MicroTrap VOD Operations Manual Revision 4-2-1

VOD Operations Manual Edition 4.2.1

Manufactured By: MREL GROUP OF COMPANIES LIMITED

IMPORTANT COMPATIBILITY NOTICE: The MicroTrap shipped with this Operations Manual is only compatible with MicroTrap Advanced Analytical Software Version 6.0 and later. Version 6.0 and later versions of the MicroTrap Advanced Analytical Software are fully compatible with earlier model MicroTraps and with data files collected by earlier model MicroTraps.

THIS PAGE IS INTENTIONALLY BLANK.

VOD Operations Manual - Edition 4.2.1 Page i

MREL Group of Companies Limited (MREL) warrants that the product is free from Manufacturer’s defects for a period of two (2) years from the date of shipment to the Customer. This Warranty covers all parts and labour. MREL does not warrant that the product will meet the Customer's requirements, or that it will operate in the combinations which may be selected by the Customer. MREL does not and cannot warrant the performance or results that may be obtained by using the product. Accordingly, the product and its documentation are sold "as is" without warranty as to their performance, merchantability or fitness for any particular purpose. The Customer assumes the entire risk as to the results and performance of the product. The MREL logo is a registered trademark of MREL Group of Companies Limited. The MicroTrap logo is a registered trademark of MREL Group of Companies Limited. Windows is a registered trademark of Microsoft Corporation. All other brand and product names are trademarks or registered trademarks of their respective companies. © Copyright 2007, MREL Group of Companies Limited. This Operations Manual and accompanying MicroTrap Advanced Analytical Software supersedes any earlier editions. All Rights Reserved. Reproduction or adaptation of any part of this documentation or Software without written permission of the Copyright owner is unlawful.

Page ii VOD Operations Manual – Edition 4.2.1

ABOUT THIS MANUAL Congratulations on your acquisition of the MicroTrap VOD/Data Recorder, manufactured by MREL Group of Companies Limited (MREL). The instructions in this VOD Operations Manual serve as a reference for the operation of the MicroTrap for recording the continuous velocity of detonation (VOD) of explosives and hole/deck delay times. The VOD Operations Manual is divided into the following Chapters: CHAPTER 1: GETTING STARTED This Chapter assists those new to the operation of the MicroTrap to ensure that: 1. All of the MicroTrap hardware has been received. 2. The MicroTrap Advanced Analytical Software is installed and that communications is confirmed between the

Operator’s computer and the MicroTrap. 3. The MicroTrap’s Recording Parameters are adjusted by the Operator to settings that are appropriate for the

Operator’s testing requirements. CHAPTER 2: INTRODUCTION This Chapter addresses the general features of the MicroTrap. It outlines some safety considerations related to the use of instrumentation in a blasting environment; and describes the main field applications of the MicroTrap for recording the VOD of explosives and the delay times between blastholes and decks of explosives. CHAPTER 3: HARDWARE This Chapter covers issues related to the various hardware components of the MicroTrap. It briefly describes the main features of the MicroTrap's front panel; provides details on the MicroTrap power source; and outlines instructions for recharging and long term storage of the MicroTrap. Also included are descriptions of the different types of VOD resistance probes available from MREL. A summary of the technical specifications of the MicroTrap is also presented. CHAPTER 4: RECORDING VOD AND HOLE/DECK DELAY TIMES This Chapter describes issues related to VOD testing of explosives in the field, and introduces the resistance wire technique for testing small explosive samples and explosives in blastholes. Also presented are safety considerations, lay out and protection of the VOD resistance probes, and the setup procedure for the MicroTrap in the field. CHAPTER 5: MICROTRAP SOFTWARE This Chapter presents the methods for retrieving data from the MicroTrap to a computer and selecting a data file for analysis. All the features and menu functions of the Software required for analysis and presentation are described. CHAPTER 6: EXAMPLES OF VOD DATA ANALYSIS This Chapter provides a detailed analysis of VOD information, starting with the selection of the data and followed by its analysis and formatting for presentation. Several examples are discussed including VOD of small explosive samples and explosives in blastholes as well as the determination of the delay times between blastholes and decks of explosives. CHAPTER 7: CONTACTING MREL FOR TECHNICAL SUPPORT This Chapter provides detailed contact information for MREL’s Blasting Instrumentation Team. It also provides instructions for emailing MicroTrap files to MREL for complimentary analysis support.

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TABLE OF CONTENTS CHAPTER 1: GETTING STARTED 1.1 Ensuring that all MicroTrap Hardware has been Received 1.1 1.2 Installing the MicroTrap Advanced Analytical Software 1.1 1.2.1 Computer System Requirements 1.1 1.2.2 Installing the Software 1.1 1.3 Communicating with the MicroTrap 1.2 1.3.1 Parallel Port (Printer Port) Configurations 1.2 1.3.1.1 Testing Communications between the Computer and the MicroTrap Using the Parallel Cable 1.3 1.3.2 USB Communication Cable Configurations 1.4 1.3.2.1 Testing Communications between the Computer and the MicroTrap Using the USB Cable 1.4 1.4 Viewing and Programming the MicroTrap’s VOD Recording Parameters 1.5 1.5 Troubleshooting MicroTrap Communications Errors 1.8 1.5.1 Parallel Cable 1.8 1.5.2 USB Cable 1.8 CHAPTER 2: INTRODUCTION 2.1 Background 2.1 2.2 Safety Considerations 2.2 2.3 VOD Applications of the MicroTrap 2.2

2.3.1 Testing of Explosive Samples 2.2 2.3.2 Testing of Explosives in Blastholes 2.2

2.4 Scope Applications of the MicroTrap with Scope Upgrade Installed 2.3 CHAPTER 3: MICROTRAP HARDWARE 3.1 Hardware Components 3.1

3.1.1 MicroTrap 3.1 3.1.2 Carrying Case 3.5 3.1.3 Battery Charger 3.5 3.1.4 Communications Cable (Parallel Port) 3.5 3.1.5 Communications Cable (USB Port) 3.5 3.1.6 BNC Adapters 3.6

3.2 MicroTrap Internal Rechargeable Battery 3.6 3.3 Testing the MicroTrap Power Status 3.6 3.4 Recharging the MicroTrap 3.6 3.5 Operating the MicroTrap from External Power Sources 3.7 3.6 Long Term Storage Considerations 3.7 3.7 VOD Resistance Probes Used by the MicroTrap 3.7 3.7.1 VOD ROBEROD 3.7 3.7.2 VOD PROBECABLE 3.7 3.8 MicroTrap Technical Specifications 3.9

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CHAPTER 4: RECORDING VOD AND HOLE/DECK DELAY TIMES 4.1 Safety Considerations for Selecting an Explosive Testing Site 4.1 4.2 The Resistance Wire Technique for Measuring VOD 4.1 4.3 Installing PROBERODs for Testing Samples of Explosives 4.2 4.4 Installing PROBECABLE for Testing Explosives in Blastholes 4.3

4.4.1 Preparation of PROBECABLE for Single Blasthole Recording 4.3 4.4.2 Preparation of PROBECABLE for Multiple Blasthole Recording 4.5

4.5 PROBECABLE and Coaxial Cable Protection 4.6 4.6 MicroTrap Setup Procedure for VOD Measurements 4.6 4.7 Probe Resistance Out of Range 4.9 4.8 Utilizing the External Trigger 4.10 4.9 Additional Information on Memory and Triggering 4.11 4.9.1 Memory 4.11 4.9.2 Triggering 4.12 CHAPTER 5: MICROTRAP SOFTWARE 5.1 Retrieving Data from the MicroTrap 5.1 5.2 Selecting Data Files for Analysis 5.3 5.3 Introduction to Analysis 5.4 5.4 Desktop 5.5 5.5 Tools Bar 5.5 5.6 Current Point Tools Bar 5.6 5.7 Menu 5.7 CHAPTER 6: EXAMPLES OF VOD DATA ANALYSIS 6.1 Sample of Explosives – Detonating Cord Example 6.1 6.2 Sample of Explosives – Other Examples 6.7 6.3 Explosives in Blastholes – Multiple Decked Holes Example 6.9 6.4 Explosives in Blastholes – Other Examples 6.16 CHAPTER 7: CONTACTING MREL FOR TECHNICAL SUPPORT 7.1 Contacting MREL 7.1 7.2 Emailing MicroTrap Files to MREL 7.1

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1.1 ENSURING THAT ALL MICROTRAP HARDWARE HAS BEEN RECEIVED Photographs of these hardware components are contained in Section 3.1. 1. MicroTrap VOD/Data Recorder. 2. MicroTrap Battery Charger that is labeled 120 VAC or 220 VAC depending on your Country’s mains power. 3. Communications Cable - parallel port printer cable. 4. Communications Cable - USB cable. 5. BNC Adapters x 2. 6. Carrying Case. 7. MicroTrap Advanced Analytical Software on CD-ROM. 8. MicroTrap VOD Operations Manual. 9. VOD resistance probes: PROBERODs and/or PROBECABLE and/or PROBECABLE-LR. 1.2 INSTALLING THE MICROTRAP ADVANCED ANALYTICAL SOFTWARE 1.2.1 COMPUTER SYSTEM REQUIREMENTS The MicroTrap Advanced Analytical Software, for Windows '95 and later, has been provided on a CD-ROM. The CD-ROM also contains a medium-resolution digital copy of this Operations Manual in Adobe Acrobat pdf format (MicroTrap VOD Operations Manual Edition 4.pdf). Additional copies of the Operations Manual may be printed for your use as required. The Software operates on any Personal Computer (PC) system with the following minimum specifications: 1. Pentium 100 or higher processor. 2. 32 MB RAM. 3. 25 MB hard drive space for Software and digital Operations Manual installation and up to an additional 20

MB for each uncompressed data file. It is recommended that 100 MB of hard drive space be available on the computer.

4. Windows '95, ’98, ME, NT, 2000, XP, Vista and 7. 5. CD-ROM drive. If the computer does not have a CD-ROM drive, but has Internet access, contact MREL

(Section 7.1) for instructions on downloading the installation Software from MREL’s Internet web site. If the computer does not have a CD-ROM and does not have access to the Internet, then contact MREL to obtain the Software on floppy disks.

6. Parallel printer port (ie: LPT1, LPT2 or LPT3) or an USB Port. 1.2.2 INSTALLING THE SOFTWARE To install the MicroTrap Software, start Windows and insert the MicroTrap CD into the CD-ROM drive. Read the Readme.txt file on the MicroTrap CD and follow the instructions. When the installation is complete, shut down the computer and re-start it.

All of the steps detailed in this Chapter should be completed before the Operator goes into the field to conduct a VOD test: 1. Ensure that all MicroTrap components have been received and are available. 2. Install the MicroTrap Software on the Operator’s computer. 3. Ensure that the Operator’s computer and MicroTrap are able to communicate with each other. 4. Program the MicroTrap’s internal Recording Parameters using the MicroTrap Software.

CHAPTER 1: GETTING STARTED

Page 1-2 VOD Operations Manual – Edition 4.2.1

1.3 COMMUNICATING WITH THE MICROTRAP 1.3.1 PARALLEL PORT (PRINTER PORT) CONFIGURATIONS Through the Communications Cable, the MicroTrap Software is used by the Operator to program the MicroTrap’s Recording Parameters and to download the data from the MicroTrap to the computer after testing is completed. The MicroTrap Software can communicate with the MicroTrap through 3 parallel port (LPT printer port) types: Standard (SPP), Enhanced (EPP), and Extended Capabilities (ECP). If the port is SPP or EPP, it uses SPP mode. If the port is ECP, it uses the faster ECP mode. The mode used is shown while communicating with the MicroTrap. Communications with the MicroTrap is usually about 10 times faster in the ECP mode. Port information for the computer can be viewed by clicking on Control Panel - System Properties and clicking on "Ports" to view the current type of printer port. Most computers built in the last few years have either ECP or EPP, or both. Some computers, however, are shipped with the BIOS set so that the parallel port is in SPP mode since this is the motherboard default. Most desktop computers allow the parallel port to be changed in the BIOS setup mode, which can be entered during the first few seconds after starting the computer. Care must be taken while in this mode since changing certain settings can prevent the computer from starting. On some computers, this mode is password protected and only a computer support person can access it. Some laptops may provide only some of the above modes in BIOS setup mode. Some do not have a BIOS setup mode at all and use a custom program from within Windows, such as "Toshiba Utilities", to view and change laptop parallel port modes. Note that parallel ports can be added to laptops with PCMCIA cards or USB to parallel port adapters.


1.3.1.1 TESTING COMMUNICATIONS BETWEEN THE COMPUTER AND THE MICROTRAP USING THE PARALLEL CABLE

It cannot be guaranteed that the MicroTrap will be able to communicate with a specific computer on the first attempt. The parallel port is an evolving standard and certain active printer, scanner, and external CD-ROM drivers may interfere with MicroTrap communications. Usually such problems can be solved with support from MREL or local computer support. To test communications between the computer and the MicroTrap: 1. Connect the Communications Cable supplied with the MicroTrap between the LPT (parallel printer port) on

the computer and the LPT COM port on the front panel of the MicroTrap. 2. Turn the MicroTrap power ON. 3. Start the MicroTrap Software by clicking on Start-Programs-

MREL-MicroTrap. 4. At the Main Menu click on the Program MicroTrap button or with

the keyboard press Alt-P. Programming the MicroTrap and retrieving data can be accomplished without the use of a computer mouse by pressing “tab” to move between data entry fields.

5. A Message will be displayed. Click on OK to continue or Cancel to return to the Main Menu.

6. When the Software successfully communicates

with the MicroTrap, the message MicroTrap Found is displayed. Also displayed is the number of Total Tests into which the MicroTrap’s memory has been divided, and the number of Remaining Tests yet to be conducted to fill the MicroTrap’s memory.

7. The Software also displays the Serial Number of the MicroTrap, when the next Calibration should be performed on the MicroTrap, and whether or not the MicroTrap has the Memory Upgrade and/or Scope Upgrade installed.

8. In the example, the MicroTrap does not contain the MicroTrap Memory Upgrade and it does not contain the MicroTrap Scope Upgrade. Since there is no MicroTrap Scope Upgrade present, then the MicroTrap will function only as a VOD Recorder. Please refer to the MicroTrap Scope Operations Manual for details on the use of the MicroTrap Software and Hardware for recording voltage signals from other types of gauges such as those for vibration, pressure and temperature.

