1. U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration - 1 - A Modification of the HSL Flash Composition Test Apparatus Spencer C. Watson, U.S. Department of Transportation, Pipeline and Hazardous Materials Safety Administration, Washington D.C. Thaine Morris, MP Associates, Los Angeles, CA David Pier, MP Associates, Ione, CA A presentation for the IGUS-EPP/CIE Joint Meeting, Oviedo, Spain April 7-13, 2013

2. U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration - 2 - At the 42 nd Session of the UNECE TDG Subcommittee meeting in December 2012, the US submitted UN/SCETDG/42/INF.28 commenting on the similarity of results of the HSL Flash Composition Test and the US Flash Composition Test In this informal paper, there was discussion of a simple modification to the design of the HSL Flash Composition Firing Plug which the US experts had found to improve the reliability of the test results and shorten the operational down time. The Chairman of the Explosives Working Group invited the US to further document the changes in the firing plug design and operating procedure so that other countries might also evaluate the modification and make comment. INTRODUCTION

3. U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration Current HSL Firing Plug Design - 3 -

4. U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration Modified HSL Firing Plug Design - 4 -

5. U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration Modified HSL Firing Plug Design-Breakout - 5 -

6. U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration Modified HSL Firing Plug Electrodes - 6 - GROUNDED AND INSULATED ELECTRODES

7. U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration Modified HSL Firing Plug Plastic Insulator - 7 -

8. U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration Modified HSL Firing Plug Thumb Screw - 8 -

9. U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration - 9 -

10. U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration - 10 - Strip approx. 4 mm of insulation from the ends of the match wires, insert thru the top holes and kink the ends of both leads slightly, then pull the wires back up until they catch on the shoulder and screw in the electrodes, forcing the silicone gel back up the openings to seal them.

11. U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration - 11 -

12. U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration - 12 - Apply a small amount of silicone grease into both electrode openings before threading in the electrodes.

13. U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration - 13 - Tighten the electrodes against the top of the exposed kinked lead wires.

14. U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration - 14 - Coil the excess match head wires and position the match head slightly above the sample cup holder and pointed down towards it.

15. U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration - 15 - Operating Instructions for Using the Modified HSL Firing Plug Design 1.Remove both screws in the base of the main plug. 2.Assure that there is no debris in the opening 3.Inject silicon heat compound into each hole using the tube in which the compound is supplied. 4.Strip 6 mm of the leg wires and insert into the small hole at the top of the plug. 5.Insert the screws and tighten finger tight assuring they have captured the leg wires. 6.Carefully wipe of all of the silicon compound that has extruded from the small holes on the top form the plug.

16. U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration - 16 - Operating Instructions for Using the Modified HSL Firing Plug Design 7.Arrange the electric match so it is positioned in the cup on the top of the plug. 8.Check the electrical continuity of the match through the two screws. If it is good, proceed. 9.Assure the lead washer is in place on the plug. 10.Load the cup with composition; insert the plug into test fixture, tighten, and proceed with testing as normal.

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18. U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration - 18 - Operational Differences Using two modified HSL firing plugs in rotation, two laboratory technicians were able to complete 36 trials on the twelve new formulations with no stoppages or interruptions in under four hours. One technician prepped the firing plug not in use while the other technician weighed the samples, assembled the apparatus and recorded the data. With the existing HSL firing plug design, two laboratory technicians had required up to two full days to collect the same amount of data.

19. U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration Conclusions ● The improved HSL Firing Plug Design produces Flash Composition results as consistent or better than the existing HSL Firing Plug design. ● The improved HSL Firing Plug Design saves considerable time and effort in operational efficiency of data collection over the existing HSL Firing Plug design. - 19 -

20. U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration Future Work ● Invite other experts to try the modified HSL Firing Plug Design to see if their results match these. ● If there is substantial corroboration among other experts, propose that the HSL Flash Composition Test Fixture Drawings in Annex 7 of the UNMTC be amended to include the modified Firing Plug design. - 20 -