ElektroPhysik MiniTest 430 Technical Document

Technical Manual and
Operating Instructions
Ultrasonic Thickness Gauges
MiniTest 430 / 440

Important Note
In ultrasonic thickness measurement it is inherent to the measuring procedure that the gauge might
use the second echo rather than the first one reflected from the material being measured. This may
result in a thickness reading TWICE as high than the actual thickness.
When measuring through extremely thick coatings in the echo-echo mode, it may occur that the
thickness of coating layer is measured instead of the wall thickness that actually was intended to
be measured.
The responsibility for proper use of the gauge and recognition of this phenomenon rests solely with
the user of the gauge.
© Editon 1, 08/2014
Version 1.0
Subject to change without notice.
ElektroPhysik
Dr. Steingroever GmbH & Co. KG
Pasteurstr. 15
50735 Koeln, Germany
Phone: [phone]
Fax : [phone]
Internet: http://www.elektrophysik.com/
Mail: [e-mail]

Table of Contents
1. Introduction...............................................................................................................................5
1.1 Important Notes on Wall Thickness Measurement ................................................................5
Prerequisites for the use of ultrasonic wall thickness gauges.................................................5
1.1.1 Training of the Person in Charge of Testing..................................................................6
1.1.2 Limitations to Ultrasonic Testing....................................................................................6
1.1.2.1 Ultrasonic Wall Thickness Testing...........................................................................6
1.1.2.2 Influence of the Material to be tested.......................................................................7
1.1.2.3 Influence of Changes in Temperature......................................................................7
1.1.2.4 Measurement of the Residual Wall Thickness .........................................................7
1.1.2.5 How to use the Couplant .........................................................................................7
1.1.2.6 Duplication of Reading.............................................................................................8
2. Technical Specifications ..........................................................................................................9
3. Measuring Principle................................................................................................................10
4. Description of the Gauge and Schedule of Supply...............................................................11
4.1 Description of the Gauge (Front and back Side)..................................................................11
4.2 Supply Schedule.................................................................................................................11
4.2 Display................................................................................................................................12
4.3 Keyboard.............................................................................................................................13
5. Preparing Measurement .........................................................................................................14
5.1 Preparing the Gauge...........................................................................................................14
5.2 Selection of the Transducer.................................................................................................14
5.3 Preparing the Surface of Measuring Object.........................................................................15
6. Operation.................................................................................................................................16
6.1 Switch ON...........................................................................................................................16
6.2 Taking Readings.................................................................................................................16
6.3 Calibration...........................................................................................................................17
6.3.1 Calibration...................................................................................................................17
How to calibrate MiniTest 430 / 440...................................................................................17
6.3.2 Determination of the Sound Velocity...........................................................................17
6.3.2.1 How to determine the Sound Velocity.......................................................................18
6.3.3 Calibration of the Transducer....................................................................................18
6.4 User Menu ..........................................................................................................................19
6.4.1 Measuring Mode (Meas. Mode) ..................................................................................19
6.4.1.1 MiniTest 430..........................................................................................................19
6.4.1.2 Operating modes of MiniTest 440..........................................................................21
6.4.1.2.1 I-E mode.............................................................................................................21
6.4.1.3.2 Echo-Echo mode................................................................................................22
6.4.2 Sound Velocity............................................................................................................23
6.4.2.1 Materials................................................................................................................23
6.4.2.2 Setting Sound Velocity (vel. custom) .....................................................................24
6.4.3 Measuring Unit............................................................................................................25
6.4.4. Data Memory .............................................................................................................25
6.4.4.1 Select a Batch (MiniTest 430 / 440).......................................................................26
6.4.4.2 Delete a Batch (MiniTest 430 / 440).......................................................................26
6.4.5 Gain Setting................................................................................................................27
6.4.6 Switch Off Mode..........................................................................................................27
6.4.7 Contrast......................................................................................................................28
6.4.8 Language....................................................................................................................28
6.4.9 Gauge Data ................................................................................................................28
6.4.10 Standard Setting.......................................................................................................28
6.5 Data Processing..................................................................................................................28

