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

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48 A P P E N D I X C This appendix provides a test procedure for measuring the specific rate of gas production on contact with water for ASTM Format Test Procedure water-reactive substances, cast in a format that corresponds to that expected for draft (still in committee) ASTM procedures.

49 Standard Test Method for Characterization and Classification of Water Reactive Substances That Produce Flammable Gas or Toxic Gas on Contact with Water This standard is issued under the fixed designation D XXXX; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (ε) indicates an editorial change since the last revision or reapproval. 1. Scope 1.1 This test method describes the determination of the rate at which flammable gas or toxic gas is produced when a substance is combined with water under laboratory conditions in a closed vessel by monitoring the change in pressure as a function of time after the substance and water are mixed. Pressure changes are converted to changes in volume by applying a calibration curve relating change in pressure within the apparatus to amounts of gas (as measured at ambient laboratory conditions) added to the vessel. 1.2 This test method is applicable to solid or liquid substances that react with water to produce gas at specific rates of gas production equal to or greater than 1 (one) liter per kg of substance per hour. 1.3 Units — The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

50 2. Referenced Documents 2.1 ASTM Standards: D1193 Specification for Reagent Water E2586-13 Standard Practice for Calculating and Using Basic Statistics E681-09 Standard Test Method for Concentration Limits of Flammability of Chemicals (Vapors and Gases) [Note, for international purposes this should be replaced by ISO 10156:2010] 3. Terminology 3.1 Definitions: 3.1.1 competent authority: n—a person or organization that has the legally delegated or invested authority, capacity, or power to define a property or set a regulation for a political or geographic region. 3.1.2 flammable gas: n—a gas which, at 20 °C and a standard pressure of 101.3 kPa is: (a) ignitable when in a mixture of 13% or less by volume with air; or (b) has a flammable range with air of at least 12 percentage points regardless of the lower flammability limit. Flammability shall be determined by tests or by calculation in accordance with methods adopted by ISO (see ISO 10156:2010; corresponding to ASTM E681-09). Where insufficient data are available to use these methods, tests by a comparable method recognized by a competent authority may be used. 3.1.3 gas: n—a substance which (a) at 50 °C has a vapor pressure greater than 300 kPa; or (b) is completely gaseous at 20 °C at a standard pressure of 101.3 kPa.

51 3.1.4 LC50: n—the concentration of vapor, mist or dust which, administered by continuous inhalation to both male and female young adult albino rats for one hour, is most likely to cause death within14 days in one half of the animals tested. 3.1.5 toxic gas: n—a gas which is (a) known to be so toxic or corrosive to humans as to pose a hazard to health; or (b) presumed to be toxic or corrosive to humans because it has an LC50 value equal to or less than 5,000 cm3/m3 (ppm). 3.1.6 water-reactive substance: n—a substance that reacts with water to product a toxic or a flammable gas at a specific rate of gas production equal to or greater than 1 (one) liter per kg of substance per hour. 4. Summary of Test Method 4.1 The test procedure encompasses the following steps: 4.1.1 The apparatus is charged with water (Method A), or for some substances (determined by test), with the test substance (Method B). 4.1.2 The pressure/volume response and calibration of the apparatus is determined. 4.1.3 The apparatus is then charged with the test substance in Method A, or for some substances water (as determined by test, see 4.1.1) in Method B, and test substance and water within it combined. 4.1.4 The pressure produced as any reaction proceeds is measured as a function of time. 4.1.5 The pressure vs. time results are converted to a specific rate of gas production (liters of gas per kg of substance reacting per hour or per minute), utilizing the pressure/volume response calibration of 4.1.2.