9. If these messages are displayed correctly, then there is proper communications between the MicroTrap and the computer. Click on the Exit button to close the Software. To view and program the MicroTrap’s Recording Parameters, refer to Section 1.4.

10. If these messages are not displayed correctly and an error message is shown, then ensure that the procedures in Sections 1.2 and 1.3.1 have been followed. Refer to Section 1.5 for some suggestions on troubleshooting the MicroTrap communications error.


1.3.2 USB COMUNICATION CABLE CONFIGURATIONS Note: The USB cable will not work with Windows 95. MicroTrap version 7 software allows downloading through the USB and parallel port, but only through the parallel port with Windows 95. Important: Ensure that the USB drivers have been installed before taking the cable into the field. The profile for a computer may not allow new drivers to be installed unless authorized from another location or in administrator mode, which may not be possible in the field. This cable is best utilized with a USB 2.0 port. To install the drivers for the USB Cable, install the MicroTrap software first, plug the cable in and then insert the MicroTrap install CD when asked for the location of the drivers. Alternatively, choose "Browse", and go to the directory where MicroTrap was installed (usually c:\Program Files\MREL\MicroTrap), then go to the "Drivers" subdirectory of that. If the window pops up from the hardware installation stating that the hardware has not passed Windows Logo Testing, click on Continue Anyway. The driver software can be uninstalled by choosing "MicroTrap Interface Device Drivers" from Add/Remove Programs in Control Panel. 1.3.2.1 TESTING COMMUNICATIONS BETWEEN THE COMPUTER AND THE MICROTRAP USING THE USB

CABLE The green light should turn on when attaching the cable to a computer. If it does not it may be connected to an "unpowered port", such as on an unpowered hub. If the green light does not come on when plugged directly into any port on a computer, there may be a problem with the cable. Note: If the drivers are uninstalled, the green light will not come on when the cable is plugged in until the computer is rebooted or "Add new Hardware" is run. The USB cable can be attached either before or after the computer has been turned on. It can also be detached without using the "Stop USB device before removing" program. Wait at least 10 seconds after detaching the cable before re-attaching it. If the cable is detached from either end while downloading: - exit the MicroTrap software. - detach the cable from the MicroTrap and the

computer. - turn the MicroTrap off for 10 seconds, then turn

it on, wait 10 seconds. - attach the cable to the computer, respond to

any requests or confirmations and then attach it to the MicroTrap.

- run the MicroTrap software. The following is the recommended practice: 1. Turn on the computer or bring the MicroTrap near an already turned on computer. 2. If the MicroTrap is off, turn it on. Allow the lights to blink for 10 seconds. 3. Attach the USB cable to the computer. Wait for 10 seconds to allow it to be detected. If Windows asks for drivers to be installed, go through that process. If the cable was already attached, it is ready for use. 4. Attach the 25-pin end of the cable to the MicroTrap. Wait for 5 seconds. 5. Run the MicroTrap software. Download and/or program the MicroTrap. Several MicroTraps can be downloaded or programmed without exiting the software or removing the cable from the computer. 6. When finished, detach the cable from the computer and store with the MicroTrap. This will save power if using a notebook computer. The computer can be left on while this is done. With a desktop computer, the cable can be connected at all times if desired.


1.4 VIEWING AND PROGRAMMING THE MICROTRAP’S VOD RECORDING PARAMETERS

To view or change the MicroTrap’s Recording Parameters: 1. Connect the Communications Cable supplied with the MicroTrap between the computer and the LPT COM

port on the front panel of the MicroTrap. 2. Turn the MicroTrap power ON. 3. Start the MicroTrap Software by clicking on Start-Programs-MREL-MicroTrap. 4. At the Main Menu click on the Program MicroTrap button or with

the keyboard press Alt-P. Programming the MicroTrap and retrieving data can be accomplished without the use of a computer mouse by pressing “tab” to move between data entry fields.

5. A Message will be displayed. Click on OK to continue or Cancel to return to the Main Menu.

6. When the Software successfully communicates

with the MicroTrap, the message MicroTrap Found is displayed. Also displayed is the number of Total Tests into which the MicroTrap’s memory has been divided, and the number of Remaining Tests yet to be conducted to fill the MicroTrap’s memory.

7. The Software also displays the Serial Number of the MicroTrap, when the next Calibration should be performed on the MicroTrap, and whether or not the MicroTrap has the Memory Upgrade and/or Scope Upgrade installed.

8. In the example, the MicroTrap does not contain the MicroTrap Memory Upgrade and it does not contain the MicroTrap Scope Upgrade. Since there is no MicroTrap Scope Upgrade present, then the MicroTrap will function only as a VOD Recorder. Please refer to the MicroTrap Scope Operations Manual for details on the use of the MicroTrap Software and Hardware for recording voltage signals from other types of gauges such as those for vibration, pressure and temperature.

9. If the Remaining Tests = 0, then no additional tests will be able to be conducted with the MicroTrap until the Operator clears the MicroTrap’s memory. If the data in the MicroTrap’s memory has already been transferred to a computer then the Operator should click on the VOD button and proceed to Step 11. Otherwise, the Operator should click on the Exit button to close the Software and then download the data to the computer as detailed in Section 5.1.

10. If the Remaining Tests > 0, then additional tests can be conducted with the MicroTrap. If this is the case, and the Operator wishes to clear the memory, view the settings, or change the settings for subsequent tests then the Operator should click on the VOD button. Otherwise, the Operator can click on the Exit button to close the Software.


11. After clicking on the VOD button, the existing settings of the MicroTrap are displayed. The Operator is able to leave the settings unchanged by clicking on the Cancel button.

12. The Operator can make changes to the Trigger Level, Pre-Trigger Time, and Recording Rate for subsequent tests to be performed. The Trigger Level is used by the MicroTrap when the MicroTrap hardware is set to begin recording on an INTernal trigger signal as detailed in Section 4.9. Changing these Recording parameters does not erase any data that may already have been recorded by the MicroTrap in previous tests.

13. The Operator should make the Recording Rate as fast as possible providing that the displayed Total Time

per Test is sufficiently long to record all of the holes, and hole/deck delays, being tested. Reducing the Recording Rate lengthens the Total Time per Test. Changing the Recording Rate does not erase any data that may already be recorded by the MicroTrap in previous tests. If the MicroTrap Memory Upgrade is installed, then the Total Time per Test and the PreTrigTime will be double that shown in this example.

14. The Operator can select the External Trigger mode to be Make Circuit or Break Circuit. External triggering is detailed in Section 4.8.

! MREL recommends a Trigger Level of about 95% and a Pre-Trigger Time of about 25% for VOD recording of explosives samples and explosives in blastholes.


15.

If in Step 8 there were Remaining Tests = 0, then the Operator must tick the Clear All Tests box to allow more tests to be conducted with the MicroTrap. When the Clear All Tests box is ticked, then the Operator may also change the Number of Tests into which the MicroTrap’s memory is divided. The Operator may divide the MicroTrap’s internal memory into 1 to 16 tests. This allows the Operator to perform up to 16 tests before having to download the data to a computer. However, dividing the memory into 16 tests causes the Total Time per Test to be divided by 16 as is displayed in the Total Time per Test window.

16. Click on the Change Settings button to accept the new Recording Parameters or click on the Cancel button to exit without making any changes.

Ensure that the data already in the MicroTrap’s memory has been downloaded to a computer (Section 5.1) before ticking the CLEAR ALL TESTS box. Ticking the CLEAR ALL TESTS box and then clicking on the CHANGE SETTINGS button will clear the MicroTrap’s memory and will delete all data from previous tests.

! MREL recommends setting the Number of Tests = 1 for VOD recording of blastholes using PROBECABLE. The Operator will normally be able to download the data from the MicroTrap to a computer before conducting the next VOD test.

! MREL recommends setting the Number of Tests = 16 for VOD recording of samples of explosives using a PROBEROD. This reduces the quantity of data collected per test and conserves the computer’s disk space. At a 2 MHz recording rate, a MicroTrap with standard memory will record for a total of 131 ms per test if the Number of Tests = 16. This is more than sufficient recording time for a sample of explosives.


17. If the Clear All Tests box has been ticked, then the Software will ask the Operator to confirm that the data in the MicroTrap’s memory is to be erased. Click OK or Cancel.

18. A confirmation message is displayed. 19. Disconnect the Communications Cable from the MicroTrap. Turn the

MicroTrap OFF and then ON. Press the Total Tests button and then the Remaining Tests button to confirm that changes to these settings, if any, have been made.

20. The Operator can confirm that all changes to Recording Parameters have been made by re-starting the MicroTrap Software and repeating Steps 4-10.

1.5 TROUBLESHOOTING MICROTRAP COMMUNICATIONS ERRORS 1.5.1 Parallel Cable 1. If the MicroTrap is connected to a parallel port switch box, ensure that the total length of all cables is less than

10 feet (3 m). 2. Do not connect the MicroTrap through a "dongle" or "pass-through port" in a Zip Drive, scanner, printer, or

other such device. 3. Some computers are shipped with the BIOS set so that the parallel (LPT) port is in “bi-directional” mode since

this is the motherboard default. Computers with their parallel port in bi-directional mode will not communicate with the MicroTrap. Most desktop computers allow the parallel port mode to be changed in the BIOS setup, which can be entered during the first few seconds after starting the computer. Care must be taken while in this mode since changing certain settings can prevent the computer from starting. On some computers, the BIOS setup mode is password protected and only a computer support person can access this setup mode. Some laptops may provide limited BIOS setup mode options. Some do not have a BIOS setup mode at all and use a custom program from within Windows, such as "Toshiba Utilities", to view and change laptop parallel port modes. Contact MREL for additional technical support.

4. If you use an external CD-ROM drive connected through your parallel (LPT) port, then the CD-ROM software sends intermittent signals to this parallel port to see if the CD-ROM drive is connected. These intermittent signals will interfere with MicroTrap communications if the signal from the CD-ROM software is sent during the time in which you are attempting to communicate with the MicroTrap. The solution is either to disable the CD-ROM software, or to change its settings to make the time delay between signals as long as possible. You will still risk having the signal happen when you are communicating with the MicroTrap. However, if the time between signals is set sufficiently long, then you will be able to successfully re-communicate with the MicroTrap. Contact MREL for additional technical support.

1.5.2 USB Cable

1. Check the end of the cable at connects to the MicroTrap and confirm that the Green light is lit. If the Green light is not lit:

a. Check and confirm that the USB cable is plugged directly into the computer. b. If the cable is plugged into the computer, open the Device Manager found in the Control Panel in

the System icon under the Hardware tab in Windows XP. c. Under the Universal Serial Bus Controllers, confirm that there is no yellow exclamation mark

beside MicroTrap USB Interface. d. If there is a yellow exclamation mark, right click on the MicroTrap USB Interface and uninstall the

driver. e. Once the driver has been uninstalled, unplug the USB cable from the computer and wait for 10

seconds. f. Follow the directions in Section 1.3.2 to reinstall the driver for the MicroTrap USB Interface.


2.1 BACKGROUND The MicroTrap VOD/Data Recorder is likely the most affordable and easiest to use portable, high-resolution recorder available. The MicroTrap is the result of merging and enhancing the most important features of the world’s most popular VOD Recorders: 1 channel MiniTrapII Explosives Continuous VOD Recorder; 16 channel DataTrap Multi-Purpose Data Recorder; and 2 channel SuperTrap High Resolution VOD/Data Recorder. The MicroTrap is a portable, 1 channel, high resolution, explosives continuous VOD recorder. The MicroTrap can be upgraded easily and inexpensively to provide an additional 4 channels of DC voltage (VDC) recording capability. Contact MREL for MicroTrap Scope Upgrade information. This provides the MicroTrap with the unparalleled ability to record high resolution VODs of explosives and simultaneously record transient events such as blast vibrations, explosion pressures, air blast, etc. at high resolutions. The MicroTrap has proven its reliability under the extreme temperature, weather, dust and rugged conditions that characterize blasting environments around the world. The MicroTrap Advanced Analytical Software allows the Operator to analyze VOD traces and convert DC voltage signals recorded by the MicroTrap into the desired engineering units for analysis and presentation. The Software is used to program the recording parameters of the MicroTrap, and to: retrieve, display, analyze, print and export VOD and data from other types of gauges. The Software runs under 32 or 64 bit Microsoft Windows. This facilitates extremely fast data handling, and the ability to copy and paste MicroTrap graphs into any word processors and/or spreadsheets running under those Windows operating systems. The main features of the MicroTrap for VOD recording are: • One VOD channel capable of recording at up to 2 MHz (2 million data points/sec). This speed provides a

time resolution of one data point for every 0.5 microseconds. • Capability to record VODs and delay times using up to 900 m (2,950 ft.) of MREL’s PROBECABLE-LR VOD

resistance cable. This ensures that the MicroTrap can record the VODs and delay times in many blastholes per test.

• A large, circular, digital memory (4 million data points) to store the recorded data in the MicroTrap. This allows the MicroTrap to record for relatively long periods (2.0 seconds) when recording at a rate of 2 MHz. The memory can be upgraded easily and inexpensively to provide twice the recording time - a total memory of 8 million data points. Contact MREL for MicroTrap Memory Upgrade information.

• A high, 14 bit vertical (or distance) resolution (214 or 1 part in 16,384). This means that even for a very long 900 m length of PROBECABLE-LR, 18 data points will be recorded along every meter of PROBECABLE-LR. Use of shorter lengths of PROBECABLE-LR provides even more data points recorded along every meter.

• The capability to store up to 16 events in its permanent (non-volatile) memory before having to download the recorded data to a computer.

• The data is downloaded to any personal computer (PC) through the LPT parallel printer port using the PC’s Enhanced Mode capability or can be downloaded using the supplied USB cable.

• The MicroTrap can be upgraded easily and inexpensively to provide the MicroTrap with an additional 4 channels of DC voltage recording capabilities at a recording rate of 1 MHz. Contact MREL for MicroTrap Scope Upgrade information.

