The development of the testing protocol reported in this publication results from a joint research project between Natural Resources Canada (CanmetCERL, Explosives R&#38;D Section) and Orica Mining Services. Permission of Orica Mining Services to publish non-proprietary information on this subject is fully acknowledged. The participation of CanmetCERL&#39;s Analytical Section to the physical characterization of the various AWEs prepared throughout the present work is also gratefully acknowledged.

NOTE: The materials and equipment used here are listed in the Table of Materials.
1. Preparation of Ignition Wire Assemblies
NOTE: Wearing nitrile gloves is recommended for this operation.
<ol>
	<li>Measure a pre-determined length of nichrome (NiCr) wire and cut using a wire cutter. Cut 85 mm lengths for 76.2 mm (3&#34;) long test cells.</li>
	<li>Using needle nose pliers, bend the NiCr wire to make a small loop at each end. With a proper crimping tool, splice each one into 50 cm length of 14 American Wire Gauge (AWG) solid core bare copper wire using uninsulated butt-end splice connectors.</li>
	<li>Repeat Step 1.1-1.2 to make as many assemblies as required. 
	NOTE: It is recommended to prepare several assemblies in advance as each MBP measurement will take 10 to 15 assemblies). A completed wire assembly is shown in Figure 1. If all wires are correctly spliced and crimped to the connector, the resistance measured across the wire assembly (as measured on the copper conductors on either side of the NiCr wire) must be less than 0.5 &#937;.</li>
</ol>
2. Sample and Test Cell Preparation
NOTE: Wearing nitrile gloves is recommended for this operation.
<ol>
	<li>Prepare test cells each consisting of a small cylindrical steel pipe with a length of 7.6 cm and an internal diameter of at least 1.6 cm. Ensure that each test cell has a 3 mm-wide slit machined along the axis to allow combustion gases to escape during the tests. 
	NOTE: AWEs are electrically conductive.</li>
	<li>To ensure that all the ignition current will go through the ignition wire, paint the interior of each cell with two coats of high-temperature non-conductive paint. Prepare several test cells in advance.</li>
	<li>Prepare several No. 0 neoprene stoppers by reaming the inside face to accommodate the splice connectors and the copper conductors of the ignition wire assembly.</li>
	<li>Use the horizontal slit on the test cell to insert the ignition wire into the middle of the cell. Carefully slide a prepared neoprene stopper along each copper wire and insert them into each end of the cell, ensuring that the ignition wire is not compressed or twisted.</li>
	<li>Pull the ignition wire taut and bend the copper leg-wires vertically to secure them (Figure 2, Figure 3).</li>
	<li>Introduce the sample into the cell through the 3 mm-wide slit with caution to avoid causing crystallization of the sample and introducing air voids in the sample. Use a spatula to tamp down the emulsion to remove air voids if necessary. Quickly tap the cell repeatedly on a countertop to ensure that the emulsion settles into voids. Repeat filling, tamping, and tapping until the emulsion no longer settles any further.</li>
</ol>
3. Loading Sample in Pressure Vessel
<ol>
	<li>Prepare a pressure vessel with the following characteristics to load the sample cell: an operating pressure resistance of 20.7 MPa (or 3,000 psig) (see the Table of Materials), made of stainless steel to avoid long-term corrosion damage from the gaseous reaction products, equipped with two insulated rigid feedthrough electrodes capable of carrying an electric current up to 20 A, and sealed to have a pressure rating equivalent to that of the vessel itself.
	<ol>
		<li>For safety reasons, install the vessel in a protected test room equipped with a rupture disc assembly (see the Table of Materials) designed to vent the vessel at a pressure slightly lower than its maximum operating pressure.</li>
		<li>In order to vent the vessel after a test, equip the gas outlet with a high-pressure valve that can be operated remotely. 
		NOTE: This can be achieved in various ways. For example, it can be achieved using a solenoid valve/air operated valve combination. The inlet of the vessel must be connected to a gas manifold system operated from a nearby protected room capable of remotely pressurizing the pressure vessel to a chosen initial pressure using a pressurized cylinder of argon (nitrogen may be an alternative but may not be as inert). This manifold would be typically custom made out of high-pressure stainless-steel tubing, and high-pressure compression fittings and valves. It is recommended that the vessel also be equipped with a 0-20.7 MPa (0-3,000 psig) pressure transducer.</li>
	</ol>
	</li>
	<li>Introduce a test cell with sample (prepared in section 2) into the pressure vessel. Position its long axis horizontally with the slit on the top (Figure 2). Connect the bare copper wires to the electrodes inside the vessel. Ensure the former are not touching the body of the vessel. Close and seal the pressure vessel.</li>
	<li>Using the multimeter ensure there is no electrical contact between each electrode and the body of the pressure vessel. 
	NOTE: If any contact is detected between an electrode and the body of the vessel, its cause(s) must be determined and actions must be taken to eliminate it before testing can proceed.</li>
</ol>
4. Performing a Test
<ol>
	<li>In the protected room, connect the signal from the pressure transducer to the data acquisition (see the Table of Materials) or available oscilloscope. Also, connect the voltage across the high precision shunt resistor to the data acquisition (or oscilloscope). Ensure that this shunt resistor is also connected in series with a constant current source. Connect the series to the electrodes on the pressure vessel to supply a constant current through the NiCr wire. 
	NOTE: Knowing its resistance, the voltage across this shunt resistor provides a measurement of the ignition current.</li>
	<li>Start the PC-based data acquisition system (or available oscilloscope).</li>