52 4.1.6 The testing of 4.1.1 through 4.1.5, except for 4.1.2, is repeated to obtain a total of 5 results, which are then averaged to yield a final result, sample standard deviation, and coefficient of variation. 5. Significance and Use 5.1 During commercial transport of reactive chemicals, small but finite chances for leaks and spills exist, and in many cases the spilled chemicals may encounter water. For substances that may react with water to produce flammable gases or toxic gases, it is therefore important to understand the rate at which those gases may be produced, for purposes of understanding and managing the attendant risks during transport. 5.1.1 This test, therefore, is used to make a quantitative measurement of the rate of gas production; this makes it possible to evaluate the relative risks of various substances in transit, and properly plan for emergency response. 5.1.2 The results from this test are generally useful for this application, in that the result is a rate that represents both the highest observed rate and a rate of gas production that is normalized to the amount of substance—it therefore is valuable in understanding outcomes as a function of the size of any possible spill. 5.1.3 Because this test provides a specific rate of gas production, under very specific conditions its utility may be limited. However, this is necessary to ensure that the results allow an equitable comparison of different substances. There are necessarily limitations on the ability to extrapolate from these test results to outcomes in the field. 5.1.4 As a result, the use of these test results should be primarily for identifying the relative reactivity of these substances. This assessment of relative reactivity may then be considered

53 within assessments of the potential risk of spills involving these substances, but it should not form the only basis for this assessment; many other factors may also need to be considered. Utilization of these test results for modeling or predicting outcomes within spill scenarios can be considered, but that is a secondary, and less certain, application than the assessment of relative reactivity. 6. Apparatus 6.1 The apparatus used in this test method is illustrated by the schematic diagram of Fig. 1. Materials and configurations other than those stipulated here may be used, so long as they achieve comparable performance and meet the performance stipulations of 6.2. Key elements of the apparatus include: 6.1.1 A reaction vessel. This will typically be a custom fabricated glass vessel, such as that illustrated in Fig. 2, with two standard size threaded fittings which can reliably form hermetic seals, and a third standard taper ground-glass joint. A convenient size is based on a 250 ml “blank,” heavy walled glass flask, which yields an apparatus of ~ 400 cm3 total internal volume. Note 1: Glass may not be suitable for use in systems where HF or fluoride ions are present. 6.1.2 Closures and adapters to fit the standard size threaded fittings and the standard taper ground-glass joint; solid plug types, as well as types that accept threaded fittings, and “thermometer adapter” types should be available. The thermometer adapter types should further accept rubber septa while maintaining a hermetic seal, even after one or more small punctures of the septum. Examples are shown in Fig. 3. Rubber, elastomer, and plastic components (such as o-rings, septa, and fittings) must be suitable for and compatible with the materials under test and the gases likely to be formed.

54 6.1.3 An arrangement that allows pre-charged solid substances to be kept separate from water in the main reaction vessel until they are deliberately and suddenly combined, maintaining vessel integrity against gas leaks throughout. An example arrangement is shown in Fig. 4. 6.1.4 A PTFE coated magnetic stirring bar to provide agitation within the reaction vessel. 6.1.5 A magnetic stirring apparatus to spin the magnetic stirring bar during reaction. 6.1.6 A pressure transducer, reporting both pressure and temperature; with a resolution of 0.1 kPa and 0.1 °C, or better. 6.1.7 A data acquisition system for recording the pressure and temperature outputs at intervals of 2 seconds. 6.1.8 Gas-tight syringes of a convenient size for the pressure/volume calibration of 4.1.2, and precision liquid syringes of convenient sizes for adding water and liquid substances to the reaction apparatus. 6.2 Regardless of the specific components used, the apparatus must: 6.2.1 Be gas tight and capable of safely withstanding internal pressures of at least 50 kPa gauge. 6.2.2 Allow for the safe combination of water with a water-reactive substance; provisions for this must include, but are not limited to, pressure relief of the apparatus at a pressure above 50 kPa gauge yet safely below a pressure at which the vessel might rupture. Appropriate personal protective equipment for laboratory personnel and an appropriate laboratory workspace to house the apparatus including fume hoods, proper hazard communication procedures for laboratory personnel, and supervision and operation by qualified personnel.

55 6.2.3 Accommodate addition of the substance to water as well as, when required, the reverse order of addition. 6.2.4 Be capable of use with both solid and liquid substances. 6.2.5 Include accurate and precise monitoring of pressure as a function of time during testing, preferably using electronic data logging at intervals as short as 2 seconds, with a pressure resolution greater than 0.1 kPa. 6.2.6 Accommodate calibration of the response of pressure to the volume of gas added to or produced within the apparatus to provide for conversion from observed pressure increases with the apparatus to volume of (as measured at ambient conditions of temperature and pressure) gas added to or produced within the apparatus (this may, for instance, be accomplished via the addition of known aliquots of gas at ambient pressure). 6.2.7 Allow, when the reactivity of the test substance warrants, for testing to occur under an inert atmosphere. FIG. 1. Schematic diagram (left) and physical example (right) of the test apparatus.