CHAPTER 2: INTRODUCTION


2.2 SAFETY CONSIDERATIONS

The MicroTrap is an easy and safe instrument to operate. However, one should be aware of the inherent risk associated with explosive’s handling and familiar with working in blasting environments. For this reason, it is always recommended that knowledgeable personnel, experienced in handling explosives and familiar with blasting procedures, operate the MicroTrap when testing explosives. The standard rules of safety used with explosives should apply when monitoring VODs or other explosive parameters. When recording VODs, the MicroTrap outputs a low voltage (less than 5 VDC) and an extremely low current (less than 50 mA) to the probes within the explosives from the VOD connector on the MicroTrap. This low excitation signal ensures that the MicroTrap will not prematurely initiate explosives and/or detonators. With the optional MicroTrap Scope Upgrade installed, the MicroTrap’s Scope channels do not output any excitation voltage or signal. Standard (and common sense) rules apply when it comes to the presence of electrical storms near the testing area. Due to the inherent hazards associated with blasting during these storms, in addition to the possibility of electrical interference causing false trigger signals to the MicroTrap, it is recommended to immediately suspend all blasting activities and evacuate the area. This is standard policy at most blasting operations. 2.3 VOD APPLICATIONS OF THE MICROTRAP When used as a VOD recorder, the main applications of the MicroTrap include: 2.3.1 TESTING OF EXPLOSIVE SAMPLES

• Test the performance of explosives against the quality control standards set by the manufacturers. • Measure the continuous VOD in any charge diameter under confined or unconfined conditions. • Determine the critical diameter and critical density of an explosive charge. • Determine the gap sensitivity of explosives. • Measure the timing accuracy of detonators. • Measure the continuous VOD of primers/boosters. • Determine the minimum booster size for any explosive by measuring run-up velocities.

2.3.2 TESTING OF EXPLOSIVES IN BLASTHOLES

• Measure the continuous VOD in any hole diameter, wet or dry holes, and in any type of rock. • Measure the continuous VOD in multiple holes per blast. • Determine whether full detonation, low order detonation or failure occurred, and where in the

explosive column it happened. • Check VODs against manufacturers' specifications in full scale blasting environments. • Determine the minimum booster size for any explosive by measuring run-up velocities in full scale

blasting environments. • Measure the timing accuracy of detonators in full scale blasting environments. • Measure the effects of water, drill cuttings, and rocks, etc. trapped within the explosive mass. • Determine the length of explosive column to use in decking operations to evaluate the effect of

stemming and drill cutting dilution, water pick-up, etc. on the explosive run-up requirements. • Determine the correct length and type of stemming material to be used between decks of explosives

to prevent sympathetic detonation or explosive desensitization from occurring.

Persons not trained and/or authorized to handle explosives should not attempt to utilize the MicroTrap for monitoring explosive properties.


2.4 SCOPE APPLICATIONS OF THE MICROTRAP WITH SCOPE UPGRADE INSTALLED As previously mentioned, with the MicroTrap Scope Upgrade, the MicroTrap has the ability to function as a digital oscilloscope to record DC voltage signals from a wide variety of commercially available gauges. DC voltage and VOD can be recorded simultaneously. Typical applications of the MicroTrap when used as a voltage recorder include:

• Measurement of detonation pressure using calibrated PVDF (polyvinylidene fluoride) gauges. • Measurement of air blast over-pressures using commercially available air blast pressure transducers. • Measurement of cross-blasthole pressures using carbon composition resistors and/or commercially

available tourmaline gauges. • Measurement of blasting vibrations using geophones or accelerometer transducers. • Measurement of temperatures using thermocouples. • Measurement of strains using strain gauges. • Measurement of any phenomena that can be instrumented with gauges producing DC voltage signals

in the range from -10 to +10 volts.




3.1 HARDWARE COMPONENTS The hardware components of the MicroTrap System include the MicroTrap, a Carrying Case, a Battery Charger, an LPT Communications Cable, an USB Communications Cable and two (2) BNC Adapters. If the MicroTrap Scope Upgrade has been installed, there are four (4) additional BNC Adapters provided. Also included with the MicroTrap System are the VOD Operations Manual and the MicroTrap Advanced Analytical Software. A brief description of each of the hardware components is in the following sections. 3.1.1 MICROTRAP The MicroTrap contains electronic circuitry and an internal rechargeable battery within a protective plastic case measuring approximately 21 x 17 x 9 cm (8.3 x 6.7 x 3.5 in) and weighing 2 kg (4.4 lbs). The protective case prevents damage from water, sand, snow, dust and similar harsh weather conditions. As well, the case offers resistance to high temperatures, shocks and vibrations. The MicroTrap’s front panel is shown below.

Complete instructions for the field operation of the MicroTrap hardware are provided in Chapter 4. The main features on the front panel of the MicroTrap are outlined below: The ON/OFF switch is used to provide power to the MicroTrap. The STATUS indicator light has three working modes:

In Active mode, the light is illuminated, indicating that the MicroTrap is ready for the Operator to press the START button. When the START button is pressed, the MicroTrap begins to monitor the event to be recorded while awaiting a trigger signal.

CHAPTER 3: MICROTRAP HARDWARE


In Stand-by mode, the light flashes slowly, indicating that the MicroTrap has finished collecting and storing data. In Stand-by mode, the MicroTrap is waiting for the Operator to either switch the MicroTrap power OFF; press the NEXT TEST button (to go to Active mode); or download the data to a computer. In Communications mode, the light flashes quickly, indicating that the MicroTrap's LPT COM communications port is connected to a computer, through the Communications Cable, for setting the MicroTrap’s Recording Parameters and for transferring data to the computer.

The LED screen is a two-digit display to show information related to the power status of the internal battery pack and the total number of tests selected and the remaining number of tests. The LED screen also displays special characters when advanced operations are being performed. The BATTERY STATUS button is pressed to display on the LED screen the remaining charge of the MicroTrap's internal battery. This one-digit value represents the percentage (%) charge remaining in the battery pack (i.e. 8 = 80% of full charge remaining). The TOTAL TESTS button is pressed to display on the LED screen the total number of tests to which the MicroTrap was set using the MicroTrap Software (Section 1.4). The REMAINING TESTS button is pressed to display on the LED screen the number of tests that can still be recorded without having to download the data to a computer. This number will be the difference between the total number of tests as programmed into the MicroTrap’s memory by the Software, and the number of tests already conducted and stored in the MicroTrap's memory. The TOTAL TESTS and REMAINING TESTS buttons also have an advanced function. They can be used by the Operator to erase the data recorded in the last test from the MicroTrap’s memory using hardware alone as opposed to using the Software procedure detailed in Section 1.4.

a. Do not turn OFF the MicroTrap after the test, the STATUS light and TRIG’D lights should be flashing.

b. To erase the data from the last test; simultaneously press the TOTAL TESTS and REMAINING TESTS buttons and hold them until this procedure is complete. The LED display will show ct. After about 2 seconds, the ct will begin blinking. After another 2 seconds, the ct will disappear. Release the buttons. The data from the last test has been deleted.

c. Turn OFF the MicroTrap. Turn ON the MicroTrap and pressing the TOTAL TESTS button and then the REMAINING TESTS button. This will confirm that the remaining tests have been increased by 1 and that the last test in the MicroTrap’s memory has been deleted.

The TRIG EXT/INT switch allows the selection of internal (INT) or external (EXT) triggering of the MicroTrap. Using the Software (Section 1.4), the internal trigger level and pre-trigger memory allocation can be set. Using the Software the external trigger mechanism: BREAK circuit or a MAKE circuit can be set. Triggering is described in Sections 4.8 and 4.9. The NEXT TEST button is used to change the MicroTrap's mode from Stand-by to Active. When in Active mode, the MicroTrap waits for the Operator to press the START button to instruct the MicroTrap to await a trigger signal. The START button instructs the MicroTrap to wait for a trigger signal to occur. When the START button is pressed the START light illuminates.

! MREL recommends the above procedure for times in which the MicroTrap triggers prematurely when the Operator is setting up the MicroTrap to record a VOD test. Premature triggering can be caused by situations such as: loose connections in the signal wires; excessive moving of or driving over the signal wires; or by the Operator inadvertently triggering the MicroTrap when using an external trigger wire.


The STOP button has several functions: 1. The STOP button is particularly useful when the MicroTrap has been set at a relatively slow sampling rate

with the Software (Section 1.4). An example is thermocouple measurements when the MicroTrap Scope Upgrade is installed. Given the large memory in the MicroTrap, if the lowest sampling rate (1 Hz) is selected, a total recording time of 4 million data points / 1 Hz = 4,000,000 seconds (46 days) will be available for recording. Pressing the STOP button, after the Operator is satisfied that the data he requires has been recorded by the MicroTrap, fills the remaining MicroTrap memory and the MicroTrap reverts to Stand-by mode. This saves the Operator from having to wait for 46 days for the MicroTrap’s memory to become full.

2. The STOP button also has an advanced function. It can be used to completely erase all of the data in the MicroTrap using hardware alone, as opposed to using the Software procedure detailed in Section 1.4: a. Turn ON the MicroTrap. b. Press the NEXT TEST button to put the MicroTrap in Active mode. The STATUS light should be

on. c. Simultaneously press the NEXT TEST and STOP buttons and hold them down. The LED will

display a blinking dE. Release the buttons. d. Simultaneously press the START and STOP buttons and hold them down. The LED will display dE

without blinking. Release the buttons. All of the data in the MicroTrap’s memory will be deleted. e. Turn OFF the MicroTrap. Turn ON the MicroTrap and pressing the TOTAL TESTS button and then

the REMAINING TESTS button will confirm that these numbers are equal and that all of the test data in the MicroTrap’s memory has been deleted.

The LPT COM port is used to connect the Communications Cable to the MicroTrap. The other end of the Communications Cable is connected to the parallel printer port or a USB Port of the computer (depending on the cable), for programming the internal Recording Parameters of the MicroTrap (Section 1.4) and for retrieval of the recorded data (Section 5.1). There are two OUT OF RANGE warning lights. They will flash when the probe resistance is out of range as discussed in Section 4.7.

! MREL recommends the above procedure for times in which the Operator is already in the field and has forgotten to Clear All Tests using the Software as detailed in Section 1.4. The Remaining Tests = 0 and thus the Operator is unable to record another test in the MicroTrap’s memory.


The back of the MicroTrap has a variety of connectors that described below: VOD: BNC connector for the VOD resistance probe. EXT TRIG: BNC connector for the trigger wire, if external triggering is used. TRIG OUT: BNC connector that produces a voltage signal of 10 volts for 6 seconds when the MicroTrap is triggered. This signal is used to trigger other instrumentation. DC IN/OUT: Used to connect the MicroTrap to the Battery Charger to recharge the MicroTrap’s internal battery, and to operate the MicroTrap from AC mains power. The DC IN/OUT port can also be used to power the MicroTrap from an external 12 VDC battery. It can also be used to supply 10 VDC as an excitation source for other types of gauges. All details and restrictions on use of the DC IN/OUT connector are contained in Sections 3.4 and 3.5. 1 2 3 4: BNC connectors for Channels 1, 2, 3 and 4 of the optional MicroTrap Scope Upgrade. These connectors have no function unless the MicroTrap Scope Upgrade has been installed in the MicroTrap. The TRIG’D indicator light on the front of the MicroTrap will illuminate when the trigger conditions are met. It will remain illuminated during collection of the data, which in turn depends on the recording rate selected for the test. The TRIG’D light flashes rapidly while the data is being stored in the MicroTrap’s non-volatile memory. The TRIG’D light flashes slowly when all data from the test has been stored in the MicroTrap’s memory. Otherwise, the light will remain off. The black knob on the front of the MicroTrap is an automatic pressure relief valve. When transporting the MicroTrap as checked baggage by air, or when the MicroTrap is transported by air freight, this valve allows pressure equalization.


3.1.2 CARRYING CASE The Carrying Case holds the MicroTrap, Battery Charger, Communications Cable and BNC Adapters. 3.1.3 BATTERY CHARGER The Battery Charger has a specification printed on it, either 120 VAC or 220 VAC. It is used to charge the MicroTrap’s internal rechargeable battery, and it can be used to operate the MicroTrap from AC mains. 3.1.4 COMMUNICATIONS CABLE (PARALLEL PORT) The Communications Cable is provided to connect the MicroTrap to a Personal Computer for programming the recording parameters of the MicroTrap and for downloading of the recorded data. The Communications Cable is connected between the LPT COM port on the front panel of the MicroTrap and the LPT parallel printer port of the computer. The Communications Cable is a standard printer cable, so should it become lost or forgotten, it can be replaced easily by the Operator from a local supplier. 3.1.5 COMMUNICATIONS CABLE (USB PORT) The Communications Cable is provided to connect the MicroTrap to a Personal Computer for programming the recording parameters of the MicroTrap and for downloading of the recorded data. The Communications Cable is connected between the LPT COM port on the front panel of the MicroTrap and a USB port of the computer.

Contact MREL if the Battery Charger that has been supplied is incorrect for the mains voltage in your country.


3.1.6 BNC ADAPTERS Two BNC Adapters are provided to facilitate easy connection between the VOD and EXT TRIG connectors on the MicroTrap to the coaxial cable (preferably RG-58/U) leading to the VOD probes, and the external trigger wire, respectively. If the MicroTrap Scope Upgrade has been installed, four additional BNC Adapters are provided, one for each Scope input channel. 3.2 MICROTRAP INTERNAL RECHARGEABLE BATTERY The MicroTrap has an internal Ni-Cad rechargeable battery. The MicroTrap is supplied with an approved 120 VAC or approved 220 VAC Battery Charger, depending on the country of use. When the internal battery is fully charged, the MicroTrap can operate for 12 hours (at maximum MicroTrap power consumption) before battery recharging is required. The MicroTrap is shipped from MREL fully charged. Since some time may elapse before the MicroTrap is actually put to use, the MicroTrap may not be charged fully the first time it is used. Full operating time will be obtained when the MicroTrap is recharged. 3.3 TESTING THE MICROTRAP POWER STATUS The procedure to check the power status of the MicroTrap is as follows: 1. With the MicroTrap switched ON, press the BATTERY STATUS button on the front panel. This button can be

pressed at any time during operation of the MicroTrap. 2. The LED will display the energy remaining in the battery as a percentage of the full charge. For example, if

the display shows the number 8, it means that 80% of the maximum charge remains in the battery. A display of 10 is shown when the MicroTrap is fully charged. A display of 0 is shown when the MicroTrap requires recharging.

