MITECH MT280 User manual
1
CONTENTS
1 Overview...................................................................................................................................................... 2
1.1 Product Specifications...................................................................................................................... 2
1.2 Main Functions...................................................................................................................................2
1.3 Measuring Principle...........................................................................................................................2
1.4 Configuration...................................................................................................................................... 3
1.5 Operating Conditions........................................................................................................................ 3
2 Structure Feature.......................................................................................................................................4
2.1 Instrument Appearance.................................................................................................................... 4
2.2 Parts of the Main Body..................................................................................................................... 4
2.3 Measurement Screen....................................................................................................................... 5
2.4 Keypad Definitions............................................................................................................................ 6
3 Preparation..................................................................................................................................................7
3.1 Transducer Selection........................................................................................................................ 7
3.2 Condition and Preparation of Surfaces..........................................................................................9
4 Operation..................................................................................................................................................... 9
4.1 Power On/Off......................................................................................................................................9
4.2 Setting the Measurement Mode......................................................................................................9
4.3 Probe Zero..........................................................................................................................................9
4.4 Sound Velocity Calibration.............................................................................................................10
4.5 Making Measurements................................................................................................................... 11
4.6 Two Point Calibration......................................................................................................................12
4.7 Scan mode....................................................................................................................................... 12
4.8 Limit Set............................................................................................................................................ 13
4.9 Resolution.........................................................................................................................................13
4.10 Unit Scale....................................................................................................................................... 13
4.11 Memory Management...................................................................................................................13
4.12 System Set.....................................................................................................................................14
4.13 System information....................................................................................................................... 15
4.14 EL Backlight................................................................................................................................... 15
4.15 Battery Information....................................................................................................................... 15
4.16 Auto Power Off.............................................................................................................................. 15
4.17 System Reset................................................................................................................................ 15
4.18 Connecting to a Computer.......................................................................................................... 15
5 Servicing....................................................................................................................................................16
6 Transport and Storage........................................................................................................................... 16
Appendix A Sound Velocities..................................................................................................................17
Appendix B Applications Notes..............................................................................................................18
User Notes.................................................................................................................................................... 20
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1 Overview
The model MT280 is a multi-mode ultrasonic thickness gauge. Based on the same operating
principles as SONAR, the instrument is capable of measuring the thickness of various materials
with accuracy as high as 0.1/0.01 millimeters.
The multi-mode feature of the gauge allows the user to toggle between pulse-echo mode
(flaw and pit detection), and echo-echo mode(eliminate paint or coating thickness).
1.1 Product Specifications
Display：4.5 digits LCD with EL backlight.
Range：Pulse-Echo mode: (0.65～600)mm (in Steel).
Echo-Echo mode: (2.5～100)mm
3) Sound Velocity Range: (1000~9999) m/s.
4) Resolution：0.1mm/0.01mm
Accuracy：±（0.5%Thickness+0.01）mm, depends on materials and conditions
Units: Metric/English unit selectable.
Seven measurements readings per second for single point measurement, and sixteen per
second for Scan Mode.
Memory for 20 files (up to 100 values for each file) of stored values.
Upper and lower limit can be pre-set. It will alarm automatically when the result value
exceeding the limit.
Power Supply：Two “AA” size, 1.5 volt alkaline batteries. 100 hours typical operating time (EL
backlight off).
Communication：USB1.1.
Case：Extruded aluminum body suitable for use under poor working conditions.
Outline dimensions：132mm×77.6mm×32 mm.
Weight：345g
1.2 Main Functions
Multi-mode: Pulse-Echo mode and Echo-Echo mode.
Capable of performing measurements on a wide range of material, including metals, plastic,
ceramics, composites, epoxies, glass and other ultrasonic wave well-conductive materials.
Transducer models are available for special application, including for coarse grain material
and high temperature applications.
Probe-Zero function, Sound-Velocity-Calibration function
Two-Point Calibration function.
Single point mode and Scan mode. Seven measurements readings per second in single point
mode, and sixteen per second in Scan Mode.
Coupling status indicator showing the coupling status.
Units: Metric/Imperial unit selectable.
Battery information indicates the rest capacity of the battery.
Auto sleep and auto power off function to conserve battery life.
