Check-line TI-25M User manual

TI-25M
ULTRASONIC
THICKNESS GAUGE
Operating Instructions
CHECK
•
LINE
®
BY ELECTROMATIC

– 2 –
TABLE OF CONTENTS
1.0 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.0 Precautions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.0 Overview of Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1 Gauge
3.2 Contents of Kit
3.3 Probe
3.4 Keypad
3.5 LCD Display
3.6 Probe Zero Plate
3.7 Probe Connector Receptacle
3.8 Battery Compartment (Battery Replacement)
4.0 Getting Started. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.1 Connecting The Probe
4.2 Turn On The Power
4.3 “Zeroing” The Probe
4.4 Changing Units — inches to mm
4.5 Checking Calibration With The Test Plate
4.6 Preparation Of The Surface
5.0 Quick Start Instructions — Steel Thickness. . . . . . . . . . . . . . 13
6.0 Calibration For Measuring Thckness
Of Materials Other Than Steel. . . . . . . . . . . . . . . . . . . . . . . . . . 15
6.1 Acoustic Velocity Table
6.2 Changing Calibration — Acoustic Velocity is Known
6.3 Changing Calibration — Acoustic Velocity is Not Known
7.0 Description of Measuring Modes . . . . . . . . . . . . . . . . . . . . . . . 19
8.0 Measuring Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
8.1 General Notes On Measurements
8.2 Measurements Of Pipes Or Cylindrical Parts
8.3 Measurements On Materials At High Temperatures
9.0 Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
10.0 Material Safety Data Sheet (MSDS) . . . . . . . . . . . . . . . . . . . . . 24
11.0 Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
OI-UT004M

– 3 –
1.0 INTRODUCTION
The CHECK•LINE®TI-25M Ultrasonic Thickness Gauge measures the
wall thickness of metals, glass, ceramics and many rigid plastics. This gauge
uses the “pulse-echo” principle of ultrasonic testing where a short ultrasonic
signal is transmitted from the probe. The signal travels through the measure-
ment sample until it is reflected back towards the probe from the back side
of the material. The elapsed time for the complete cycle is measured and
converted to an accurate thickness reading.
The TI-25M can be used to measure the extent of corrosion on the opposite,
inaccessible side of the wall by using the “Subtractive Method.” When the
thickness of the original wall is known, subtracting the thickness reading
obtained from the TI-25M will determine the extent of corrosion at the point
of probe placement. If the original wall thickness is not known, test readings
should be made along a grid of equally-spaced points to obtain a profile of
the thickness readings. The smallest thickness reading will locate the area of
greatest concern.
The TI-25M is factory-set to measure steel. The gauge can be easily adjust-
ed for accurate thickness readings on other materials. Refer to sections 6.0
through 6.3. To change the measuring units from inch (factory setting) to
mm refer to section 4.4.
2.0 PRECAUTIONS
Do not use the standard probe in applications where material temperatures
exceed 200 °F (100 °C) as the probe will be damaged. Special High
Temperature Probes should be used. Consult factory.
Keep the gauge free of dust (especially metal powders, carbon, etc.) as they
will damage the gauge. Use a damp cloth to clean the gauge after use.
DO NOT USE CHECMICAL SOLVENTS OF ANY KIND.

– 4 –
3.0 OVERVIEW OFGAUGE
3.1 Gauge
Probe
Receptacles
Probe Zero Test Plate and
Battery Compartment Cover
Backlit LCD
Display
Membrane
Keypad
Probe

– 5 –
3.2 Contents Of Kit
The TI-25M is supplied as a complete kit with the following:
a. Gauge
b. Two (2) AA batteries
(installed in gauge)
c. Probe/cable assembly
d. 4 oz. Bottle of coupling fluid
e. NIST-traceable calibration
certificate
f. Operating instruction manual
g. Foam-filled carrying case
3.3 Probe
The probe transmits and receives the ultrasonic sound waves which the
TI-25M uses to calculate the thickness of the material being measured. The
probe must be used correctly in order for the TI-25M to produce accurate
and reliable results.
A small amount of “coupling” fluid, commonly called “couplant” is used to
insure that there are no air gaps between the probe and the material surface.
Grasp the probe by the molded rubber grip and place it on top of the mater-
ial surface. Apply moderate pressure to the top surface of the probe with
your index finger (A) or thumb (B) to stabilize the probe and to keep the
wearface seated flat against the measurement surface.
d
c
e
g
Probe
Wearface
AB

