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16 MEASUREMENT - DETECTING FLAWS
Disclaimer: Inherent in ultrasonic measurement is the possibility that the instrument will use the
second rather than the first echo from the back surface of the material being measured. This may
result in a incorrect readings.
Responsibility for proper use of the instrument and recognition of this phenomenon rests solely with
the user of the instrument.
Other errors may occur from measuring coated materials where the coating is insufficiently bonded
to the material surface. Irregular and inaccurate readings may result. Again, the user is responsible
for proper use and interpretation of the measurements acquired.
16.1 BEFORE YOU START
•
Prepare the surface - see "Condition and Preparation of Surfaces" on page 56.
•
Set transducer type, calibrate and set the zero - see "Setting Up The Flaw Detector" on
page 28.
•
Set up the Gate or Gates - see "Gates" on page 35.
•
Choose the measurement view - see "The Measurement Screen" on page 26.
16.2 PROCEDURE
See "Procedure" on page 21.
17 ADJUSTING THE WAVEFORM DISPLAY
If the waveform around the detection point is not visible on the display, use one of the following
methods to adjust the viewable range of the display:
•
Use the Auto Find function - see "Auto Find" on page 23. This is the preferred method and
provides a quick and easy method of adjusting the viewable range.
•
Change the values of the DELAY and RANGE functions until the measurement falls inside the
viewable range of the display - see instructions below.
17.1 AUTO FIND
Your gauge includes a function for locating the detection point of a back wall echo that is not
currently in the viewable region of the display. Suppose the gauge is currently setup with a delay of
0.0 and a width of 1.0, and you are measuring material with a thickness of 2.5. The gauge will make
the correct measurement and display it digitally, however, the waveform will not be visible without
adjusting the values of Delay and Width.
The AUTO FIND function solves this problem by letting the gauge find the detection point and bring
the waveform signal into view automatically. If necessary you can then make small adjustments to
the range once the signal is displayed on the screen.
To use the AUTO FIND function:
1. Place the transducer on the test material and obtain a reading.
2. Press MENU/UTIL menu and then highlight the AUTO FIND function.
3. Press ENTER.
4. Press OK. This will adjust the settings automatically and the waveform is brought into view on
the measurement screen.
5. Press MEAS to return to the measurement screen, ready to begin taking readings.
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