	<li>Remotely close the vessel&#39;s outlet valve (see section 3.1 Note). Using a pressurized argon cylinder in the instrument room and the gas manifold (described in section 3), start pressurizing the vessel to the required initial pressure for the test. 
	NOTE: Depending on the formulation of the AWE, this pressure can vary anywhere from 0.3 to 19.3 MPa (50 to 2500 psig). If this is the first test with a given AWE product, make an educated guess of the MBP, based on the formulation of the sample, to decide at what pressure this first test must be performed.
	<ol>
		<li>Once pressurization is achieved, close the vessel&#39;s inlet valve and leave the vessel pressurized for 5 to 10 min to check that the system has no significant leaks. Once this is established, re-open the inlet valve, adjust the pressure to the chosen initial value, and re-close the inlet valve. If a significant leak rate is detected, postpone testing until required maintenance has been performed.</li>
	</ol>
	</li>
	<li>Turn on the constant current source and allow a 10.5 A current to flow through the ignition wire. Keep the current on until the sample ignites and melts the ignition wire, stopping the flow of current; this is expected to take a few s. Turn the power supply off after ignition has taken place and the pressure has started to increase. 
	NOTE: The pressure may go through one or two minima and maxima and should start to decrease continuously. When this has happened, wait for an extra 10 min before doing anything.</li>
	<li>Once the test is completed, remotely open the outlet valve and vent all combustion gases to an appropriate exhaust system. Slowly purge with argon for a few min to remove all toxic gas species before opening the vessel. Ensure the vessel is back to ambient pressure before re-entering the test room.</li>
	<li>Lock out the constant current power supply (either using a lock out key or unplugging it from the AC power) and walk to the pressure vessel room. Wearing a face mask with appropriate general-purpose cartridge, open the vessel. Recuperate the test cell by undoing the copper conductors from the electrodes and note down all visual observations.
	<ol>
		<li>By removing the neoprene stoppers try to observe how much of the sample has burned. Further document these observations by taking photographs. Once finished, clean the vessel thoroughly (see section 6). 
		NOTE: From these observations, if the sample has burned completely (combustion front reached the wall of the test cell; small amount of sample can be left on the neoprene stoppers), the result is deemed to be a &#39;go&#39;. Decrease the pressure for the next test. Otherwise the result is deemed to be a &#39;no-go&#39; and the pressure must be increased for the next test (see typical observations in Figure 4A). The pressure record from the transducer can also be used as evidence of sustained combustion or not (Figure 4B).</li>
	</ol>
	</li>
	<li>Use the steps outlined in section 5 below to analyse the acquired current and pressure data. Repeat steps 4.1 to 4.6 while gradually decreasing the pressure increments (or decrements) until the MBP has been determined to the desired degree of precision (see typical examples in Figure 5).
	<ol>
		<li>Perform a minimum of 10 to 12 tests using this &#39;up-and-down&#39; methodology. 
		NOTE: The quoted MBP must be the mean between the initial pressure of the highest &#39;no-go&#39; event (Pn,max) and that of the lowest &#39;go&#39; event (Pg,min) (Figure 5). The error bar on the measured MBP must be specified as: 
		<img alt="Equation" src="/files/ftp_upload/56167/56167eq1.jpg" /></li>
	</ol>
	</li>
</ol>
5. Data Analysis
NOTE: See Figure 6 for an example of a graph showing an analyzed MBP experiment.
<ol>
	<li>First determine the time, t0, when the ignition wire was turned on (current suddenly increases to 10.5 A). Determine the time when the ignition wire burned out (current suddenly returns to 0), tb. Record the difference &#916;tw = tb &#8211; t0 as the &#34;wire lasted&#34; time.</li>
	<li>Determine the average ignition wire current, Iiw; this is the average of all the data points of the current record between t0 and tb. Determine the time when the pressure trace first deviates from the initial baseline, tp0. Record the difference &#916;tp = tp0 &#8211; t0 as the &#34;Time to Pressure Rise&#34;.</li>
	<li>Determine the average initial pressure, Pi; this is the average of all the data points of the pressure record between t0 and tp0. Determine the maximum pressure, Pmax; this is the maximum value of the pressure record. 
	NOTE: The pressure trace may contain several minima and maxima.</li>
	<li>Locate the last maximum (just before the pressure starts to continuously decrease when burning is complete); this is the burn stop time (ts). Calculate the difference &#916;tb = ts &#8211; tp0 and enter it as the &#34;Burn Time&#34;.</li>
</ol>
6. Cleaning up
<ol>
	<li>Clean and reuse the test cells as much as possible. Dispose of a test cell whenever it is found that solid residues are very difficult to clean out. Clean the cells with water, ethanol and paper towel. If the non-conductive paint is damaged, repaint the cell before re-using it. 
	NOTE: Using soap or any detergent to clean the cells is not recommended because detergent residues may destabilize the surfactant in some emulsion formulations.</li>
	<li>Clean the vessel after each run. 
	NOTE: Wearing a face mask with appropriate general-purpose cartridges is recommended for the person cleaning the vessel. Certain formulations, especially those that contain chemical sensitizers, may create more irritating residues than others.</li>
	<li>Remove dirt and moisture from the pressure vessel using paper towels, applying water or ethanol as required. Ensure that the electrodes are cleaned in a similar manner, including the washers and nuts.</li>
	<li>At the end of the day, return all unused sample material and wastes to an appropriate storage location (usually an explosives magazine).</li>
	<li>Turn off the data acquisition system and computer (or storage oscilloscope).</li>
	<li>Close the main valve on the argon (or nitrogen) cylinder and bleed the argon (or nitrogen) lines.</li>
</ol>