3.4 RECHARGING THE MICROTRAP

The procedure to recharge the MicroTrap is as follows: 1. Ensure that the Battery Charger is labeled appropriately for the AC voltage mains power available. 2. With the MicroTrap switched OFF, connect the Battery Charger between the DC IN/OUT port on the back of

the MicroTrap and the wall outlet. The LED will display Ch indicating that charging is progressing. 3. Full recharging will take up to 16 hours. When charging has been completed, the Ch indication on the LED

will flash. 4. Unplug the Battery Charger from the wall outlet and then from the MicroTrap. The MicroTrap battery status

can be tested as detailed in Section 3.3.

Contact MREL if the Battery Charger that has been supplied is incorrect for the mains voltage in your country.

! The MicroTrap will operate appropriately at low power levels as indicated by 0 on the LED. The MicroTrap will emit a beeping sound continuously for 30 minutes before the MicroTrap shuts itself OFF. The MicroTrap shuts itself off to help prevent complete discharging of the internal battery. It is important to note that the MicroTrap has a non-volatile memory, allowing the data to be stored safely regardless of the power status of the internal battery.

! The MicroTrap internal battery can not be overcharged. According to the battery Manufacturer’s specifications, full battery pack recharging will take up to 16 hours. The Manufacturer also recommends recharging the MicroTrap at temperatures from 20 to 30 °C (68 to 86 °F).


3.5 OPERATING THE MICROTRAP FROM EXTERNAL POWER SOURCES The MicroTrap can be operated from AC voltage mains power using the Battery Charger. When operating the MicroTrap from AC mains through the Battery Charger, the LED will display P. The MicroTrap can be operated from a 12 VDC battery connected to the DC IN/OUT port on the back of the MicroTrap. Contact MREL to obtain the 12 VDC Battery Adapter required for connecting the battery to the DC IN/OUT port. When operating the MicroTrap from a 12 VDC battery, the LED will display P. 3.6 LONG TERM STORAGE CONSIDERATIONS No special procedures, other than those pertaining to the internal battery, should be taken for long term storage of the MicroTrap. In the eventuality that the MicroTrap remains idle for long periods, it is recommended to recharge the MicroTrap once per month per the procedure in Section 3.4. This will maintain the conditioning of the internal battery. 3.7 VOD RESISTANCE PROBES USED BY THE MICROTRAP The following types of VOD resistance probes are available from MREL and are uniquely suitable for use with the MicroTrap: 3.7.1 VOD PROBEROD The VOD PROBEROD, shown below, is a rigid probe consisting of a high resistance insulated wire placed within a small diameter, metal tube, which acts as the return lead of the circuit. PROBERODs are specifically designed to measure VODs of explosive cartridges and/or of short sample tubes of explosives, under confined or unconfined conditions. They are available from MREL in a standard length of 3 ft. (0.9 m) and are supplied with leads ready to be connected to the RG-58 coaxial cable, which connects to the VOD connector on the back of the MicroTrap. PROBERODs are also available in custom lengths. Contact MREL for additional PROBEROD information.

3.7.2 VOD PROBECABLE Two types of flexible resistance wire are available from MREL: VOD PROBECABLE "GREEN" and VOD PROBECABLE-LR "BLUE". These cables have been specially developed and refined by MREL with extensive feedback and assistance from MREL's VOD Instrumentation Customers since 1987. They are ideally suited to all explosive types loaded into all blasthole conditions including wet holes. They have the classical configuration of a standard RG-type coaxial cable, where the high resistance wire is the central conductor and the braided shield acts as the return lead. A dielectric material placed between the resistance wire and the return lead provides both electrical insulation and a physical barrier between them. The latter feature reduces the possibilities of short circuits during handling of the PROBECABLE. A plastic outer layer protects the PROBECABLE from tearing actions during loading.


PROBECABLE and PROBECABLE-LR are used for measuring VODs of explosives in blastholes, and the delay times between holes and decks. The selection of either PROBECABLE or PROBECABLE-LR is based on the total resistance of the circuit, which in turn depends on the number of holes being monitored. The only difference between these two cables relates to their nominal or unit resistance. PROBECABLE has a unit resistance of 10.8 ohm/m (3.29 ohm/ft) while PROBECABLE-LR (LR stands for Low-Resistance) has a unit resistance of 3.38 ohm/m (1.03 ohm/ft). The latter allows VOD recording for lengths up to approximately 850 m (2,800 ft) per test. Both types of PROBECABLE are available directly from MREL in a unique "reel-in-a-box" packaging with 1,000 m per box. The reel-in-a-box allows free spooling of the PROBECABLE into the blasthole by one operator without the need for a cable reel stand or another person to hold the reel of cable. Contact MREL for additional PROBECABLE information.


3.8 MICROTRAP TECHNICAL SPECIFICATIONS Number of Channels

1 channel for VOD. Upgradeable to provide an additional 4 channels for DC voltage recording of other types of gauges.

Vertical Resolution 14 bits, 1 part in 16,384. Recording Rate User selectable by Software from 1 Hz to 2 MHz. Total Recording Time @ 2 MHz Recording Rate

2.0 seconds (4 million data points). Reducing the Recording Rate increases the Total Recording Time. Upgradeable to provide twice the amount of memory (8 million data points).

Pre-Trigger Time User selectable by Software from 0-100% of the Total Recording Time. Trigger Modes User selectable on MicroTrap by switch: Internal or External.

External Mode: user selectable by Software “wire make” or “wire break”. Internal Trigger Level: user selectable by Software from 2.4 to 98% of signal level.

Power Internal rechargeable Ni-Cad battery pack providing up to 12 hours of active operation when fully charged. The non-volatile memory allows the data to be stored securely regardless of the status of the internal battery pack. The Battery Charger is provided in 120 or 220 VAC configurations. Recharging takes up to 16 hours. Operational from AC mains power through Battery Charger and from external DC power.

Multiple Event Storage

User selectable by Software: up to 16 tests stored in permanent memory.

Components Provided

MicroTrap, Battery Charger, Communications Cables, BNC Adapters, Padded Carrying Case, Operations Manual and MicroTrap Advanced Analytical (32 or 64 bit) for Windows '95, ’98, ME, NT, 2000, XP, Vista and 7.

Size and Weight MicroTrap: 21 x 17 x 9 cm (8.3 x 6.7 x 3.5 in.); 2 kg (4.4 lbs.). System in Carrying Case: 23 x 16.5 x 21.5 cm (9 x 6.5 x 8.5 in); 3 kg (6.6 lbs.).

Environmental Fully operational at -40 to +60 °C (-40 to +140 °F). Snow, rain, dust and sand proof. Drop proof from a height of at least 1 m (3 ft.).

PC Connection After conducting the test(s) the MicroTrap to a computer’s (LPT) printer port or USB port using the Communications Cable to allow fast downloading of the data to the computer. The MicroTrap supports all port configurations (Standard, ECP and EPP). The connection between the MicroTrap and the computer also allows the operator to confirm and/or change the MicroTrap recording parameters.

Software The MicroTrap Advanced Analytical Software operates under Windows ’95 and later. It provides an easy-to-use and familiar graphical-user-interface that allows the operator to easily set the recording parameters of the MicroTrap, download the data to the computer and analyze the data. VOD data are automatically displayed as graphs of distance versus time. All Software operations are “point and click”. The Software allows unlimited graphical zoom on graphs, creation of annotated sub-graphs and VOD and hole/deck delay time analyses of any parts of the VOD graph. Annotating, printing, saving and export of graphs and data to other Windows software are all easily accomplished. The operator can select Metric (m/s) or Imperial (ft/sec.) units.

VOD Excitation/Safety

The MicroTrap automatically adjusts its excitation voltage for the maximum 14-bit resolution across the VOD probe. All VOD operating parameters are recorded by the MicroTrap with no requirements for additional instrumentation. For safety considerations, the MicroTrap is physically unable to output as much as 50 mA of current to a VOD probe.

VOD Resistance Probes

A complete line of VOD probes is available from MREL to record the VOD of explosive samples and multiple holes in large surface mine blasts. The MicroTrap can record VODs across PROBECABLE-LR (resistance cable) lengths of up to 900 m (2,950 ft.) per test.




4.1 SAFETY CONSIDERATIONS FOR SELECTING AN EXPLOSIVE TESTING SITE

Care must be taken to select a good site for detonation and VOD recording of explosive samples. If convenient, permanent test sites may be constructed. A pit surrounded by an earth wall suffices as a simple detonation site. A similarly protected shelter for the MicroTrap and personnel can be constructed some distance away. The distance will depend on the amount of explosive being detonated at one time, and if the explosives are confined (hazard from steel fragments). Ensure that the area is well demarcated and that access is restricted. If samples of explosives are to be detonated at an unprepared site, then the Operator must be careful when deciding upon what type of ground the charges are to be placed. Avoid placement on ground with stones, rubble or anything that is likely to turn into a projectile. The best surfaces are fines, sand or tailings. It is always good practice to have maximum control over the time of firing of the test, therefore safety fuse initiation is not recommended. Electric or shock tube initiation is best with the detonator either initiating the sample of explosives or initiating the primer/booster in the explosive sample. 4.2 THE RESISTANCE WIRE TECHNIQUE FOR MEASURING VOD The MicroTrap is capable of monitoring the continuous VOD profile along the entire length of an explosives column. The MicroTrap can measure the VOD of relatively short explosive samples such as cast boosters or explosive cartridges. The MicroTrap can also measure the VOD of explosives loaded in blastholes in surface or underground blasts, in single and multiple hole blasts. The MicroTrap provides a regulated constant excitation signal to the probes and monitors the drop in voltage across them. The MicroTrap uses the proven continuous resistance wire technique for monitoring VODs. An MREL-qualified probe of known linear resistance (i.e. ohm/m or ohm/ft) is placed axially in the explosive sample or explosive column. As the detonation front of the explosive consumes the probe, the resistance of the circuit will decrease in proportion to the reduction in length of the probe. The MicroTrap records the resulting decrease in voltage across the probe versus time. The MicroTrap’s Advanced Analytical Software automatically converts the recorded data into a graph of distance versus time. The slope of this graph at any position is the VOD of the explosive at that particular position. The Software includes menu functions that will automatically calculate and display the VOD of an explosive at any selected location in the graph. Other functions allow the Operator to calculate and display the delay time between selected blastholes or between selected explosive decks within a blasthole.

Contact MREL for site specific recommendations for testing samples of explosives.

This Chapter provides the Operator with detailed instructions on: 1. Selecting a suitable site for testing samples of explosives. 2. Loading PROBERODs into explosives samples and PROBECABLE into blastholes. 3. Connecting the probes to the MicroTrap and setting the MicroTrap hardware to record the VODs

and hole/deck delay times.

CHAPTER 4: RECORDING VOD AND HOLE/DECK DELAY TIMES


4.3 INSTALLING PROBERODS FOR TESTING SAMPLES OF EXPLOSIVES The equipment and supplies that are required to conduct VOD tests on samples of explosives or on explosive cartridges are: 1. The MicroTrap System. 2. VOD PROBEROD (available from MREL) - one (1) per explosive sample. 3. Coaxial cable (type RG-58 is recommended) - sufficient length to run between the MicroTrap location and the

explosives. 4. Wire cutters and electrical tape. 5. Explosives, detonators and shot exploder. The procedure for preparing a VOD test is as follows: 1. Demarcate the charge detonation area. 2. Place the MicroTrap in a protective shelter and/or a safe distance away from the detonation area. This

distance may be closer than what is considered safe for the Operator. Once the setup is completed, the MicroTrap does not require an Operator to collect the data; it does so automatically without Operator assistance.

3. Run a length of coaxial cable from the MicroTrap to the detonation area with enough excess length to compensate for cable shortening or cable damage from each test. Shorter lengths of coaxial cable may be connected together using the wire cutters and electrical tape. A male BNC connector should be attached to the end of the coaxial cable that is to be attached to the VOD input at the back of the MicroTrap. Convenient BNC Adapters have been supplied with the MicroTrap for this purpose. The Adapters can be connected to the coaxial cable using the wire cutters and electrical tape. The connection should be shielding to shielding and center conductor to center conductor. Ensure that the center conductor and the shielding connections do not touch each other.

4. Note the Unit Resistance of the probe by reading the value in ohm/m or ohm/ft from the MREL factory label on the PROBEROD. Note the ohm/m value if the VOD is to be reported in m/s. Note the ohm/ft value if the VOD is to be reported in ft/sec. The Unit Resistance information will be requested later by the MicroTrap Software.

5. Insert a PROBEROD axially in the sample of explosives. Start at the opposite end from where the detonator will be placed as shown below.

If bulk explosives are being tested in paper tubes, plastic tubes or steel pipes which have been sealed at both ends, make a small central hole to allow the PROBEROD to be inserted. If a measurement of run-up to detonation is required, ensure that the PROBEROD is pushed well into the explosives so that it reaches the position of the detonator or booster. If the PROBEROD reaches the booster or protrudes past it, the effect of the booster will be recorded by the MicroTrap. The same holds true for cartridges of explosives. To test the VOD of detonation cord, tape the detonation cord along the entire length of the PROBEROD.

6. Connect the PROBEROD to the coaxial cable using the wire cutters and electrical tape. The polarity of the connection is not important.

Coaxial CableTo MicroTrap


7. At the MicroTrap end, connect the coaxial cable to the VOD connector located on the outside and at the back of the MicroTrap.

8. The PROBEROD installation aspects of the test are complete. The Operator can now place the detonator and connect it to the shot exploder as per standard procedures. The MicroTrap is now ready to be prepared to record the test as detailed in Section 4.6.

4.4 INSTALLING PROBECABLE FOR TESTING EXPLOSIVES IN BLASTHOLES The equipment and supplies that are required to conduct VOD tests on samples of explosives in blastholes are: 1. The MicroTrap System. 2. VOD PROBECABLE "GREEN" or VOD PROBECABLE-LR "BLUE" (available from MREL). 3. Coaxial cable (type RG-58 is recommended) - sufficient length to run between the MicroTrap location and the

last blasthole in the blast to be recorded. 4. Wire cutters and electrical tape. 5. Explosives, detonators and shot exploder. 4.4.1 PREPARATION OF PROBECABLE FOR SINGLE BLASTHOLE RECORDING 1. Prepare the end of the PROBECABLE by using the

wire cutters to remove the insulation from the end. Then short the PROBECABLE by connecting the shielding wire to the center conductor wire and twist them together. Protect the connection well with electrical tape.

