Check-line TI-25S User manual

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TABLE OF CONTENTS
01.0 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 02
1.1 Accessories
02.0 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 03
2.1 Gauge
2.2 Complete Kit
03.0 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 04
3.1 Keypad
3.2 Display
3.3 Transducer
04.0 Condition & Preparation Of Surfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 07
05.0 Zeroing The Probe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 08
06.0 Selecting Material Type (Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 09
07.0 Downloading Custom Calibrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
08.0 Transducer Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
09.0 Making Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
10.0 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
11.0 Appendix A: Application Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
12.0 Appendix B: Sound Velocities Of Common Materials . . . . . . . . . . . . . . . . 17
13.0 Appendix C: User-Selected Material Types. . . . . . . . . . . . . . . . . . . . . . . . . 18
14.0 Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
IMPORTANT NOTE:
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. This may result in a thickness reading that is TWICE what it should be.
Responsibility for proper use of the instrument and recognition of this phenomenon rests
solely with the user of the instrument.
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NOTES

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1.0 INTRODUCTION
The TI-25S is ideal for the person who tests a few different materials regularly.
The TI-25S contains 8 common material velocities (see list of materials on
page 9) and two velocities that the user can set using a simple software program.
The tool’s backlit display is easy to read, even in dim light, and the unit operates
for up to 200 hours on a single set of batteries. The TI-25S comes complete,
ready to use, and is protected by our 5-year limited warranty.
1.1 Accessories
NIST-Traceable Steel Test Block - 3 Sizes Available
• Precision Machined and Finished
• Includes NIST-Traceable Report and Test Data
Uncertified Steel Test Block For Ultrasonic Gauges
• For convenient confirmation of thickness gauge
calibration
TICC-M Protective Holder for Ultrasonic Gauges
• Constructed from heavy duty Cordura Nylon
CF12 Coupling Fluid (12 oz. bottle)
• Used to create an ultrasonic coupling between
the probe and material to be measured
V-Block Transducer Holder
• The V-Block transducer holder offers the operator
greater control and repeatabily when measuring on
pipes and other curved areas.
To order, visit, www.checkline.com.
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14.0 WARRANTY
ELECTROMATIC Equipment Co., Inc. (ELECTROMATIC) warrants to the
original purchaser that this product is of merchantable quality and confirms
in kind and quality with the descriptions and specifications thereof. Product
failure or malfunction arising out of any defect in workmanship or material
in the product existing at the time of delivery thereof which manifests itself
within five years from the sale of such product, shall be remedied by repair
or replacement of such product, at ELECTROMATIC’s option, except where
unauthorized repair, disassembly, tampering, abuse or misapplication has
taken place, as determined by ELECTROMATIC. All returns for warranty
or non-warranty repairs and/or replacement must be authorized by
ELECTROMATIC, in advance, with all repacking and shipping expenses
to the address below to be borne by the purchaser.
THE FOREGOING WARRANTY IS IN LIEU OF ALL OTHER
WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING BUT NOT
LIMITED TO, THE WARRANTY OF MERCHANTABILITY AND
FITNESS FOR ANY PARTICULAR PURPOSE OR APPLICATION.
ELECTROMATIC SHALL NOT BE RESPONSIBLE NOR LIABLE FOR
ANY CONSEQUENTIAL DAMAGE, OF ANY KIND OR NATURE,
RESULTING FROM THE USE OF SUPPLIED EQUIPMENT, WHETHER
SUCH DAMAGE OCCURS OR IS DISCOVERED BEFORE, UPON OR
AFTER REPLACEMENT OR REPAIR, AND WHETHER OR NOT SUCH
DAMAGE IS CAUSED BY MANUFACTURER’S OR SUPPLIER’S
NEGLIGENCE WITHIN FIVE YEARS FROM INVOICE DATE.
Some State jurisdictions or States do not allow the exclusion or limitation of
incidental or consequential damages, so the above limitation may not apply
to you. The duration of any implied warranty, including, without limitation,
fitness for any particular purpose and merchantability with respect to this
product, is limited to the duration of the foregoing warranty. Some states
do not allow limitations on how long an implied warranty lasts but, not
withstanding, this warranty, in the absence of such limitations, shall extend
for five years from the date of invoice.
ELECTROMATIC Equipment Co., Inc.
600 Oakland Ave. Cedarhurst, NY 11516—USA
Tel: [phone]/ Tel: [phone]/ Fax: [phone]
Every precaution has been taken in the preparation of this manual. Electromatic Equipment Co., Inc.,
assumes no responsibility for errors or omissions. Neither is any liability assumed for damages resulting
from the use of information contained herein. Any brand or product names mentioned herein are used for
identification purposes only, and are trademarks or registered trademarks of their respective holders.

