When calibrating a UT instrument, that has a delay line with single element unit, use:

When calibrating a UT instrument, that has a delay line with single element unit, use:

• A. A single block with thickness near the mid range
• B. At least 2 test blocks with thicknesses near the max and min to be examined
• C. No test blocks required
• D. Three blocks all near max thickness

Answer: (B)