VISIBLE DYE PENETRANT (PT): An intensely colored (usually red) highly penetrating liquid which will provide
maximum contrast with the white developer when used for detection of surface discontinuities under normal light.
VISIBILITY (MT): The ability of magnetic particles to be seen against a contrasting background.
VOID: Discontinuities in which there is a physical separation between opposite walls.
VOLTAGE: The unit of electromotive force that tends to cause an electric current to flow through a conductor.
VOLTAGE REGULATOR: A device that automatically compensates for variations in line-power voltage, thus
maintaining nearly constant voltage on the electrical circuit.
WATER-BREAK (MT): A method of testing the water suspension for the proper amount of wetting agent. The
inability of the rinse water to cover the entire surface in an unbroken film.
WATER-COOLED TUBE (RT): An X-ray tube for which the principal method of cooling is dissipation of heat,
directly or indirectly, by means of water.
WATER DELAY COLUMN (UT): A hollow column filled with water and attached to a search unit; causes a time
delay between the initial pulse and front surface signal.
WATER PATH (UT): In immersion inspection or inspection using a water column delay, the distance from the search
unit face to the test part front surface.
WATER TOLERANCE (IT): The amount of water that a penetrant or emulsifier can absorb before its effectiveness is
WATER TRAVEL (UT): In immersion testing the distance from the face of the search unit to the entry surface of the
material under test.
WATER WASHABLE (PT): A water-washable penetrant is an oil-like material containing an emulsifying agent that
makes it washable by water rinsing.
WATER-WASHABILITY (PT): The property of a penetrant that permits it to be cleaned from the surface of a part by
washing with water.
WAVE FRONT (UT): In a wave disturbance, a continuous surface drawn through the most forward points which have
the same phase.
WAVE INTERFERENCE (UT): The production of a series of maxima and minima of sound pressure, as a consequence
of the superimposition of waves having different phases.
WAVELENGTH: The distance between two points having the same phase in two consecutive cycles of a periodic wave,
along a line in the direction of propagation.
WAVELENGTH (UT): The distance between two corresponding points of the periodic pattern of particle motion that is
a characteristic of ultrasonic energy propagation.
WAVE TRAIN (UT): Succession of ultrasonic waves arising from the same source, having the same characteristics,
and propagating along the same path.