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2.0 OVERVIEW
2.1 Gauge
2.2 Complete Kit
Probe Receptacles
Probe Zero Test Plate and
Battery Compartment Cover
Backlit LCD
Display
Membrane
Keypad
Probe
The TI-25S is supplied as a complete
kit with the gauge, probe, 4 oz. bottle
of coupling fluid, 2 AA batteries,
NIST Calibration Certificate, and
Operating Instruction Manual—
all in a foam-fitted carrying case.
NOTE: Data cable must be ordered
seprately to program User #1
and #2 customer velocities.
– 18 –
13.0 APPENDIX C: USER-SELECTED MATERIAL TYPES
Each time the “MATL” key is pressed, the material type (the calibration
setting of the accoustic velocity) changes from one type to the other.
The abbreviations, descriptions and sequence is shown below.
NOTE: If the Custom 1 and 2 are needed, they are set using the PC software
(free) and downloaded to the gauge using the data cable (optional,
p/n N-306-0010).

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3.0 OPERATION
The TI-25S interacts with the operator through the
membrane keypad and the LCD display. The functions
of the various keys on the keypad are detailed below,
followed by an explanation of the display and its
various symbols.
3.1 The Keypad
This ON/OFF key is used to turn the TI-25S on and off. When
the gauge is turned ON, it will first perform a brief display test by
illuminating all of the segments in the display. After one second,
the gauge will display the internal software version number. After
displaying the version number, the display will show “0.000” (or
“0.00” if using metric units), indicating the gauge is ready for use.
The TI-25S is turned OFF by pressing the ON/OFF key. The gauge
has a special memory that retains all of its settings even when the
power is off. The gauge also features an auto-powerdown mode
designed to conserve battery life. If the gauge is idle for 5 minutes, it
will turn itself off.
The MAT’L key is used to toggle through the 8 hard set and 2 user
programmed material types. When this key is pressed, the abbreviat-
ed material name will be displayed followed by the material velocity
for that specific material. The two user-defined material locations
will display “Usr 1” and “Usr 2” respectively.
NOTE: The material velocities in the TI-25S are approximate
velocities only. Materials of the same type may have
slightly different material velocities introducing error into
the overall measurement.
NOTE: The material types hard set in the TI-25S are listed by
type, abbreviation, and velocity on the back of the TI-25S.
The PRB-0 key is used to “zero” the TI-25S in much the same way
that a mechanical micrometer is zeroed. If the gauge is not zeroed
correctly, all of the measurements that the gauge makes may be in
error by some fixed value. Refer to page 8 for an explanation of this
important procedure.
The IN/MM key is used to switch back and forth between English
and Metric units. This key may be used at any time, whether the
gauge is displaying a thickness (IN or MM) or a velocity value
(IN/µs or M/s).
ON
OFF
MAT’L
IN
MM
PRB
0
– 17 –
Aluminum 0.2500 6350
Bismuth 0.8600 2184
Brass 0.1730 4394
Cadmium 0.1090 2769
Cast Iron 0.18000 4572
Constantan 0.2060 5232
Copper 0.1840 4674
Epoxy resin 0.1000 2540
German silver 0.1870 4750
Glass, crown 0.2230 5664
Glass, flint 0.1680 4267
Gold 0.1280 3251
Ice 0.1570 3988
Iron 0.2320 5898
Lead 0.8500 2159
Magnesium 0.2280 5791
Nickel 0.2220 5639
Nylon 0.1020 2591
Paraffin 0.0870 2210
Platinum 0.1560 3962
Plexiglass 0.1060 2692
Polystyrene 0.0920 2337
Porcelain 0.2300 5842
PVC 0.0940 2388
Quartz glass 0.2220 5639
Rubber, vulcanized 0.0910 2311
Silver 0.1420 3607
Steel, common 0.2330 5920
Steel, stainless 0.2230 5664
Stellite 0.2750 6985
Tin 0.1310 3327
Titanium 0.2400 6096
Tungsten 0.2100 5334
Zinc 0.1660 4216
Water 0.058 1473
Material Velocity Velocity
Type Inches/µs Meters/s
Notes: 1. These values are to be used only when a suitable sample of known
thickness is not available for calibrating, as slight variations in material
composition, finishing (hardening, polishing, etc.) or shape can affect the
acoustic velocity.
...
Notes: 2. “✔” denotes the factory default setting for acoustic velocity.
✔
12.0 APPENDIX B: SOUND VELOCITIES OF COMMON MATERIALS