6.6 Storing Readings.................................................................................................................28
7. Measuring Technology...........................................................................................................29
7.1 Measuring Methods.............................................................................................................29
7.2 Measurement on Pipes and Tubes......................................................................................29
8. Maintenance and Precautions................................................................................................30
8.1 Power Check.......................................................................................................................30
8.2 Precautions.........................................................................................................................30
8.2.1 General Precautions ...................................................................................................30
8.2.2 Precautions to take during Measurement....................................................................30
9. Table of Materials and their typical Sound Velocity (Longitudinal Wave) .....................31
10. Safety Notes..........................................................................................................................32
11. Declaration of Conformity....................................................................................................33
11. After-Sales Service ...............................................................................................................33
13. Change History .....................................................................................................................33

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1. Introduction
The MiniTest 420 and 440 model are non-destructive ultrasonic thickness gauges for portable or
stationary use. Working according to the ultrasonic principle it enables quick and easy measurement
of wall thickness. It can also be used forthe measurement of the sound velocity of metals and various
other materials.
Prior to use, please read the operating instructions carefully in order to get familiar with the use
and all functionalities of the MiniTest 430/440 gauges.
Even if you are already familiar with measurement according to the ultrasonic principle, it is highly
recommended to read section 1.1 carefully. This section provides important information on the
limitations to and conditions for reliable wall thickness measurement such as technical training,
required knowledge on the specific requirements for testing and the selection of a suitable test
equipment.
The gauge is easy to use. To enable its quick use, please read the sections below to get familiar
with the preparatory requirements and basic functions.
1.1 Important Notes on Wall Thickness Measurement
Before using the wall thickness gauge, please read the following instructions
carefully. Make sure to fully understand and follow the instructions in order to
avoid errors that might lead to erratic readings. Any decisions based on erratic
readings may cause damage to property or personal injury.
Prerequisites for the use of ultrasonic wall thickness gauges
This manual contains essential information on how to operate your measurement device. In
addition, there are a number of other factors to influence measurement. A detailed description of all
such factors would be beyond the scope of this manual. For that reason, this manual is limited to
the three most important requirements for reliable ultrasonic wall thickness measurement:
adequate training of the person in charge of measurement
fundamental knowledge on the specific requirements on and limitations to the measuring
technique used for testing
choice of a suitable measuring equipment

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1.1.1 Training of the Person in Charge of Testing
The proper use of ultrasonic test equipment requires an adequate training in the field of ultrasonic
wall thickness testing. Such training should include the following subjects:
theory of sound propagation in materials
effect of the sound velocity inherent to material to be tested
behaviour of sound waves at the interfaces between different materials
propagation of the sound beam in the material
effect of the surface quality of the material to be tested
Insufficient knowledge on the above topics may result in erratic readings and thus lead to
unforeseen consequences. For more information on the availability of training opportunities for
examiners in ultrasonic testing, qualifications and certificates, please contact your national NDT
partner, or, in Germany Deutschen Gesellschaft für Zerstörungsfreie Prüfung e.V., Motardstraße
54, D-13629 Berlin.
1.1.2 Limitations to Ultrasonic Testing
The results obtained from measurement solely relate to areas of the measuring object that have
been targeted by the sound beam. Conclusions to other areas of the measurement object are not
admissible. They are only allowed if extensive experience on the process of manufacture of the
measuring objects is available and if appropriate methods of statistical evaluation can be applied.
It should be taken into consideration that the ultrasound beam might be completely reflected by
interfaces being present in the measuring object so that deeper reflection points will not be
reached by the ultrasound any more. For that reason it must be ensured that all areas of the
measuring objects to be measured can be reached by the sound beam.
1.1.2.1 Ultrasonic Wall Thickness Testing
Ultrasonic wall thickness measurement is based on the measurement of travel times of sound
pulses in the object to be measured. For reliable wall thickness measurement it is presumed on the
assumption that the velocity in the measuring object remains constant. Generally, this is given for
the majority of work-pieces made of steel. Even if they include different alloy components, the
sound velocity changes will be small enough to be neglected (unless high-precision measurement
is required).

