Dakota Ultrasonics ZX-6DL Operating Manual
OPERATION MANUAL
DAKOTA ULTRASONICS
ZZXX--66 DDLL
Ultrasonic Multi-Echo Data
Logging Thickness Gauge
P/N P-306-0002 Rev 1.10, March 2019
CONTENTS
CHAPTER ONE INTRODUCTION ...................................................................... 1
DISCLAIMER ......................................................................................................................... 1
1.1
CHAPTER TWO KEYPAD, MENU, DISPLAY & CONNECTORS ..................... 2
2.1
ON/OFF/ENTER KEY… ..................................................................................................... 2
2.2
PRB 0 KEY… ....................................................................................................................... 2
2.3
CAL KEY…. ......................................................................................................................... 3
DATA KEY… ....................................................................................................................... 3
2.4
2.5
CLR KEY…. ......................................................................................................................... 3
2.6
+/- INCREMENT/DECREMENT KEY’S…. .................................................................................. 3
2.7
MULTI KEY…. ..................................................................................................................... 3
2.8
MENU KEY… ...................................................................................................................... 3
2.9
THE DISPLAY ....................................................................................................................... 5
THE TRANSDUCER .............................................................................................................. 6
2.10
2.11
TOP & BOTTOM END CAPS ................................................................................................. 8
CHAPTER THREE PRINCIPALS OF ULTRASONIC MEASUREMENT ......... 10
3.1
TIME VERSUS THICKNESS RELATIONSHIP ............................................................................. 10
3.2
SUITABILITY OF MATERIALS ................................................................................................. 10
RANGE OF MEASUREMENT AND ACCURACY .......................................................................... 10
3.3
3.4
COUPLANT ......................................................................................................................... 10
3.5
TEMPERATURE ................................................................................................................... 11
3.6
MEASUREMENT MODES ...................................................................................................... 11
CHAPTER FOUR SELECTING THE MEASUREMENT MODE ....................... 14
4.1
WHICH MODE & TRANSDUCER DO I USE FOR MY APPLICATION? ............................................ 14
CHAPTER FIVE MAKING MEASUREMENTS ................................................. 16
5.1
PROBE ZERO ...................................................................................................................... 16
5.2
MATERIAL CALIBRATION ..................................................................................................... 18
CHAPTER SIX THROUGH PAINT MEASUREMENT - MULTI MODE ............ 2 5
6.1
INTRODUCTION ................................................................................................................... 25
MULTI MODE TRANSDUCERS .............................................................................................. 25
6.2
CHAPTER SEVEN VELOCITY GAUGE ........................................................... 27
7.1
VELOCITY GAUGE (VX) ....................................................................................................... 27
7.2 CALIBRATION TO A KNOWN THICKNESS ................................................................................ 28
7.3
CALIBRATION TO A KNOWN VELOCITY .................................................................................. 29
CHAPTER EIGHT ADDITIONAL FEATURES ................................................. 31
8.1
GAIN ................................................................................................................................. 31
8.2
HIGH SPEED SCAN ............................................................................................................. 32
8.3
ALARM ............................................................................................................................... 33
8.4
DIFFERENTIAL .................................................................................................................... 34
8.5
UNITS ................................................................................................................................ 35
8.6
LITE ................................................................................................................................... 36
BEEP ................................................................................................................................. 37
8.7
8.8
ZERO ................................................................................................................................. 38
8.9
VELOCITY (VX) .................................................................................................................. 39
8.10
PROBE DIAMETER & FREQUENCY ..................................................................................... 40
8.11
LOCK ............................................................................................................................... 41
FACTORY DEFAULTS ........................................................................................................ 42
8.12
CHAPTER NINE DATA STORAGE ................................................................. 44
9.1
INTRODUCTION .................................................................................................................. 44
9.2
OPENING A DATA FILE ........................................................................................................ 44
9.3
STORING A MEASUREMENT ................................................................................................ 45
CLEARING A FILE ............................................................................................................... 46
9.4
9.5
CLEAR ALL FILES ............................................................................................................... 47
CHAPTER TEN DATA TRANSFER & POWER OPTIONS.............................. 49
10.1
CONNECTIVITY ................................................................................................................. 49
10.2
OPENING A FILE ............................................................................................................... 49
10.3
COPYING/OPENING FILES ................................................................................................. 49
LINE POWER .................................................................................................................... 50
10.4
APPENDIX A - VELOCITY TABLE .................................................................. 51
APPENDIX B- APPLICATION NOTES ........................................................... 53
CHAPTER ONE
INTRODUCTION
The Dakota Ultrasonics model ZX-6 DL is a basic dual element thickness gauge with
through paint measurement capability, and the ability to locate blind surface pitting
and internal defects/flaws in materials. Based on the same operating principles as
SONAR, the ZX-6 DL is capable of measuring the thickness of various materials with
accuracy as high as 0.001 inches, or 0.01 millimeters. The principle advantage of
ultrasonic measurement over traditional methods is that ultrasonic measurements
can be performed with access to only one side
Dakota Ultrasonics maintains a customer support resource in order to assist users
with questions or difficulties not covered in this manual. Customer support may be
reached at any of the following:
Dakota Ultrasonics Corporation
1500 Green Hills Road, #107
of the material being measured.