<ol>
	<li>Bluhm, H. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ammonium+nitrate+emulsion+blasting+agent+and+method+of+preparing+same.">Ammonium nitrate emulsion blasting agent and method of preparing same.</a> US Patent. , (1969).</li><li>Persson, P. -. A., Holmberg, R., Lee, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Rock Blasting and Explosives Engineering. , 86 (1993).</li><li>Perlid, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pump+Safety+Tests+Regarding+Emulsion+Explosives.">Pump Safety Tests Regarding Emulsion Explosives.</a> Proceedings of the 22nd Annual Conference on Explosives and Blasting Techniques, International Society of Explosives Engineers. 2, 101-107 (1996).</li><li>Chan, S. K., Kirchnerova, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ignition+and+Combustion+Characteristics+of+Water-gel+Explosives.">Ignition and Combustion Characteristics of Water-gel Explosives.</a> Proceedings of the 18th Explosives Safety Seminar, U.S. DOD. , 193-200 (1978).</li><li>Guidelines for the Pumping of Water-Based Explosives. Natural Resources Canada, Explosives Regulatory Division, Minister of Public Works and Government Services Canada, Catalog no. M37-53/2003E Available from: <a target="_blank" href="https://miningandblasting.files.wordpress.com/2009/09/canadian-guidelines-for-pumping-of-water-based-explosives.pdf">https://miningandblasting.files.wordpress.com/2009/09/canadian-guidelines-for-pumping-of-water-based-explosives.pdf</a> (2016)</li><li>. Guidelines for the Pumping of Bulk, Water-Based Explosives Available from: <a target="_blank" href="https://miningandblasting.files.wordpress.com/2009/09/pumping-of-water-based-explosives-june-2010.pdf">https://miningandblasting.files.wordpress.com/2009/09/pumping-of-water-based-explosives-june-2010.pdf</a> (2010)</li><li>Wang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Ignition and Combustion Characteristics of Emulsion Explosives under Pressure. , (1991).</li><li>Hirosaki, Y., Suzuki, S., Takahashi, Y., Kato, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Burning+Characteristics+of+Emulsion+Explosives+(I)+–+Pressurized+Vessel+Test.">Burning Characteristics of Emulsion Explosives (I) – Pressurized Vessel Test.</a> Kayaku Gakkaishi. 61, 35-41 (2000).</li><li>Turcotte, R., Lightfoot, P. D., Badeen, C. M., Vachon, M., Jones, D. E. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Pressurized+Vessel+Test+to+Measure+the+Minimum+Burning+Pressure+of+Water-Based+Explosives.">A Pressurized Vessel Test to Measure the Minimum Burning Pressure of Water-Based Explosives.</a> Propellants, Explos., Pyrotech. 30, 118-126 (2005).</li><li>Turcotte, R., Goldthorp, S., Badeen, C., Chan, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hot-wire+Ignition+of+AN-based+Emulsions.">Hot-wire Ignition of AN-based Emulsions.</a> Propellants, Explos., Pyrotech. 33, 472-481 (2008).</li><li>Chan, S. K., Turcotte, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Onset+Temperatures+in+Hot-wire+Ignition+of+AN-Based+Emulsions.">Onset Temperatures in Hot-wire Ignition of AN-Based Emulsions.</a> Propellants, Explos., Pyrotech. 34, 41-49 (2009).</li><li>Goldthorp, S., Turcotte, R., Badeen, C. M., Chan, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Minimum+Pressure+for+Sustained+Combustion+in+AN-based+Emulsions.">Minimum Pressure for Sustained Combustion in AN-based Emulsions.</a> Proceedings of the 35th International Pyrotechnics Seminar. , 385-394 (2008).</li><li>Turcotte, R., Goldthorp, S., Badeen, C. M., Feng, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+Physical+Characteristics+and+Ingredients+on+the+Minimum+Burning+Pressure+of+Ammonium+Nitrate+Emulsions.">Influence of Physical Characteristics and Ingredients on the Minimum Burning Pressure of Ammonium Nitrate Emulsions.</a> Propellants, Explos., Pyrotech. 35, 233-239 (2010).</li><li>Badeen, C. M., Goldthorp, S., Turcotte, R., Feng, H., Chan, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+Formulation+Changes+on+the+Minimum+Burning+Pressure+of+Ammonium+Nitrate+Emulsions.">Effect of Formulation Changes on the Minimum Burning Pressure of Ammonium Nitrate Emulsions.</a> Proceedings of the "10i&#232;me Congr&#232;s International de Pyrotechnie", in conjunction with the 37th International Pyrotechnics Seminar (Europyro 2011) , Session S1a. , (2011).</li><li>Turcotte, R., Goldthorp, S., Badeen, C. M., Johnson, C., Feng, H., Chan, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+Physical+Characteristics+and+Ingredients+on+the+Minimum+Burning+Pressure+of+Ammonium+Nitrate+Emulsions.">Influence of Physical Characteristics and Ingredients on the Minimum Burning Pressure of Ammonium Nitrate Emulsions.</a> , 197-206 (2009).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Recommendations on the Transport of Dangerous Goods, Manual of Tests and Criteria. , 200-207 (2015).</li><li>The Minimum Burning Test for Ammonium Nitrate Emulsions. SAFEX Newsletter Available from: <a target="_blank" href="https://www.safex-international.org/safex/page-newsletter.html">https://www.safex-international.org/safex/page-newsletter.html</a> (2016)</li></ol>