– 6 –
3.4 Keypad
The TI-25M is supplied with a membrane keypad mounted
on the front of the instrument body. It consists of six (6)
keys, each performing one or more functions as described
below.
The CAL key is used to enter and exit the Tl-25M’s two
Calibration modes. The Acoustic Velocity Calibration mode is
used to adjust the acoustic velocity for the material to be mea-
sured. The Measurement Calibration mode is used to increase or
decrease the displayed thickness reading to calibrate to a known
thickness value.
The INCH/MM key is used to change the measuring units from
inches to mm. Each time the key is pressed the units will change
from one to the other.
The UP arrow key performs the following two functions:
1. When in the Calibration mode, pressing the UP arrow
key will cause the numeric values to increase. By
pressing and holding the key, the numbers will change
more rapidly.
2. When in the Measuring mode, pressing the UP arrow key
will turn the Scan Measuring mode on and off each time
it is pressed. The display will momentarily flash indicating
whether the Scan mode is on or off.
The DOWN arrow key performs the following two functions:
1. When in the Calibration mode, pressing the DOWN
arrow key will cause the numeric values to decrease. By
pressing and holding the key, the numbers will change
more rapidly.
2. When in the Measuring mode, pressing the DOWN
arrow key will change the Display Backlight mode from
OFF to AUTO to ON. The currently selected mode will
momentarily flash on the display.
The PROBE ZERO key is used to “zero” the probe in a similar
way as a micrometer is “zeroed” before use. If the tool is not
zeroed correctly, the measurements will not be accurate.
The ON/OFF key is used to turn the power on as well as turning
the power off. If the Tl-25M is idle for five (5) minutes the gauge
will automatically power off.
CAL
INCH
MM
PROBE
ZERO
ON
OFF
CAL PROBE
ZERO
INCH
MM ON
OFF

– 7 –
3.5 LCD Display
The LCD Display provides the operator with important information as
detailed below. The display has a user-selected Backlight mode which can
be set for the following operation:
1. ON. The backlight is illuminated whenever the power is on.
2. OFF. The backlight is never illuminated (to save battery power).
3. AUTO. The backlight is automatically illuminated each time a
measurement is made.
The Backlight mode is set by pressing the key. Each time the key is
pressed, the mode will change from one to the other. “ON,” “OFF” or
“AUTO” will momentarily flash on the display indicating the currently set
Backlight mode..
• Measurement values
• Acoustic velocity values
• Units of measure
• Bar graph signal stability indicator
• Configuration messages
The numeric portion of the display consists of
4-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-25M is displaying thick-
ness measurements, the display will retain the last measured value, until a
new measurement is performed.
The eight vertical bars shown form the Stability
Indicator. When the TI-25M is idle, only the
left-most bar and underline will be illuminated.
When a measurement is being performed, six or
seven bars should be illuminated indicating that it is a stable measurement.
If fewer than five bars are illuminated, the TI-25M is having difficulty
obtaining a stable and reliable measurement and the thickness value shown
should be ignored, as it is most likely erroneous.
1.8.8.8.8
+INMM/µs
1.8.8.8.8
+INMM/µs
1.8.8.8.8
+INMM/µs