56 FIG. 2. Vendor drawing of a reaction vessel. FIG. 3. Detail (left) of a solid addition apparatus and (right) a friction fit closure that accommodates both a septum and provides (via the friction-fit) pressure relief for the test apparatus.

57 FIG. 4. Test apparatus configured for solid addition, before (left) and after (right) solid test substance is added to water. 6.3 The apparatus should be assembled and used in a modern, properly equipped chemical laboratory and positioned within a properly designed and functioning fume hood when tests are conducted. Ambient conditions in the laboratory must be such that the air temperature in the laboratory is between 18 °C and 24 °C, with a nominal temperature of 21 °C preferred, and that the absolute atmospheric pressure (i.e., not corrected to sea level) is between 96 and 106 kPa, with a nominal pressure of 101.3 kPa preferred. 7. Reagents and Materials 7.1 Other than the test substance, the reagents required are: D1193 Type IV purified water ACS Reagent grade sodium chloride, NaCl. When required, a dry, inert gas supply.

58 8. Hazards 8.1 Warning, Reactive Materials—This test is intended to measure the evolution of gas when reactive materials are combined with water. 8.1.1 Some of these materials may react violently with water, and many may need to be handled under dry, inert atmosphere prior to their careful reaction with water in order to preserve their integrity and to preclude the possibility of hazardous reactions. Furthermore, some of these materials may produce toxic gases when combined with water. 8.1.2 These materials should be handled by trained, qualified personnel with experience in handling water-reactive and/or air-sensitive materials using appropriate laboratory facilities and proper personal protective equipment. Laboratory facilities should include properly designed and operating fume hoods in addition to other facilities and equipment that may be required. Typical personal protective equipment will include flame-retardant laboratory coats (preferably using intrinsically flame-retardant materials, such as Nomex® fabric), safety glasses, face shields, chemically resistant gloves, and other equipment as needed. A transparent shield may be used to deflect debris from the hood when the door is opened. There are several texts and other resources on the topics of laboratory safety and the handing of air-sensitive materials that should be consulted prior to work (see References). 8.1.3 This test should be carried out under the supervision of a qualified, experienced chemist who is thoroughly familiar with the materials being handled, their reactivity, and water- and air- sensitive materials in general.

59 8.2 Warning, Elevated Pressures within Closed Apparatus—The test apparatus shown in Fig. 1 and Fig. 2 is intended to contain gas as it is produced, and therefore will become pressurized during testing. 8.2.1 Pressure relief for the apparatus must be provided. In the apparatus shown in Fig. 1 and Fig. 2, it is provided by the friction fit of the closure in the central, standard taper ground glass joint. Experience with the type of closures shown in Fig. 1, Fig. 2, and Fig. 4 shows that if the pressure exceeds ~ 50 kPa, this friction fit closure will yield, venting the apparatus. Venting is not violent and occurs with a soft (but definite) “pop” as the closure is expelled. The closure is expelled with enough force to reach the hood ceiling, but the rebound is gentle and is comparable to dropping the closure from a height of a few feet. Users commissioning new apparatus must verify both tolerance of the planned pressures and successful relief performance. 8.2.2 During the application of this test procedure, prior to charging the apparatus with the substance to be tested and/or water, estimates of the maximum amount of gas that can be produced must be made, and the amounts charged chosen so that anticipated pressure is within the capacity of the apparatus. See Annex A-1 for sample calculations. 9. Sampling, Test Specimens, and Test Units 9.1 Samples being evaluated in order to better understand the relative risks of substances in commercial transport should be representative of the larger bulk of the substance as it is to be offered for transport. Samples shall be withdrawn from well mixed containers of the substance, with smaller samples taken from multiple positions within the container, if necessary, and then thoroughly mixed. If, at any time, subsamples—such as small aliquots for each test run—are

