cells. 2. A disease caused by
the invasion of the body by germs.
INFECTIOUS: Capable of causing a disease in a
susceptible host.
INFILTRATION: Air leakage inward through cracks
and interstices, and through ceilings, floors
and walls of a space or building.
INSECTICIDE: Any material or agent capable of
killing insects.
ION: An electrically charged atom. An atom that
has lost one or more of its electrons is left
with a positive electrical charge. Those that
have gained one or more extra electrons are left
with a negative charge.
IONIZATION: The process whereby one or more electrons
is removed from a neutral atom by the action of
radiation. Specific ionization is the number of
ion pairs per unit distance in matter, usually
air.
ISOTHERMAL: An adjective used to indicate a change
taking place at constant temperature.
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