When the “IN” indicator is illuminated,
the TI-25M is displaying a wall thickness
measurement in INCH units.
When the “MM” indicator is illuminated, the
TI-25M is displaying a wall thickness measure-
ment in MM units.
When the “IN” and the “µs” indicators are
illuminated simultaneously, the TI-25M is
displaying an acoustic velocity in inches per
microsecond.
When the “M” and the “s” are illuminated
simultaneously, the TI-25M is displaying an
acoustic velocity in meters per second.
3.6 Probe ZeroPlate
When first connecting the probe supplied with the TI-25M, the user should
perform a “Probe Zero” as described in Section 4.3. The Probe Zero Test
Plate is used for this task. It is located on the top edge of the gauge as
shown in the photo below. It also serves as the battery compartment cover
Note: The thickness of this plate is not imporatnt, and it should not be
used as a Calibration Test Plate. A precision 4-step Test Block is optionally
available for this purpose.
– 8 –
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

3.7 Probe Connector Receptacle
Located on the top edge of the TI-25M housing are the receptacles for the
probe and the probe zero plate.
The connectors for the probe
are non-polarized so the con-
nector at the end of the probe
cable can be inserted into
this receptacle in either
orientation. Make sure the
connector is “well seated” in
the receptacle.
3.8 Battery Compartment (Changing The Battery)
The battery compartment is
located under the probe zero
test plate. To open the battery
compartment, unscrew the
probe zero plate by rotating it
counterclockwise. The TI-25M
operates on two (2) AA
Batteries (1.5 V). If desired,
rechargeable batteries may be
used.
The TI-25M is shipped with the batteries installed. Insert batteries in the
polarity indicated on the rear label.
Note: When the display elements begin to flash off and on repeatedly, the
batteries are low and should be replaced.
Battery Cover
Probe Receptacles
Probe Zero
Plate
– 9 –

– 10 –
4.0 GETTING STARTED
4.1 Connecting The Probe
Grasp the connector located at the end of the probe cable and carefully
insert the connector plugs into the receptacle located at the top edge of the
gauge. Make sure the connector is fully inserted into the receptacle. The
orientation of the plugs does not matter as they are non-polarized.
4.2 Turn On The Power
Press the key. All of the LCD Display elements will momentarily
illuminate. The firmware revision will then be momentarily shown
(for factory troubleshooting purposes only). Eventually the display will
show “0.000” (or “0.00” if using metric units), indicating it is ready for
use.
Note: 1. The gauge is turned off by pressing the key again.
2. The gauge will automatically power off after 5 minutes of
non-use.
3. All settings will be retained in non-volatile memory.
4.3 “Zeroing”The Probe
The Probe Zero Plate is used to “zero” the probe for calibration purposes.
Normally, this procedure is required only when the probe is connected to
the instrument for the first time, but since this process takes less than 10
seconds, we recommend performing the Probe Zero function occasionally
as described below.
1. Check that the probe face (wear surface) is clean and free of debris.
2. Place a small drop of the supplied coupling fluid on the built-in
Probe Zero Plate located on the top of the gauge.
3. Press the probe firmly against the Plate.
4. The Stability Indicator on the LCD display should have six or
seven bars illuminated and a value should be shown in the display.
5. While maintaining probe contact with the Test Plate, press the
key. The display will show “Prb0” while the TI-25M
calculates its zero point.
Note: The value shown on the display can be recorded and used in the
future to confirm that the gauge is functioning properly.

