OKTANTA EM4000 User manual

EM4000_M_921806721
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Electromagnetic–acoustic thickness gauge
EM4000
User Manual
Saint Petersburg
2021

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CONTENT
CONTENT ............................................................................................................................................ 2
WORKING PRINCIPLE ...................................................................................................................... 3
SPECIFICATIONS .............................................................................................................................. 4
DEVICE APPEARANCE .................................................................................................................... 5
DESCRIPTION OF OPERATIONS WITH THE DEVICE ................................................................. 6
Enabling and disabling the device ................................................................................................ 6
Switching between device windows ............................................................................................. 6
The main window ......................................................................................................................... 7
A-scan window ........................................................................................................................... 10
Settings window .......................................................................................................................... 13
Files window ............................................................................................................................... 15
Presets and calibration ................................................................................................................ 16
Measurement of the thickness of the test sample ........................................................................ 23
Measurement of coating thickness at the test sample ................................................................. 25
Data saving ................................................................................................................................. 26
Battery charge ............................................................................................................................. 27
Features of working with the device ........................................................................................... 27
DEVICE VERIFICATION TECHNIQUE ......................................................................................... 28
MAINTENANCE ............................................................................................................................... 31
Converter replacement ................................................................................................................ 31
Battery replacement .................................................................................................................... 32
TRANSPORTATION AND STORAGE ........................................................................................... 33
DELIVERY KIT ................................................................................................................................. 34
MANUFACTURER’S WARRANTY ................................................................................................ 35
WARRANTY CARD ......................................................................................................................... 35
REPAIR INFORMATION ................................................................................................................. 36
VERIFICATION INFORMATION ................................................................................................... 37

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PURPOSE OF THE DEVICE
Electromagnetic–acoustic thickness gauge EM4000 (hereinafter referred to as
the device) is designed to measure the wall thickness of steel pipes, sheet metal, rods
and other products made of steel, as well as aluminium and other metals, without the
use of couplant and without preliminary surface preparation, with a working a gap
between the sensor and metal up to 3 mm. The gap can be a layer of rust, a layer of salt
deposits or other non-conductive coating (paint, varnish, enamel, plastic etc.). The
device also allows you to measure the thickness of non-conductive coatings such as
paint, varnish, enamel, plastic etc. in the range from 0 to 5 mm.
WORKING PRINCIPLE
The operation of the device is based on two physical methods. The ultrasonic
method is used to measure the thickness of a metal sample. The eddy current method
is used to measure the thickness of non-conductive coatings.
The ultrasonic method for measuring thickness is based on measuring the transit
time of an acoustic wave through the material of the test sample. The measured time is
converted into thickness using the specified value for the propagation speed of the
ultrasonic wave. In this case, for the formation of an acoustic wave, the device uses an
electromagnetic–acoustic conversion, due to which the formation of a wave occurs
directly on the surface of the test sample, bypassing the contact medium between the
converter and the sample. Thanks to this, there is no distortion of the wave in this
environment.
The eddy current method for measuring the thickness of non-conductive coatings
is based on measuring the amplitude of the field of eddy currents that are formed near
the surface of the test sample due to the emitting coil located in the sensor of the device.

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SPECIFICATIONS
Measured thickness range for steel 2…80 mm
Measured thickness range for steel without gap 2..220 mm
Thickness measurement error 0.08 mm
Permissible gap between the sensor and the test sample up to 3 mm
Measured thickness range of non-conductive coatings 0..5 mm
Coating thickness measurement error 0.1 mm ± 3 %
Permissible misalignment of the sensor relative to the
normal to the surface of the test sample
±25

The minimum permissible radius of curvature of the
surface of the test sample
≥10 mm
Maximum number of measurements per second 16
Speed of sound setting range 1000…9999 m/s
step of 1 m/s
Device operating frequency 4 MHz
Time of continuous work without recharging the
battery
7 h
Working ambient temperature range −20…+50 °C
Working temperature range of the test sample surface −20...+80 °C
(−20 ...+750 °C
using the EMT40004T
converter)
Dimensions 185 × 44 × 34 mm