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In other materials such as non-ferrous metals or plastics, the sound velocities are subject to major
changes that might impair the measuring accuracy.
1.1.2.2 Influence of the Material to be tested
Material discontinuities may lead to strong variations of the sound velocity within a measuring
object. In such case, an average sound velocity should be used for testing.
However, the best results will obtained when calibrating the gauge by means of a reference
sample. This sample must be made of the same material as the object to be measured and should
exhibit plane parallel surfaces. Its thickness should equal the maximum thickness of the later
object to be measured. Please note that any heat treatment might considerably change the sound
velocity and thus influence the measuring precision accordingly.
If dramatic changes of the sound velocity are to be expected, it is recommended to readjust the
sound velocity within shorter time intervals. This is to avoid erratic readings.
1.1.2.3 Influence of Changes in Temperature
The sound velocity is also influenced by the temperature prevailing in the material. If the gauge has
been adjusted to a “cold” reference sample and wall thickness measurement is made on a “warm”
object, major measuring errors are very likely to occur.
To avoid such measuring errors, it is recommended to use a temperature-adapted reference
sample for adjusting the gauge. Another option would be to correct for the applicable temperature
influence by means of the sound velocity/temperature correction table.
1.1.2.4 Measurement of the Residual Wall Thickness
Measuring the residual wall thickness of internally eroded or corroded objects such as tubes,
containers or reaction vessels makes it necessary to choose a most suitable test equipment and to
handle the sensor with utmost care. In addition, the nominal wall thickness as well as the
suspected degree of wall thickness loss should be known.
1.1.2.5 How to use the Couplant
Make sure the user is familiar with the use of couplant. For each measurement, the couplant must
be applied evenly over the surface of the measuring object. Any variations in couplant layer thickness
will influence measuring accuracy. Both, adjustment of the gauge and wall thickness measurement
must be made under the same coupling conditions. Make sure to use a quantity of couplant as small
as possible and to apply a constant contact pressure of the sensor.

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When measuring on curved surfaces such as pipes or tubes make sure the coupling of the
transceiver is made properly. The acoustic layer interface of the transceiver must be aligned so as
to form a right angle to the axis of curvature of sample (longitudinal axis of tube). For small tube
diameters it is recommended to carry out two measurements: one with the layer interface in vertical
position to the longitudinal axis of tube, another one in parallel position to the longitudinal axis of
tube. The smaller of the two readings obtained should be used as the correct one for this measuring
spot.
(senkrecht = vertical)
1.1.2.6 Duplication of Reading
Do not measure in a range lower than the measuring range specified for the sensor. In such case,
the first back wall echo would not be strong enough for being processed whereas the amplitude of
the second one would be strong enough to be processed accordingly. As a result, the reading
obtained would be twice the actual wall thickness. In order to avoid such errors when measuring at
the limit of the measuring range it is recommended to verify results by using another sensor.
In critical cases, it is recommended to use display screen equipment to provide additional information
on the echo curve.
.

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2. Technical Specifications
Display screen: 128 x 64 pixel dot matrix LC display, backlit
Digital display: four-digits
Measuring range: 0.65 mm ... 500.0 mm (steel) depending on transducer
Display resolution: 0.1 mm (if readings > 100 mm)
0.01 mm (if readings < 100 mm)
Measuring accuracy: 0.65 mm... 9.99 mm: ± 0.04 mm 10 mm… 99.99 mm: ± (0.04 mm + 0.1% of reading)
100 mm... 500 mm: ± (0.3 % of reading)
Sound velocity: 1000...9999 m/s
Data memory: 10 batches for a maximum of 500 readings per batch
Measuring frequency: 2 readings/second in the standard mode
10 readings/second in the high-performance mode (scan)
Zero point calibration: automatic
Auto switch-off: 2 minutes, 5 minutes or shut down manually
Power supply: 2 x AA battery, battery life 80 h in continuous operation
Operating temperature: -20°C ... 50°C
Storage temperature: -25°C ... 60°C
Dimensions: 130 x 73 x 24 mm
Weight: 190 g (without batteries)
Options Transducers U2.0, U5.0, U7.5, U10.0, U5.0HT

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3. Measuring Principle
The ultrasonic sensor head emits an ultrasonic signal to travel through the sensor head, the
couplant and finally to the measuring object. A portion of the ultrasound signal is reflected from the
surface of measuring object, another one is reflected from the opposite side of the object when
travelling back. The sensor receives both echoes. The wall thickness is calculated according to the
exact time of travel of pulse and shown as reading on display.