2. Using tape or wire, attach the short circuit end of the PROBECABLE to the primer/booster or to a rock and lower the PROBECABLE into the hole as shown on the following page. Detonation cord downlines may damage the PROBECABLE or cause side initiation of the bulk explosive. When initiating with detonation cord, attach the PROBECABLE to a rock and lower it on the side of the hole opposite to the detonation cord downline.

3. The PROBECABLE can then be cut at the top of the hole.

4. Note the Unit Resistance of the probe by reading the value in ohm/m or ohm/ft from the MREL factory label on the spool of PROBECABLE. Note the ohm/m value if the VOD is to be reported in m/s. Note the ohm/ft value if the VOD is to be reported in ft/sec. The Unit Resistance information will be requested later by the MicroTrap Software. When measured with a blaster’s galvanometer, the Probe Resistance should compare favorably with the calculated resistance of the PROBECABLE (Unit Resistance multiplied by length). If this is not the case then remove the length of PROBECABLE and reload another length into the hole.

5. The hole can now be loaded with explosives and stemming per usual procedure. Hold the PROBECABLE taut during the loading of the explosive to avoid slack in the hole. In the absence of the Operator, this may be accomplished by tying the PROBECABLE taut around a hole marker stake, or around a rock at the top of the hole. After loading, the Operator may wish to check the Probe Resistance to ensure that no PROBECABLE damage has occurred. As the PROBECABLE is well protected with PVC coating, no problems should be anticipated.



6. Connect the PROBECABLE to the coaxial cable using the wire cutters and electrical tape. The connection should be shielding to shielding and center conductor to center conductor. Ensure that the center conductor and the shielding connections do not touch each other.

7. Place the MicroTrap in a protective shelter and/or a safe distance away from the blast area as dictated by flyrock. This distance may be closer than what is considered safe for the Operator. When set, the MicroTrap does not require an Operator to collect the data; the MicroTrap collects the data automatically without Operator assistance.

8. Run the coaxial cable from the PROBECABLE to the MicroTrap. If necessary, shorter lengths of coaxial cable may be connected together using the wire cutters and electrical tape to make a longer length of coaxial cable. Somewhere along the length of the coaxial cable, loop the coaxial cable around a large rock. When the blast is fired, and the ground moves, looping the coaxial cable around a large rock will stop the blast from pulling the coaxial cable and the MicroTrap with the blast. Alternatively, leave sufficient slack in the coaxial cable to allow for ground movement.

9. A male BNC connector should be attached to the end of the coaxial cable that is to be attached to the VOD input at the back of the MicroTrap. Convenient BNC Adapters have been supplied with the MicroTrap for this purpose. The BNC Adapters should be connected to the coaxial cable using the wire cutters and electrical tape. The connection should be shielding to shielding and center conductor to center conductor. Ensure that the center conductor and the shielding connections do not touch each other. It is a good idea to check the total resistance of the PROBECABLE and coaxial cable circuit at the BNC connector to ensure that there are no bad connections.

10. At the MicroTrap, connect the coaxial cable to the VOD connector located on the outside and at the back of the MicroTrap.

11. The PROBECABLE installation aspects of the test are complete. The MicroTrap is now ready to be prepared to record the test as detailed in Section 4.6.


4.4.2 PREPARATION OF PROBECABLE FOR MULTIPLE BLASTHOLE RECORDING 1. Prepare the end of the PROBECABLE by using the wire cutters to remove the insulation from the end. Then

short the PROBECABLE by connecting the shielding wire to the center conductor wire and twist them together. Protect the connection well with electrical tape.

2. Start with the blasthole that is designed to detonate first of the multiple holes to be recorded by the MicroTrap. Using tape or wire, attach the short circuit end of the PROBECABLE to the booster or to a rock, and lower the PROBECABLE into the hole. Detonation cord downlines may damage the PROBECABLE or cause side initiation of the bulk explosive. When initiating with detonation cord, attach the PROBECABLE to a rock and lower it on the side of the hole opposite to the detonation cord downline.

3. Run the PROBECABLE between the first hole and the second hole leaving sufficient slack between the holes to allow for ground movement between the delayed holes. Excess PROBECABLE between holes is not a concern.

4. There are two common methods of lowering a doubled length of PROBECABLE in the second and subsequent holes to be recorded. The first, and easiest, method is to run the PROBECABLE through a wire loop that has been tied or taped around a rock or booster. This allows the rock to slide along the PROBECABLE as the PROBECABLE is lowered into the hole until the rock reaches the bottom of the hole. The second method is to measure the correct length of PROBECABLE so that it reaches the bottom of the hole where the PROBECABLE has been doubled over and attached to the booster or a rock.

5. After the last hole to be recorded has been loaded with PROBECABLE, the PROBECABLE can then be cut at the top of the hole.

6. Note the Unit Resistance of the probe by reading the value in ohm/m or ohm/ft from the MREL factory label on the spool of PROBECABLE. Note the ohm/m value if the VOD is to be reported in m/s. Note the ohm/ft value if the VOD is to be reported in ft/sec. The Unit Resistance information will be requested later by the MicroTrap Software. When measured with a blaster’s galvanometer, the Probe Resistance should compare favorably with the calculated resistance of the PROBECABLE (Unit Resistance multiplied by its length). If this is not the case then remove the length of PROBECABLE and reload another length into the hole.

7. The holes can now be loaded with explosives and stemming per usual procedure. Hold the PROBECABLE taut during the loading of the explosive to avoid slack in the hole. In the absence of the Operator, this may also be accomplished by tying the PROBECABLE taut around a hole marker stake, or around a rock at the top of each hole. After loading, the Operator may wish to check the Probe Resistance again to ensure that no PROBECABLE damage has occurred. As the PROBECABLE is well protected with PVC coating, no problems should be anticipated.

8. At the top of the last hole, connect the PROBECABLE to the coaxial cable using the wire cutters and electrical tape. The connection should be shielding to shielding and center conductor to center conductor. Ensure that the center conductor and the shielding connections do not short with each other.

9. Place the MicroTrap in a protective shelter and/or a safe distance away from the blast area as dictated by flyrock. This distance may be closer than what is considered safe for the Operator. When set, the MicroTrap does not require an Operator to collect the data; the MicroTrap collects the data automatically without Operator assistance.



10. Run the coaxial cable from the PROBECABLE to the MicroTrap. If necessary, shorter lengths of coaxial cable may be connected together using the wire cutters and electrical tape to make a longer length of coaxial cable. Somewhere along the length of the coaxial cable, loop the coaxial cable around a large rock. When the blast is fired, and the ground moves, looping the coaxial cable around a large rock will stop the blast from pulling the coaxial cable and the MicroTrap with the blast. Alternatively, leave sufficient slack in the coaxial cable to allow for ground movement.

11. A male BNC connector should be attached to the end of the coaxial cable that is to be attached to the VOD input at the back of the MicroTrap. Convenient BNC Adapters have been supplied with the MicroTrap for this purpose. The BNC Adapters should be connected to the coaxial cable using the wire cutters and electrical tape. The connection should be shielding to shielding and center conductor to center conductor. Ensure that the center conductor and the shielding connections do not touch each other. It is a good idea to check the total resistance of the PROBECABLE and coaxial cable circuit at the BNC connector to ensure that there are no bad connections.

12. At the MicroTrap, connect the coaxial cable to the VOD connector located on the outside and at the back of the MicroTrap.

13. The PROBECABLE installation aspects of the test are complete. The MicroTrap is now ready to be prepared to record the test as detailed in Section 4.6.

4.5 PROBECABLE AND COAXIAL CABLE PROTECTION It is important to protect the PROBECABLE and the coaxial cable from damage caused by personnel and machinery operating on the blast. It is also important to protect the PROBECABLE from damage caused by detonation of other holes and/or surface accessories such as detonating cord, detonating relays, and shock tube bunch blocks. The cables may be protected in many ways. Experience has shown that it is best to lead the PROBECABLE and coaxial cable under the detonating cord and leave a barrier of sand or drill cuttings between the cables and the detonating cord. A danger point is the collar area of the holes as the detonating cord or shock tube bunch blocks that initiate the downlines may cross directly over the PROBECABLE or coaxial cable. A good procedure is to protect the area where there is a cross over for about 1.5 m (5 ft) along the length of cable. Experience has shown that a sand or stemming barrier thickness of 15-30 cm (0.5-1 ft) suffices to protect the cables. 4.6 MICROTRAP SETUP PROCEDURE FOR VOD MEASUREMENTS Once the VOD probe has been placed in the explosive and connected to the RG-58 coaxial cable running to the VOD connector on the MicroTrap, the Operator can start setting the MicroTrap to record VOD experiments. Changing the MicroTrap's recording parameters, such as recording rate, trigger level, pre-trigger memory and allocating the MicroTrap’s memory to multiple tests should all have been accomplished, if required, in the office environment. All changes are accomplished through use of the MicroTrap Advanced Analytical Software (Section 1.4).


The procedure to record a new VOD test consists of the following steps: 1. Ensure that the coaxial cable coming from the PROBEROD or PROBECABLE is connected to the MicroTrap

signal input connector labeled VOD. 2. Turn the MicroTrap ON. The STATUS light will illuminate and begin to flash quickly for approximately 2

seconds while the MicroTrap conducts some internal verification testing. If the MicroTrap passes the internal verification tests, the STATUS light will begin to flash slowly (Stand-by mode). The Operator can go to Step 3. If the MicroTrap fails to pass the internal verification tests, the STATUS light will flash three times in succession and EE will appear on the LED. If this happens, switch the MicroTrap OFF and start again at the beginning of Step 2. If the MicroTrap continues to fail the internal verification tests, then contact MREL as the MicroTrap requires service.

3. Press the NEXT TEST button; the STATUS light will stop flashing and will remain illuminated (Active mode). 4. Press the TOTAL TESTS button and notice the total number of tests in to which the MicroTrap’s internal

memory has been divided. 5. Press the REMAINING TESTS button and notice the number of tests available to be conducted to fill the

MicroTrap’s internal memory. If this number does not equal the TOTAL TESTS number, then there are one or more tests already in the MicroTrap’s internal memory. This would occur under the following situations: a. The test about to be conducted is part of a series of tests that is being conducted in succession before

the data from all of the tests is to be transferred to a computer. b. The MicroTrap’s internal memory was not cleared by the Software during the previous data transfer to

the computer (Section 1.4).

! When shipped from MREL, the MicroTrap’s recording parameters have been pre-set to settings appropriate for most blasthole VOD recording situations. Recording Rate = 2 MHz. Total Recording Time = 2 seconds, with standard memory and 4 seconds with the MicroTrap Memory Upgrade installed. Memory Allocation = 1 test fills the MicroTrap’s internal memory. Pre-trigger Time = 25% of Total Recording Time = 0.5 seconds. Trigger Level = 95%. These settings recommendations are based on MREL’s extensive worldwide experience in VOD recording.

! MREL recommends a Trigger Level of about 95% and a Pre-Trigger Time of about 25% for VOD recording of explosives samples and explosives in blastholes.

! MREL recommends setting the Number of Tests = 1 for VOD recording of blastholes using PROBECABLE. The Operator will normally be able to download the data from the MicroTrap to a computer before conducting the next VOD test.

! MREL recommends setting the Number of Tests = 16 for VOD recording of samples of explosives using a PROBEROD. This reduces the quantity of data collected per test and conserves the computer’s disk space. At a 2 MHz recording rate, a MicroTrap with standard memory will record for a total of 131 ms per test if the Number of Tests = 16. This is more than sufficient recording time for a sample of explosives.


6. Ensure the EXT/INT TRIG switch is set to the INTernal position. The use of external EXTernal triggering is

discussed in Section 4.8. 7. Look for the OUT OF RANGE warning light indicators (↓ and ↑). If there is a warning light, there is a problem

with the resistance probe, the coaxial cable and/or the BNC Adapter. If this is the case, the Operator is referred to Section 4.7 for possible solutions. It is worth noting that, as a safety feature, the START button will be blocked and the MicroTrap will be unable to record VODs when an OUT OF RANGE condition exists. If the OUT OF RANGE lights are not illuminated the Operator can proceed with the next step.

8. Press the START button. The START light will illuminate steadily. The MicroTrap then starts monitoring the blast, waiting for the trigger signal to start collecting VOD data. Personnel can now vacate the MicroTrap location.

9. When the triggering condition is met (i.e. a sufficient length of PROBEROD or PROBECABLE has been consumed by the detonation), the MicroTrap will trigger and start collecting VOD information. Upon triggering, the TRIG’D light will illuminate and remain illuminated during the collection of data (this time depends of the Recording Rate programmed into the MicroTrap). The START and STATUS lights will be on. Immediately upon triggering, the MicroTrap will send a 10 VDC signal to the TRIG OUT connector. This will cause a 6 second signal to be emitted from the TRIG OUT connector. Some Operators may wish to trigger other instrumentation from the 10 VDC signal, which is sent to the TRIG OUT connector when the MicroTrap triggers. For the information of those Operators, the rise time on the signal is approximately 2 microseconds from the time that the MicroTrap is triggered to record.

10. Once data collection ends, the TRIG’D and START lights flash rapidly and the MicroTrap starts storing data into its non-volatile memory. During the storing period, the STATUS light is on. Do not switch the MicroTrap OFF at this point.

If the Operator is sure he does not wish to keep the existing data in memory, then the Operator can either clear the MicroTrap’s internal memory using the Software (Section 1.4) or by the following procedure: a. Turn ON the MicroTrap. b. Press the NEXT TEST button to put the MicroTrap in Active mode. The STATUS light should

be on. c. Simultaneously press the NEXT TEST and STOP buttons and hold them down. The LED will

display a blinking dE. Release the buttons. d. Simultaneously press the START and STOP buttons and hold them down. The LED will

display dE without blinking. Release the buttons. All of the data in the MicroTrap’s memory will be deleted.

e. Turn OFF the MicroTrap. Turn ON the MicroTrap and pressing the TOTAL TESTS button and then the REMAINING TESTS button will confirm that these numbers are equal and that all of the test data in the MicroTrap’s memory has been deleted.

f. Go to Step 3.