The authors declare that they have no competing financial interests.

Our work demonstrated that the linear hot-wire geometry with 0.5 mm diameter NiCr straight wire and 10 to 16 A ignition current was adequate to ignite AWEs with water contents up to 25 mass %. For high viscosity formulations (such as packaged emulsion products), horizontal and vertical configurations provide almost identical results 17. However, for low viscosity formulae (such as bulk emulsion products) gravity effects in vertical configuration induce emulsion flow which disturbs the ignition pro...

The ammonium nitrate water-based emulsion (AWE) explosive was invented in 1961. It consists of microscopic droplets of a liquid oxidizer solution surrounded by a continuous oil phase. The first stable and practically useful emulsion blasting explosive was developed by Harold F. Bluhm in the USA (1969) 1,2. However, the successful commercialization of this type of explosive did not really happen before the beginning of the 1980s.
With the large scale of modern mining operations and the advent of fast bulk explosive loading methodology, very large volumes of AWE explosives have to be manufactured and transported. One tanker load typically transports 20 tons of AWE and many such truck loads are usually necessary to load only one blast. Accidental initiation of such large quantities of explosives would be particularly disastrous and, therefore, a good knowledge of their hazardous properties is required to design corresponding safe handling systems. While it is well known that emulsions are relatively insensitive to mechanical events (i.e. impact and friction events), accidental explosions have still been reported 3 while handling this type of explosive, particularly in pumping applications.
It has been known since the 1970&#39;s 4 that a minimum ambient pressure is required for self-sustained combustion to take place into water-based explosives. This latter value has usually been termed the &#34;Minimum Burning Pressure&#34; (MBP). From a safety point of view, knowledge of this threshold could allow manufacturers to better estimate safe operating pressures for various handling equipment.
The Department of Natural Resources of the Government of Canada has published &#34;Guidelines for the Pumping of Water-Based explosives&#34; 5, which state that using pumping pressures well below the MBP of the emulsions or watergels is a good safety practice. It should be noticed that these guidelines were designed with the collaboration of most commercial manufacturers and that, in the USA, the Institute of Makers of Explosives (IME) has also published very similar guidelines 6. However, in these documents, there was no description or prescription on how the MBP should be measured.
In the last decades, only a few studies related to MBP measurements have been reported. Chan et al. 4 reported the results of MBP measurements for watergel explosives, which are also ammonium nitrate and water-based. They have concluded that the MBP can have a strong dependency on several formulation factors such as water content, presence of chemical sensitizers or metallic powders. In another study, Wang 7 described a 2.5 L pressure vessel pressurized with N2 and used a Bruceton up-and-down method to determine the MBP for basic AWEs. With this system, MBP values of the order of 15 MPa were measured for a basic emulsion having a water content of 16 mass %.
Using a similar pressurized vessel test, Hirosaki et al. 8 have reported the results of some MBP measurements for AWE explosives. They have noted that the nature (i.e. glass or resin) of the micro-spheres being used to sensitize the explosives also has a strong influence on the results. More recently, Turcotte et al. 9 have developed a system similar to that of Wang and Hirosaki et al. and have attempted to use it to measure the MBP of some AWEs. However, they have found many possible problems that may lead to erroneous MBP determinations. In particular, it was noted that the ignition source geometry (nichrome wire coil) had never been properly validated for AWEs. In 2008, Turcotte et al. 10 and Chan et al. 11, have developed both an apparatus based on a calibrated ignition wire system and an associated methodology to measure the MBP of AWEs. They have also used the facility to study the ignition characteristics of typical AWEs, measured the energy requirements to obtain reliable ignitions 12 and studied the influence of physical characteristics and ingredients on the MBP of a wide variety of AWE explosives 13,14. This MBP measurement technique is presently being proposed as a standard test within the United Nation Transport of Dangerous Goods (UN TDG) Tests and Criteria for the classification for transport of AWEs 15.

