148
EPOCH 4PLUS
Figure 100 Pressing [F1] to Store the REF B Value
9.16.3
Adding Scanning Gain
AWS codes require that an operator enter a certain amount of scanning gain to the REF B
dB value allowing the operator to locate flaws that may be smaller or deeper into the test
piece than the reference flaw. By pressing [F4], you can enter the amount of scanning gain
necessary to perform the inspection as outlined by AWS Code.
The EPOCH 4PLUS allows scanning gain to be entered in increments of 0.1 dB and 6.0 dB
by default. However, you can customize these settings by using the Editable Parameters
feature that is included with all EPOCH 4PLUS instruments. This feature is located in the
Options Menu. On-screen prompts explain how to adjust the F-Key presets values. Once
the scanning gain is setup, press [F4] to toggle the scanning gain on and off as necessary.
When a discontinuity is located within the test piece, the EPOCH 4PLUS provides a D
value corresponding to the discontinuity. However, in order to display a D value, the gated
echo must peak at an amplitude less than 100% FSH. Often, you will have to press [F4] to
turn off scanning gain and bring the echo peak on the screen. In some cases, further gain
adjustments are necessary.
9.16.4
Calculating A and C Values
When a gated echo has a peak below 100% FSH, the EPOCH 4PLUS automatically
calculates the A and C values necessary to provide a D value. In order to calculate the A
value, the EPOCH 4PLUS automatically calculates the required dB value to bring the
gated echo to 80% FSH. In order to calculate the C value, the EPOCH 4PLUS uses the data
in the soundpath calculator to generate an attenuation factor.
Note:
In order for this calculation to be accurate, you must enter the correct
thickness for the test piece. The EPOCH 4PLUS displays the value for D in
the upper right portion of the A-Scan waveform display.
Summary of Contents for Panametrics Epoch 4 Plus
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