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The BACKLIGHT key switches the display backlight between three avail-
able settings. OFF will be displayed when the backlight is switched off.
AUTO will be displayed when the backlight is set to automatic mode, and
ON will be displayed when the backlight is set to stay on. In the AUTO
setting, the backlight will illuminate when the TI-25S is actually making a
measurement.
3.2 The Display
Numerals: The numeric portion of the
display consists of 4 complete digits
preceded by a leading “1”, and is used
to display numeric values, as well as
occasional simple words, to indicate
the status of various settings. When
the TI-25S is displaying thickness
measurements, the display will hold the
last value measured, until a new measure-
ment is made. Additionally, when the
battery voltage is low, the entire display
will begin to flash. When this occurs, the
batteries should be replaced.
Stability Indicator: These 8 vertical
bars form the Stability Indicator. When the
TI-25S is idle, only the left-most bar and
the underline will be on. When the gauge
is making a measurement, six or seven of
the bars should be on. If fewer than five
bars are on, the TI-25S is having difficulty
achieving a stable measurement, and the
thickness value displayed will most likely
be erroneous.
IN Symbol: When the IN symbol is on,
the TI-25S is displaying a thickness value
in inches. The maximum thickness that
can be displayed is 19.999 inches.
MM Symbol: When the MM symbol is
on, the TI-25S is displaying a thickness
value in millimeters. If the displayed
thickness exceeds 199.99 millimeters, the
decimal point will shift automatically to
the right, allowing values up to 1999.9
millimeters to be displayed.
1.8.8.8.8
+INMM/μs
1.8.8.8.8
+INMM/μs
1.8.8.8.8
+INMM/μs
1.8.8.8.8
+INMM/μs
– 16 –
An additional important consideration when measuring laminates is that
any included air gaps or pockets will cause an early reflection of the
ultrasound beam. This effect will be noticed as a sudden decrease in thick-
ness in an otherwise regular surface. While this may impede accurate
measurement of total material thickness, it does provide the user with
positive indication of air gaps in the laminate.

– 6 –
IN/µs Symbol: When the IN
symbol is on, in conjunction with
the /µs symbol, the TI-25S is
displaying a sound-velocity value in
inches-per-microsecond.
M Symbol: When the M symbol is on,
in conjunction with the /s symbol, the
TI-25S is displaying a sound-velocity
value in meters-per-second.
3.3 Transducer
The transducer is the “business end” of the
TI-25S. It transmits and receives the ultra-
sonic sound waves which the TI-25S uses
to calculate the thickness of the
material being measured. The transducer
connects to the TI-25S viathe attached
cable and two coaxial connectors. When using the transducer, the
orientation of the dual coaxial connectors is not critical: either plug
may be fitted to either socket in the TI-25S.
The transducer must be used correctly in order for the TI-25S to produce
accurate, reliable measurements. Below is a short description of the trans-
ducer, followed by instructions for its use.
This is a bottom view of a typical transducer.
The two semicircles of the wearface are
visible, as is the barrier separating them. One
of the semicircles is responsible for conduct-
ing ultrasonic sound into the material being
measured, and the other semicircle is respon-
sible for conducting the echoed sound back
into the transducer. When the transducer is
placed against the material being measured,
it is the area directly beneath the center of the
wearface that is being measured.
This is a top view of a typical transducer.
Press against the top with the thumb or index
finger to hold the transducer in place.
Moderate pressure is sufficient, as it is only
necessary to keep the transducer stationary,
and the wearface seated flat against the
surface of the material being measured.
1.8.8.8.8
+INMM/μs
1.8.8.8.8
+INMM/μs
– 15 –
11.0 APPENDIX A: APPLICATION NOTES
Measuring pipe and tubing
When measuring a piece of pipe to determine
the thickness of the pipe wall, orientation of the
transducers is important. If the diameter of the
pipe is larger than approximately four inches,
measurements should be made with the transducer oriented 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.
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 9) 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-25S to correctly calculate the velocity
of sound through the hot material.
When measuring 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 itself, and through thermal expan-
sion and other effects, may begin to adversely affect the accuracy of measure-
ments.
Measuring laminated materials
Laminated materials are unique in that their density (and therefore sound-
velocity) may vary considerably from one piece to another. Some laminated
materials may even exhibit noticeable changes in sound-velocity across a sin-
gle surface. The only way to reliably measure such materials is by
performing a calibration procedure 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. By calibrating to each
test piece individually, the effects of variation of sound-velocity
will be minimized.
Perpendicular Parallel

– 7 –
4.0 CONDITION AND PREPARATION OF MEASURING SURFACE
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.
– 14 –
10.0 SPECIFICATIONS
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.

