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3 .0
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AU GE
3.1 Gauge
Probe
Receptacles
Probe Zero Test Plate and
Battery Compartment Cover
Backlit LCD
Display
Membrane
Keypad
Probe
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1 3 .0 A
PPLI CAT I ON
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13.1 Measuring pipe and tubing
When measuring a piece of pipe to determine the thickness of the pipe wall, ori-
entation of the transducers is important. If the diameter of the pipe is larger than
approximately 4 inches, measurements should be made with the transducer orient-
ed so that the gap in the wearface is perpendicular (at right angle) to the long axis
of the pipe. For smaller pipe diameters, two measurements should be performed,
one with the wearface gap perpendicular, another with the gap parallel to the long
axis of the pipe. The smaller of the two displayed values should then be taken as
the thickness at that point.
13.2 Measuring hot surfaces
The velocity of sound through a substance is dependent upon its temperature.
As materials heat up, the velocity of sound through them decreases. In most
applications with surface temperatures less than about 200 °F (100 °C), no
special procedures must be observed. At temperatures above this point, the
change in sound velocity of the material being measured starts to have a
noticeable effect upon ultrasonic measurement.
At such elevated temperatures, it is recommended that the user perform a
calibration procedure (refer to page 11) on a sample piece of known thickness,
which is at or near the temperature of the material to be measured. This will
allow the TI-25M-MMX to correctly calculate the velocity of sound through the
hot material.
When performing measurements on hot surfaces, it may also be necessary to use
a specially constructed high-temperature transducer. These transducers are built
using materials which can withstand high temperatures. Even so, it is recom-
mended that the probe be left in contact with the surface for as short a time as
needed to acquire a stable measurement. While the transducer is in contact with
a hot surface, it will begin to heat up, and through thermal expansion and other
effects, may begin to adversely affect the accuracy of measurements.
A
B
Parallel
Perpendicular