Scotts Valley, CA 95066
Tel: (831) 431-9722
Fax: (831) 431-9723
www.dakotaultrasonics.com
1.1 Disclaimer
Inherent in ultrasonic thickness measurement is the possibility that the instrument will
use the second rather than the first echo from the back surface of the material being
measured. This may result in a thickness reading that is TWICE what it should be.
Responsibility for proper use of the instrument and recognition of this phenomenon
rest solely with the user of the instrument. Other errors may occur from measuring
coated materials where the coating is insufficiently bonded to the material surface.
Irregular and inaccurate readings may result. Again, the user is responsible for
proper use and interpretation of the measurements acquired.
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CHAPTER TWO
KEYPAD, MENU, DISPLAY & CONNECTORS
The Keypad
2.1 ON/OFF/ENTER Key
The ON/OFF/ENTER key powers the unit ON or OFF. Since the same key is also
used as an ENTER key, the gauge is powered off by pressing and holding down the
key until the unit powers off.
Once the gauge is initially powered on, this key will function as the ENTER key,
similar to a computer keyboard. This key will be used to select or set a menu option.
Note: Unit will automatically power off when idle for 5 minutes. All current settings
are automatically saved prior to powering off.
2.2 PRB 0 Key
The PRB 0 key is used to “zero” the ZX-6 DL in much the same way that a
mechanical micrometer is zeroed. If the gauge is not zeroed correctly, all of the
measurements that the gauge makes may be in error by some fixed value. Refer to
page 38 for a further explanation of this important feature.
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ZX- 6 DL Ultrasonic Multi-Mode Thickness Gauge
2.3 CAL Key
The CAL key is used to enter and exit the ZX-6 DL's calibration mode. This mode is
used to adjust the sound velocity value that the ZX-6 DL will use when calculating
thickness. The tool will either calculate the sound-velocity from a sample of the
material being measured, or allow a known velocity value to be entered directly. This
provides increased linearity between transducers. Refer to page 19 for an
explanation on the various calibration options.
2.4 DATA Key
The DATA key accesses the data logging section of the ZX-6 DL, which consists of
50 sequential (single column) files with 250 storage locations per file. Refer to page
44 for an explanation on the various calibration options.
2.5 CLR Key
The CLR key is used in conjunction with the data logging section to clear a single
stored memory location. Refer to page 44 for an explanation on the various
calibration options.
2.6 +/- Increment/Decrement Key’s
The +/- Keys are used to increment/decrement values, navigate menus, select menu
options, and navigate data files and storage locations.
2.7 MULTI Key
The MULTI key toggles between pulse-echo (P-E) and echo-echo (E-E)
measurement modes. (P-E) is used primarily for flaw and pit detection, while (E-E) is
used for through paint and coatings measurement without having to remove the
paint/coating and eliminating any error as a result of the paint/coating. Refer to page
25 for an explanation on the various calibration options.
2.8 MENU Key
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The MENU key is used to access and set all of the additional features of the ZX-6 DL
that are not at the top level of the keypad with a dedicated key. The features and
setting are outlined in the table below:
Menu Feature Items:
Gain Matl Scan Alarm Diff Unit Lite Beep Zero VX Probe
VLOW Aluminum On On On English On On Manual On .18 5
LOW Steel Off Off Off Metric Off Off Auto Off .18 5
MED Stainless Options Options Options .25 5
HIGH Iron Set Lo Set
Nominal
VHI Plexiglass Set Hi Med .50 3
PVC High .50 5
Plastic
Poly Urea
User 1
User 2
Lo .25 7
Here’s a quick overview of navigating through the various features in MENU:
Navigating the Features in Menu
1) Press the key once to enter the sub menu items.
2) Press the keys to toggle through the features.
3) To enable or edit the status of any feature, press the key.
4) The edit icon will start blinking to indicate that the ZX-6 DL is currently in
EDIT mode.
5) Press the keys to toggle through the setting options.
