Dakota VX User Manual

OPERATION MANUAL

P/N P

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138

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0002

Rev 1.

9, January

200

8

DAKOTA ULTRASONICS MODEL VX ULTRASONIC VELOCITY GAUGE

Copyright  2008 Dakota Ultrasonics. All rights reserved.

No part of this publication may be reproduced, translated into another
language, stored in a retrieval system, or transmitted in any form or by any
means; electronic, mechanical, photocopying, recording, or otherwise,
without the prior written consent of Dakota Ultrasonics.

Every precaution has been taken in the preparation of this publication.
Dakota Ultrasonics assumes no responsibility for errors or omissions.
Neither is any liability assumed for damages resulting from the use of
information contained herein.

Any brand or product names mentioned herein are used for identification
purposes only, and are trademarks or registered trademarks of their
respective holders.

1500 Green Hills Road, #107 Scotts Valley, CA 95066 USA

Tel [phone] Fax [phone]

www.dakotaultrasonics.com

CONTENTS

VX Ultrasonic Velocity Gauge

INTRODUCTION
OPERATION

THE KEYPAD
THE DISPLAY
THE TRANSDUCER
MAKING MEASUREMENTS
CONDITION AND PREPARATION OF SURFACES
PROBE ZERO
CALIBRATION

SCAN MODE
TRANSDUCER SELECTION
APPENDIX A: PRODUCT SPECIFICATIONS
APPENDIX B: APPLICATION NOTES

1
3
3
6
8

9
11
12
13
17
18
21
23

APPENDIX C: SOUND VELOCITIES OF COMMON MATERIALS
WARRANTY INFORMATION

27
29

DISCLAIMER

Inherent in ultrasonic 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 reading that is TWICE what
it should be. This typically occurs when the material being measured is
thinner than the minimum capability of the transducer being used.
Responsibility for proper use of the instrument and recognition of this
phenomenon rests solely with the user of the instrument.

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VX Ultrasonic Velocity Gauge

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INTRODUCTION

The Dakota Ultrasonics model VX is an Ultrasonic Velocity Gauge. A
velocity gauge displays the speed of sound through materials of a known
thickness by measuring one-half the time-of-flight of a sound wave
transmitted and received at a single point. The sound velocity is
represented in units of Inches-per-microsecond or Meters-per-second. A
velocity gauge is useful when a material type or consistency is not known.

This manual is presented in three sections. The first section covers
operation of the VX, and explains the keypad controls and display. The

second section provides guidelines in selecting a transducer for a specific
application. The last section provides application notes and a table of
sound velocity values for various materials.

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, 1500 Green Hills Road, #107
Scotts Valley, CA 95066 USA

• Telephone: [phone]

• Facsimile: [phone]

• www.dakotaultrasonics.com

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VX Ultrasonic Velocity Gauge

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OPERATION

The VX interacts with the operator through the membrane keypad and
the LCD display. The functions of the various keys on the keypad are
detailed below, followed by an explanation of the display and its various
symbols.

The Keypad

This key is used to turn the VX on and off. When the gauge is turned
ON, it will first perform a brief display test by illuminating all of the

segments in the display. After one second, the gauge will displ ay the
internal software version number. After displaying the version number, the

display will show .0000 IN / µs (or 0000 M /s if using metric units), indicating
the gauge is ready for use.

Pressing the ON/OFF key turns OFF the VX. The gauge has a special
memory that retains all of its settings even when the power is off. The
gauge also features an auto-powerdown mode designed to conserve
battery life. If the gauge is idle for 5 minutes, it will turn itself off.

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The PRB- 0 key is used to "zero" the VX 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 12 for an explanation of this important procedure.

The CAL key is used to enter and exit the VX's calibration mode. This
mode is used to adjust the material thickness value that the VX will use

when calculating sound velocity. The gauge will either calculate the sound­velocity from a sample of the material being measured, or allow a known
velocity value to be entered directly. Refer to page 13 for an explanation of
the two CAL functions available.

The IN/MM key is used to switch back and forth between English and
metric units. This key may be used at any time, whether the gauge is

displaying a thickness (IN or MM) or a velocity value (IN/µs or M/s).

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The UP arrow key has two functions. When the VX is in calibration
mode, this key is used to increase numeric values on the display. An auto­repeat function is built in, so that when the key is held down, numeric

values will increment at an increasing rate. When the VX is not in
calibration mode, the UP arrow key switches the SCAN measurement
mode on and off. Refer to page 16 for an explanation of the SCAN
measurement mode.

The DOWN arrow key has two functions. When the VX is in the CAL
mode, this key is used to decrease numeric values on the display. An
auto-repeat function is built in, so that when the key is held down, numeric
values will decrement at an increasing rate. When the VX is not in
calibration mode, the DOWN arrow key switches the display backlight
between three available settings. OFF will be displayed when the backlight
is switched off. AUTO will be displayed when the backlight is set to
automatic mode, and ON will be displayed when the backlight is set to stay
on. In the AUTO setting, the backlight will illuminate when the VX is
actually making a measurement.

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The Display

The numeric portion of the display consists of 4 complete digits
preceded by a leading "1", and is used to display numeric values, as well
as occasional simple words, to indicate the status of various settings.

When the VX is displaying velocity measurements, the display will hold the
last value measured, until a new measurement is made. Additionally,

when the battery voltage is low, the entire display will begin to flash.
When this occurs, the batteries should be replaced.

These eight vertical bars form the Stability Indicator. When the VX is
idle, only the left -most bar and the underline will be on. When the gauge is
making a measurement, six or seven of the bars should be on. If fewer

than five bars are on, the VX is having difficulty achieving a stable
measurement, and the value displayed may not be accurate.

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When the IN symbol is on, the VX is displaying a thickness value in
inches. The maximum thickness that can be displayed is 19.999 inches.

When the MM symbol is on, the VX is displaying a thickness value in
millimeters. If the displayed thickness exceeds 199.99 millimeters, the
decimal point will shift automatically to the right, allowing values up to

1999.9 millimeters to be displayed.

When the IN symbol is on, in conjunction with the /µs symbol, the VX is
displaying a sound-velocity value in inches-per-microsecond.

When the M symbol is on, in conjunction with the /s symbol, the VX is
displaying a sound-velocity value in meters-per-second.