Dakota Ultrasonics DFX-8 plus MANUAL1 - Manual (Page 85)

DFX-8 Series Ultrasonic Flaw Detectors
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Trigger Curve: Enables the user to set the detection curve to either DGS or GATE.
This will be the curve used to trigger the alarms and display the effective reflector
size (ERS) during the inspection process.
Effective Probe Diameter: A variable used to calculate the near field length of a
given transducer, and determine the defect size. The effective diameter will be noted
on the transducer calibration certificate for a standard DGS transducer. However,
this can be estimated using the formulas outlined in section 10.3.
Probe Frequency: Refers to the center frequency of the transducer being used, and
used in the calculation of the near field length.
Curve Size (ERS): Used to select which curve will be used, based on the reflector
size, from the DGS(AVG) chart in section 10.1. If the value entered is not an exact
curve value represented in the diagram, the DFX-8 will compare and interpolate
between the two closest curves, and mathematically derive a curve for that value.
Attenuation: Used to additionally compensate other factors leading to the loss of
sound/energy. Refer to section 10.5 for more information on the attenuation
parameters. If all the attenuation values are set to zero, the attenuation feature will
display off.
Delay Velocity: The longitudinal velocity of the delay line, most commonly used with
angle beam style probes, but also used with 90 degree compression probes. It’s
important to note that in order for this to be accurate, the ‘probe zero’ must be
accurate. This is easily accomplished performing a two point calibration (auto cal).
Reference Type: This option enables the user to select the type of reflector that will
be used during calibration and setup. The options are Back Wall, Flat Bottom Hole
(FBH), or Side Drilled Hole (SDH).
Reference Size: Assuming the reference type selected is either FBH or SDH, the
user will be required to enter the size of the reference reflector.
10.5 Attenuation Parameters
The attenuation section is setup to accommodate additional factors that can affect
the accuracy of the amplitude or sound energy, considering different application
scenarios. The following parameters are outline below:
DVK (Curvature Correction): If a V1/K1 or V2/K2 (A2/A4, IIW/Kidney) calibration
standard is used as a reference reflector, the curved surface offers additional focus