<table><tbody><tr><td>Nitrile gloves (100/pk)</td><td>Fisher Scientific</td><td>19149863B</td><td>https://www.fishersci.ca/shop/products/purple-nitrile-exam-gloves-6/19149863b?searchHijack=true&amp;amp;searchTerm=19149863B&amp;amp;searchType=RAPID&amp;amp;matchedCatNo=19149863B</td></tr><tr><td>NiCr60 wire 24 AWG (200 feet per roll)</td><td>Omega Engineering</td><td>NIC60-020-200</td><td>http://www.omega.ca/pptst_eng/NI60.html</td></tr><tr><td>Wire cutters: Mini Diagonal Cutting Pliers, 5 in.</td><td>Canadian Tire</td><td>Product #058-4736-0</td><td>http://www.canadiantire.ca/en/pdp/mastercraft-mini-diagonal-cutting-pliers-0584736p.html#srp</td></tr><tr><td>Mini needle nose pliers, 5 in.</td><td>Canadian Tire</td><td>Product #058-4731-0</td><td>http://www.canadiantire.ca/en/pdp/mastercraft-mini-needle-nose-pliers-0584731p.html#srp</td></tr><tr><td>Crimping tool, 8.5 in.</td><td>Canadian Tire</td><td>Product #058-4617-4</td><td>http://www.canadiantire.ca/en/pdp/mastercraft-8-in-crimping-tool-0584617p.html#srp</td></tr><tr><td>Bare copper wire (14AWG)</td><td>Electronics Plus</td><td>2000BC-14-5/5 lb roll</td><td>Bare (uninsulated) copper wire</td></tr><tr><td>Non-insulated butt-splice connectors (100 units)</td><td>Electrosonic</td><td>Panduit BS14-C</td><td>http://www.alliedelec.com/panduit-bs14-c/70044299/?mkwid=si03ezhXY&amp;amp;pcrid=64596948257&amp;amp;pkw=panduit%20bs14-c&amp;amp;pmt=b&amp;amp;pdv=c&amp;amp;gclid=CM_1jO-DsdMCFZKIswodMugASw</td></tr><tr><td>Stainless Steel pipe nipples (10 - 20 units)</td><td>Wolseley Inc.</td><td>SSNKX3</td><td>sample cells: 76.2 mm long x 12.7 mm od (3&quot; long x 0.5&quot; od) with 3 mm slit machined along the length of the cell, painted inside and out with two coats of non-conductive paint (e.g., high-heat barbeque Armor Coat or Krylon brands).</td></tr><tr><td>High-temperature non-conductive paint</td><td>Canadian Tire</td><td>Product #048-0648-8</td><td>http://www.canadiantire.ca/en/pdp/armor-coat-bbq-paint-0480648p.html#srp</td></tr><tr><td>Solid green neoprene stoppers (size 0; 1 package of 68)</td><td>Cole-Palmer</td><td>OF-62991-04</td><td>https://www.coleparmer.ca/i/cole-parmer-solid-green-neoprene-stoppers-standard-size-0-68-pk/6299104?searchterm=OF-62991-04</td></tr><tr><td>Spatula, stainless steel</td><td>Fisher Scientific</td><td>14-375-10</td><td>https://www.fishersci.ca/shop/products/fisherbrand-spoonula-lab-spoon/1437510?searchHijack=true&amp;amp;searchTerm=1437510&amp;amp;searchType=RAPID&amp;amp;matchedCatNo=1437510</td></tr><tr><td>7.5 L Pressure Vessel</td><td>Autoclave Engineers</td><td>40A-9104, 9122, 40C-1365, 2376</td><td>minimum internal diameter of 127 mm; equipped with 20.7 MPa (3000 psi) rupture disc assembly; Solenoid&amp;amp; air operated valve on the outlet; http://www.autoclaveengineers.com/products/pressure_vessels/PV_Bolted_Closure/index.html</td></tr><tr><td>Electrodes (set of 2)</td><td>Electo-meters</td><td>Conax EG-375-A-SS-T, 25.4 cm (10&quot;) conductor</td><td>with Teflon sealing glands; https://www.conaxtechnologies.com/wp-content/uploads/2016/03/5001D-80-105-Flanges-and-Accessories.pdf</td></tr><tr><td>Rupture disc</td><td>Oseco</td><td>39859-3-1</td><td>http://www.oseco.com/imgUL/files/STD_0515.pdf</td></tr><tr><td>Universal safety head (rupture disc assembly)</td><td>Autoclave Engineers</td><td>SS-4600-1/2F</td><td>http://www.autoclave.com/products/accessories/universal_safety_heads/index.html</td></tr><tr><td>High-pressure valve (air-operated, fail-open)</td><td>Autoclave Engineers</td><td>1/2&quot; SW8XXX-CM</td><td>http://www.autoclave.com/aefc_pdfs/OM_P1_Manual_Air_Valve.pdf?zoom_highlightsub=air+operated+valve#search=&quot;air operated valve&quot;</td></tr><tr><td>Pressure transducer</td><td>Omega Engineering</td><td>PX176-3KS5V</td><td>Amplified Voltage Output Transducer for Absolute; 0-20.7 Mpa (0-3000 psi) sealed gauge, 91 cm (36&quot;) cable http://www.omega.ca/pptst_eng/PX176.html</td></tr><tr><td>Digital multimeter</td><td>Amazon.com</td><td>Fluke Model 110 Plus</td><td>https://www.amazon.com/Fluke-110-Plus-essential-multimeter/dp/B01JX912I2</td></tr><tr><td>Data acquisition Interface</td><td>IOTECH</td><td>Model Daqlab 2000 with DBK15 acquisition board</td><td>http://www.mccdaq.com/products/daqlab2000s</td></tr><tr><td>Personal Computer with monitor and National Instruments DASYLab Software (V13, basic) installed</td><td>DELL</td><td>CORETMi7 vProTM</td><td>Computer must meet requirements for Dasylab 13: 1GHz + x86 compatible; Windows 7 or 8, 32-bit or 64-bit; 2 GB+ RAM</td></tr><tr><td>oscilloscope</td><td></td><td></td><td>Any storage oscilloscope with 2 input channels (0-10 V), 12k samples per channel and acquisition frequency of 10 ms/sample.</td></tr><tr><td>Precision Shunt Resister</td><td>Canadian Shunt Industries</td><td>LA-20-100</td><td>(20 A, 100 mV) Enclosed in custom box http://www.cshunt.com/pdf/la.pdf</td></tr><tr><td>Constant Current Power Supply</td><td>Agilent</td><td>N6700B Low-Profile MPS Mainframe, 400W; N6754A DC Power Supply with High Speed Test Extensions option</td><td>http://www.keysight.com/en/pd-1125217-pn-N6754A/high-performance-autoranging-dc-power-module-60v-20a-300w?cc=CA&amp;amp;lc=eng</td></tr><tr><td>Inlet valve</td><td>Ottawa Valves and Fittings</td><td>Swagelok SS-43GS4-PT</td><td>https://www.swagelok.com/en/catalog/Product/Detail?part=SS-43GS4</td></tr><tr><td>Full face mask</td><td>Cooper Safety</td><td>3M 7800 series</td><td>http://www.coopersafety.com/product/3m-7800-series-full-face-respirator-1124.aspx</td></tr><tr><td>General purpose cartridges</td><td>Cooper Safety</td><td>3M 60923</td><td>http://www.coopersafety.com/product/3m-60923-organic-vapor-acid-gas-p100-cartridge-1533.aspx?sid=101950</td></tr></tbody></table>

minimum burning pressures of water-based emulsion explosives

This manuscript describes a protocol to measure the minimum pressure required for sustained burning of water-based emulsion explosives. Pumping water-based emulsion explosives for blasting applications can be very hazardous, as demonstrated by a number of pump accidents around the globe in the last decades, including some that resulted in fatalities. In Canada, the recognition of this hazard has led to the development of pumping guidelines that were endorsed by both the explosives industry and the Explosive Regulatory Division of the Canadian government. In these guidelines, it was noted that the minimum burning pressures (MBP) measured in a laboratory would provide a good guide to characterize the behaviour of these products in pumping systems. The same guidelines also call for the design of pump systems that prevent, whenever possible, pressures from exceeding the MBP of the product being pumped. At the time of publication of these guidelines, a methodology existed for measuring such MBP values but it had never been validated to measure the MBP of ammonium nitrate water-based emulsions (AWEs). AWEs are now used much more widely than any other water-based explosives and precursors in on-site bulk loading operations.
The Canadian Explosives Research Laboratory (CanmetCERL) has been conducting research over the last ten years to develop a validated testing protocol to measure and interpret representative MBP values for AWEs. The test, as it is performed today, will be described and the critical components will be justified by reference to recent published data. Results of MBP measurements, for a range of AWE products, will be presented. Inclusion of the MBP test in the test standards for the authorization of high explosives in Canada will also be discussed.

Typical raw signals from a test resulting in a fully propagated event (i.e. &#34;go&#34;) are shown in Figure 6. The ignition current (blue curve) is seen to come on at t0 = 0 and to stay on until the NiCr wire burns at tb = 19.1 s. The computed average ignition current (i.e. average of all data points between t0 and tb is Ihw = 10.59 A. On the pressure record (red curve), the first sign...

