Understanding Acoustic Emission Testing- Reading 1 Part B-A

■ Method of testing (Linear)
The method of testing requires the use of non intrusive sensing devices
(accelerometers) or intrusive devices (hydrophones) placed on existing
pipeline fittings as well as conditioning, acquisition and signal analysis
instrumentation in order to detect and locate leaks.
The location of the leaking point in the pipe is obtained knowing: the distance
between the sensors that span the leak, the propagation velocity of the leak
sound in the pipeline and the time delay, measured by the cross-correlation
function (see figure 2), that the leak sound takes to reach the two sensors.
D = 2x + v∙∆T, x = ½•(D- v•∆T)
T 2 v
X= T 1 v
∆d = v(T1-T2) =v∙∆T
X= T 1 v
Charlie Chong/ Fion Zhang
http://www.ndt.net/article/wcndt00/papers/idn183/idn183.htm