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DAC curve construction procedure
T
o construct the DAC curve, once the full scale calibration is performed, it is necessary to have samples with
sample flaws equivalent to those you want to work on.
11. Go to the DAC function of the main MEAS menu;
12. Select DRAW in the MODE video window; put the coupling liquid on the part;
13. Place the probe, and maximize the response at the flaw;
14. Enable the CURSOR window using the adjacent key;
15. Adjust the cursor position using the
keys until only the flaw peak is contained;
1
6. Press the SET key to confirm the point;
17. Repeat the previous steps for each point of the curve, up to a maximum of 10;
18. Select the MODE window using the adjacent key;
19. Activate the ON option using
.
T
he DAC curve is displayed on the video and it is possible to set the remaining parameters:
• Activate the CURVE box and select the type of display with the
keys: DAC; -6/-
1
2dB; -6/-14dB; -2/-6/-10dB; -2dB; -6dB; -10dB.
• Select the trigger between Gate or DAC.
• Select the measurement type between dB, %fsh and %DAC.
11.4.5 AVG Menu
This menu is used to create the AVG curve for calculation of the flaw dimension based on the backwall echo
and the reference reflector selected by the operator.
MODE:
OFF
Start mode. Disables displaying of the ADA curve.
FREQ
Used to set the transducer frequency (data which can be found on the
datasheet of the probe used).
NFL
Used to set the next field length (data which can be found on the datasheet
of the probe used).
ERS
Used to set the dimension of the equivalent flaw. This is the setting of the
ADA curve test sensitivity and represents the diameter, expressed in mm,
of an equivalent flaw supplied by an echo which touches the curve tracked
on the video.
MODE:
SET PRB
Mode used to set the correction factor of the curves and probe delay.
dVK
Used to set the curve factor in dB. This parameter makes it possible to use
a curved surface to obtain a backwall echo to use as reference signal.
DELAY
Used to set the probe delay velocity, expressed in meters per second. It is
the velocity of the longitudinal waves of the material making up the probe
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