E-8
ElektroPhysik
Making Measurements
This is a top view of a typical transducer. Press against
the top with the thumb or index finger to hold the trans-
ducer in place. Moderate pressure is sufficient, as it is
only necessary to keep the transducer stationary, and
the wearface seated flat against the surface of the ma-
terial being measured
4.
Making Measurements
In order for the transducer to do its job, there must be
no air gaps between the wear-face and the surface of
the material being measured. This is accomplished with
the use of a „coupling“ fluid, commonly called „couplant“.
This fluid serves to „couple“, or transmit, the ultrasonic
sound waves from the transducer, into the material, and
back again. Before attempting to make a measurement,
a small amount of couplant should be applied to the
surface of the material being measured. Typically, a
single droplet of couplant is sufficient
After applying couplant, press the transducer (wearface
down) firmly against the area to be measured. The
Stability Indicator should have six or seven bars
darkened, and a number should appear in the display.
If the MINITEST 403 has been properly „zeroed“ (see
section „Probe Zero“) and set to the correct sound
velocity (see Sound Velecity Selection Table), the number
in the display will indicate the actual thickness of the
material directly beneath the transducer.
If the Stability Indicator has fewer than five bars darkened,
or the numbers on the display seem erratic, first check
to make sure that there is an adequate film of couplant
beneath the transducer, and that the transducer is seated
flat against the material. If the condition persists, it may
be necessary to select a different transducer (size or
frequency) for the material being measured. See section
„Transducer Selection“ for information on this issue.
While the transducer is in contact with the material being
measured, the MINITEST 403 will perform four
measurements every second, updating its display as it
does so. When the transducer is removed from the
surface, the display will hold the last measurement made.