6) Press the key to accept changes and return to the top level of
features, or the key at any time to abort changes and return the
measurement screen.
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ZX- 6 DL Ultrasonic Multi-Mode Thickness Gauge
2.9 The Display
The ZX-6 DL uses a custom glass LCD backlit low temperature display for use in a
variety of climate conditions. It contains graphic icons, as well as both 7 and 14
segment display areas. Let’s take a closer look and what all these things are telling
us:
A. Edit: This icon will be displayed, and blinking, to let a user know when they
are in an edit mode to change a value or setting.
B. Large 7 segment: The thickness measurement, velocity or alpha message
will be displayed in this area.
C. Measurement Modes: This group of icons indicates which measurement
mode the ZX-6 DL is currently using. The modes are pulse-echo, for flaw and
pit detection, and echo-echo for through paint and coating measurements.
D. Stability/Repeatability Indicator:
thickness measurement as a reference for the validity of the measurement.
The ZX-6 DL takes multiple measurements per second, and when all the
vertical bars are illuminated, it’s a reference that the same thickness value is
reliably being measured multiple times per second.
E. Battery: Indicates the amount of battery life the ZX-6 DL has remaining.
F. Backlight : When this icon is illuminated, it indicates the backlight is on.
G. Small 7 Segment:
through a given medium/material, is displayed in this area, informing the user
what material the ZX-6 DL is currently calibrated too. This area is also used
for alpha messages in the menu and edit modes.
H. Units: This combination of icons are illuminated in different sequences to
inform the user what measurement units are currently being displayed in the
small 7 segment area.
The material velocity, speed the sound wave travels
This is used in conjunction with the
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Dakota Ultrasonics
I. Small 14 Segment: Displays the current gain setting of the ZX-6 DL. MED is
the default, with the options of VLOW, LOW, MED, HIGH, VHI (40dB to 52db
gain range with MED at 46dB).
J. Units: This combination of icons are illuminated in different sequences to
inform the user what measurement units are currently being displayed in the
large 7 segment area. The plus/minus icon is illuminated when the DIFF
(differential) feature is activated.
K. Small 14 Segment: The material type is displayed in this area. If it is set to a
value of one of the materials in our material list, it will be displayed in alpha
characters indicating the material type. Otherwise it will be set to CUST,
indicating custom material type.
L. Features: The icons illuminated in this row across the bottom of the LCD
display which features are currently enabled. For a complete list of the menu
features in the ZX-6 DL, Refer to page 4 for a list. The ZX-6 DL can be locked
once calibrated, to avoid accidently changing the calibration. When this icon is
illuminated, the ZX-6 DL is in lock mode. Refer to page 41 for an explanation
on locking the ZX-6 DL.
M. File/Loc: This area is exclusively for the data storage section of the ZX-6 DL.
The icons and segment fields represent the current file open, and the current
storage location in the file. Refer to page 44 for an explanation of the data
storage feature in the ZX-6 DL.
2.10 The Transducer
The Transducer is the “business end” of the ZX-6 DL. It transmits and receives
ultrasonic sound waves that the ZX-6 DL uses to calculate the thickness of the
material being measured. The transducer connects to the ZX-6 DL via the attached
cable, and two coaxial connectors. When using transducers manufactured by Dakota
Ultrasonics, the orientation of the dual coaxial connectors is not critical: either plug
may be fitted to either socket in the ZX-6 DL.
The transducer must be used correctly in order for the ZX-6 DL to produce accurate,
reliable measurements. Below is a short description of the transducer, followed by
instructions for its use.
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ZX- 6 DL Ultrasonic Multi-Mode Thickness Gauge
This is a bottom view of a typical transducer. The two semicircles of the wear face
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 wear face that is being measured.
This is a top view of a typical transducer. Press against the top with the thumb or
index finger to hold the transducer in place. Moderate pressure is sufficient, as it is
only necessary to keep the transducer stationary, and the wear face seated flat
against the surface of the material being measured.
Measuring
In order for the transducer to do its job, there must be no air gaps between the wearface 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 (wear face down) firmly against the
area to be measured. The Stability Indicator should have six or seven bars
darkened, and a number should appear in the display. If the ZX-6 DL has been
properly "zeroed" (see page 16) and set to the correct sound velocity (see page 18),
the number in the display will indicate the actual thickness of the material directly
beneath the transducer.
If the Stability Indicator has fewer than five bars darkened, or the numbers on the
display seem erratic, first check to make sure that there is an adequate film of
couplant beneath the transducer, and that the transducer is seated flat against the
material. If the condition persists, it may be necessary to select a different transducer
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Dakota Ultrasonics
(size or frequency) for the material being measured. See page 14 for information on
transducer selection.
