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Operation manual
Ultrasonic Flaw Detector NOVOTEST UD3701
This mode allows to make full-scaled testing of the received signal on the sample. All the device
functions are available, the same as in «FLAW DETECTOR» mode when testing the real signal,
except «GAIN» function.
So, user can study previously saved testing more detailed with possible displaying of additional
parameters on the screen.
2.5 Calibration of flaw detector
2.5.1 Determination of delay in the prism for straight beam probe
While operating with straight beam probe, the prism of the probe is scatting. As a result, signal
delay in the prism changes. Taking into account, that time of UT waves penetration into the probe
prism makes a big influence on correct calculation of reflector coordinates, it is very important to
make precise measurement of delay in the prism and to correct this parameter regularly.
Determination of delay in the prism of the straight beam probe is made by standard calibration
block SO-2.
For determination of delay in the probe prism user has to get the first reflected signal (first echo-
signal) on standard calibration block SO-2 along the 59 mm side and put this signal in one of the
control gates, for example in A-gate.
Delay measurement could be made by time or distance of UT waves penetration.
Method 1: by time:
Select measurement parameters to display – output on the screen the value of penetration time for
required control gate, in this particular case – Та.
Time (in microseconds) of UT waves penetration in the prism of the probe is equal to:
– time between excitation impulse and echo-signal from the surface of the calibration
where t
1
block SO-2 along the 59 mm side, when the probe is set in position for getting the maximum echo-
signal amplitude, in our case – value of the parameter Та;
(≈ 20µs) – time of UT waves penetration in the calibration block SO-2 along the 59 mm side.
t
block
Method 2: by distance:
Select measurement parameters to display – output on the screen the value of the reflector distance
along the probe beam or coordinate of signal depth for required control gate, in this particular case –
La and Ya respectively.
Set the parameter «VEL» (velocity of UT waves penetration in the calibration block, is taken from
the block specification).
By changing parameter «DELAY» in parameter group «Probe» make the value of La or Ya, equal
the value from the block specification or measured by caliper.
2.5.2 Determination of delay in the prism for angle beam probe
While operating with angle beam probe, the refractive prism of the probe is scatting. As a result,
signal delay in the prism changes. Taking into account, that time of UT waves penetration into the
probe prism makes a big influence on correct calculation of reflector coordinates, it is very important
to make precise measurement of delay in the prism and to correct this parameter regularly.
For determination of delay in the probe prism, standard calibration block SО-3 is used.
For determination of delay it is necessary to get the signal, that reflects from the radius surface of
the standard calibration block SО-3.
Procedure of delay determination the prism for angle beam probe:
1. Set the probe, through contact lubricant layer, on the standard calibration block CB3 in a way, that
output point of the probe beam coincides with zero point of the block (figure 2.70).
Page 55
2t = t
- t
,
1
block
(2.1)
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