– 11 –
6. The display will show a measurement value of 0.250 inches
(or 6.35 mm) if the gauge is calibrated for common steel factory
(default setting) with an acoustic velocity of 0.233 in/µs (5920m/sec).
If the gauge is calibrated for any material other than common steel then
the measured value of the Test Plate will be higher or lower than
described above. Refer to the “Equivalent Value Of Test Plate” column
of the Acoustic Velocity Table in section 6.1.
4.4 Changing Units — inches to mm
To change the measuring units from inch (factory setting) to mm, press the
key. Each time the key is pressed, the units will change.
4.5 Checking Calibration With The Probe ZeroPlate
The built-in Probe Zero Plate can also be used whenever desired to confirm
that the gauge is working properly. The steel Test Plate will measure 0.250"
(6.35) if the TI-25M is calibrated for steel (factory default) or some other
value higher or lower depending upon the material type that the gauge is
calibrated for. Refer to the “Equivalent Value Of Test Plate” column of the
Acoustic Velocity Table in section 6.1.
4.6 Preparation Of The Surface
The TI-25M can be used to measure thickness over existing paint or
coatings as long as the coating is in good condition, is well adhered to the
surface and does not exceed 0.020" (20 mils or 500 microns) in thickness.
Please note that the paint or coating thickness will be included in the over-
all wall thickness measurement.
The surface to be measured should be relatively clean and smooth, free of
any small particulate, rust or scale. The presence of any of these conditions
will prevent stable and reliable readings. Often, a wire brush, sandpaper or
scraper will be helpful in cleaning the measurement surface. In situations
where the surface is heavily corroded or pitted, a rotary sander, or grinding
wheel will be necessary to properly prepare the surface for measurement. If
the surface is still “rough” after preparation, using a more viscous couplant
fluid similar to petroleum jelly or K-Y jelly will help obtain a stable, reli-
able measurement. This type of “thick” coupling fluid is a good choice
when measuring on vertical surfaces or on the underside as it will help
adhere the probe to the measurement surface while also acting as the
coupling agent.

– 12 –
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 acts on light; the beam becomes diffused
and scattered in all directions.
Rough surfaces also contribute to excessive wear of the probe, especially in
applications where the probe is “scrubbed” along the measurement surface
for use in the Scanmode. The probe should be inspected regularly for signs
of uneven wear on the probe surface (wearface). If this is detected, the
probe should be returned to the factory for repair or replacement.

– 13 –
5.0 QUICK START INSTRUCTIONS — STEEL THICKNESS
These Quick Start procedures are intended for those applications where the thick-
ness of steel is to be measured. If a material other than steel will be measured,
the gauge must be calibrated for use on this particular material. Refer to Sections
6.0 through 8.0 for additional details.
Quick Start Instructions
1. Turn on the power by pressing the key.
2. Plug the probe cable into the receptacle at the top of the gauge.
3. Place a drop of coupling fluid on the built-in Probe Zero Plate.
4. Grasp the probe and place it on top of the Probe Zero Plate.
Apply moderate pressure to the top surface of the probe with
your index finger or thumb to stabilize the probe and to keep
the wearface seated flat against the measurement surface.
5. The display will show some thickness value and the Stability Indicator
will have most of its bars illuminated.
6. While keeping the probe on the Probe Zero Plate, press the key.
The display will show a value that can be recorded for future use.
7. Remove the probe from the Probe Zero Plate. The gauge is now ready to
perform thickness readings on steel samples.
8. Place a small amount of coupling fluid on the steel surface to be
measured and proceed as explained in step #4 above.
9. The gauge will display the thickness of the steel wall along with the
Stability Indicator showing the relative stability of the reading. If fewer
than five (5) bars are illuminated, the thickness reading displayed is most
likely inaccurate.
Notes
a. When the probe is removed from the sample after a measurement, the
last reading will be retained on the display.
b. Occasionally, a small film of couplant will be drawn out between the
probe and the surface as the probe is removed. When this happens, the

– 14–
TI-25M may perform a measurement that is larger or smaller than it
should be. This phenomenon is obvious when one thickness value is
observed while the probe is in contact with the material, and another
value after the probe is removed.
c. The gauge will automatically power off after 5 minutes of non-use.

– 15 –
6.0CALIBRATION FOR MEASURING THICKNESS OF
MATERIALS OTHER THAN STEEL
Ultrasonic Thickness Gauges use sound waves to measure wall thickness.
Different types of materials have different inherent acoustic velocities. For
instance, the acoustic velocity of steel is 0.2330 IN/µs (inches-per-microsecond),
versus that of aluminum, which is about 0.2500 IN/µs. It is critical that the
TI-25M be set for the correct acoustic velocity depending upon the material to be
measured.
The TI-25M is shipped from the factory calibrated for steel with an acoustic
velocity of 0.2330 IN/µs (5920 M/s). To measure the thickness of any other
material, the calibration will have to be changed by adjusting the acoustic
velocity to the appropriate value for the specific material being measured.
When checking the thickness of the built-in Test Plate, the gauge should display
the “Equivalent Value” (inches or mm) listed in theAcoustic Velocity Tablein
section 6.1.
To determine the proper acoustic velocity for the non-steel material, refer to the
Acoustic Velocity Table, section 6.1. After determining the proper acoustic
velocity, the gauge must be re-calibrated for this new value as described in
section 6.2 Changing Calibration - Acoustic Velocity Is Known.
If you do not know the type of material to be measured or if the material type is
not listed in the Acoustic Velocity Table, refer to section 6.3, Changing
Calibration - Acoustic Velocity Is Not Known.