60 required, the sample shall be thoroughly mixed in advance to ensure that the subsample is representative of the whole of the sample. 9.2 In the case of solid substances, the substance shall be inspected for any particles of less than 500 µm diameter. If that powder constitutes more than 1% (mass) of the total, or if the substance is friable, then the whole of the sample shall be ground to a powder before testing. 9.3 In the case of substances known to be, or which are discovered to be, pyrophoric or air sensitive, sampling and testing shall be conducted under an inert atmosphere; the atmosphere shall also be dry (dew point -40° C), with the exception of the atmosphere within the apparatus when the substance and water are combined. 10. Calibration and Standardization 10.1 Prior to the first use, and at reasonable intervals afterward, the apparatus must be assembled (without a test substance or water included) and measurements of the pressure/volume response of the apparatus made. While any equivalently effective approach may be used, this can conveniently be accomplished by using calibrated and standardized syringes to add known volumes of gas (at ambient conditions within the laboratory) to the apparatus. For an apparatus with ~ 400–500 cm3 total internal volume, 4 aliquots of 50 cm3 each are convenient (See Fig. 5). This procedure can also be used to test the pressure relief provided for the apparatus; the apparatus should safely vent at an internal pressure between 40 and 60 kPa gauge. Note that the pressure volume response of the apparatus also yields the internal volume of the apparatus (see Annex A1 for Sample Calculations).

61 FIG. 5. For a test apparatus with total internal volume of ~ 450 cm3. 10.2 The gas syringes must be calibrated to deliver known volumes, and this may be either via NIST (or equivalent) traceable calibration or else by conducting a local calibration with reagent grade water and, a NIST traceably calibrated balance and temperature measurement, and standard reference tables for the density of water as a function of temperature. 10.3 Temperature and pressure measurements must be made with NIST traceably calibrated instrumentation. 11. Procedure 11.1 Method A: This is the starting point method (see 12.3 below) and shall be conducted first. It assesses the rate of gas production when a water-reactive substance is added to an excess of water. 11.1.1 Assemble a test apparatus.

62 11.1.2 Charge the apparatus with purified water; in cases where it is judged likely that saltwater (3.5% w/w ACS Reagent grade NaCl in purified water) will result in a greater rate of gas production, then saltwater shall be used. The mass of water shall be measured, and be such that the total volume of water does not occupy more than ~ 2.5% of the internal volume of the apparatus. For instance, 10.0 g (10.0 ml) could be used in an apparatus with internal volume of 400 ml. Note that if the flammable or toxic gas produced on contact with water is known to have appreciable solubility in water, the amount of water shall be reduced to ~0.5% of the internal volume of the apparatus. The mass of water added shall be determined weighing the syringe before and after the water is charged to the vessel. The mass is determined by difference and is recorded to ±0.0001 g. 11.1.3 If the substance under test is a solid, add it to the apparatus, but in a way that does not yet put it in contact with the liquid water in the apparatus. If the substance under test is a liquid, proceed directly to 11.1.4. Use an amount of test substance chosen so that complete reaction with water, via the reaction expected according to established chemical knowledge, or else established in separate testing, would create an amount of gas with a volume of ~ 1/3 of the internal volume of the apparatus calculated at 20° C and 101.3 kPa. See Annex A.1 for sample calculations. 11.1.4 Close the apparatus and check the apparatus pressure/volume response calibration (see 10.1). The result (the slope of a line fitted to the volume vs. pressure measurements) should be within 5% of the apparatus calibration curve. If it is, proceed, using this check result for test calculations; if not, then the apparatus should be checked and, if necessary, a full pressure/volume response calibration conducted. 11.1.5 Equilibrate the apparatus pressure with ambient pressure.

