Checkline TI-25S - Manual (Page 7)

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4.0 C ONDITION AND P REPARATION OF M EASURING S URFACE
In any ultrasonic measurement scenario, the shape and roughness of the test
surface are of paramount importance. Rough, uneven surfaces may limit the
penetration of ultrasound through the material, and result in unstable, and
therefore unreliable, measurements. The surface being measured should be clean,
and free of any small particulate matter, rust, or scale. The presence of such
obstructions will prevent the transducer from seating properly against the surface.
Often, a wire brush or scraper will be helpful in cleaning surfaces. In more
extreme cases, rotary sanders or grinding wheels may be used, though care
must be taken to prevent surface gouging, which will inhibit proper transducer
coupling.
Extremely rough surfaces, such as the pebble-like finish of some cast irons,
will prove most difficult to measure. These kinds of surfaces act on the sound
beam like frosted glass on light, the beam becomes diffused and scattered in all
directions.
In addition to posing obstacles to measurement, rough surfaces contribute to
excessive wear of the transducer, particularly in situations where the transducer is
“scrubbed“ along the surface. Transducers should be inspected on a regular basis,
for signs of uneven wear of the wearface. If the wearface is worn on one side
more than another, the sound beam penetrating the test material may no longer be
perpendicular to the material surface. In this case, it will be difficult to exactly
locate tiny irregularities in the material being measured, as the focus of the
soundbeam no longer lies directly beneath the transducer.
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10.0 S PECIFICATIONS
Measuring Range 0.025 to 19.999 inches (0.63 to 500 mm)
Resolution: 0.001 inch (0.01mm)
Accuracy ±0.001 inch (0.01mm, depends on
material and conditions
Sound Velocity
Range
0.0492 to 0.3930 in/µs (1250 to 10000µ/s)
Keypad Sealed membrane, resistant to water and
petroleum products.
Display Liquid-Crystal-Display, 4.5 digits,
0.500 inch high numerals. LED backlight
Power Source Two AA size, 1.5 volt alkaline
or 1.2 volt NiCad cells.
Battery Life 200 hours typical operating time using alkaline,
120 hours typical operating time using NiCad.
Weight 10 ounces
Size 2.5W x 4.75H x 1.25D inches
(63.5W x 120.7H x 31.8D mm).
Operating
Temperature
–20 to 120 °F (–20 to 50 °C)
Case Extruded aluminum body
nickel plated aluminum end caps.