11. Upon finishing the data storing process, the START light will go off, and the STATUS and TRIG’D lights will begin to flash slowly. The MicroTrap returns to the Stand-by mode.

12. If testing has been completed then go to Step 13. Otherwise, press the REMAINING TESTS button to

confirm how many tests can be still hosted by the MicroTrap before downloading of the data to a computer is required. If there are 1 or more tests remaining in the memory: a. The MicroTrap’s Recording Parameters can be changed for subsequent tests by using the Software,

Section 1.4, or b. If the Recording Parameters are to remain the same and another test is to be performed then go to

Step 3. If there are 0 tests remaining in the memory, then either download the data to a computer (Section 5.1) and return to Step 1, or go to Step 13.

13. If no more experiments are to be conducted and the data storing process has been finished (Step 11 above), then the data are ready to be transferred to a computer using the Software as detailed in Section 5.1. If data transfer is to be conducted later, then the MicroTrap can be switched OFF and the data will remain in the MicroTrap’s non-volatile memory.

4.7 PROBE RESISTANCE OUT OF RANGE There are two OUT OF RANGE warning lights on the MicroTrap. One is labeled ↑, which illuminates when the total resistance (resistance probe plus coaxial cable) is greater than 3,000 ohms. The other is labeled ↓, which illuminates when the total resistance is less than 50 ohms. The MicroTrap is only calibrated to perform VOD tests between these two initial resistance values (50 – 3,000 ohms). There can be several reasons for total resistance to be LOW: 1. A short circuit somewhere in the coaxial cable and probe assembly, including any BNC connector(s) or BNC

Adapter; 2. A damaged PROBEROD; 3. An insufficient length of PROBECABLE. Items 1 and 2 above can be tested using a blaster’s galvanometer to test the resistance/continuity of the coaxial cable and probe assembly and solved by remaking the connections and/or replacing the damaged PROBEROD. If Item 3 is the cause, then attach some more PROBECABLE to the probe circuit. This will not affect the VOD results. If PROBECABLE-LR is being used in the test, then considering using PROBECABLE for such tests in the future. The unit resistance of PROBECABLE is approximately 3 times that of PROBECABLE-LR.

If the MicroTrap has triggered prematurely and the data collected is of no use, for example due to someone driving over the signal lines, then the Operator may reset the MicroTrap’s internal memory back one test using the following procedure: a. Do not turn OFF the MicroTrap after the test, the STATUS light and TRIG’D lights should be

flashing. b. To erase the data from the last test; simultaneously press the TOTAL TESTS and REMAINING

TESTS buttons and hold them until this procedure is complete. The LED display will show ct. c. After about 2 seconds, the ct will begin blinking. After another 2 seconds, the ct will

disappear. Release the buttons. The data from the last test has been deleted. d. Turn OFF the MicroTrap. Turn ON the MicroTrap and pressing the TOTAL TESTS button and

then the and REMAINING TESTS button will confirm that the remaining tests have been increased by 1 and that the last test in the MicroTrap’s memory has been deleted.

e. Go to Step 3.


There can be several reasons for the total resistance to be HIGH: 1. An open circuit somewhere in the coaxial cable and probe assembly, including any BNC connector(s) or BNC

Adapter; 2. A damaged PROBEROD; 3. Too long a length of PROBECABLE. Items 1 and 2 above can be tested using a blaster’s galvanometer to test the resistance/continuity of the coaxial cable and probe assembly and solved by remaking the connections and/or replacing the damaged PROBEROD. If Item 3 is the cause, then reduce the length of the PROBECABLE used in the test by cutting out excess PROBECABLE between holes and remaking the connections using the wire cutters and electrical tape. Alternatively, this can be achieved by reducing the number of holes being recorded by cutting the PROBECABLE and remaking the appropriate connection with the wire cutters and electrical tape. If PROBECABLE is being used in the test, then considering using PROBECABLE-LR for such tests in the future. The unit resistance of PROBECABLE-LR is approximately 1/3 that of PROBECABLE. 4.8 UTILIZING THE EXTERNAL TRIGGER In some VOD and data recording applications, it may be desirable to have the MicroTrap begin to record exactly when a specific event occurs. For the specific event to start at time = 0 on the graph, the EXT TRIG connector, on the outside and back of the MicroTrap, is used. Connect one of the BNC Adapters to the EXT TRIG connector. Connect a duplex wire to the BNC Adapter using cutters and electrical tape. The polarity of the connection does not matter. The assembly consisting of the BNC Adapter and duplex wire is called the “Trigger Wire”. When the EXT/INT TRIG switch on the front panel of the MicroTrap is set to EXT, the MicroTrap will begin recording when either the Trigger Wire becomes shorted (if the Software has been set for MAKE Circuit); or when the Trigger Wire becomes open circuit (if the Software has been set to BREAK Circuit). The procedure for using the Software to set MAKE or BREAK EXTernal trigger is detailed in Section 1.4. To prepare the "test" end of the duplex wire to wait for a MAKE Circuit trigger: remove the insulation from one of the wires and wrap it around the second insulated wire such that the circuit remains open. Upon the duplex wire circuit becoming shorted, the MicroTrap will begin recording data. Any explosive event such as a detonator firing, detonating cord firing or a booster firing will short such a circuit and cause the MicroTrap to collect data. Pre-trigger points will still be collected per the settings of the MicroTrap, but time=0 on the graph will be the precise time when the Trigger Wire became shorted. To prepare the "test" end of the duplex wire to wait for a BREAK Circuit trigger: connect the two ends of the duplex wire together such that the circuit is closed. Upon the duplex wire circuit becoming broken, the MicroTrap will begin recording data. Any explosive event such as a detonator firing, detonating cord firing or a booster firing will break such a circuit and cause the MicroTrap to collect data. Pre-trigger points will still be collected per the settings of the MicroTrap, but time=0 on the graph will be the precise time when the Trigger Wire became broken.


4.9 ADDITIONAL INFORMATION ON MEMORY AND TRIGGERING 4.9.1 MEMORY The MicroTrap, with standard memory, has a large circular memory containing 4,194,000 data points that are allocated according to the number of tests to which the MicroTrap’s memory has been divided. These values, for a selected Recording Rate, define the available Total Recording Time for each test. Selection of the number of tests to be recorded and the Recording Rate is done using the Software as detailed in Section 1.4. The MicroTrap Software automatically calculates and displays the Total Recording Time per Test and the Pre-Trigger Time. For those Operators with additional interest in recording times: A general equation to calculate the Total Recording Time (Pre-trigger Time + Post-trigger Time) is:

Total Recording Time (seconds) = 4,194,000/((# of tests)x(recording rate)) If the number of tests selected is one, the available recording time will be maximized for a given Recording Rate. For example, at the maximum Recording Rate 2 MHz, the Total Recording Time will be:

4,194,000/((1 test)x(2,000,000 points/sec)) = 2.097 seconds At a slower Recording Rate of 1 MHz (for example), the Total Recording Time will become 4.194 seconds. If the MicroTrap’s internal memory is divided into 4 tests, the MicroTrap will partition the memory allocating 4,194,000 points/4 tests = 1,048,500 points per test. Following the previous example, the Total Recording Time per test can be calculated as follows:

4,194,000/((4 tests)x(2,000,000 points/sec)) = 0.524 seconds

If the Recording Rate is reduced to 1 MHz, the Total Recording Time will become 1.048 seconds per test. If these recording times are insufficient for your testing applications, then contact MREL and ask about the MicroTrap Memory Upgrade, which doubles the MicroTrap’s internal memory and thus doubles the Total Recording Time.


4.9.2 TRIGGERING When the EXT/INT switch is set to the EXT position, the trigger signal that the MicroTrap receives is from the Trigger Wire as detailed in Section 4.8. This corresponds to time = 0 on the resulting VOD graph. When the EXT/INT switch is set to the INT position, then the MicroTrap is triggered by the signal received from the probe placed in the explosives. This trigger signal occurs according to the following principle: when the explosive detonates, the probe is consumed and the probe length is reduced. This in turn reduces the resistance and thus the voltage across the probe decreases from the initial 5.0 VDC (approximately) set automatically by the MicroTrap. When the voltage across the probe reaches the value corresponding to the Trigger Level selected by Software (Section 1.4), the MicroTrap is triggered. This represents time = 0 on the resulting VOD graph. For example, with a Trigger Level setting of 95%, the MicroTrap will be triggered when the voltage signal coming from the probe crosses the 95% level (4.75 VDC of the full-scale voltage, which is approximately 5.0 VDC). Once the MicroTrap receives the trigger signal, it stores the VOD information received immediately prior to the trigger signal into the pre-trigger memory; the VOD information received after the trigger signal is stored into the post-trigger memory. The recording time for each memory allocation (pre and post-trigger) will depend on the setting selected, using the Software (Section 1.4), for Pre-Trigger %. The MicroTrap Software automatically calculates and displays the Total Recording Time per Test and the Pre-Trigger Time. For those Operators with additional interest in recording times:

Pre-Trigger Time = (Total Recording Time) x Pre-Trigger % Post-Trigger Time = (Total Recording Time) - (Pre-Trigger Time)

For the PROBECABLE or PROBECABLE-LR length loaded in the blastholes, and the recommended TRIG% setting of 95.3%, the graphs on the following pages show the lengths of PROBECABLE and PROBECABLE-LR that must be consumed for the MicroTrap to receive the INTernal trigger signal. PROBECABLE-LR should be used for tests involving several holes where if PROBECABLE was used it would result in the Total Resistance exceeding the maximum resistance accepted by the MicroTrap (3,000 ohms). For example, at a 95.3% Trigger Level and with 250 metres of PROBECABLE loaded into blastholes, then 28 metres of PROBECABLE must be consumed to trigger the MicroTrap. If the first hole does not consume a sufficient length of PROBECABLE to trigger the MicroTrap, then all of the VOD data for the first hole will be before time = 0. The Operator should ensure that there is sufficient Pre-Trigger time to record the time it takes for the trigger length of PROBECABLE to be consumed in the blast. This is particularly important if several delayed holes must be detonated in order for sufficient PROBECABLE to be consumed. The MicroTrap has a very large memory and a very long Total Recording Time. At a Pre-Trigger % setting of 25%, the MicroTrap has a long Pre-Trigger Time. It is likely that there will always be sufficient Pre-Trigger Time to record the time it takes for the trigger length of PROBECABLE to be consumed in the blast. If there is insufficient Pre-Trigger time, the best procedure is for the Operator to re-program the MicroTrap using the Software and increase the Pre-Trigger % to increase the amount of Pre-Trigger Time to suit the test. Alternatively, the Operator can reduce the Recording Rate to increase the amount of both Pre and Post-Trigger Time.


PROBECABLE TRIGGER LENGTH DETERMINATION

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PROBECABLE-LR TRIGGER LENGTH DETERMINATION

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5.1 RETRIEVING DATA FROM THE MICROTRAP The procedure to retrieve data from the MicroTrap to a computer is as follows: 1. Connect the Communications Cable supplied with the MicroTrap between the LPT (parallel printer port) or

the USB Port (depending on which cable is used) on the computer and the LPT COM port on the front panel of the MicroTrap.

2. Turn the MicroTrap power ON. 3. Start the MicroTrap Software by clicking on Start-Programs-MREL-MicroTrap. 4. At the Main Menu click on the Retrieve Data button or with the keyboard

press Alt-R. Data retrieval can be accomplished without the use of a computer mouse by pressing “tab” to move between data entry fields.

5. Choose a drive, directory and file name in which the MicroTrap data

will be stored. The directory defaults to C:\MicroTrap\Data. The file name, in this case, is 2000Jun015, which indicates the 15th time data has been downloaded from the MicroTrap in June of 2000. The Operator can name the file anything he wishes. The numbers from 01 to 16 will be added to the name, depending on the number of tests downloaded from the MicroTrap’s memory, in case of multiple tests in the MicroTrap memory. Other MicroTrap files already stored in the directory are also displayed. Clicking on the Compress Data tick box turns the file compression on or off. With Compress Data on, the retrieval from the MicroTrap takes longer for some computers; however but the file size is reduced conserving computer disk space. Note that new directories can be created from this window using the Create New Directory button. As well, that the current directory can be Set as Default Start Directory for saving files. When all information is entered, click on the Retrieve Data button. Otherwise, click on the Cancel button to return to the Main Menu.

Ensure that Chapter 1 has been successfully completed prior to beginning Chapter 5.

CHAPTER 5: MICROTRAP SOFTWARE


6. A reminder message window is then displayed. Click on OK.

7. Since there was only one test

recorded in the MicroTrap’s memory, the downloading starts automatically and displays the download progress.

8. If there were multiple tests recorded

in the MicroTrap’s memory, then the Operator is asked to click on which tests he wants to download.

9. After the retrieval is finished, a Message is displayed.

Click on OK. 10. For each test that the

Operator downloaded, an Enter Resistances window is displayed in sequence. The Operator must click on the preferred units of velocity measurement, m/s or ft./sec. He must also tick the type of VOD resistance probe used in the test. Finally, the Operator can add comments about the test. These comments will allow the Operator to see what is in the file when he looks for a file to analyze. Notice that the test in the example will be stored in a file named 2003Mar002_01.mcr. If the Operator downloaded 2 tests then a new Enter Resistances window would


appear after the Operator clicks on Accept Test 1. The second test would be stored in the file named 2003Mar002_02.mcr. Click on the Accept Test 1 button when the resistance information for Test 1 has been entered for the test. Repeat this procedure for any subsequent tests.

11. After all of the data has been entered for all of the tests downloaded, and the final Accept Test button has

been pressed, the Communications Cable can be detached from the computer and the MicroTrap and the Operator can proceed to analyze the data.

5.2 SELECTING DATA FILES FOR ANALYSIS The procedure to select a MicroTrap file for analysis is as follows: 1. If the MicroTrap Software is not running, start the MicroTrap Software by

clicking on Start-Programs-MREL-MicroTrap. 2. At the Main Menu click on the Analyze Data button or with the keyboard

press Alt-A. 3. Click on the file name of interest. Use the File

Comments box as a guide to each file’s content. 4. Click on the Open button when a file has been

selected, otherwise click on the Cancel button to return to the Main Menu. Note that the current directory can be set as the default directory for opening files.