63 11.1.6 Combine the test substance with the water in the apparatus. In the case of liquid substances, this can be accomplished by adding the test substance directly to the apparatus in a manner that brings it into immediate contact with the water, with the stirrer operating, while maintaining the gas-tight integrity of the apparatus. When adding liquids via syringe, the syringe needle should be long enough to reach nearly to the liquid (i.e., water) in the reaction vessel, and the syringe operated so that the liquid is added rapidly, and as nearly all at once as possible. For a solid substance, operate the apparatus so that the test substance that was inserted as described above is rapidly mixed with the water while maintaining the gas-tight integrity of the apparatus. In the case of liquid substances, use an amount of test substance chosen so that complete reaction with water, according to the reaction expected according to established chemical knowledge, or else established in separate testing, would create an amount of gas with a volume of ~ 1/3 of the internal volume of the apparatus (see Annex A.1 for sample calculations.). In all cases, the amount of water present in the reaction vessel must be sufficient for complete reaction, according to reactions expected from accepted chemical principles. 11.1.7 Monitor the pressure (and, therefore, volume of gas produced) within the apparatus as a function of time. Continue monitoring until a steady state is observed. 11.1.8 If the change in pressure is too low for accurate measurement, repeat the test (starting at 11.1.1) using an increased amount of substance, but [Important!] do not exceed the apparatus capacity. If necessary, continue to repeat the test using increased amounts of substance, until a readily and accurately measureable response is observed. An ideal result would be an increase in pressure within the apparatus, as reaction proceeds, of from 10 to 25 kPa. Once a satisfactory response is achieved, conduct 4 additional replicate runs, to obtain a total of 5 measurements.

64 11.2 Method B: This is an alternative method (see 12.3 below) that may be required if Method A proves unsatisfactory because of interference from the vapor pressure of the test substance, or if the gas evolved appears to be absorbed by excess water in the reaction vessel more rapidly than it is produced. It is only necessary to conduct Method B if called for in 12.3. It assesses the rate of gas production when water is added to an excess of water reactive substance. This is a reversal of the conditions in Method A, and is generally most applicable to liquid test substances. 11.2.1 Assemble a test apparatus 11.2.2 Close the apparatus and check the apparatus pressure/volume response calibration (see 10.1). The result (the slope of a line fitted to the volume vs. pressure measurements) should be within 5% of the apparatus calibration curve. If it is, proceed, using this check result for test calculations; if not, then the apparatus should be checked and, if necessary, a full pressure/volume response calibration conducted. 11.2.3 Charge the apparatus with test substance; the mass of test substance shall be measured, and be such that the total volume of substance under test shall not occupy more than 2.5% of the internal volume of the apparatus. Often, an amount in the range of 0.5% to 1% of the internal volume of the apparatus will be sufficient. The mass of substance added shall be determined by weighing the syringe before and after the substance is charged to the vessel. The mass is determined by difference and is recorded to ±0.0001 g. 11.2.4 Equilibrate the apparatus pressure with ambient pressure. 11.2.5 Prepare a syringe with an amount of water chosen such that complete reaction via the reaction expected according to established chemical knowledge, or else established in separate

65 testing, will create an amount of gas with a volume of ~ 1/3 of the internal volume of the apparatus. See Annex A1 for sample calculations. 11.2.6 Add the water to the test substance by adding the water directly to the apparatus in a manner that brings it into immediate contact with the test substance, with the stirrer operating, while maintaining the gas-tight integrity of the apparatus. The syringe needle should be long enough to reach nearly to the liquid (i.e., test substance) in the reaction vessel and the syringe operated so that the water is added rapidly, and as nearly all at once as possible. 11.2.7 Monitor the pressure (and, therefore, volume of gas produced) within the apparatus as a function of time. Continue monitoring until a steady state is observed. 11.2.8 If the change in pressure is too low for accurate measurement, repeat the test (starting at 11.2.1 ) using an increased amount of water, but [Important!] do not exceed the apparatus capacity. If necessary, continue to repeat the test using increased amounts of water, until a readily and accurately measureable response is observed. An ideal result would be an increase in pressure within the apparatus, as reaction proceeds, from 10 to 25 kPa. Once a satisfactory response is achieved, conduct 4 additional replicate runs, to obtain a total of 5 measurements. 12. Calculation or Interpretation of Results 12.1 For each of the 5 measurements made (starting with Method A; only continue to Method B if required in 12.3), find the period of time during the reaction that shows the greatest rate of pressure increase (gas production). This may be as short as the interval between consecutive data points (2 seconds) or a few data points. In this case, convert the observed change in pressure to a net change in volume; this divided by the elapsed time constitutes the raw gas production rate (volume/time; e.g., liters/min or liters/hour). Alternatively, it may be a longer