Optional software to process the memory data on the PC.
1.3 Measuring Principle
The digital ultrasonic thickness gauge determines the thickness of a part or structure by
accurately measuring the time required for a short ultrasonic pulse generated by a transducer to
travel through the thickness of the material, reflect from the back or inside surface, and be
returned to the transducer. The measured two-way transit time is divided by two to account for the
down-and-back travel path, and then multiplied by the velocity of sound in the material. The result
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is expressed in the well-known relationship:
2
tv
H
Where：H－Thickness of the test piece.
v－Sound Velocity in the material.
t－The measured round-trip transit time.
1.4 Configuration
Table 1-1
No
Item
Qty.
Note
Standard
Configura
tion
1
Main body
1
2
Probe P5EE
1
3
Couplant
1
4
Instrument Case
1
5
Operating Manual
1
6
Screwdriver
1
7
Alkaline battery
2
AA size
8
Optional
Configura
tion
9
Probe N02 (2.5MHz)
See
Table3-1
10
Probe N05 (5MHz)
11
Probe N05/90°(5MHz)
12
Probe N07(7MHz)
13
Probe HT5(5MHz)
14
DataPro Software
1
15
Communication Cable
1
1.5 Operating Conditions
Operating Temperature: －20～＋50℃;
Storage Temperature：-30℃～＋70℃
Relative Humidity ≤90％；
The surrounding environment should avoid of vibration, strong magnetic field, corrosive medium
and heavy dust.
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1 Communication Socket 2 Aluminum Case 3 Belt Hole
4 Battery Cover 5 Keypad 6 LCD Display
7 Socket of Transducer (no polarity) 8 Probe zero disc
9 Aluminum Case 10 Label
2.3 Measurement Screen
Thickness Reading
Units Label
Battery Info
Transducer Model
Record No./count
File Name
Coupling Status
Operating Hint
Sound Velocity
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Battery Information: Display the information of the rest capacity of the battery.
Coupling Status: Indicate the coupling status. While the gauge is taking a measurement, the
coupling status should be on. If it is not on, the gauge is having difficulty achieving a stable
measurement, and the thickness value displayed will most likely be erroneous.
Operating Hint: Show hints of current operation
FIL: File selection；
MEM：Memory data viewing；
PRB：Transducer set；
VEL：Change velocity;
CAL：Velocity calibration；
DPC：Dual Point Calibration state；
ZER：Probe zero state
SCA: Indicate that current thickness measurement mode is scan mode, and not single point mode.
File Name: show current file name.
Record No./Count: Indicate current record number while this item is highlighted, or total record
counts while it is not highlighted.
Transducer Model: Current transducer model setting in the instrument
Sound Velocity: Current sound velocity setting
Thickness Reading：Display present single time measured value. means exceeding upper
measuring limit. means lower than bottom measuring limit.
Units Label ：When the mm symbol is on, the instrument is displaying the thickness value in
millimeters and the sound velocity value in m/s. When the in symbol is on, the instrument is
displaying the thickness value in inches and the sound velocity value in inch/us.
2.4 Keypad Definitions
Turn the instrument
on and off
Exit from current
selection
Turn on/off the EL
backlight
Enter
Probe Zero
operation
Plus or scroll up
Switch selection
among items
Minus or scroll
down
Data Save or Data
Delete
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3 Preparation
3.1 Transducer Selection
The gauge 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 measurement. 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 ultrasonic energy
into the material being measured such that a strong, stable echo is received by the gauge. Several
factors affect the strength of ultrasound as it travels. 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 transducer. A
large emitting area will send more energy into the material being measured 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 the sound travels has any grain structure, the sound waves will
experience scattering. Both of these effects reduce the strength of the waves, and thus, the
gauge’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 contacting 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.
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.
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.
The transducer is the “business end” of the instrument. It transmits and receives ultrasonic
sound waves that the instrument uses to calculate the thickness of the material being measured.
The transducer connects to the instrument via the attached cable, and two coaxial connectors.
When using transducers, the orientation of the dual coaxial connectors is not critical: either plug
may be fitted to either socket in the instrument.
The transducer must be used correctly in order for the instrument to produce accurate,
reliable measurements. Below is a short description of the transducer, followed by instructions for
its use.
