UFC 3-410-04N
25 October 2004
FRP
Fiberglass reinforced plastic used in construction of such
items as boats and airplanes. It is also used for ductwork in
corrosive environments.
Fumes
Small, solid particles formed by the condensation of vapors
of solid materials.
Gases
Formless fluids which tend to occupy an entire space
uniformly at ordinary temperatures and pressures.
Gravity, specific
Ratio of the mass of a unit volume of a substance to the
mass of the same volume of a standard substance at a
standard temperature. Water at 39.2 degrees F is the
standard substance usually referred to for gases, dry air, at
the same temperature and pressure as the gas is often
taken as the standard substance.
Hood
A shaped inlet designed to capture contaminated air and
conduct it into the exhaust duct system.
Humidity, relative
Ratio of the actual partial pressure of the water vapor in a
space to the saturation pressure of pure water at the same
temperature.
Lower explosive limit
Lower limit of flammability or explosiveness of a gas or
(LEL)
vapor at ordinary ambient temperatures expressed in
percent of the gas or vapor in air by volume. This limit is
assumed constant for temperatures up to 250 degrees F.
Above these temperatures, it should be decreased by a
factor of 0.7 since explosiveness increases with higher
temperatures.
Manometer
An instrument for measuring pressure; essentially a U-tube
partially filled with a liquid, usually water, mercury or a light
oil, so constructed that the amount of displacement of the
liquid indicates the pressure being exerted in the instrument.
Micron
A unit of length; the thousandth part of 1 millimeter or the
millionth of a meter (approximately 1/25,000 of an inch).
Mists
Small droplets of materials that are ordinarily liquid at normal
temperature and pressure.
Plenum
A pressure equalizing chamber.
Glossary-2
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