– 8 –
5.0 ZEROING THE PROBE
Setting the Zero Point of the TI-25S is important for the same reason that setting
the zero on a mechanical micrometer is important. If the gauge is not “zeroed”
correctly, all of the measurements the gauge makes will be in error by some fixed
number. When the TI-25S is “zeroed,” this fixed error value is measured and
automatically corrected for in all subsequent measurements. The TI-25S may be
“zeroed” by performing the following procedure:
1. Make sure the TI-25S is on.
2. Plug the transducer into the TI-25S. Make sure that the connectors are fully
engaged. Check that the wearface of the transducer is clean and free of any
debris.
3. On the top of the TI-25S, above the display, is the metal
probe-disc. Apply a single droplet of ultrasonic couplant
to the face of this disc.
4. Press the transducer against the probe-disc, making sure
that the transducer sits flat against the surface of the
probe-disc. The display should show some thickness
value, and the Stability Indicator should have nearly
all of its bars illuminated.
5. While the transducer is firmly coupled to the probe-disc,
press the PRB-0 key on the keypad. The TI-25S will
display “Prb0” while it is calculating its zero point.
6. Remove the transducer from the probe-disc.
At this point, the TI-25S has successfully calculated itsinternal error factor,
and will compensate for this value in any subsequent measurements. When
performing a “probe-zero,” the TI-25S will always use the sound-velocity value
of the built-in probe-disc, even if some other velocity value has been entered for
making actual measurements. Though the TI-25S will remember the last
“probe-zero” performed, it is generally a good idea to perform a “probe-zero”
whenever the gauge is turned on, as well as any time a different transducer is
used. This will ensure that the instrument is always correctly zeroed.
– 13 –
9.0 TAKING MEASUREMENTS
In order for the transducer to do its job, there must be no air gaps between the
wear-face and the surface of the material being measured. This is accomplished
with the use of a “coupling“ fluid, commonly called “couplant.” This fluid
serves to “couple” or transmit, the ultrasonic sound waves from the transducer,
into the material, and back again. Before attempting to make a measurement, a
small amount of couplant should be applied to the surface of the material being
measured. Typically, a single droplet of couplant is sufficient.
After applying couplant, press the transducer (wearface down) firmly against the
area to be measured. The Stability Indicator should have six or seven bars dark-
ened, and a number should appear in the display. If the TI-25S has been properly
“zeroed” (see page 8) and set to the correct sound velocity (see page 9), the
number in the display will indicate the actual thickness of the material directly
beneath the transducer.
If the Stability Indicator has fewer than five bars darkened, or the numbers on the
display seem erratic, first check to make sure that there is an adequate film of
couplant beneath the transducer, and that the transducer is seated flat against the
material. If the condition persists, it may be necessary to select a different trans-
ducer (size or frequency) for the material being measured. See page 10 for
information on transducer selection.
While the transducer is in contact with the material being measured, the TI-25S
will perform four measurements every second, updating its display as it does so.
When the transducer is removed from the surface, the display will hold the last
measurement made.
IMPORTANT: Occasionally, a small film of couplant will be drawn out between
the transducer and the surface as the transducer is removed.
When this happens, the TI-25S may perform a measurement
through this couplant film, resulting in a measurement that is
larger or smaller than it should be. This phenomenon is obvious
when one thickness value is observed while the transducer is in
place, and another value is observed after the transducer is
removed.