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Left figure 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 conducting
ultrasonic sound into the material being measured, and the other semicircle is responsible 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.
Right figure 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.
Table 3-1 Transducer Selection
Model
Freq
MHz
Φ
mm
Measuring
Range
Lower limit
Description
N05
5
10
1mm～
600.0mm（In
Steel）
Φ20mm×
3.0mm
Normal
Measurement
N05
/90°
5
10
1mm～
600.0mm（In
Steel）
Φ20mm×
3.0mm
Normal
Measurement
N07
7
6
0.65mm～
200.0mm
（In Steel）
Φ15mm×
2.0mm
For thin pipe wall
or small
curvature pipe
wall
measurement
HT5
5
14
1～600mm （In
Steel）
30mm
For high
temperature
(lower than
300℃)
measurement.
P5EE
5
10
P-E: 2~600mm
E-E: 3~100mm
Φ20mm×
3.0mm
Normal
Measurement
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3.2 Condition and Preparation of Surfaces
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 iron, 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 sound beam no longer
lies directly beneath the transducer.
4 Operation
4.1 Power On/Off
The instrument is turned on by pressing the key. When the gauge is initially turned on, the
model type, the manufacture information and the serial number will be displayed prior to entering
into the main measurement screen.
It is turned off by pressing the key when it is on. The tool has a special memory that
retains all of its settings even when the power is off.
4.2 Setting the Measurement Mode
Often times users and inspectors in the field are faced with coated materials such as pipes
and tanks. Typically inspectors will need to remove the paint or coating prior to measuring, or allow
for some fixed amount of error introduced by the paint or coating thickness and velocity.
The error can be eliminated with this gauge by using a special echo-echo mode to perform
measurements for applications such as this. The gauge gives you this feature in a simple way, one
button toggle, eliminating the need to remove the paint or coating.
You can change the transducer model set by menu operation. Press the key to 【Test
Set】-> ->【Work Mode】->
4.3 Probe Zero
Note: Probe Zero operation apply only to Pulse-Echo mode. Do not perform Probe Zero in
Echo-Echo mode.
The key is used to “zero” the instrument in much the same way that a mechanical
micrometer is zeroed. If the gauge is not zeroed correctly, all the measurements that the gauge
makes may be in error by some fixed value. When the instrument is “zeroed”, this fixed error value
is measured and automatically corrected for all subsequent measurements. The instrument may
be “zeroed ” by performing the following procedure.:
1. Plug the transducer into the instrument. Make sure that the connectors are fully engaged.
Check that the wearface of the transducer is clean and free of any debris.
2. Press the key to activate the probe zero mode.
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3. Use the key and the key to scroll to the probe model currently being used. Be sure to
set the right probe model to the instrument. Otherwise, there will be erroneous.
4. Apply a single droplet of ultrasonic couplant to the face of the metal probe-disc.
5. Press the transducer against the probe disc, making sure that the transducer sits flat against
the surface.
6. Remove the transducer from the probe disc.
At this point, the instrument has successfully calculated its internal error factor, and will
compensate for this value in any subsequent measurements. When performing a “probe zero”, the
instrument 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 instrument 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.
Press while in probe zero mode will stop current probe zero operation and return to the
measurement mode.
4.4 Sound Velocity Calibration
In order for the gauge to make accurate measurements, it must be set to the correct sound
velocity for the material being measured. Different types of material have different inherent sound
velocities. If the gauge is not set to the correct sound velocity, all of the measurements the gauge
makes will be erroneous by some fixed percentage. The One-Point calibration is the simplest and
most commonly used calibration procedure optimizing linearity over large ranges. The Two-point
calibration allows for greater accuracy over small ranges by calculating the probe zero and
velocity.
Note:One and Two point calibrations must be performed on material with the paint or coating
removed. Failure to remove the paint or coating prior to calibration will result in a multi material
velocity calculation that may be different from the actual material velocity intended to be
measured.
4.4.1 Calibration to a known thickness
Note: This procedure requires a sample piece of the specific material to be measured, the exact
thickness of which is known, e.g. from having been measured by some other means.
1Perform a Probe-Zero.
2Apply couplant to the sample piece.