For this example, Example Detonating Cord is chosen to illustrate the results of a VOD test on a sample of detonating cord. Example Detonating Cord and Example Multiple Decked Holes are data files which have all been included as examples with the MicroTrap Software. Chapter 6 provides the detailed procedures for analyzing the data in both of these files. Clicking on the Open button automatically starts the MicroTrap Advanced Analytical Software with the chosen data file. The following Section outlines the capabilities of the Analytical Software.


5.3 INTRODUCTION TO ANALYSIS The following screen is displayed when a VOD file has been chosen for analysis and all of the sub-graphs previously saved with the file are opened:

The screen contains three main areas that are summarized below, and are discussed in more detail in the following Sections as well as in Chapter 6: Desktop: the area having the MREL logo as background. One or more graphs can be displayed in maximized, normalized or minimized size states in the area. Tools Bar: a moveable menu of icons, which allows the Operator to access analysis and graphics tools. Current Point Tools Bar: a moveable menu of icons and data display windows which allows the Operator to access analysis tools. Menu Bar: located across the top of the screen. It includes pull down menus for File, Graph, Edit, Analyze, Window and Help.


5.4 DESKTOP When a data file is initially opened, the Desktop area of the Software, which has as a background the MREL logo, shows the Original VOD graph in a minimized state. The data and graphics on the original graphs can not be changed. New graph names must be given to the modified graphs (or sub-graphs). In this way, the original data for the test can never be lost. In the example in Section 5.3, the Example Detonating Cord data file at this point in the analysis has only 1 graph, which is the Original VOD graph. From this Original VOD graph, other sub-graphs can be made and saved by the Operator under new graph names. These sub-graphs can include some or all of the data in the original graph and can include graphics, text and analysis information as added by the Operator. The next time the data file is chosen for analysis, the original graph and all sub-graphs will be opened. There is no limit to the number of sub-graphs which can be created from an Original VOD. The procedure for creating sub-graphs is discussed in Chapter 6. By clicking on either the normalize icon or on the maximize icon on any minimized graphs (per normal Windows procedures) the data can be viewed and analyzed. 5.5 TOOLS BAR The Tools Bar contains a selection of ten (10) tool buttons used to add or modify the graph’s characteristics, text and graphics and to apply analysis procedures to the data in the graphs to calculate VODs and delay times between holes. The Tools Bar can be moved anywhere on the Desktop. The basic functions of each of the tool buttons are outlined below:

The Select Tool has many functions including: selecting, moving, minimizing, maximizing and normalizing graphs; selecting and modifying any component of the graphs by double clicking on the component (i.e. x-axis, y-axis, data, text, titles).

The Text Tool allows the Operator to add new text/titles/comments to graphs. The Zoom In Tool allows the Operator to zoom in on any part of the data and graph.

The Zoom Out Tool restores the data to the previous range before a zooming in operation was performed.

The Data Value Tool displays the digital x, y (time, distance) value of any data point on the graph.

The Line Tool allows the Operator to add a straight line to graphs. The Arrow Tool allows the Operator to add a straight arrowhead line/pointer to graphs.

The VOD Tool allows the Operator to automatically calculate the VOD for any part of the VOD graph by doing a linear regression on all of the data between any two data points on the graph.

The Delay Tool allows the Operator to automatically calculate the delay time between any two data points on the graph.

The Print Tool allows the Operator to print the active graph.


5.6 CURRENT POINT TOOLS BAR The Current Point Tools Bar contains three (3) data display windows and several buttons. The purpose of the Current Tools Bar is to allow the Operator to use the Data Value Tool (Section 5.4) to display and store two data points for conducting analysis. The Tools Bar can be moved anywhere on the Desktop. The Current Points Tools Bar does not need to be utilized to analyze VOD graphs if the Operator prefers only to utilize the VOD Tool and Delay Tool in the Tools Bar. The top data display window displays the most recent point (Time, Y-axis value) that was clicked on the current graph. The main purpose of the other buttons is to help choose points precisely for functions that require a start and end point. The typical use for this would be: 1. Zoom in to a small area, then choose a start point. For more precision, you can right click on the graph and

choose "Plotting - Line + Point". Press the button to set it as point 1. 2. Unzoom. 3. Zoom in to another small area and choose the end point. Press the button to set it as point 2. 4. Unzoom. 5. Choose one of the 2 point functions as described below. Once this has been done, the "C" button can be pressed to copy some lines of text that describe the result of the most recent function pressed. If no functions have been pressed, but a point has been clicked, it copies the X and Y value of that point. The text can then be pasted into another application. Note that some programs, such as MS Word, erase the clipboard when they are first opened. If there is more than one graph open, the toolbar keeps track of recently clicked points for each graph. The functions calculate a result based on the chosen points (T1, Y1) and (T2, Y2). For VOD graphs, Y1 and Y2 are the Distance values for the 2 points chosen. For Scope graphs, Y1 and Y2 are the Voltage values for the 2 points chosen, or an operator-defined unit such as Pressure.

This uses Linear Regression to calculate the Velocity of Detonation between the 2 times chosen, considering all of the data between the two points. This is suitable for data that does not contain many noise spikes. This function is not available for Scope graphs.

This calculates the Velocity of Detonation between the 2 points chosen, without consideration of the data between the two points. It is suitable for noisy data sets. Usually, it is clear which points are noise (an abrupt jump to a value for 1 or 2 points, then a return to a value similar to the start or slightly

higher, since the distance is increasing). In practice, the user chooses 2 points, then checks to see if the line between them goes over most of the "non-noisy" points. If not, the line and message can then be erased by double clicking on them and choosing "erase". This function is not available for Scope graphs. If the line covers the data for part of the area examined, but not for a later part, there may be a different VOD for the early and later part of the data. Try calculating VODs for smaller sections of the data.

This calculates and displays the time between 2 points. This calculates and displays the difference in Y values between 2 points. For VOD graphs, this calculates the distance between the points. For Scope graphs, it uses the Y-axis unit chosen by the user.

If a 2 point function has been recently calculated for the current graph, this copies the relevant numbers to the clipboard. If a point has been clicked in the current graph, but no functions have been used, this copies the value for that point to the clipboard. If no points have been chosen, no data is copied.


5.7 MENU BAR

The Menu Bar contains a selection of six (6) pull down menus used to open data files and their associated graphs, save sub-graphs, print graphs, export data and graphics, move and erase bad data points, arrange graphs on the Desktop and provide access to the digital VOD Operations Manual. The Menu Bar is always located at the top of the Desktop. The basic functions of each of the pull down menus are outlined below: The File menu allows the Operator to Open data files, display the name of the Current data file, Save the current data file including the associated graphs and Exit the Analysis section of the Software.

The Graph menu allows the Operator to List the graphs associated with the current data file, Save and Rename the sub-graphs, Delete the sub-graphs, Close the sub-graphs for the current analysis session, and Print the active graph.

The Edit menu allows the Operator to Change the Axes of the graph and Copy the Graph to the computer’s memory for pasting into other Windows applications such as word-processors. Additionally the Operator can Copy the X Data and Copy the Y Data, which comprises the graph, for subsequent pasting into Windows spreadsheets.


MicroTrap VOD Data

The Analyze menu allows the Operator to Zoom in on the graph, Undo the last Zoom, Reset the graph to full range, Remove bad data points, Move bad data points, calculate a VOD using Linear Regression, calculate a VOD from 2 Points on the graph, Remove Negative Distance Changes on a graph, calculate a Y value Difference and calculate a time Delay.

The Remove and Remove Negative Distances Changes menu items can be used on data points that sometimes result from inefficient shorting of the probe, causing downward spikes in the data. For example, when explosives react very slowly, there may be inefficient shorting of the probe. This may result in a graph similar to that shown which is a VOD record from a MicroTrap Explosives Continuous VOD Recorder. The trend of the VOD is apparent, however there are many downward spikes on the trace; this makes the normal Calculate VOD using the Linear Regression inaccurate. In such cases the Operator can Calculate VOD From 2 Points from the Analyze menu. The Remove Negative Distance Changes item allows the Operator to improve the appearance of the graph for presentation purposes in an automated fashion.


The Window menu allows the Operator to automatically arrange the non-minimized graphs on the Desktop in three (3) ways: Cascade, tile Vertically, and tile Horizontally. This menu also allows the Operator to automatically Arrange the minimized graph icons.

The Help menu allows the Operator to access the Adobe Acrobat format of this MicroTrap VOD Operations Manual on his computer. The Operator must have Adobe Acrobat Reader Software to read and print the VOD Operations Manual. The Adobe Acrobat Reader Software is available free of charge from the Adobe Internet web site at www.adobe.com. The Help menu also displays information About the MicroTrap Software, including contact information for MREL.




6.1 SAMPLE OF EXPLOSIVES – DETONATING CORD EXAMPLE This Section presents a detailed analysis of a VOD test performed on a sample of detonating cord using a PROBEROD. The Operator is encouraged to follow the example using the MicroTrap Software. As outlined in Section 4.3, a typical VOD test of an explosive sample is shown below.

In the following example, the explosive sample is a length of detonating cord that has been taped along the length of a PROBEROD. The procedure to select a MicroTrap file for analysis is as follows: 1. From the Main Menu click on the Analyze Data button

or with the keyboard press Alt-A. 2. Click on the file name Example Detonating Cord. 3. Click on the Open button, which automatically starts

the MicroTrap Advanced Analytical Software.


CHAPTER 6: EXAMPLES OF VOD DATA ANALYSIS


The following window will be shown after all the graphs in the file have been loaded. Click on OK or press Enter.

Maximizing the Original VOD graph and moving the Tools Bar, results in the screen shown below:

MicroTrap VOD Data


The graph shows a line plot of distance versus time for the complete duration of a VOD test. The length of the detonating cord and PROBEROD is approximately 0.9 m. The data was collected with a MicroTrap that has the MicroTrap Memory Upgrade installed (8,000,000 data points recorded). The Recording Rate was 1 MHz. The graph has two time areas: before time = 0 (pre-trigger time) and after time = 0 (post-trigger time). In all VOD tests, the MicroTrap is triggered to begin recording at time = 0 but has a pre-trigger data memory before time = 0 (Section 4.9). This allows the MicroTrap to record the information from the probe as it is being consumed to the probe length at which the MicroTrap will trigger. The MicroTrap records post-trigger data after time = 0. Since only a sample of explosive was tested, and the time for the explosive to detonate (approximately 0.15 ms) is far less than the total time that the MicroTrap records, a large amount of extra data was recorded after the detonation. Using the Zoom In Tool (Section 5.5), the Operator can focus on the area of interest: the part of the graph that shows the explosive detonating. The following screen shows results from zooming in several times on the data of interest. If the wrong area is chosen, use the Zoom Out Tool to undo the previous Zoom In.

MicroTrap VOD Data


To analyze the data for VOD, choose the VOD Tool (Section 5.5). The Software calculates the VOD by conducting a linear regression on the data contained between two data points chosen by the Operator. The Software prompts the Operator to click on the “first” data point and then on the “second” data point, thus defining a data range for the VOD calculation. The Operator will know when he/she is on a data point as the arrow will change to a hand. The VOD result is automatically shown with a colored straight VOD line over the data range of interest. The Operator can perform an unlimited number of VOD analyses on a graph. The VOD text can be chosen with the Select Tool for moving. By double clicking on the VOD text and VOD line with the Select Tool, the Operator can change the properties of these items or delete them.

The Text Tool (Section 5.5) can be used to add additional comments on the graph. When the graph has been annotated to the satisfaction of the Operator, the graph can be saved as a sub-graph. The Operator cannot overwrite the Original VOD graph that contains the original data and graphics. The Operator chooses Graph-Save As and then types in a name for the sub-graph. This sub-graph will be stored with the Example file and will be automatically opened along with the Original VOD graph the next time the Example file is chosen for analysis. The Operator may wish to copy the graph into a Windows word-processor for a report. To do this the Operator chooses Edit-Copy Graph from the Menu Bar. The Operator can then minimize the MicroTrap Software, open the word-processor and Paste the graph. To print directly from the MicroTrap Software, the Operator can either use the Print Tool or select Graph-Print from the Menu Bar.

MicroTrap VOD Data


To change the format of the graph, the x and y-axis, plot type etc… use the Select Tool (Section 5.5) to double click on the graph window. Double clicking with this tool on the graph window, axis titles and other objects allows some changes to be made to the attributes of these items. In the screen below, the Select Tool was used to double click on the graph window. The following window is displayed. Under the Plot tab, the property of the graph was changed to display data points only.

MicroTrap VOD Data


On the next screen, for interest only, the graph with the VOD analysis has been enlarged further using the Zoom In Tool. The Data Value Tool (Section 5.5) has been used to click on the graph to find the distance at which time = 0. The x, y (time, distance) coordinates of this point are shown in the Current Point Window. Notice that when the Data Value Tool is chosen, an arrow appears and in the upper left corner of the graph, the position of the arrow on the graph window is displayed (x, y). When the arrow is placed over the graph line, the arrow will change to a hand. When the Operator clicks on the graph line then the Current Point Window displays the value of the data point on the graph line. Note: the arrow and hand cursors are not shown on the screen below.

The Operator is encouraged to experiment with analyzing, formatting and printing the data and graphs contained in the Example file. Note: changes are made to the data in the sub-graphs; the Original VOD graph cannot be changed and will always be available for subsequent analyses.

MicroTrap VOD Data


-0.1 0.0 0.1 0.2 0.3 0.40.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

VOD in this region is 4,510 m/s

Explosive Begins to Fail at 0.36 meters

Explosive Fails to Detonate Fully

VOD RESULT FOR AN EXPLOSIVES SAMPLE- 0.9 METER LONG UNCONFINED SAMPLE -

Dis

tanc

e (m

)

Time (ms)

6.2 SAMPLE OF EXPLOSIVES – OTHER EXAMPLES The following examples are provided as an illustration of the VOD analysis capabilities of the MicroTrap when the Operator is testing samples of explosives. This result is typical for an explosive failing to detonate completely. This result illustrates the effect of confining the explosive in Schedule 40 steel pipe (a standard substitute for rock). The explosive detonates fully when loaded in steel pipe but fails when unconfined as shown in the previous graph.