Watch this Scientific Journal Video about Minimum Burning Pressures of Water-based Emulsion Explosives at JoVE.com

Minimum Burning Pressures of Water-based Emulsion Explosives

We present an apparatus based on hot-wire ignition in a pressurized enclosure and an associated methodology to measure the minimum pressure required to induce sustained combustion in water-based emulsion explosives. This method improves product characterization to allow one to use them more safely during pumping and mixing operations.

This manuscript describes a protocol to measure the minimum pressure required for sustained burning of water-based emulsion explosives. Pumping ...

minimum-burning-pressures-of-water-based-emulsion-explosives

Universidad de Cartagena UDEC

Research

JoVE Journal

Chemistry

8.3K Views.  Natural Resources Canada. We present an apparatus based on hot-wire ignition in a pressurized enclosure and an associated methodology to measure the minimum pressure required to induce sustained combustion in water-based emulsion explosives. This method improves product characterization to allow one to use them more safely during pumping and mixing operations.

Video: Minimum Burning Pressures of Water-based Emulsion Explosives

Quantitative Detection of Trace Explosive Vapors by Programmed Temperature Desorption Gas Chromatography-Electron Capture Detector

The direct liquid deposition of solution standards onto sorbent-filled thermal desorption tubes is used for the quantitative analysis of trace explosive vapor samples. The direct liquid deposition method yields a higher fidelity between the analysis of vapor samples and the analysis of solution standards than using separate injection methods for vapors and solutions, i.e., samples collected on vapor collection tubes and standards prepared in solution vials. Additionally, the method can account for instrumentation losses, which makes it ideal for minimizing variability and quantitative trace chemical detection. Gas chromatography with an electron capture detector is an instrumentation configuration sensitive to nitro-energetics, such as TNT and RDX, due to their relatively high electron affinity. However, vapor quantitation of these compounds is difficult without viable vapor standards. Thus, we eliminate the requirement for vapor standards by combining the sensitivity of the instrumentation with a direct liquid deposition protocol to analyze trace explosive vapor samples.

Trace explosive vapors of TNT and RDX collected on sorbent-filled thermal desorption tubes were analyzed using a programmed temperature desorption system coupled to GC with an electron capture detector. The instrumental analysis is combined with direct liquid deposition method to reduce sample variability and account for instrumentation drift and losses.

The direct liquid deposition of solution standards onto sorbent-filled thermal desorption tubes is used for the quantitative analysis of trace explosive ...

Preparation and Reactivity of Gasless Nanostructured Energetic Materials

High-Energy Ball Milling (HEBM) is a ball milling process where a powder mixture placed in the ball mill is subjected to high-energy collisions from the balls. Among other applications, it is a versatile technique that allows for effective preparation of gasless reactive nanostructured materials with high energy density per volume (Ni+Al, Ta+C, Ti+C). The structural transformations of reactive media, which take place during HEBM, define the reaction mechanism in the produced energetic&#160;composites. Varying the processing conditions permits fine tuning of the milling-induced microstructures of the fabricated composite particles. In turn, the reactivity, i.e., self-ignition temperature, ignition delay time, as well as reaction kinetics, of high energy density materials depends on its microstructure. Analysis of the milling-induced microstructures suggests that the formation of fresh oxygen-free intimate high surface area contacts between the reagents is responsible for the enhancement of their reactivity. This manifests itself in a reduction of ignition temperature and delay time, an increased rate of chemical reaction, and an overall decrease of the effective activation energy of the reaction. The protocol provides a detailed description for the preparation of reactive nanocomposites with tailored microstructure using short-term HEBM method. It also describes a high-speed thermal imaging technique to determine the ignition/combustion characteristics of the energetic materials. The protocol can be adapted to preparation and characterization of a variety of nanostructured energetic composites.

This protocol describes the preparation of gasless nanostructured energetic materials (Ni+Al, Ta+C, Ti+C) using the short-term high-energy ball milling (HEBM) technique. It also describes a high-speed thermal imaging method to study the reactivity of mechanically fabricated nanocomposites. These protocols can be extended to other reactive nanostructured energetic materials.

High-Energy Ball Milling (HEBM) is a ball milling process where a powder mixture placed in the ball mill is subjected to high-energy collisions from the ...

Engineering

Research and Development of High-performance Explosives

Developmental testing of high explosives for military applications involves small-scale formulation, safety testing, and finally detonation performance tests to verify theoretical calculations. For newly developed formulations, the process begins with small-scale mixes, thermal testing, and impact and friction sensitivity. Only then do subsequent larger scale formulations proceed to detonation testing, which will be covered in this paper. Recent advances in characterization techniques have led to unparalleled precision in the characterization of early-time evolution of detonations. The new technique of Photonic Doppler Velocimetry (PDV) for the measurement of detonation pressure will be shared and compared with traditional fiber-optic detonation velocity and plate-dent calculation of detonation pressure. In particular, the role of aluminum in explosive formulations will be discussed. Recent developments led to the development of explosive formulations that result in reaction of aluminum very early in the detonation product expansion. This enhanced reaction leads to changes in the detonation velocity and pressure due to reaction of the aluminum with oxygen in the expanding gas products.

Developmental testing of high explosives for military applications involves small-scale formulation, safety testing, and finally detonation performance tests to verify theoretical calculations. This paper will share typical development tests associated with the measurement of detonation velocity and detonation pressure.

Developmental testing of high explosives for military applications involves small-scale formulation, safety testing, and finally detonation performance ...