3Press the transducer against the sample piece, making sure that the transducer sits flat
against the surface of the sample. The display should show some thickness value, and the
coupling status indicator should appear steadily.
4Having achieved a stable reading, remove the transducer. If the displayed thickness
changes from the value shown while the transducer was coupled, repeat step 3.
5Press the key to activate the calibration mode. The MM (or IN) symbol should begin
flashing.
6Use the key and the key to adjust the displayed thickness up or down, until it
matches the thickness of the sample piece.
7Press the key again. The M/S (or IN/μS) symbols should begin flashing. The gauge
is now displaying the sound velocity value it has calculated based on the thickness value that was
entered.
8Press the key once again to exit the calibration mode and return to the measurement
mode. The gauge is now ready to perform measurements.
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4.4.2 Calibration to a known velocity
Note: This procedure requires that the operator knows the sound velocity of the material to be
measured. A table of common materials and their sound velocities can be found in Appendix A of
this manual.
1On the measurement screen, press the key multiple times to tab to the sound velocity
item.
2Press the key to switch among the preset commonly using velocities. Use the
key and the key to adjust the sound velocity value up or down, until it matches the sound
velocity of the material to be measured.
3Press the key to exit from the calibration mode. The gauge is now ready to perform
measurements.
4Another method to set the instrument with a known sound velocity is as following:
5Highlight the 【Test Set】－>【Velocity Set】submenu item, press to enter the sound
velocity set screen.
6Press the key multiple times to tab to the numeric digit to be changed; Use the /
key to increase/decrease numeric values on the display until it matches the sound velocity of the
material to be measured. An auto repeat function is built in, so that when the key is held down,
numeric values will increment/decrement at an increasing rate.
7Press the key to confirm the modifying ；or press the key to cancel the
calibration.
To achieve the most accurate measurements possible, it is generally advisable to always
calibrate the gauge to a sample piece of known thickness. Material composition (and thus, its
sound velocity) sometimes varies from lot to lot and from manufacturer to manufacturer.
Calibration to a sample of known thickness will ensure that the gauge is set as closely as possible
to the sound velocity of the material to be measured.
4.5 Making Measurements
When the tool is displaying thickness measurements, the display will hold the last value
measured, until a new measurement is made.
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 transfer, 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 coupling status indicator should appear, and a number should appear in the
display. If the instrument has been properly “zeroed” and set to the correct sound velocity, the
number in the display will indicate the actual thickness of the material directly beneath the
transducer.
If the coupling status indicator does not appear, or the numbers on the display seem erratic,
firstly 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 transducer (size or frequency) for the material being measured.
While the transducer is in contact with the material that is being measured, the instrument will
perform four measurements every second, updating its display as it does so. When the transducer
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is removed from the surface, the display will hold the last measurement made.
Note ：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 gauge 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. In addition,
measurements through very thick paint or coatings may result in the paint or coating being
measured rather than the actual material intended. The responsibility for proper use of the
instrument, and recognition of these types of phenomenon, rest solely with the user of the
instrument.
4.6 Two Point Calibration
Note: This procedure requires that the operator has two known thickness points on the test piece
that are representative of the range to be measured.
1. On the 【Test Set】－>【2-Point Cal】submenu item, press to toggle the Two Point mode
to ON. Then exit from the menu to the measurement screen. The string “DPC” will appear on
the operating hint area of the main measurement screen.
2. Press to start the calibration procedure. The string “NO1” will appear on the operating hint
area, indicating measuring the first point.
3. Apply couplant to the sample piece.
4. Press the transducer against the sample piece, at the first/second calibration point, making
sure that the transducer sits flat against the surface of the sample. The display should show
some (probably incorrect) thickness value, and the coupling status indicator should appear.
5. Having achieved a stable reading, remove the transducer. If the displayed thickness changes
from the value shown while the transducer was coupled, repeat step 4.
6. Use the key and the key to adjust the displayed thickness up or down, until it
matches the thickness of the sample piece.
7. Press the key to confirm. The hint will changes to “NO2”, indicating measuring the second
calibration point.
8. Repeat steps 3 through 7. The hint will change back to “DPC”.
9. The gauge is now ready to perform measurements within this range.
4.7 Scan mode
While the gauge excels at making single point measurements, it is sometimes desirable to
examine a larger region, searching for the thinnest point. The gauge includes a feature, called
Scan Mode, which allows it to do just that.
In normal operation, the gauge performs and displays four measurements every second,
which is quite adequate for single measurements. In Scan Mode, however, the gauge performs ten
measurements every second, and displays the readings while scanning. While the transducer is in
contact with the material being measured, the gauge is keeping track of the lowest measurement it
finds. The transducer may be “scrubbed” across a surface, and any brief interruptions in the signal
will be ignored. When the transducer loses contact with the surface for more than two seconds, the
gauge will display the smallest measurement it found. When the transducer is removed from the
material being scanned, the gauge will display the smallest measurement it found.
On the 【Test Set】－>【Work Mode】menu item, press to toggle between single point
mode and scan mode.
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4.8 Limit Set
The Limit Set feature of the gauge allows the user to set an audible and visual parameter when
taking measurements. If a measurement is beyond the limit range, set by the user, the beeper will
sound, if enabled. This improves the speed and efficiency of the inspection process by eliminating
constant viewing of the actual reading displayed. The following section outline how to enable and
set up this feature:
1. On the 【Test Set】->【Tolerance Limit】menu item，press the key to activate the limit set
screen.
2. Use the key, the key and the key to change the bottom limit and the upper limit
value to the desired values.
3. Press the key to confirm the change and return to the previous screen, or press the
key to cancel the change.
If the limit setting exceeds the measurement range, the gauge will remind you to re-set. If the
bottom limit is larger than the upper limit, the values will be exchanged automatically.
4.9 Resolution
The gauge has selectable display resolution, which is 0.1mm and 0.01mm.
On the 【Test Set】->【Resolution】menu item, press the key to switch between “High”
and “Low”.
4.10 Unit Scale
On the 【Test Set】->【Unit】menu item，press the key to switch back and forth between
Engilish and metric units.
4.11 Memory Management
4.11.1 Storing a reading
There are twenty files (F00-F19) that can be used to store the measurement values inside the
gauge. At most 99 records can be stored to each file. The following procedures outline this
process:
1Press the key to activate the 【File Name】item on the main measurement screen.
2Use the key and the key to select the desired file to save the data.
3After a new measurement reading appears, press the key to save the measurement
value to current file.
4If the 【Auto Save】function is enabled, the measurement value will be automatically
saved to current file after a new measurement operation.
4.11.2 Viewing stored readings
Press the key multiple times until the 【Record No】area On the measurement screen is
highlighted. Use the key and the key to change the record number. The gauge will
automatically read the stored values according the record number from the memory and display
them on the “Thickness Reading” area of the screen simultaneously. If you want to delete the
displaying record data from the memory, just press the key.
The other way to view the stored record is by menu operations. On the 【Memory Manager】
->【View Mem Data】menu, press the key to activate the memory viewing screen.
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F00 05 5%
F01 00 0%
F02 00 0%
F03 00 0%
F04 00 0%
F05 00 0%
F06 00 0%
↓F07 00 0%
At most eight files,
including the file
name, the record
counts and the ratio
used of the file can be
showed on one
screen.
Use the / key
to scroll up/down.
Press to exit
browsing. Press
to see details of that
file.
F01 00 0%
F02 00 0%
F03 00 0%
F04 00 0%
F05 00 0%
F06 00 0%
↓F07 00 0%
Press or to
move the cursor to
the line which you
want to see details.
Press to see
details of that file.
4.00 5.01 6.01
7.00 8.01
The left screen
displays the total five
record data in the file
F00.
4.11.3 Clearing selected files
Enter the 【Memory Management】menu screen and highlight the 【Delete by File】menu
item. Then press the key. This function provides the user with the ability to delete the selected
data files previously saved in memory.
4.11.4 Clearing all the files
Enter the 【Memory Management】menu screen and highlight the 【Delete All Data】menu
item. Then press the key. This operation will delete all the measurement data stored in the
memory after confirmation.
4.12 System Set
From the main menu screen, press on the 【System Set】menu item and enter its submenu.
1. When【Auto Save】is set to <On>，could store the measured data automatically to current file
after measurement
2. When 【Key Sound】is set to 【On】，the buzzer would make a short hoot while press the key
each time.
