KERN & SOHN TN 60-0.01EE - Manual (Page 11)

TN_EE-BA-e-1410 11
4.5 Performing Measurements
When the instrument is displaying thickness measurements, the display will hold the
last value measured, until a new measurement is made.
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
transfer, 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 (bearing face down) firmly against the
area to be measured. The coupling status indicator should appear, and a digit num-
ber should appear in the display. If the instrument has been properly “zeroed” and set
to the correct sound velocity, the number in the display will indicate the actual thick-
ness of the material directly beneath the transducer.
If the coupling status indicator does not appear, not stable, or the numbers on the
display seem erratic, firstly 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.
While the transducer is in contact with the material that is being measured, the in-
strument 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.
Note：Occasionally, a small film of couplant will be drawn out between the transduc-
er and the surface as the transducer is removed. When this happens, the gauge may
perform a measurement through this couplant film, resulting in a measurement that is
larger or smaller than it should be. This phenomenon is obvious when one thickness
value is observed while the transducer is in place, and another value is observed af-
ter the transducer is removed. In addition, measurements through very thick paint or
coatings may result in the paint or coating being measured rather than the actual ma-
terial intended. The responsibility for proper use of the instrument, and recognition of
these types of phenomenon, rests solely with the user of the instrument.
4.6 Scan mode
While the gauge excels at making single point measurements, it is sometimes desir-
able to examine a larger region, searching for the thinnest point. The gauge includes
a feature, called Scan Mode, which allows it to do just that.
In normal operation, the gauge performs and displays four measurements every se-
cond, which is quite adequate for single measurements. In Scan Mode, however, the
gauge performs ten measurements every second, and displays the readings while
scanning. While the transducer is in contact with the material being measured, the
gauge is keeping track of the lowest measurement it finds. The transducer may be
“scrubbed” across a surface, and any brief interruptions in the signal will be ignored.
When the transducer loses contact with the surface for more than two seconds, the
gauge will display the smallest measurement it found. When the transducer is re-
moved from the material being scanned, the gauge will display the smallest meas-
urement it found.