KERN & SOHN TU 300-0.01US - Manual (Page 10)

Sauter GmbH
Ziegelei 1
D-72336 Balingen
E-Mail: [email protected] Tel: +49-[0]7433- 9933-199
Fax: +49-[0]7433-9933-149
Internet: www.kern-sohn.com
Instruction Manual
TU_US
TU_US-BA-e-1212 10
If there should appear some abnormal phenomena to the
instrument, please do not dismantle or adjust any fixed
assembly parts on your own. Instead of this, the present
warranty card has to be filled out and the instrument has to
be sent to us. The warranty service can be carried on.
7. Transport and Storage
The instrument has to be kept away from vibration, strong
magnetic fields, corrosive medium, dumpiness or dust.
Storage in ordinary temperature.
Appendix A Sound velocities
Material Sound Velocity
In/us m/s
Aluminum 0.250 6340-6400
Steel, common 0.233 5920
Steel, stainless 0.226 5740
Brass 0.173 4399
Copper 0.186 4720
Iron 0.233 5930
Cast Iron 0.173-0.229 4400－5820
Lead 0.094 2400
Nylon 0.105 2680
Silver 0.142 3607
Gold 0.128 3251
Zinc 0.164 4170
Titanium 0.236 5990
Tin 0.117 2960
Epoxy resin 0.100 2540
Ice 0.157 3988
Nickel 0.222 5639
Plexiglass 0.106 2692
Polystyrene 0.092 2337
Porcelain 0.230 5842
PVC 0.094 2388
Quartz glass 0.222 5639
Rubber, vulcanized 0.091 2311
Teflon 0.056 1422
Water 0.058 1473
Appendix B Application Notes
Measuring pipe and tubing
When a piece of pipe is measured to determine the
thickness of the pipe wall, the orientation of the transducer
is of importance. If the diameter of the pipe is larger than
approximately 4 inches, measurement should be
performed with the transducer orientated in the way that
the gap in the surface of the sensor is perpendicular (at
right angle) to the long axis of the pipe.
For smaller pipe diameters, two measurements should be
performed, one with the surface gap of the sensor
perpendicular, another with the gap parallelto the long axis
of the pipe. The smaller one of the displayed values should
be taken as the thickness of that point.
Measuring hot surfaces
The sound velocity through a substance is dependent on
its temperature. As materials heat up, the velocity of sound
through them decreases. In most applications with surface
temperatures of less than 100°C, no special procedures
must be observed. At temperatures above that point, the
change in sound velocity of the material being measured
starts having a noticeable effect upon ultrasonic
measurement. At such elevated temperatures it is
recommended to first performing a calibration on a sample
piece of known thickness, which is at or near the
temperature of the material being measured. This will allow
the instrument to correctly calculate the sound velocity
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 of
materials which can withstand high temperatures.
It is also recommended that the sensor has to be left in
contact with the surface for a short time in order to aquire a
stable measurement. While the transducer is in contact
with the hot surface, it will be heated up and with termal
expansion and other effects, the accuracy of measurement
may adversely be affected.
Measuring laminated materials
Laminated materials are unique because of their density
(and therefore sound velocity) may considerably vary from
one piece to another. Some laminated materials may even
exhibit noticeable changes in sound velocity across a
single surface. The only way to a reliable measurement is
to perform a calibration on a sample piece of known
thickness. Ideally, this sample material should be a part of
the same piece being measured, or at least from the same
lamination batch. The effects of variation of sound velocity
will be minimized by calibrating each test piece
individually.
An additional important consideration is , that any included
air gaps or air pockets will cause an early reflection of the
ultrasound beam. This will be noticed as a sudden
decrease in thickness in an otherwise regular surface.
While this may impede accurate measurement of the total
material thickness, it does positively indicate any air gaps
in the laminate.
Suitability of materials
Ultrasonic thickness measurement relies on passing a
sound wave through the material being measured. Not all