While the transducer is in contact with the material that is being measured, the ZX-6
DL will perform four measurements every second, updating its display as it does so.
When the transducer is removed from the surface, the display will hold the last
measurement made.
2.11 Top & Bottom End Caps
The top & bottom end panels are where all connections are made to the ZX-6 DL.
The diagram above shows the layout and description of the connectors:
Transducer Connectors
Refer to Diagram: The transducer connectors and battery cover/probe zero disk are
located on the ZX-6 DL’s top end cap. The transducer connectors are of type Lemo
“00”.
Note: There is no polarity associated with connecting the transducer to the ZX-6 DL,
it can be plugged into the gauge in either direction.
Probe Zero Disk & Battery Cover
Refer to Diagram: The Battery cover is the large round disk shown in the diagram.
Note: This same disk is also used as a probe zero disk when the zero feature is set
to the ‘manual’ option. Simply remove the cover when replacing the batteries (2 AA
cells). When performing a manual probe zero function, simply place the transducer
on disk making firm contact. Important: Be sure the battery polarity is correct,
which can be found on the back label of the ZX-6 DL.
Note: Rechargeable batteries can be used, however they must be recharged outside
of the unit in a standalone battery charger.
USB-C Connector
Refer to Diagram: The USB-C connector, located on the bottom end cap, is a mini
type C female connector. It is designed to connect directly from the ZX-6 DL to a
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ZX- 6 DL Ultrasonic Multi-Mode Thickness Gauge
standard USB type A port on a PC. The cable supplied with the ZX-6 DL is a USB
type C to a USB type A (pt# N-003-0330). See page 49 for information on
connectivity.
Note: This connector is also used to upgrade the ZX-6 DL with the latest version of
firmware.
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CHAPTER THREE
PRINCIPALS OF ULTRASONIC MEASUREMENT
3.1 Time versus thickness relationship
Ultrasonic thickness measurements depend on measuring the length of time it takes
for sound to travel through the material being tested. The ratio of the thickness
versus the time is known as the sound velocity. In order to make accurate
measurements, a sound velocity must be determined and entered into the
instrument.
The accuracy of a thickness measurement therefore depends on having a consistent
sound velocity. Some materials are not as consistent as others and accuracy will be
marginal. For example, some cast materials are very granular and porous and as a
result have inconsistent sound velocities.
While there are many different ultrasonic techniques to measure thickness, which will
be discussed below, all of them rely on using the sound velocity to convert from time
to thickness.
3.2 Suitability of materials
Ultrasonic thickness measurements rely on passing a sound wave through the
material being 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.
3.3 Range of measurement and accuracy
The overall measurement capabilities, based on the wide variety of materials, is
determined by the consistency of the material being measured
The range of thickness that can be measured ultrasonically depends on the material
type and surface, as well as the technique being used and the type of transducer.
The range will vary depending on the type of material being measured.
Accuracy, is determined by how consistent the sound velocity is through the sound
path being measured, and is a function of the overall thickness of the material. For
example, the velocity in steel is typically within 0.5% while the velocity in cast iron
can vary by 4%.
3.4 Couplant
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 frequencies used in ultrasonic thickness measurement do not travel
through air efficiently. By using a liquid couplant between the transducer and test
piece the amount of ultrasound entering the test piece is much greater.
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ZX- 6 DL Ultrasonic Multi-Mode Thickness Gauge
3.5 Temperature
Temperature has an effect on sound velocity. The higher the temperature, the slower
sound travels in a material. High temperatures can also damage transducers and
present a problem for various liquid couplants.
Since the sound velocity varies with temperature it is important to calibrate at the
same temperature as the material being measured.
Normal temperature range
Most standard transducers will operate from 0F to 250F.
High temperature measurements
Special transducers and couplants are available for temperatures above 250F up to
1000F with intermittent contact. It is necessary to cool the transducer by
submerging it in water between measurements.
Modes and temperature errors
In addition to errors caused by velocity changing with temperature, some modes
(measurement techniques) are affected more than others. For example, dual
element pulse-echo mode has larger errors due to changes in the temperature of the
transducer. However, multi-echo techniques offer temperature compensation help to
minimize these errors.