66 duration over which a nearly linear increase in pressure with time occurs. In this case, convert the rate of pressure increase represented by the slope of a line fitted to the data in that period of time to a rate of gas production, which then constitutes the raw gas production rate (volume/time; e.g., liters/min or liters/hour). See Annex A1 for sample calculations. 12.2 Divide the raw gas production rate for each measurement by the amount of substance used to obtain a specific gas evolution rate (volume/(time*mass); e.g., liters/kg-min or liters/kg- hour) normalized to the mass of substance used. In the case of Method A, the mass of substance used is simply the amount of substance added to the vessel in 11.1.6. In the case of Method B, use chemical principles to estimate the amount of substance that, in theory, would react with the water used. This estimated amount of the “mass of substance used” then becomes the basis (denominator) for the calculation of the specific rate of gas production. Combine the 5 specific gas evolution rate measurements to obtain an average of the observed specific gas evolution rates, the sample standard deviation, and the coefficient of variation (standard deviation divided by the average expressed in percent). These form the nominal specific gas evolution rate and precision estimate. See Annex A1 for sample calculations. 12.3 For results obtained with Method A, and particularly in the case of liquid test substances, consider whether the observed gas production is due to reaction with water or to evaporation of the material or substance under test. This should be assessed by a qualified chemist, taking into consideration the observed yield of gas vs. that expected (low yields of gas may reflect evaporation) and the magnitude of the change in pressure (small changes, comparable to the vapor pressure of the test substance may reflect evaporation). If the observed gas production may credibly be due simply to evaporation of the test substance, then the measurement (with 5 replicates) shall be repeated using a reversed order of addition—charging

67 the apparatus first with test substance, then adding water for the measurement, using Method B. In addition, should it be apparent that production of gas may be masked by absorption of the gas by excess water within the reaction vessel during Method A, then the measurement (with 5 replicates) shall be repeated using a reversed order of addition—charging the apparatus first with test substance, then adding water for the measurement, using Method B. 12.4 Generally, a comparison of the specific gas evolution rates and overall gas yields from the two orders of addition (Method A and Method B) will make it clear which observation best represents gas production from the reaction between the test substance and water. Criteria to consider in this determination include the following. 12.4.1 If the addition of substance to water yields an increase in pressure similar to what would be expected solely from the vapor pressure of the substance, and the amount of gas produced is low in comparison to what is expected, while the addition of water to substance produces an amount of gas close to what is expected with a pressure increase greater than the vapor pressure of water, then the latter result shall be used. 12.4.2 If the addition of substance to water yields an increase in pressure in excess of what would be expected solely from the vapor pressure of the substance, the amount of gas produced is similar to what is expected, and the specific rate of gas production is greater than for the addition of water to substance, then the former result shall be used. 12.4.3 For intermediate cases, the judgment of a qualified, independent chemist should be used to determine which result best represents the rate of gas production from reaction with water.

68 13. Report 13.1 The report shall include: 13.1.1 The full IUPAC chemical name and, if applicable, proper shipping name of the substance tested. 13.1.2 The average result for the specific rate of gas production found in 12.1, as well as the sample standard deviation and coefficient of variation for that result. Any significant increase in temperature during the test shall also be noted. 13.1.3 An indication of whether the test result was based on Method A, adding the substance to water, or Method B, adding water to the substance. 14. Precision and Bias 14.1 Interlaboratory precision testing for this method is pending. 14.1.1 Precision: The precision of Test Methods A and B consists of repeatability, which is the agreement that occurs when identical specimens are run sequentially in the same laboratory by the same operator and equipment, and reproducibility, that is, the agreement that occurs when identical specimens are run with the same method at different laboratories. The interlaboratory testing has not yet been completed. However, the repeatability has been measured on 9 substances by a single lab.

69 Table 1. Validation testing results. Material Method Result (l/kg-min) Std. Dev. (l/kg-min) Coeff. Var. 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 SiCl4 A 1020 210 20% 1818 SOCl2 B 370 110 30% 1836 TiCl4 A 5500 900 16% 1838 Mg3N2 A 7900 1800 23% 3132 Method: A = Substance added to water, B = water added to substance 14.2 In these cases, the standard deviations were found to be proportional to the average gas generation rates so that the coefficient of variation, CV, is the proper measure of precision variability. The value obtained from the combined CVs of the 9 substances tested was: CVr = 21% , Repeatability, r, is defined as 2.8 times CVr. r = 59% 14.3 Bias—These test methods have no bias because the gas generation rate measured by these test methods is defined only in terms of these methods. Observations in uncontrolled field conditions may vary from those observed with this test.