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4. Description of the Gauge and Schedule of Supply
4.1 Description of the Gauge (Front and back Side)
1. display
2. keyboard
3. battery compartment (back panel)
4. name plate (back panel)
5. transducer socket (Identify PIN)
6. USB interface (MiniTest 430 / 440)
4.2 Supply Schedule
1. 1 x plastics carrying case
2. 1 x MiniTest gauge (model 430 or 440)
3. 1 x ultrasonic transducer (U5.0 for MiniTest 430; U5.0E for MiniTest 440)
4. 1 x couplant (gel, 200ml)
5. 1 x operating instructions (German / English / French)
6. 1 x CD with data transfer software
7. 1 x USB connecting cable
8. 2 x 1,5V (AA) batteries

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4.2 Display
1. active batch and number or readings stored in this batch
2. transducer model
3. battery state
fully charged
empty
4. measuring mode
5. measuring icon and measuring unit
6. gain mode of amplifier selection (A = Auto, L= Low , M = Medium, H = High).
7. sound velocity selection
8. current reading
①
②
③
⑤
⑥
④
⑧
⑦

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4.3 Keyboard
ON / OFF button
Menu key
Press to enter the operating menu
Arrow UP/DOWN keys
Press UP/DOWN to scroll through the different
menu options.
Press arrow UP to enable / disable the backlight.
OK/ESC key
Press OK to confirm a selection in the menu.
Press ESC to quit the menu.
CAL key
Quick access for sound velocity calibration (it is
required the wall thickness is known).
Data memory short-cut key

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5. Preparing Measurement
5.1 Preparing the Gauge
Please check gauge and accessories immediately upon receipt. For the supply schedule, please
refer to section 4.1.2 of this manual. Please contact your supplier in case delivery is not complete
or does not comply with the supply schedule you have ordered. Any damage of the gauge should
be reported upon delivery. Do not use the gauge in case it seems to be damaged!
5.2 Selection of the Transducer
Type Frequency Measuring range Temperature
U2.0 2,0 MHz 2.0 mm...500 mm < 60°C
U5.0E 5,0 MHz E-E 3.0 mm...25 mm
I-E 1.0 mm...200 mm < 60°C
U5.0 5,0 MHz 0.8 mm...300 mm < 60°C
U5.0HT 5,0 MHz 3.0 mm...200 mm < 350°C
U7.5 7,5 MHz 0.65 mm...50 mm < 60°C
U10.0 10,0 MHz 0.65 mm…20 mm < 60°C

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Make sure to select a suitable transducer according to the thickness of your measuring object.
The transducer used for measurement must be in a good condition. Make sure transducer tip and
coupling surface are not worn off. The measuring range of transducer should cover the complete
wall thickness range to be measured (application range). The temperature of measuring object
must not exceed the temperature range specified for the transducer you have selected.
Transducer type Application
U5.0:
(5.0 MHz) Standard transducer for MiniTest 430 to cover a wide
range of applications such as measurement on
- flat surfaces
- large curvature radii
- objects with a thickness > 50 mm
U5.0E
(5.0 MHz) Standard transducer for MiniTest 440. When connected to MiniTest 440, this transducer is able to measure in the
E-E mode the wall thickness of steel through a coating
applied to the steel.
U2.0
(2.0 MHz) Rough surfaces, such as on cast components
U5.0HT
(5 MHz) Suitable for temperatures < 350°C
U7.5
(7,5 MHz) Thin wall thickness and small curvature radius
U10.0
(10 MHz) Thin wall thickness and small curvature radius (small geometries)
U2.0
(2.0 MHz) Rough surfaces, such as on cast components
5.3 Preparing the Surface of Measuring Object
Very rough and/or corroded surfaces should be pre-treated as follows:
1. Smoothen the surface by grinding, polishing or filing or use a high-viscosity couplant.
2. Apply some couplant to the surface of measuring object.
3. Take several readings around the measuring spot.

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6. Operation
6.1 Switch ON
Connect the transducer to the gauge socket. Press the ON/OFF button to switch on. The
following appears on display:
If no transducer has been connected prior to switch ON, the following message will appear:
”Please insert the transducer”. Insert the transducer into the gauge socket and wait for the
measuring status to appear.
Please make sure to connect solely original ElektroPhysik transducers suitable for
MiniTest 430 / 440. Otherwise, the gauge will not work correctly and the error
message “ERROR” will appear.
6.2 Taking Readings
There are two options to access the measuring mode:
1. Connect transducer and switch on the gauge.
2. From the menu you can press ESC and go back to the measuring mode.
Once you have put the transducer onto the measuring object, the display will show the
measuring icon to indicate the coupling action. Once the reading has stabilized, you
can detach the transducer from the measuring object. Remove the transducer in a
quick action. The last reading taken appears on display.