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DEVICE APPEARANCE
Device appearance
The device has a colour liquid crystal screen for displaying measurement results.
The device is controlled using the keyboard. On the side of the device there is a USB-
C connector for connecting a charger. The device has a removable sensor that can be
easily replaced with a new one due to the presence of a quick-detachable connection.
Control buttons have the following functions:
“OK” button — turning on / off the device, as well as the navigation
button in the device menu;
“Return” button — allows one to return to the previous menu items, as
well as close the menu;
“Up” button — navigation in the device menu, zoom control in the A-scan
display mode, as well as control of gates;
“Down” button — navigation in the device menu, zoom control in the A-
scan display mode, as well as control of gates;
“Save” button — allows one to save the measurement results in the
memory of the device.

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DESCRIPTION OF OPERATIONS WITH THE DEVICE
Enabling and disabling the device
To turn on the device, press the button and hold it for some time. After
that, the following window will appear on the device screen:
Device information window
After that, the main window of the device appears with the display of the
measured thickness and other information.
The main window of the device with information display
To turn off the device, press and hold the button for some time.
Switching between device windows
The device has four windows, namely the main window, the A-scan window, the
device settings window and the window for working with saved data. To move between
windows, use and buttons.

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The figure below shows the options for windows that appear when you press the
button:
Instrument window options
You can also navigate through the windows with the button, in this case,
the movement will occur in the other direction.
The main window
The figure below shows the main window of the device:
The main window of the device
The following information is displayed in the main window:

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 Signal level indicator. It shows how good the signal is at the measuring
point. The more bars the indicator has, the stronger the useful signal.
 Material. This field displays information about what material is currently
selected on the device.
 Sound speed. This field displays the value of the speed of sound used by
the device to measure the thickness.
 Temperature. This field displays the temperature value of the test sample,
which is currently selected in the device.
 Battery charge level. It shows the battery charge level
 Coating thickness. This field displays the measured thickness value of the
non-conductive coating at the test sample.
 Thickness. This field displays the measured value of the thickness of the
test sample.
 Averages. This field displays the number of accumulations (averages) used
in the device.
 Measurement mode. This field displays information about which of the
three measurement modes (auto, one-gate or two-gate) is currently selected.
The user can change the value of the fields "Material", "Sound speed",
"Temperature", "Thickness", "Averages", "Measurement mode". To do this, first, you
must select an editable field, and then enter this field and edit.
In order to select the required field, press the button while in the main
window. After that, one of the fields will be highlighted with a brighter colour, as
shown in the figure below:
Editable field selection mode

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Further, by pressing the or buttons, you need to select the desired
field. The different options for the editing fields are shown in the figure below:
After the required field is selected, you must press the button to enter
the edit mode for the value of this field. In this case, the highlight colour of the selected
field will change to a darker one, as shown in the figure below:
In the mode of value editing of the selected field, you must set the desired value
by pressing or holding the or buttons.
After finishing editing the field, you must press the button to return to
the field selection mode and again press the button to exit to the main window
of the device.

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A-scan window
The A-scan window is shown in the figure below:
A-scan display mode
The horizontal axis on the A-scan is measured in millimetres or inches,
depending on the units of measurement selected in the instrument settings (see the
“Settings window” section). In addition to the A-scan, this window also displays the
measured thickness of the test sample. The gain level in the device is shown in the right
part of the window.
The user has the ability to change the scale of the A-scan, set the position of
two gates, as well as change the gain.
Changing the scale of the A-scan display
To change the scale, press the button. The “scale” message will appear
on the screen. An example of such a window is shown in the figure below:
A-scan scaling

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In this case, the user can zoom in or out by pressing or buttons.
Pressing the button again switches the “scale” mode to the “offset”
mode, in which you can move along the enlarged A-scan by selecting the necessary
part of it. The appearance of such a window is shown in the figure below:
A-scan offset mode
In this case, the user can navigate the A-scan by pressing the or
buttons.
To exit the “scale” mode, press the button.
Pressing the button again leads to reset of all changes of the A-scan scale
and setting the scale to default.
Gain change
The user has the ability to change the gain of the device. In this case, this
opportunity appears only if the automatic gain control (AGC) mode is disabled in the
device settings (see the “Settings window” section).
To select the gain change mode, press the button three times. In this
case, the screen will display the “gain” message, as shown in the figure below:
Manual gain mode

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In this case, the user can change the gain by pressing or holding the or
buttons.
To exit the manual gain control mode, press the button.
Gate installation
The device has three measurement modes: auto, one-gate and two-gates. To
operate in manual one-gate and two-gates measurement modes, the device has the
ability to install these gates on the A-scan.
To set gate 1, press the button several times until the message “Gate 1”
appears on the screen. An example of such a window is shown below:
Setting the position of the gates
In this case, the user can change the position of gate 1 by pressing or holding
the or buttons. It should be borne in mind that the possibility of setting
gate 1 appears only when the measurement mode “one-gate” or “two-gates” is selected
in the main window of the device (see “The main window” section).
Similarly, the user can change the position of the gate 2. It should be mentioned
that the possibility of setting gate 2 appears only when the measurement mode “two-
gates” is selected in the main window of the device (see “The main window” section).
To exit the gate setting mode, press the button.

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Settings window
The figure below shows the window with the device settings:
Settings window
To navigate through the lines in this window, press the button and after
that select the desired line using or buttons.
To change the values of the selected line or enter a submenu, press the
button.
To exit the line parameters editing mode, use the button.
This window contains the following lines:
 A-scan length
This parameter can take the following values: 10 mm, 25 mm, 50 mm, 100
mm, 150 mm, and 220 mm. It limits the length of the horizontal axis on
the A-scan.
 AGC
This parameter can be “on” or “off”. It determines whether the device is
using the automatic gain control mode or not.
In most cases, it is recommended to use this setting “on”.
 Resolution

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This parameter can take values of “0.1” and “0.01”. It determines how
many decimal places are displayed on the device when measuring the
thickness of the test sample and the thickness of the non-conductive
coating.
 Measurement of coating thickness
This parameter can be “on” and “off”. It determines whether the device
measures the thickness of the coatings or not.
 Gap calibration
 This menu item is designed to calibrate the coating thickness
measurement channel. To enter this menu, press the button. In this
case, the user enters the submenu, the appearance of which is shown in
the figure below:
Coating thickness measurement channel calibration menu
There are 4 items in this menu: zero calibration, air calibration, thickness
calibration and reset calibration.
Navigation through the menu items is carried out using the and
buttons. To select the desired item, press the button. To
exit to the previous menu, press the button.
For more information on calibrating the coating thickness measurement
channel, see the “Presets and Calibration” section.
 Brightness
This parameter can take values in the range from 1 % to 100 %. It
determines the brightness of the screen.

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 Date
This menu allows you to set the date in the device.
 Time
This menu allows you to set the time in the device.
 Language
The device allows you to choose one of three interface languages:
Russian, Chinese and English.
 Units
This parameter can take the value of millimetres or inches.
Files window
The appearance of this window is shown in the figure below:
Files window
To enter this window, press the button. After that, the appearance of the
window will change and become as shown in the figure below:

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After that, you can select one of the saved files using the and
buttons. After the desired file is selected, you need to press the button to view
or delete this file. In this case, the window will change and will be as shown below:
In this window, using , and buttons you need to select the
action that you want to perform with the selected file. The file can be opened or deleted.
Additionally, in this menu it is possible to delete all saved files.
To exit the menu, press the button the required number of times.
Presets and calibration
There are a number of steps to take before starting measurements:
1) In the main window of the device, select the material of the test sample from
the list (see “The main window” section).
2) Select the temperature of the test sample (see “The main window” section).
The speed of sound in a material is temperature dependent. Therefore, it is
necessary to try to set the temperature of the test sample as accurately as
possible so that the device takes into account the change in the speed of
sound. This is especially important for measuring the thickness of heated
samples.
ATTENTION!
When measuring the thickness of a sample with a surface temperature of more
than 80 °C, it is necessary to use the EMT40004T converter.

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The external view of the device with the EMT40004T sensor is shown in
the figure below:
Device with EMT40004T sensor
Standard EMT40001 converter is designed for operation in the range of
−20.. +80 °C
ATTENTION!
Using the EMT40001 converter at temperatures above 80 °C may damage it.
EMT40004T converter characteristics:
Excited wave type Transverse, radially polarised
Working frequency range 1 MHz…10 MHz
Aperture diameter 23 mm
Dimensions 40 mm × 150 mm
Operating temperature range −20 °C... 750 °C
Measurement modes with EMT40004T converter:
Temperature range, °C Measurement duration, s
0–320 continuously
320–700 0–5 (interval between measurements
is 15 seconds)

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ATTENTION!
When working with test samples, the temperature of which is higher than 350
degrees, the thickness measurement with the EMT40004T converter must be
performed for a short time, with pauses, according to the table above.
3) Set the speed of sound in the device (see “The main window” section).
When you select a material, the speed of sound is automatically set from the
default values for that material. But the user can set any value of the speed
of sound if it is known more precisely. The device uses a transverse acoustic
wave. The speed of this wave for various materials is presented in the table
below:
Material Speed of sound, m/s
Steel 3250
Stainless steel 3250
Aluminium 3130
Bronze 2500
Copper 2260
Brass 2120
Titanium 3120
The speed of propagation of a transverse wave in metals
ATTENTION!
The device uses a transverse wave. The typical transverse wave speed in steel is
3250 m/s.

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4) Set the required number of averages. The user can select the number of
averages from the range of 16, 32, 64, 128, 256, and 1024. For most cases,
it is recommended to use the number of averages equal to 128. The larger
the number of averages, the higher the quality of the useful signal, but the
slower the device works. If the test sample is strongly corroded or has a
large layer of dirt or rust on the surface, then it is recommended to increase
the number of averages up to 256..512. If measurements take place on
samples without coatings and without corrosion, then the number of
averages can be reduced to 32..64, this will increase the operation rate of the
device.
5) Select the measurement mode. In the EM4000 thickness gauge, three
thickness measurement algorithms are implemented: an automatic
algorithm, a one-gate thickness measurement algorithm and a two-gate
thickness measurement algorithm.
The automatic algorithm is suitable for most applications and allows you to
obtain the thickness value without operator intervention.
The algorithm for measuring the thickness in “one-gate” mode calculates
the position of the maximum in the first gate on the A-scan and recalculates
the found value into the thickness. The position of the first gate and its length
are set by the operator. The algorithm is recommended to be used to test
samples made by casting, as well as test samples subject to severe corrosion,
for example, ship hulls.
The algorithm for measuring the thickness in “two-gate” mode calculates
the position of the maxima in two gates. The difference between the
maximum position in one gate and the maximum position in the other gate
is used to calculate the thickness. The position of the gates is set by the
operator.
6) Calibrate if necessary. The device has two independent measuring channels.
This is the channel for measuring the thickness of the test sample and the
channel for measuring the thickness of the non-conducting coating. These
channels are also calibrated independently.

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Calibration of the channel for measuring the thickness of the test
sample.
This calibration allows you to determine automatically the speed of sound
in a sample with a predetermined thickness. To perform the calibration, you
must perform the following steps:
 Place the device on a sample of known thickness.
 In the main window of the device, highlight the value of the
measured thickness (see “The main window” section). The
appearance of such a window is shown below:
Highlighted thickness value
 Next, you need to press the button and using and
buttons set the real known value of the sample thickness
instead of the measured value. Then press the button and
after that press the button. In this case, the device will set
a new value for the speed of sound.
Calibration of the coating thickness measurement channel.
This calibration is required when replacing the EMT40001 converter.
Calibration is performed using a sample supplied with the device. The
sample is made of steel; therefore, it should be set as the “steel” material
(see “The main window” section). The sample is shown in the figure below:
Sample supplied with the device