– 16 –
6.1 Acoustic Velocity Table
Aluminum 0.2500 6350 0.269 6.82
Bismuth 0.860 2184 0.085 2.16
Brass 0.1730 4394 0.183 4.66
Cadmium 0.1090 2769 0.1112.83
Cast Iron 0.18000 4572 0.191 4.86
Constantan 0.2060 5232 0.219 5.58
Copper 0.1840 4674 0.195 4.97
Epoxy resin 0.1000 2540 0.101 2.57
German silver 0.1870 4750 0.199 5.05
Glass, crown 0.2230 5664 0.238 6.06
Glass, flint 0.1680 4267 0.177 4.51
Gold 0.1280 3251 0.133 3.37
Ice 0.1570 3988 0.166 4.20
Iron 0.2320 5898 0.248 6.31
Lead 0.850 2159 0.084 2.14
Magnesium 0.2280 5791 0.245 6.21
Nickel 0.2220 5639 0.238 6.04
Nylon 0.1020 2591 0.104 2.63
Paraffin 0.0870 2210 0.086 2.19
Platinum 0.1560 3962 0.165 4.18
Plexiglass 0.1060 2692 0.108 2.74
Polystyrene 0.0920 2337 0.092 2.34
Porcelain 0.2300 5842 0.246 6.26
PVC 0.0940 2388 0.095 2.40
Quartz glass 0.2220 5639 0.238 6.04
Rubber, vulcanized 0.0910 2311 0.091 2.31
Silver 0.1420 3607 0.149 3.78
Steel, common 0.2330 5920 0.250 6.35
Steel, stainless 0.2230 5664 0.238 6.06
Stellite 0.2750 6985 0.296 7.52
Tin 0.1310 3327 0.136 3.46
Titanium 0.2400 6096 0.257 6.53
Tungsten 0.2100 5334 0.225 5.71
Zinc 0.1660 4216 0.176 4.46
Material Velocity Velocity Equivalent Value Equalvalent Value
Type Inches/µs Meters/s Of Test Plate (Inches) Of Test Plate (mm)
Notes: 1. The “Equivalent Values” shown above are accurate to within ±2 units.
... 2. “✔”denotes the factory default setting for acoustic velocity.
✔

– 17 –
6.2Changing Calibration - Acoustic Velocity Is Known
To change the calibration for a material where the acoustic velocity is
known from either prior knowledge or from the Acoustic Velocity table,
proceed as follows:
1. Turn on the gauge by pressing the key .
2. Press the key.
3. If the units of measure indicators “IN” or “MM” are flashing press
the key again.
4. The acoustic velocity units indicator “IN/µs” or “M/s” should be
flashing showing that the Acoustic Velocity Calibrationmode is
enabled.
5. Use the and keys to adjust the displayed value to
match the desired acoustic velocity setting. By pressing and holding
the key, the numbers will change more rapidly.
6. When the desired value is reached press the key to exit the
calibration mode and return to measurement mode.
Note:If the key is pressed while in the calibration mode, the
TI-25M will be reset to the factory default calibration for common steel
(0.2330 IN/µs or 5920 M/s).

