DeFelsko PosiTector 200 Manual De Instrucciones página 4

Additionally, the PosiTector gage body accepts a wide variety of
probe types including magnetic, eddy-current, and ultrasonic
coating thickness, surface profile, environmental, hardness, salt
contamination and ultrasonic wall thickness probes. See
www.defelsko.com/probes
Couplant is required to propagate ultrasound into the coating.
Water is a good couplant for smooth coatings. Use the supplied
glycol gel for rougher coatings. While it is unlikely that the
couplant will damage the finish or leave a stain on the surface,
we suggest testing the surface by using the couplant on a
sample. If testing indicates that staining has occurred, a small
amount of water can be used instead of couplant. Consult the
Material Safety Data Sheet available on our website and your
coating supplier if you suspect the couplant may damage the
coating. Other liquids such as liquid soap may also be used.
PosiTector 200 - Theory of Operation
PosiTector 200 probes emit a high frequency sound pulse that
travels into the coating via a couplant and reflects from ANY
surface that is different in density. Coating thickness readings are
obtained by measuring the time taken for the ultrasonic signal to
propagate from the probe to the coating/substrate interface and
back. The travel time is divided by two and multiplied by the
velocity of sound for the coating to obtain the thickness of the
coating.
Coating 1
Coating 2
Substrate
Couplant
Couplant
Probe
3
The PosiTector 200
interprets the largest
"echo" within the
selected range as
the coating/coating
or coating/substrate
echo, unless Max
Thick Mode is
activated (pg. 9).