70 ANNEX A1. SAMPLE CALCULATIONS A1.1 P/V Calibration of test apparatus. A test apparatus as in Fig. 1 is assembled and calibrated according to Section 10. Using a syringe with an internal volume of 50.0 cc and adding 4 sequential aliquots of gas, the following data results: Gas Addion Net Volume Added Pressure Observed cc kPa Zero 0 0.0 1st add. 50 11.2 2nd add. 100 22.4 3rd add. 150 33.5 4th add. 200 44.7 This is the data shown in Fig. 5. A line fit to this data by least-squares linear regression yields a slope of 4.4713 cc/kPa. This indicated that the volume of the apparatus is 453 cc, if the ambient pressure was 101.325 kPa. A1.2 Estimation of the amount of gas likely to be formed in a test reaction. Suppose that the test substance is TiCl4. This is expected to react according to Equation (1): TiCl4 (l) + 2 H2O (l) TiO2 (s) + 4 HCl (g) (1) For the case where TiCl4 was to be tested with Method A, and from Equation (1), for ambient pressure of 101.325 kPa and ambient temperature of 21.1 °C, 0.150 g of TiCl4 would be expected to form 76.4 cc of gas.

71 76.4 cc would be, for instance, less than 1/3 of the volume of a reaction apparatus with total internal volume of 453 cc, so this would be a suitable starting amount for testing, as in 11.1.3. For the case where TiCl4 was to be tested with Method B, Equation (1) shows production of two moles of gas per mole of water. In that case, 0.050 g of water would be expected to form 134 cc of gas: 134 cc would be, for instance, less than 1/3 of the volume of a reaction apparatus with total internal volume of 453 cc, so this would be a suitable starting amount for testing, as in 11.1.3. A1.3 Estimation of the amount of test substance that would react with water in Method B. For the case where TiCl4 was to be tested with Method B, Equation (1) shows that every two moles of water would consume 1 mole of TiCl4. For the case where 0.050 g of water was added to excess TiCl4, the amount of TiCl4 consumed would be: A1.4 Calculation of the raw rate of gas production and specific rate of gas evolution from a test run. Suppose that 0.1638 g of TiCl4 was added to 2.0218 g water, in an apparatus with a P/V calibration of 4.584 cc/kPa, yielding a change in pressure of 7.57 kPa over 2 seconds. Then:

72 and REFERENCES (1) CRC Handbook of Laboratory Safety, 5th Ed. Furr, A.K. (2000). (2) Handbook of Chemical Health and Safety, Alaimo, R. J. Ed. (2001). (3) Identifying and Evaluating Hazards in Research Laboratories, American Chemical Society (2013). (4) The Manipulation of Air-Sensitive Compounds, 2nd Edition; Duward F. Shriver; M. A. Drezdzon (1986). (5) Guidelines for Handling Air-Sensitive Compounds; Gill, GB; Whiting, DA, Aldrichchimica Acta, 1986, 19(2), 31-41. (6) Safe Laboratory Practices: Working with Air-Sensitive or Highly Reactive Compounds, Stanford University, 2/13/09, rev 10/15/10-- OHS Report#:09-016a. (7) ISO 10156:2010 Gases and gas mixtures—Determination of fire potential and oxidizing ability for the selection of cylinder valve outlets.

Abbreviations and acronyms used without definitions in TRB publications: A4A Airlines for America AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACI–NA Airports Council International–North America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers MAP-21 Moving Ahead for Progress in the 21st Century Act (2012) NASA National Aeronautics and Space Administration NASAO National Association of State Aviation Officials NCFRP National Cooperative Freight Research Program NCHRP National Cooperative Highway Research Program NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board PHMSA Pipeline and Hazardous Materials Safety Administration RITA Research and Innovative Technology Administration SAE Society of Automotive Engineers SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005) TCRP Transit Cooperative Research Program TEA-21 Transportation Equity Act for the 21st Century (1998) TRB Transportation Research Board TSA Transportation Security Administration U.S.DOT United States Department of Transportation