– 18 –
6.3Changing Calibration - Acoustic Velocity IsNot Known
In applications where the type of material is not known or the material is
not listed in the Acoustic Velocity Table, the following procedure can be
used to calibrate the gauge for highest accuracy.
1. Obtain a sample of the material with a known thickness or use a
micrometer, caliper or similar device to accurately measure it.
2. Turn on the gauge by pressing the key.
3. Place a small amount of coupling fluid on the sample of known
thickness and place the probe on the sample. The Stability Indicator
should have nearly all its bars illuminated. Having achieved a stable
reading remove the probe from the sample.
4. Press the key.
5. The units of measure indicator “IN” or “MM” will be flashing
indicating that you are in the Measurement Calibrationmode.
(The other calibration mode is the Acoustic Velocity Calibration mode,
as described in section 6.2, which is used to adjust the acoustic
velocity to another known value.)
6. Use the and keys to adjust the displayed measurement
value to match the thickness of the known sample. By pressing and
holding the key, the numbers will change more rapidly.
7. Press the key again and the acoustic velocity units indicator
“IN/µs” or“M/s” will be flashing showing the acoustic velocity
value that was calculated for this sample. If desired, record this
value so it can be re-entered easily in the future.
8. Press the key again to exit the calibration mode and return to
the measurement mode.
Note:If the key is pressed while in the calibration mode, the
TI-25M will be reset to the factory default calibration for common steel
(0.2330 IN/µs or 5920 M/s).

– 19 –
7.0DESCRIPTION OF MEASURING MODES
The TI-25M can be used in either the Single Thickness Readingmode or the Scan
mode.
The Single Thickness Readingmode is suitable for most applications. While the
probe remains in contact with the material being measured, the TI-25M performs
four (4) measurements every second, updating the LCD display after each read-
ing. When the probe is removed from the surface, the last reading is retained on
the display.
The Scanmode is used to survey or examine larger sections of material. When
set for Scanmode, the TI-25M performs sixteen (16) measurements every
second, but does not display each reading. This mode is designed for those
applications where the probe will be “dragged” or lightly “scrubbed” over the
measuring surface. While the probe maintains contact with the material being
measured, the TI-25M is keeping track of the lowest (thinnest) measurement it
encounters. Any brief interruptions in the signal will be ignored. When the probe
is removed from the surface for more than one second, the TI-25M will display
the thinnest reading encountered during the measurement survey.
To enable and disable the Scan mode:
Press the key.
Each time the key is pressed the Scan mode status will change from
Off-to-On-to-Off-etc. As the mode is changed, the current status “Off” or “On”
will momentarily flash on the display.

– 20 –
8.0MEASURING PROCEDURE
After setting the TI-25M for the correct acoustic velocity, or retaining the
factory-set acoustic velocity for steel, the gauge is ready to take wall thickness
measurements.
1. Turn on the power by pressing the key.
2. Plug the probe cable into the receptacle at the top of the gauge.
3. Place a small amount of coupling fluid on the surface to be
measured.
4. Grasp the probe by the molded rubber grip and place it on top
of the material surface. Apply moderate pressure to the top
surface of the probe with your index finger or thumb to
stabilize the probe and to keep the wearface seated flat against
the measurement surface.
5. The gauge will display the thickness of the steel wall along with the
Stability Indicator showing the relative stability of the reading.
6. Repeat steps #3 - #5 as required.
8.1 General Notes On Measurements
1. When the probe is removed from the sample after a
measurement, the last reading will be retained on the display.
2.If fewer than five (5) bars of the Stability Indicator are illuminated,
the thickness reading displayed is most likely inaccurate.
3. Occasionally, a small film of couplant will be drawn out between
the probe and the surface as the probe is removed. When this
happens, the TI-25M may perform a measurement that is larger or
smaller than it should be. This phenomenon is obvious when one
thickness value is observed while the probe is in contact with the
material, and another value after the probe is removed.
4. The gauge will automatically power off after 5 minutes of non-use.
5. The following surface conditions can prevent accurate
measurements (refer to section 4.6 Preparation Of The Surface):
• More than 0.020" (20 mils or 500 µm) of paint or other coating
• Flaking or loosely adhered coatings
• Rough or heavily pitted surface