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6.3 Calibration
Errors occurring during the first operating steps might be due to the following reasons:
•Transducer failure or strong variations in temperature
•System error caused by base unit / transducer incompatibility
•Computing error caused by sound velocity/material setting error
For troubleshooting please proceed as follows:
Press -key followed by or to select a suitable option.
6.3.1 Calibration
How to calibrate MiniTest 430 / 440
Worn off transducer or the use of different transducer models as well as the ambient temperature
may lead to erratic readings. To compensate for such errors, the both models feature an
“automatic calibration”.
Important note:
Prior to calibration make sure the transducer tip is clean and free from any residual couplant or
other dirt particles that might impair measurement and thus the calibration accuracy. In case
temperature varies strongly during measurement, it is recommended to use the calibration function
more frequently in order to ensure accuracy of measurement.
6.3.2 Determination of the Sound Velocity
The sound velocity in the measuring object depends on the material the object is made of. In
addition, measuring objects might exhibit material irregularities (if produced in different product
batches). As a result, the sound velocity might vary according to the sample to be tested. To
prevent measuring errors based on divergent sound velocities, it is absolutely necessary to
determine the precise sound velocity of an object unless measuring errors are small enough to be
neglected. To calibrate the gauge to the correct sound velocity of an object, the function “Sound
velocity” is available.

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6.3.2.1 How to determine the Sound Velocity
1. Select a stored sound velocity or set the gauge to a sound velocity as close as possible to
the sound velocity of the material to be measured.
2. Take a sample of a defined thickness as close as possible to the thickness of the later
measuring object. If no such sample is available, take your measuring object and measure
its thickness using a caliper or another measuring tool.
3. Now use MiniTest 430 or 440 to measure the sample in order to get a thickness value.
4. First press -key to go to the “Sound velocity”. Then press or in order to
adjust to the thickness reading you have measured and get the correct sound velocity
accordingly.
5. Adjust the sound velocity so that the material thickness shown on display corresponds to
the measured thickness of sample.
6. Re-measure the sample and check the deviation between reading and actual thickness. If
both values are identical, the sound velocity is correct for this material.
6.3.3 Calibration of the Transducer
The transducer calibration function is to be used to compensate for errors or system errors that
cannot be remedied by “Automatic calibration”. The cause of such error might be for instance a
transducer change. First make sure the error is not due the setting of an unsuitable sound velocity.
To carry out the transducer calibration please proceed as follows:
1. Adjust the gauge to the sound velocity 5920 m/s.
2. Take a reading on test block supplied with the gauge and take. The reading obtained
should be 4.00 mm ± 0.01 mm. If the reading obtained differs from that value, press the
-key. Then press or . Choose “Transducer calibration“ and press OK to
confirm.
Now use arrow keys or to adjust the reading you obtained to the thickness of
test block, i.e. 4.00 mm. Press OK to confirm the value. Then press ESC to go to the
measuring mode.

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6.4 User Menu
Press key to go to the main menu. Use arrow keys or to scroll up/down the menu
items.
Once your selected item appear press OK to confirm.
Press ESC to quit the menu and to go to the measuring mode.
MiniTest 430 / 440
6.4.1 Measuring Mode (Meas. Mode)
6.4.1.1 MiniTest 430
The gauge offers 5 different measuring modes. Please select the correct mode according to your
requirements and measuring conditions.
Standard mode: The current reading is shown. This mode applies if you are satisfied with the
standard measuring needs.
Minimum mode: In this mode, the lowest values is shown during measurement. This mode is
recommended for curved surfaces or if it is required to indicate the lowest thickness values. This
would be a typical application of tube measurement.
Important note: This mode is NOT recommended for cast iron or Aluminium alloys.

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Difference mode: If you have adjusted a set point previously, this mode will indicate the difference
between the current reading and set point. This mode is particularly suitable for quality inspection
and if it is required to identify the products within the admissible thickness tolerance range.
Alarm mode (Limitation): In this mode, a visual alarm will be given once the upper or lower limit
(if set previously) has been exceeded. This mode enables a quick and easy checking of readings
so that a permanent monitoring of readings will not be necessary. In practical operation, this mode
is more frequently used than the “Difference mode“.
Scan mode (high-performance mode): This mode is particularly suited for measurement on high-
temperature samples.
The different modes are shown on display as follows: