DMQ QS3 B, Руководство пользователя

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VII
untreated steel, but the sound velocities vary significantly. Instruments
should be calibrated before and after testing to minimize errors.
Transducers must be in good condition and show no visible signs of
excessive wear or defects on their surface. Badly worn transducers can
provide erroneous measurements.
The thickness of the material being tested must be within the specified
thickness range of the transducer and the temperature of the material
must also be within the specified temperature range of the transducer.
Calibration as well as actual testing should be performed under similar
coupling conditions. Couplant must be applied in an even and
consistent manner to minimize variations in couplant layers that may
result in testing errors. The amount of couplant should be kept to a
minimum and consistent pressure should be applied on the transducer
when measuring.
Doubling refers to a thickness measurement that displays a reading
that is twice or even three times the real test piece thickness. Doubling
often may happen when trying to measure below and above the
specified range for the transducer and when using worn transducers.
When in doubt, the test piece thickness must be measured using other
methods and or instruments and the unit must then be calibrated
using reference test blocks of known thickness values that are made of
the same material as the actual test piece. This is very important when
measuring unknown test pieces for the first time.
When possible calibrate your instrument on-site using a test block that
is at the same temperature as the test piece in order to minimize
errors.