Blast Quantification Using Hopkinson Pressure Bars

Near-field blast load measurement presents an issue to many sensor types as they must endure very aggressive environments and be able to measure pressures up to many hundreds of megapascals. In this respect the simplicity of the Hopkinson pressure bar has a major advantage in that while the measurement end of the Hopkinson bar can endure and be exposed to harsh conditions, the strain gauge mounted to the bar can be affixed some distance away. This allows protective housings to be utilized which protect the strain gauge but do not interfere with the measurement acquisition. The use of an array of pressure bars allows the pressure-time histories at discrete known points to be measured. This article also describes the interpolation routine used to derive pressure-time histories at un-instrumented locations on the plane of interest. Currently the technique has been used to measure loading from high explosives in free air and buried shallowly in various soils.

This protocol details the use of Hopkinson pressure bars to measure reflected blast loading from near-field explosive events. It is capable of interpolating a pressure-time history at any point on a reflective boundary and as such can be used to fully characterize the spatial and temporal variations in loading produced.

Near-field blast load measurement presents an issue to many sensor types as they must endure very aggressive environments and be able to measure pressures ...

Experimental Methodology for Estimation of Local Heat Fluxes and Burning Rates in Steady Laminar Boundary Layer Diffusion Flames

Modeling the realistic burning behavior of condensed-phase fuels has remained out of reach, in part because of an inability to resolve the complex interactions occurring at the interface between gas-phase flames and condensed-phase fuels. The current research provides a technique to explore the dynamic relationship between a combustible condensed fuel surface and gas-phase flames in laminar boundary layers. Experiments have previously been conducted in both forced and free convective environments over both solid and liquid fuels. A unique methodology, based on the Reynolds Analogy, was used to estimate local mass burning rates and flame heat fluxes for these laminar boundary layer diffusion flames utilizing local temperature gradients at the fuel surface. Local mass burning rates and convective and radiative heat feedback from the flames were measured in both the pyrolysis and plume regions by using temperature gradients mapped near the wall by a two-axis traverse system. These experiments are time-consuming and can be challenging to design as the condensed fuel surface burns steadily for only a limited period of time following ignition. The temperature profiles near the fuel surface need to be mapped during steady burning of a condensed fuel surface at a very high spatial resolution in order to capture reasonable estimates of local temperature gradients. Careful corrections for radiative heat losses from the thermocouples are also essential for accurate measurements. For these reasons, the whole experimental setup needs to be automated with a computer-controlled traverse mechanism, eliminating most errors due to positioning of a micro-thermocouple. An outline of steps to reproducibly capture near-wall temperature gradients and use them to assess local burning rates and heat fluxes is provided.

We describe the use of micro-thermocouples to estimate local temperature gradients in steady laminar boundary layer diffusion flames. By extension of the Reynolds Analogy, local temperature gradients can be further used to estimate the local mass burning rates and heat fluxes in such flames with high accuracy.

Modeling the realistic burning behavior of condensed-phase fuels has remained out of reach, in part because of an inability to resolve the complex ...

Nanothermite with Meringue-like Morphology: From Loose Powder to Ultra-porous Objects

The goal of the protocol described in this article is to prepare aluminothermic compositions (nanothermites) in the form of porous, monolithic objects. Nanothermites are combustible materials made up of inorganic fuel and an oxidizer. In nanothermite foams, aluminum is the fuel and aluminum phosphate and tungsten trioxide are the oxidizing moieties. The highest flame propagation velocities (FPVs) in nanothermites are observed in loose powders and FPVs are strongly decreased by pelletizing nanothermite powders. From a physical standpoint, nanothermite loose powders are metastable systems. Their properties can be altered by unintentional compaction induced by shocks or vibrations or by the segregation of particles over time by settling phenomena, which originates from the density differences of their components. Moving from a powder to an object is the challenge that must be overcome to integrate nanothermites in pyrotechnic systems. Nanothermite objects must have both a high open porosity and good mechanical strength. Nanothermite foams meet both of these criteria, and they are prepared by dispersing a nano-sized aluminothermic mixture (Al/WO3) in orthophosphoric acid. The reaction of aluminum with the acid solution gives the AlPO4 &#34;cement&#34; in which Al and WO3 nanoparticles are embedded. In nanothermite foams, aluminum phosphate plays the dual role of binder and oxidizer. This method can be used with tungsten trioxide, which is not altered by the preparation process. It could probably be extended to some oxides, which are commonly used for the preparation of high performance nanothermites. The WO3-based nanothermite foams described in this article are particularly insensitive to impact and friction, which makes them far safer to handle than loose Al/WO3 powder. The fast combustion of these materials has interesting applications in pyrotechnic igniters. Their use in detonators as primers would require the incorporation of a secondary explosive in their composition.

This manuscript describes the synthesis of combustible aluminophosphate matrices by the reaction of orthophosphoric acid (H3PO4) with aluminum nanopowder. When this reaction is carried out with excess aluminum in the presence of tungsten trioxide nanopowder, it leads to a solid, porous nanothermite foam.

The goal of the protocol described in this article is to prepare aluminothermic compositions (nanothermites) in the form of porous, monolithic objects. ...

Experimental Procedure for Laboratory Studies of In Situ Burning : Flammability and Burning Efficiency of Crude Oil

A new method for the simultaneous study of the flammability and burning efficiency of fresh and weathered crude oil through two experimental laboratory setups is presented. The experiments are easily repeatable compared to operational scale experiments (pool diameter &#8805;2 m), while still featuring quite realistic in situ burning conditions of crude oil on water. Experimental conditions include a flowing water sub-layer that cools the oil slick and an external heat flux (up to 50 kW/m2) that simulates the higher heat feedback to the fuel surface in operational scale crude oil pool fires. These conditions enable a controlled laboratory study of the burning efficiency of crude oil pool fires that are equivalent to operational scale experiments. The method also provides quantitative data on the requirements for igniting crude oils in terms of the critical heat flux, ignition delay time as a function of the incident heat flux, the surface temperature upon ignition, and the thermal inertia. This type of data can be used to determine the required strength and duration of an ignition source to ignite a certain type of fresh or weathered crude oil. The main limitation of the method is that the cooling effect of the flowing water sub-layer on the burning crude oil as a function of the external heat flux has not been fully quantified. Experimental results clearly showed that the flowing water sub-layer does improve how representative this setup is of in situ burning conditions, but to what extent this representation is accurate is currently uncertain. The method nevertheless features the most realistic in situ burning laboratory conditions currently available for simultaneously studying the flammability and burning efficiency of crude oil on water.

