910-269-EN, Rev. B, June 2011
140 Chapter 9
A thickness measurement reading appears in large text above the A-scan.
12. Once a steady reading is achieved, choose 1/5 > Auto CAL > CAL Velocity.
The screen freezes and the Enter Value for Velocity Cal dialog box appears.
13. Adjust the value to match the known thickness of the gated indication (0.500 in. in
this example), and then choose Calculate to complete the calibration process.
It is possible to use the auto-calibration on a test block with only one known
thickness. In this scenario, leave the transducer coupled on the unique thickness,
move the gate over to one of the multiple back-wall echoes, and then enter the
correct sound path thickness (the appropriate multiple of the first back-wall echo)
during the velocity portion of the calibration.
9.4 Calibrating with a Delay Line Transducer
The sample delay line calibration described below is performed using Olympus
transducer part number V202-RM, with a frequency of 10.0
MHz and an element
diameter of 0.25
in. (6 mm).
The calibration requires a test block with two known thicknesses, made from the
material to be measured. Ideally, the two thickness measurements are both below and
above the expected thickness of the material to be inspected. For this example, we are
using Olympus standard 5-step steel-test block, part number 2214E. The steps
measure 0.100
in., 0.200 in., 0.300 in., 0.400 in., and 0.500 in.
If the EPOCH 1000 Series is set to work in metric units, the calibration process is
exactly the same, except that the entries are in millimeters rather than inches.
To calibrate using a delay line transducer
1. Follow the initial setup procedure outlined in section 9.1 on page 134.
2. Connect the transducer to an appropriate cable and then connect the cable to
either of the conventional transducer connectors at the top of the instrument.
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