Ultrasonic Flaw Detector DFD30
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22.
Frequency of echo: inverse of time of peak interval obtained by observing when the echo extends on the time
axis.
23.
Sensitivity: a kind of dimension for the min. ultrasonic signal identifiable that is generated on the ultrasonic
detector’s fluorescent screen.
24.
Allowance of sensitivity: difference between the standard and max. defect-detecting sensitivity in term of certain
electric level in an ultrasonic detection system.
25.
Resolution: capability of an ultrasonic detecting system for extinguishing two adjacent defects of certain size
that are most close to each other in transverse, longitudinal or depth direction.
26.
Suppress: a kind of controlling way to reduce or remove signal of low amplitude (electric noise or noise from
material) so as to highlight the high signal in an ultrasonic detector.
27.
Gate: An electronic method for selecting a time range for monitoring the detecting signal or for further
processing.
28.
Attenuator: a unit changing quantitatively the signal voltage (sound voltage).The attenuated volume is expressed
by dB.
29.
S/N ratio: ratio of ultrasonic signal’s amplitude to the max. background noise’s amplitude. It is normally
expressed by dB.
30.
Blockage: a phenomenon occurred in the moment after the receiver receives the sending pulse or strong pulse
signal where its sensitivity drops or it fails.
31.
Gain: the log form of voltage amplification of the receiving amplifier of the ultrasonic detector. It is expressed
by dB.
32.
Distance-amplitude curve (DAC): a set of curve plotted according to specified condition by three parameters, i.e.
distance of the known reflector, gain of the detector and size of the reflector that generates echo. During the
actual detection, one can estimate the equivalent size of defect from this curve based on the measured defect
distance and gain.
33.
Coupling: action that transmits acoustic wave between the probe and the inspected part.
34.
Test block: a sample for determining the features and the detecting sensitivity of an ultrasonic detection system.
35.
Standard test block: a test block whose material, shape and size are calibrated by a body in charge or
authoritative institute. It is used for testing the performance and adjusting sensitivity of an ultrasonic detection
unit or system.
36.
Comparing test block: the test block used for adjusting the sensitivity of an ultrasonic detection system or
comparing the defect. Generally it is made of the material similar with the material to be detected.
37.
Probe: electric-sound converting component for sending or receiving (or both) ultrasonic energy. This kind of
device normally consists of trademark, plug, casing, back lining, piezoelectric component, protective film or
wedge.
38.
Straight probe: a probe for vertical flaw detection, which is mainly for detecting longitudinal wave.
39.
Angle probe: a probe for angle-sending flaw detection, which is mainly for detecting transversal wave.