Experimental Procedure for Laboratory Studies of In Situ Burning : Flammability and Burning Efficiency of Crude Oil

Here, we present a protocol to simultaneously study the flammability and burning efficiency of fresh and weathered crude oil under conditions that simulate in situ burning operations on the sea.

A new method for the simultaneous study of the flammability and burning efficiency of fresh and weathered crude oil through two experimental laboratory ...

Achieving Moderate Pressures in Sealed Vessels Using Dry Ice As a Solid CO2 Source

Herein is presented a general strategy to perform reactions under mild to moderate CO2 pressures with dry ice. This technique obviates the need for specialized equipment to achieve modest pressures, and can even be used to achieve higher pressures in more specialized equipment and sturdier reaction vessels. At the end of the reaction, the vials can be easily depressurized by opening at room temperature. In the present example CO2 serves as both a putative directing group as well as a way to passivate amine substrates, thereby preventing oxidation during the organometallic reaction. In addition to being easily added, the directing group is also removed under vacuum, obviating the need for extensive purification to remove the directing group. This strategy allows the facile &#947;-C(sp3)-H arylation of aliphatic amines and has the potential to be applied to a variety of other amine-based reactions.

Achieving Moderate Pressures in Sealed Vessels Using Dry Ice As a Solid CO2 Source

Here we present a protocol for performing reactions in simple reaction vessels under low-to-moderate pressures of CO2. The reactions can be performed in a variety of vessels simply by administering the carbon dioxide in the form of dry ice, without the need for costly or elaborate equipment or set-ups.

Herein is presented a general strategy to perform reactions under mild to moderate CO2 pressures with dry ice. This technique obviates the need for ...

Laboratory Scale Slow Cook-Off Testing of Rocket Propellants: The Combustion Rate Analysis of a Slowly Heated Propellant (CRASH-P) Test

Solid rocket propellants are widely used for propulsion applications by military and space agencies. Although highly effective, they can be dangerous to personnel and equipment under certain conditions, with slow heating in confined conditions being a particular danger. This paper describes a more affordable laboratory test that is easier to set up and was developed for screening rocket propellant ingredients. Rocket propellants are cast into sample holders that have been designed to have the same confinement as standard rocket motors (propellant volume to total volume in the container) and ensure that the propellant is not easily vented. Reaction violence is quantified by the time it takes to reach 90% of the maximum pressure after autoignition, which is analogous to blast overpressure gauges used to measure violence in a full-scale test. A positive correlation was observed between the speed and pressure produced from the reaction and the power produced by the rocket propellant during the reaction.

Laboratory Scale Slow Cook-Off Testing of Rocket Propellants: The Combustion Rate Analysis of a Slowly Heated Propellant CRASH-P Test

We present a protocol for a laboratory-scale slow cook-off test for solid rocket propellants called the Combustion Rate Analysis of a Slowly Heated Propellant (CRASH-P) test. Confined rocket propellants are slowly heated until autoignition, and both the cook-off temperature and the violence of reaction are measured with dynamic pressure sensors.

Solid rocket propellants are widely used for propulsion applications by military and space agencies. Although highly effective, they can be dangerous to ...

Evaluating Primary Blast Effects In Vitro

Exposure to blast events can cause severe trauma to vital organs such as the lungs, ears, and brain. Understanding the mechanisms behind such blast-induced injuries is of great importance considering the recent trend towards the use of explosives in modern warfare and terrorist-related incidents. To fully understand blast-induced injury, we must first be able to replicate such blast events in a controlled environment using a reproducible method. In this technique using shock tube equipment, shock waves at a range of pressures can be propagated over live cells grown in 2D, and markers of cell viability can be immediately analyzed using a redox indicator assay and the fluorescent imaging of live and dead cells. This method demonstrated that increasing the peak blast overpressure to 127 kPa can stimulate a significant drop in cell viability when compared to untreated controls. Test samples are not limited to adherent cells, but can include cell suspensions,&#160;whole-body and tissue samples, through minor modifications to the shock tube setup. Replicating the exact conditions that tissues and cells experience when exposed to a genuine blast event is difficult. Techniques such as the one presented in this article can help to define damage thresholds and identify the transcriptional and epigenetic changes within cells that arise from shock wave exposure.

Evaluating Primary Blast Effects In Vitro

Understanding how cells are modulated by exposure to shock waves can help identify the mechanisms behind injuries triggered from blast events. This protocol uses custom-built shock tube equipment to apply shock waves at a range of pressures to cell monolayers and to identify the subsequent effects on cell viability.

Minimum Burning Pressures of Water-based Emulsion Explosives

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Rozdziały w tym wideo

Quantitative Detection of Trace Explosive Vapors by Programmed Temperature Desorption Gas Chromatography-Electron Capture Detector

Preparation and Reactivity of Gasless Nanostructured Energetic Materials

Research and Development of High-performance Explosives

Blast Quantification Using Hopkinson Pressure Bars

Experimental Methodology for Estimation of Local Heat Fluxes and Burning Rates in Steady Laminar Boundary Layer Diffusion Flames

Nanothermite with Meringue-like Morphology: From Loose Powder to Ultra-porous Objects

Experimental Procedure for Laboratory Studies of In Situ Burning : Flammability and Burning Efficiency of Crude Oil

Achieving Moderate Pressures in Sealed Vessels Using Dry Ice As a Solid CO₂ Source

Laboratory Scale Slow Cook-Off Testing of Rocket Propellants: The Combustion Rate Analysis of a Slowly Heated Propellant (CRASH-P) Test

Evaluating Primary Blast Effects In Vitro