3. When 【Warn Sound】is set to 【On】, if the measured value exceeds the tolerance limit, the
buzzer would make a long hoot.
4. LCD Brightness Set: Press on the【System Set】->【LCD Brightness】menu item to enter
the LCD brightness set screen. On the screen, press to enhance the brightness, or press
to weaken the brightness. Press to confirm the modifying, or press to cancel the
F00 05 5%
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modifying.
4.13 System information
This System information function will display the information about the main body and the
firmware. The version would change with the firmware.
4.14 EL Backlight
With the background light, it is convenient to work in the dark condition. Press key to
switch on or switch off the background light at any moment as you need after power on. Since the
EL light will consume much power, turn on it only when necessary.
4.15 Battery Information
Two AA size alkaline batteries are needed as the power source. After several hours’ usage of
the preset batteries, the battery symbol on the screen will be shown as . The more of dark
part indicates the more close to fill. When the battery capacity runs out, the battery symbol will be
shown as and will begin to flash. When this occurs, the batteries should be replaced.
Refer to the sketch below during battery replacing. Please pay much attention to the polarity
of the battery.
+
-
+
-
Cathode
Anode
MT280
Procedure:
1 Power Off the instrument
2 Take off the cover of the
battery and take out the two
batteries
3 Insert the new batteries
into the instrument
4 Replug the battery cover
5 Power on the instrument to
check.
Please take out the batteries when not working during a long period of time.
Suggest to replace the batteries when the battery capacity indicator shows half capacity.
4.16 Auto Power Off
The instrument features an auto power off function designed to conserve battery life. If the
tool is idle for 5 minutes, it will turn itself off. While the voltage of the battery is too low this function
will also work.
4.17 System Reset
Press down the key while powering on the instrument will restore factory defaults. All the
memory data will be cleared during system reset. The only time this might possibly helpful is if the
parameter in the gauge was somehow corrupted.
4.18 Connecting to a Computer
The gauge is equipped with USB serial port. Using the accessory cable, the gauge has the
ability to connect to a computer, or external storage device. Measurement data stored in the
memory of the gauge can be transferred to the computer through the USB port. Detailed
16
information of the communication software and its usage refer to the software manual.
5 Servicing
When the hardness tester appears some other abnormal phenomena, please do not
dismantle or adjust any fixedly assembled parts. Fill in and present the warranty card to us. The
warranty service can be carried on.
6 Transport and Storage
Keep it away from vibration, strong magnetic field, corrosive medium, dumpiness and dust.
Storage in ordinary temperature.
With original packing, transport is allowed on the third grade highway.
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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
0.109
2760
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
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Appendix B Applications 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 4 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 dependant upon its temperature. As materials heat
up, the velocity of sound through them decreases. In most applications with surface temperatures
less than about 100℃, 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 on a sample piece of known thickness, which is at or near the
temperature of the material to be measured. This will allow the gauge 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 recommended 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.
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 single 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.
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 thickness 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.
Suitability of materials
Ultrasonic thickness measurements rely on passing a sound wave through the material being
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measured. Not all materials are good at transmitting sound. Ultrasonic thickness measurement is
practical in a wide variety of materials including metals, plastics, and glass. Materials that are
difficult include some cast materials, concrete, wood, fiberglass, and some rubber.
Couplants
All ultrasonic applications require some medium to couple the sound from the transducer to
the test piece. Typically a high viscosity liquid is used as the medium. The sound used in ultrasonic
thickness measurement does not travel through air efficiently.
A wide variety of couplant materials may be used in ultrasonic gauging. Propylene glycol is
suitable for most applications. In difficult applications where maximum transfer of sound energy is
required, glycerin is recommended. However, on some metals glycerin can promote corrosion by
means of water absorption and thus may be undesirable. Other suitable couplants for
measurements at normal temperatures may include water, various oils and greases, gels, and
silicone fluids. Measurements at elevated temperatures will require specially formulated high
temperature couplants.
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 while in
standard pulse-echo mode. This may result in a thickness reading that is TWICE what it should be.
The Responsibility for proper use of the instrument and recognition of these types of
phenomenons rest solely with the user of the instrument.
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