3.6 Measurement Modes
This section will cover the different measurements modes of the ZX-6 DL, the
transducers required, and the reasons for using specific modes:
Pulse-Echo (P-E) Mode:
Pulse-echo mode measures from the initial pulse (sometimes referred to as an
artificial zero) to the first echo (reflection). In this mode, either an automatic or
manual zero can be performed depending on the zero probe setting. If the manual
mode has been selected, the transducer is placed on the reference disk located on
top of the ZX-6 DL, and the PRB 0 key pressed to establish a zero point for the
transducer connected. If the Auto Zero feature is enabled, simply pressing the PRB
0 key will perform an electronic zero to establish the same zero point.
In pulse-echo mode, errors can result from surface coatings and temperature
variations. Since pulse-echo only requires one reflection, it is the most sensitive
mode for measuring flaw/defects when measuring heavily corroded metals.
V-Path Correction
Dual element delay line transducers have two piezoelectric elements focused
towards one another at a slight angle, mounted on a delay line. One element is used
for transmitting sound, while the other element receives the sound reflection. The
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Dakota Ultrasonics
two elements and their delay lines are packaged in a single housing but acoustically
isolated from each other with an insulated sound barrier. This allows the transducer
the ability to achieve very high sensitivity for detecting small defects. Also, the
surface of the test material does not have to be as flat in order to obtain good
measurements.
Dual element transducers are normally used in pulse-echo mode for finding defects,
and in echo-echo mode for through coating measurements.
Dual element delay line transducers are have a usable range of 0.025” and up,
depending on the material, frequency, and diameter.
A limitation of dual element delay-line transducers is the V shaped sound path.
Because the sound travels from one element to another, the time versus thickness
relationship is non-linear. Therefore, a correction table in the instruments software is
used to compensate for this error.
Dual Element Transducer showing V-path of signal
Searching for small defects
Dual element delay line transducers are especially useful in searching for small
defects. In pulse-echo mode with high amplifier gain, very small defects can be
located. As a result, this configuration is commonly used for corrosion inspections.
The dual element style transducer will find wall deterioration, pits, cracks, and any
porosity pockets during tank and pipeline inspections.
Echo-Echo (E-E) Mode – Through Paint
The echo-echo mode measures between the first and second return
echoes/reflections. This technique is commonly used when measuring through a
surface coating and measuring only the second layer of material. Tanks and pipes
commonly have a protective coating applied to the surface. Echo-echo mode will
enable the user to measure just the steel without having to remove the coating. The
disadvantage is that two return echoes are required to effectively measure the test
material. Additionally, echo-echo mode does not have the capability to find defects.
Therefore, both modes will commonly be used; echo-echo mode to find the nominal
thickness of the material without removing the coating, and pulse-echo to locate
defects.
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ZX- 6 DL Ultrasonic Multi-Mode Thickness Gauge
Dual Element Transducer in Echo to Echo mode
13
CHAPTER FOUR
SELECTING THE MEASUREMENT MODE
4.1 Which mode & transducer do I use for my application?
High penetration plastics and castings
The most common mode for these types of applications is pulse-echo. Cast iron
applications require 1 - 5MHz frequencies, and cast aluminum requires a 7 - 10MHz
frequency depending on the thickness. Plastics typically require lower frequencies
depending on the thickness and make-up of the material as well. Larger diameters
offer greater penetration power based on the size of the crystal.
Corrosion & Pit Detection in steel and cast materials
Pulse-echo mode is commonly used for locating pits and defects. Typically a 5MHz
transducer, or higher, will be used for these types of applications. Use low
frequencies for greater penetration and use higher frequencies for better resolution.
Measuring Material & Coatings
The pulse-echo coating mode should be used when both material and coating
thickness are required, while still requiring the ability to detect flaws and pits. A
special coating style transducer is required for use in this mode. There are a variety
of coating transducers in various frequencies available from Dakota.
Thru Paint & Coatings
Often times, users will be faced with applications where the material will be coated
with paint or some other type of epoxy material. Since the velocity of the coating is
approximately 3 times slower than that of steel, pulse-echo mode will result in an
error if the coating or paint is not completely removed. By using echo-echo mode,
the user is able to successfully measure through both the coating and steel, and
completely eliminate the thickness of the paint or coating. Therefore, the steel can
be measured without having to remove the coating prior to measuring. Users will
often use pulse-echo mode and echo-echo mode in conjunction when performing
inspections on coated materials.
Thru coating measurements require special high damped transducers. The most
common transducers are the 3.5, 5, and 7.5MHz hi damped transducers. These
transducers are suitable for use in both pulse-echo and echo-echo modes. This
conveniently enables the user to accurately measure overall material thickness using
the thru Coating mode, and then conveniently switch to pit detection mode without
changing transducers. The ¼” 5MHz Hi damped transducer is the most commonly
used transducer for standard thru coating applications.
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