Test Procedures and Classification Criteria for Release of Toxic Gases from Water-Reactive Materials (2014)

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1 Test Procedures and Classification Criteria for Release of Toxic Gases from Water-Reactive Materials This final research report for HMCRP Project HM-14 relates the development of a new test method for measuring the rate of gas production when a water-reactive substance evolv- ing either a flammable gas or a toxic gas is combined with water. The report includes the following: • Overview reporting of the background, research approach, and findings for HMCRP Project HM-14 (Chapters 1 through 4). • Comprehensive technical reporting on an apparatus and experimental validation work demonstrating the test, as well as a documenting example and experimental validation outcomes from testing (within Appendix A). • A proposed system for classification of water-reactive substances (Appendix B). • A concise, generalized protocol for the test (in American Society for Testing and Materials [ASTM] format, within Appendix C). Test N.5 in Section 33.4 of the United Nations’ (UNs’) Recommendations on the Transport of Dangerous Goods: Manual of Tests and Criteria, 5th revised edition (1), is applicable to cur- rent substances of Division 4.3 within the framework of Recommendations on the Transport of Dangerous Goods: Model Regulations (2), which in contact with water evolve flammable gas. Test N.5 is used to establish whether a substance should be classified in Division 4.3, and, if so, which of three possible packing groups applies. In its present form, the text pro- vides only very general guidance for conducting the test (“The tap of the dropping funnel is opened to let the water into the conical flask and a stop watch is started. The volume of gas is measured by any suitable means.”). The new test, described herein, provides a more com- prehensive specification for the test procedure and expands testing to also accommodate materials that in contact with water evolve toxic gas. The test described herein stipulates (1) an apparatus meeting particular performance cri- teria and (2) a test procedure that employs that apparatus. The performance criteria require the apparatus to be • Gas tight • Safe to operate • Able to accommodate the combination of test substance/material and water, with either substance/material added to water, or the reverse • Able to accommodate both solid and liquid test substances/materials • Capable of accurate monitoring of pressure as gas is produced within the apparatus • Able to accommodate calibration of a pressure/volume (P/V) response as gas is added to the apparatus • Capable of operation with an inert atmosphere. S U M M A R Y

2The test procedure using this apparatus then encompasses the following (general) steps: • Charging the apparatus with water (or test substance, depending on specific test outcomes). • Checking the P/V calibration and response. • Charging with the test substance (or water, depending upon specific test outcomes) and combining the test substance and water within the apparatus. • Accurate and precise measurement of the pressure produced as the reaction proceeds. • Conversion of the pressure-versus-time results to a specific rate of gas production (liters of gas per kg of substance reacting per hour or per minute). • Replicating testing to obtain five results that are averaged to find the outcome used for classification. In addition to defining an improved test, this report includes extensive experimental test validation work. This work includes a comprehensive description of a specific, working apparatus that meets the specific performance criteria stipulated for the test. Although the test does not explicitly dictate an exact configuration for the test apparatus, thereby allow- ing users to find the best combination of performance and equipment for their particular facilities, the apparatus defined here provides a concrete example of a working apparatus that users may duplicate, should they choose to do so. As noted above, full details of the apparatus and experimental work on test method validation done with it can be found in Appendix A. An ASTM format procedure is also included in Appendix C. Results from the experimental work on test validation with several model compounds are tabulated in Table S-1. Table S-1. Validation testing results. Material Approach Result (l/kg-min) Standard Deviation (l/kg-min) Relative Standard Deviation UN Number (CH3)2SiCl2 B 36 8 22% 1162 NaNH2 A 9600 2000 20% 1390 NaBH4 A 2 (120 l/kg-h) 0.5 (30 l/kg-h) 25% 1426 CH3COCl B 665 60 9% 1717 AlCl3 A 7500 1700 23% 1726 POCl3 A, B 1–3000 (& up) n/a n/a 1810 SiCl4 A 1020 210 20% 1818 SOCl2 B 370 110 30% 1836 TiCl4 A 5500 900 16% 1838 Mg3N2 A 7900 1800 23% 3132 A = Substance added to water, B = water added to substance