-0.10 -0.05 0.00 0.05 0.10 0.15 0.200.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

AVERAGE VOD = 4,540 m/s

VOD RESULT FOR AN EXPLOSIVES SAMPLE- 0.9 METER LONG STEEL CONFINED SAMPLE -

Dis

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e (m

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Time (ms)


The following is the result of a VOD test on unconfined bulk explosive. It can be observed that a second booster was placed in the explosive column that had not been tied into the shot exploder. As can be seen, the Operator can determine the VOD anywhere along the 0.9 m long unconfined sample.


0 ms

25 ms

50 ms

84 ms

109 ms

134 ms

126 ms

151 ms

176 ms

168 ms

193 ms

218 ms

HOLE 1HOLE 2 HOLE 3HOLE 4

To MicroTrap

6.3 EXPLOSIVES IN BLASTHOLES – MULTIPLE DECKED HOLES EXAMPLE This Section presents a detailed analysis of a VOD test performed in a quarry by a MicroTrap Customer. PROBECABLE was loaded into four 30 m long blastholes as shown in the following figure. There were 3 explosive decks in each of the holes. There were 42 ms delays between holes and the 3 decks were designed to fire at 25 ms intervals starting with the bottom deck. The relative design delay times as pertaining to the 4 holes loaded with PROBECABLE are shown. Notice that the top decks of Holes 2 and 3 would not be recorded by the MicroTrap as bottom decks in subsequent holes would fire first, thus cutting off the PROBECABLE. The MicroTrap Customer had blasting vibration concerns and wanted to ensure that the decks of explosives were detonating at the designed times. The Operator is encouraged to follow the example using the MicroTrap Software. The procedure to select a MicroTrap file for analysis is as follows: 1. From the Main Menu click on the Analyze Data button or with

the keyboard press Alt-A. 2. Click on the file name Example Multiple Decked Holes. 3. Click on the Open button, which automatically starts the

MicroTrap Advanced Analytical Software.


The following window will be shown after all the graphs in the file have been loaded. Click on OK.

Maximizing the Original VOD graph, and moving the Tools Bar, results in the screen shown below:

MicroTrap VOD Data


The graph shows a line plot of distance versus time for the complete duration of a VOD test. The total length of the PROBECABLE was approximately 260 m. The data was collected with a MicroTrap with standard memory (4,000,000 data points recorded). The Recording Rate was 2 MHz. It is important when viewing VOD graphs from tests in blastholes to focus in on the leading edges of the data where the data changes distance quickly. In this example, 4 holes were recorded. As the second and subsequent holes detonate, the booster cuts the PROBECABLE resulting in a large increase in the graph distance instantaneously. During the delay periods between decks of explosives, between delayed holes, and after all of the holes have detonated, the end of the PROBECABLE or coaxial cable may become intermittently short circuited or open circuited causing noise on the VOD graph. This is a normal occurrence. There are no VOD data in the noise. On first glance, the locations of the holes and the noise after the holes have detonated can be approximated as shown below.

MicroTrap VOD Data


Using the Zoom In Tool, the Operator can focus on the area of interest: the part of the graph that shows the four holes detonating more clearly. If the wrong area is chosen, use the Zoom Out Tool to undo the previous Zoom In.

MicroTrap VOD Data


VOD = 3990 m/s

6.0 m column

VOD = 3820 m/s

10.1 m column

Delay = 16.2 ms

Channel 1VOD Data - EVENTS #1 #2

Dist

ance

(m)

Time (ms)

10.0

12.5

15.0

17.5

20.0

22.5

25.0

27.5

30.0

32.5

-92.5 -90.0 -87.5 -85.0 -82.5 -80.0 -77.5 -75.0

MicroTrap

MicroTrap

The following graphs show results from zooming in several times on each of the hole locations. If the wrong area is chosen, use the Zoom Out Tool to undo the previous Zoom In. The VOD Tool and Delay Tool have been used to determine the average VOD of the explosive decks, and the delay times between decks and holes. When the regression VOD line (from the VOD Tool) does not appear to fit the VOD data properly due to the influence of noise on the trace, then use the Calculate VOD from 2 Points from the Analyze menu. For purposes of this example, “Event” is used to describe a VOD trace. Events 1 and 2 correspond to the middle and top decks of Hole #1 respectively. Delay between these decks was designed to be 25 ms. The delay achieved was 16.2 ms. Notice that there was no record for the bottom deck and that initiation of the middle deck cut off the PROBECABLE at approx. the 10.8 m mark. Therefore the firing sequence in Hole #1 was: Middle deck fires, 16.2 ms delay, top deck fires. The bottom deck could have shot any time after (or at the same time as) the middle deck. Notice the noise between the decks as the PROBECABLE is being partially consumed/shorted by the pressures from the middle deck travelling through the stemming towards the top deck. If the detonation of the middle deck had caused sympathetic detonation of the top deck, then the delay time between these two events would have been significantly shorter than 16.2 ms. This result demonstrates that sympathetic detonation of the top deck by the middle deck did not occur in this blasthole. Event 3 occurs 76.4 ms after Event 2. This timing leads MREL to believe that it is the top deck in the Hole #2 which was designed to fire 84 ms after Event 2 (the top deck in Hole #1). When Event 3 occurs it cuts the PROBECABLE such that 87.8 m of the original length of PROBECABLE has been consumed. The Customer did not record the explosive column rises as each deck was loaded, so MREL cannot confirm that this trace is from the top deck of Hole #2 or the middle deck of Hole #2.


VOD = 3930 m/s

9.6 m column

163

164

165

166

167

168

169

170

171

172

173

174

175

36.5 37.0 37.5 38.0 38.5 39.0

Channel 1VOD Data - EVENT #4

Dist

ance

(m)

Time (ms)

MicroTrap

12 m column

VOD = 4185 m/s

242.5

245.0

247.5

250.0

252.5

255.0

68.0 68.5 69.0 69.5 70.0 70.5


Dist

ance

(m)

Time (ms)

MicroTrap

When Event 4 begins, the position corresponds to 164.3 m of PROBECABLE being consumed. It occurs 35.9 ms after Event 3. Of course without knowing the explosive column lengths, it is not possible to confirm that Event 4 corresponds to the middle Deck of Hole #3. Event #5 is the middle deck of Hole #4. Event #6 (next page) is the final event and therefore corresponds to the top Deck of Hole #4. It is apparent that the middle deck of Hole #4 fired before the bottom deck. Event #5 occurs 31.3 ms after Event #4, which lends support to Event #4 being the middle deck of Hole #3. This would indicate that the middle deck of Hole #3 fired before the bottom deck of Hole #3.


VOD = 4071 m/s

1.4 m column

258.0

258.5

259.0

259.5

260.0

126.25 126.30 126.35 126.40 126.45 126.50 126.55 126.60 126.65 126.70 126.75 126.80


Dis

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)

Time (ms)

MicroTrap Event #6 corresponds to the top deck of Hole 4. This is known because it is the last event recorded by the MicroTrap and the MicroTrap recorded for at least a second after this event occurred. Summarizing the relative designed firing times and recorded firing times:

Hole

# Deck Design Delay Time (ms) Recorded Delay Time (ms)

1 Bottom 0 After the middle deck Middle 25 0 (-92.6 ms on graph) Top 50 16.3 (-76.4 ms on graph)

2 Bottom 84 After the middle deck Middle 109 92.7 (0.1 ms on graph) Top 134 not recorded by design

3 Bottom 126 After the middle deck Middle 151 128.7 (36.1 ms on graph) Top 176 not recorded by design

4 Bottom 168 After the middle deck Middle 193 160 (67.4 ms on graph) Top 218 218.9 (126.3 ms on graph)

Recommendations: 1. When conducting VOD recordings of multiple decked holes, the explosive column rise and decking material

rise should be recorded for each deck to give an accurate hole profile. This makes correlating the VOD results to the correct deck much easier.

2. Ensure that the blast is tied-in correctly. Other than Hole 1, the middle deck seems to consistently fire before the bottom deck.

3. No sympathetic detonation between explosives decks was observed. No desensitization of the explosive decks, due to previous decks/holes firing, was observed.

The Operator is encouraged to experiment with analyzing, formatting and printing the data and graphs contained in the Example file. No matter what changes are made to the data in the sub-graphs, the Original VOD graph cannot be changed and will always be available for subsequent analyses.


6.4 EXPLOSIVES IN BLASTHOLES – OTHER EXAMPLES The following examples are provided as an illustration of the VOD analysis capabilities of the MicroTrap when the Operator is testing explosives in blastholes. As detailed in Section 4.4.1, a typical VOD test on a single blasthole using PROBECABLE is shown. The length of the explosive column is approximately 18 m. Since only one hole was tested, and the time for the explosive to detonate (approximately 5 ms) is far less than the total amount of time the MicroTrap records, a large amount of extra data was recorded after the detonation in the hole was complete. Using the Zoom In Tool, the Operator can focus on the area of interest: the part of the graph that shows the explosive detonating. The Operator can determine the run-up VOD of the explosive and what distance it takes for the explosive to reach full detonation velocity. In this way, the effect of using different sizes of boosters can be evaluated.

Coaxial Cable To MicroTrap


As detailed in Section 4.4.2, a typical VOD test on multiple (3 in this case) blastholes using PROBECABLE is shown. Three 10 m holes were monitored. Each hole contained a column of approximately 5 m of explosives and the blast was tied in with a 17ms delay between holes. Notice on the diagram that the PROBECABLE in Hole 1 was not terminated at the booster but was run down and out of the hole in a method similar to Holes 2 and 3. In this way, the detonation of the booster in Hole 1 immediately cuts off or shortens the PROBECABLE by 10 m thereby assuring that the MicroTrap will be triggered to record (time = 0) upon the booster in Hole 1 firing. This is evident on the graph. Also notice that if Hole 2 fired before Hole 1 then approximately 35 m of PROBECABLE (comprised of 20 m in Hole 1 + 5 m spacing between holes + 10 m in Hole 2) would have been cut off. Of course, in that case no data would have been recorded for Hole 1, only for Holes 2 and 3. The data can be analyzed to determine the actual delays between holes and the VODs of the explosives in each of the holes.

0 5 10 15 20 25 30 35 400

10

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30

40

50

60

70

80

Dis

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Time ( ms )



The Delay Tool is used to determine the delays between holes. The Software calculates the delay time by measuring the difference in time between two data points chosen by the Operator. The Software prompts the Operator to click on the “first” data point and then on the “second” data point, thus defining a data range for the delay calculation. The delay result is automatically shown with a colored line over the data range of interest. The Operator can perform an unlimited number of delay analyses on a graph. The delay text and line can be chosen with the Select Tool for moving or deleting. The colours and properties of these items can be changed or the item can be deleted by double clicking with the Select Tool. Delay times between Holes 1 and 2, and 2 and 3 are shown on the graph.

The Operator can zoom in on each of the three holes to calculate the VODs in each hole and save the zoomed VOD results for each hole as sub-graphs as illustrated on the following page.

-5 0 5 10 15 20 25 30 35 40 450

10

20

30

40

50

60

70

21.7 ms delay17.6 ms delay

Hole #3

Hole #2

Hole #1 Dis

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Time (ms)


-0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.60

2

4

6

8

10

12

14

16

18

VOD = 5,335 m/s

DOWN-THE-HOLE VOD RESULT- AVG. VOD FOR HOLE #1 -

Dis

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)

Time (ms)

17.4 17.6 17.8 18.0 18.2 18.4 18.6 18.830

32

34

36

38

40

42

44

VOD = 4,835 m/s


Dis

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)

Time (ms)

39.0 39.2 39.4 39.6 39.8 40.0 40.2 40.4 40.6 40.8 41.0

58

60

62

64

66

68

VOD = 4890 m/s


Dis

tanc

e (m

)

Time (ms)




7.1 CONTACTING MREL MREL GROUP OF COMPANINES LIMITED Blasting Instrumentation Team 1555 Sydenham Road Kingston, Ontario K7L 4V4 Canada Toll Free Canada/USA: 1-877-544-MREL Tel: +1-613-545-0466 Fax: +1-613-542-8029 Email: [email protected] 7.2 EMAILING MICROTRAP FILES TO MREL It is an easy procedure to send a MicroTrap file for its analysis/review by another Operator who also has the MicroTrap Software. When a file is saved on a computer, the file name takes the form of filename.filetype, otherwise known as root.extension. When a MicroTrap file is saved using a name chosen by the Operator (for example: test), several files with different filetypes are automatically created by the MicroTrap Software all with the same filename, test. To email a MicroTrap file called "Example", attach the entire MicroTrap files with the same filename, to the email. It is better if all of the files are contained in one ZIP file for transfer by email, particularly if the MicroTrap data were not compressed when downloaded to your computer. Normally MREL only requires the *.mcr and *.raw or *.cmp files to conduct an analysis. If you want MREL to review the sub-graphs you have saved containing VOD analyses you have performed on the original data, then all of the files below will be required. For example: Example.mcr (the MicroTrap settings file, which is a readable text file). MREL requires this file. Example.raw (the MicroTrap data file if the data were not compressed). MREL requires this or the *.cmp file. Example.cmp (the MicroTrap data file if the data were compressed). MREL requires this or the *.raw file. Example.plot001, Example.plot002 etc… (the series of sub-graph files the Operator saved during analysis) Example.r01 (the data points removed from a sub-graph by the Operator) Example.ml001 (the series of x values of data points moved in a sub-graph by the Operator) Example.mv.001 (the series of new y values of data points moved in a sub-graph by the Operator) When giving files to another person on CD-ROM, the files can only be viewed. To modify the files, they must be copied to the computer's hard drive and the files must be changed from Read Only using Windows procedures. As part of MREL’s ongoing commitment to Customer Satisfaction, MREL VOD Specialists will be pleased to review your analysis of your MicroTrap data. If you would like to have a “second opinion” from MREL on your analysis of a specific test, send an email to [email protected] with a brief description of the test and attach all of the files. MREL looks forward to providing you with assistance.

CHAPTER 7: CONTACTING MREL FOR TECHNICAL SUPPORT



Documents

MicroTrap VOD Operations Manual Revision 4-2-1