Page 195 - Intro Predictive Maintenance

186 An Introduction to Predictive Maintenance

Quantitative infrared thermography The practice of measuring temperatures of
the observed patterns of infrared radiation.
Radar band Frequency and designation with wave-
lengths within the range of approximately
100 microns to 2 meters.
Radiation The emission and propagation of waves
transmitting energy through space or
through some medium.
Radio band The range of wavelengths or frequencies
of electromagnetic radiation designated as
radio waves; approximately 4 to 9Hz in
frequency.

Reflectivity The fraction of the incident radiant energy
reflected by a surface that is exposed to
uniform radiation from a source that fills its
field of view.

Spectral band An interval in the electromagnetic spectrum
defined by two wavelengths, two frequen-
cies, or two wave numbers.

Temperature gradient Rate of change of temperature with
distance.

Thermal emittance Emittance of radiation by a body not at
absolute zero because of the thermal agita-
tion of its molecules.
Thermography The recording of the thermal qualities of
objects and surfaces by means of scanning
equipment in which the infrared radiation or
microwave radiation recorded can be con-
verted into a thermal image.
Transmittance The ratio of energy transmitted by a body to
that incident on it.
Ultraviolet band That portion of the electromagnetic spec-
trum ranging from just above the visible
(about 4,000ang.) to below 400ang., on the
border of the X-ray region.
Visible band The band of the electromagnetic spectrum,
which can be perceived by the naked eye.
This band ranges from 7,500ang. to 4,000
ang., being bordered by the infrared and
ultraviolet bands.