– 9 –
6.0 SELECTING MATERIAL TYPE (CALIBRATION)
The TI-25S is supplied with eight preset material types, each corresponding to a
specific sound velocity. Each time the “MATL Key” is pressed the velocity will
toggle from one to the next in a circular pattern. The list of preset velocities are
as follows:
01. Aluminum 2024 (0.251 in/µs )
02. Stainless Steel 303 (0.223 in/µs )
03. Steel4340 (0.233 in/µs)
04. Cast Iron (0.179 in/µs )
05. Plexiglas (0.106 in/µs )
06. PVC (0.094 in/µs)
07. Polystyrene (0.092 in/µs)
08. Polyurethane (0.070 in/µs)
09. Custom 1
10. Custom 2
NOTE: If the Custom 1 & 2 are needed, they are set using the PC software
(free) & downloaded to the gauge using the data cable (optional,
p/n N-306-0010).
– 12 –
Temperature of the Material
When it is necessary to measure on surfaces that are exceedingly hot, high
temperature transducers must be used. These transducers are built using special
materials and techniques that allow them to withstand high temperatures without
damage. Additionally, care must be taken when performing a “Probe-Zero”
or “Calibration to Known Thickness” with a high temperature transducer.
See Appendix A for more information on measuring materials with a high
temperature transducer.
NOTE: Selection of the proper transducer is often a matter of tradeoffs between
various characteristics. It may be necessary to experiment with a variety
of transducers in order to find one that works well for a given job.
Electromatic can provide assistance in choosing a transducer, and
offers a broad selection of transducers for evaluation in specialized
applications.

– 10 –
7.0 DOWNLOADING CUSTOM CALIBRATIONS TO THE TI-25S
In addition to the eight (8) preset calibration (material types), the TI-25S is s
upplied with two custom calibrations (Custom1 and Custom 2) which are set
using the free Datacomm Software and then downloaded to the TI-25S using
the option Data Cable p/n N-306-0010. To utilize one or both of these User-Set
Calibrations, follow the procedure outlined below. Approximate sound velocities
for common materials can be found in Appendix B.
1. Connect the serial cable (Part No. N-306-0010) to a COM port on a
computer and to the RS232 connector located on the bottom of the
TI-25S. Remove and replace the rubber plug before and after
programming.
2. Assuming that PC software is installed and running, select the TI-25S
icon from the gauge selector icons. A window will appear with the
title “TI-25S Velocity Upload Utility.”
3. Under the Preset Velocity heading are two options. The first option is a
test box with a velocity number displayed. The text box is editable. To
change the velocity, click in the text field and type in the appropriate
velocity number. The second option is a list box with a material type
displayed. To change the material type, click the down arrow located to
the right of the list box. Use the arrows or slider bar to scroll through
the available material types. Click on a material to select it.
4. To select the units (english or metric), click on the radio button located
to the left of the units title. A black dot will appear in th button when
selected.
5. Click on the Program Gauge button located in the top right of the
window. A pop up window will be display with the following message
“Turn on gauge power.” Press the ON/OFF button on the TI-25S to
download the velocity. The TI-25S will display the new velocity.
– 11 –
8.0 TRANSDUCER SELECTION
The TI-25S is inherently capable of performing measurements on a wide range
of materials, from various metals to glass and plastics. Different types of
material, however, will require the use of different transducers. Choosing the
correct transducer for a job is critical to being able to easily perform accurate
and reliable measurements. The following paragraphs highlight the important
properties of transducers, which should be considered when selecting a
transducer for a specific job.
Generally speaking, the best transducer for a job is one that sends sufficient ultra-
sonic energy into the material being measured such that a strong, stable echo is
received by the TI-25S. Several factors affect the strength of ultrasound as it trav-
els. These are outlined below:
Initial Signal Strength
The stronger a signal is to begin with, the stronger its return echo will be. Initial
signal strength is largely a factor of the size of the ultrasound emitter in the trans-
ducer. A large emitting area will send more energy into the material being meas-
ured than a small emitting area. Thus, a so-called “1/2-inch” transducer will emit
a stronger signal than a “1/4-inch” transducer.
Absorption and Scattering
As ultrasound travels through any material, it is partly absorbed. If the material
through which it travels has any grain structure, the sound waves will also
experience scattering. Both of these effects reduce the strength of the waves,
and thus, the TI-25S’s ability to detect the returning echo.
Higher frequency ultrasound is absorbed and scattered more than ultrasound of
a lower frequency. While it may seem that using a lower frequency transducer
might be better in every instance, low frequencies are less directional than high
frequencies. Thus, a higher frequency transducer would be a better choice for
detecting the exact location of small pits or flaws in the material being measured.
Geometry of the Transducer
The physical constraints of the measuring environment sometimes determine a
transducer's suitability for a given job. Some transducers may simply be too large
to be used in tightly confined areas. Also, the surface area available for contact-
ing with the transducer may be limited, requiring the use of a transducer with a
small wearface. Measuring on a curved surface, such as an engine cylinder wall,
may require the use of a transducer with a matching curved wearface.

ELECTROMATIC
E Q U I P M E N T C O., I N C.
600 Oakland Ave., Cedarhurst, NY 11516–U.S.A.
TEL: [phone] • FAX: [phone]
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