9
Suitability of materials
Ultrasonic thickness measurements rely on passing a sound wave through the material being measured. Not all
materials are good at transmitting sound. Ultrasonic thickness measurement is practical in a wide variety of
materials including metals, plastics, and glass. Materials that are difficult include some cast materials, concrete,
wood, fiberglass, and some rubber.
Couplant Gels
All ultrasonic applications require some medium to couple the sound from the transducer to the test piece.
Typically a high viscosity liquid is used as the medium. The sound used in ultrasonic thickness measurement does
not travel through air efficiently.
A wide variety of couplant materials may be used in ultrasonic gauging. Propylene glycol is suitable for most
applications. In difficult applications where maximum transfer of sound energy is required, glycerin is
recommended. However, on some metals glycerin can promote corrosion by means of water absorption and thus
may be undesirable.
Other suitable couplants for measurements at normal temperatures may include water, various oils and
greases, gels, and silicone fluids. Measurements at elevated temperatures will require specially formulated high
temperature couplants.
Inherent in ultrasonic thickness measurement is the possibility that the instrument will use the second rather
than the first echo from the back surface of the material being measured while in standard pulse-echo mode. This
may result in a thickness reading that is TWICE what it should be. The Responsibility for proper use of the
instrument and recognition of these types of phenomenon rests solely with the user of the instrument.
8.Standard Package Contents
Items Qty
UTG-2650(main gauge unit)
1
Probe 1
Coupling gel
1
Operation Manual
1
Alkaline Battery(size AA)
2
Carry case
1
