Testing of fireworks

British Standards are created by a committee that includes representatives from those involved in the manufacturing industry, and in this case the result was BS7114 which is divided into three parts Part 1, Classihcation of Fireworks Part 2, Specihcation of Fireworks and Part 3, Methods of Test of Fireworks. 

Part 3 of BS7114 is concerned with the methods of testing of fireworks and certain items of auxiliary equipment such as rocket launchers. In essence, the standard calls up chemical and physical test methods that are applied to all types of firework, from toy caps to large rockets. Fireworks that are incomplete or not intended for sale to the general public are excluded. 

A welcome addition to the controls imposed by the HSE which relate to the manufacture, keeping, safe conveyance and importation of explosives, including fireworks, is the British Standard BS7114. This standard applies specifically to consumer fireworks and was promulgated in 1988 in order to deal with aspects such as the categorisation, performance testing, quality control and labelling of all types of fireworks. 

BRITISH STANDARD (Fireworks) BS7114 Part 1 Classihcation of Fireworks, Part 2 Specihcation for Fireworks, Part 3 Methods of Test for Fireworks (BSI Sales Dept, Linford Wood, Milton Keynes MK14 6SL, UK). 

Eye protection — safety glasses or goggles - is mandatory whenever any pyrotechnic composition is being prepared or tested. Necessary equipment includes a mortar and pestle, a laboratory balance, a soft bristle brush, several 2-3 inch lengths of fireworks-type safety fuse (available from many hobby stores), and a fireproof stone or composite slab on which to conduct burning tests. 

Class C Explosive Under the U.S. Department of Transportation (DOT) safety regulations, as per 49 CFR 173.100, Class C explosives are defined as certain types of manufactured articles which contain Class A, or Class B explosives, or both as components but in restricted quantities, and certain types of fireworks. The regulations include specific descriptions of, prescribed uses for, and tests for Class C explosives. 

When ammonium perchlorate is mixed with red phosphorus it becomes very sensitive to shock, but not so much to friction. With realgar, sulphur, antimony trisulphide etc. it also becomes sensitive almost like the above. The degree of shock sensitivity of ammonium perchlorate due to such substances is almost the same as that of potassium chlorate, but higher than that of potassium perchlorate. The low friction sensitivity of ammonium perchlorate due to these substances is one of its attractive features in comparison with potassium chlorate and perchlorate(T.Shimizu Sensitivity tests on firework compositions, J. Exp.Soc. Japan, 2, No.6, p. 3 3... 

You ve probably noticed that flames can be various colors, particularly in a fireworks display or when you burn logs treated with various salts in the fireplace. These colors are the result of electrons in metal atoms moving from higher energy levels to lower energy levels. The colors produced when compormds containing metals are heated in a flame can be used to identify the metals. The procedure is known as a flame test. In this MiniLab, you will study the flame tests of a few elements and identify an unknown element. 

In fact, it had been known for several decades that when certain metal cations are heated in a Bunsen burner, they will emit light of a characteristic color. These are the common flame tests of a qualitative general chemistry laboratory and that form the basis for the different colors in fireworks. For instance, Li+ and... 

Figure 21.14 shows the results of a wiping test of chemicals used in fireworks. The chemicals tested were... 

Chemical testing is carried out in an approved laboratory because the firework must first be dismantled. Wet methods of analysis are applied that involve analytical grade reagents to detect, in particular, the presence of chlorates in admixture with elemental sulfur. Sulfur-chlorate mixtures are banned in the UK, and one use of sulfurless gunpowder is in fireworks where chlorates are also present. 

Figure 56. C. G. Storm. Author of numerous articles and government publications on the properties, testing, and analysis of smokeless powder and high explosives. Explosives Chemist at Navy Powder Works, 1901-1909, at U. S. Bureau of Mines, 1909-1915 Directing Chemist, Aetna Explosives Company, 1915-1917 Major and Lieutenant-Colonel, Ordnance Department, 1917-1919 Research Chemist, Trojan Powder Company, 1919 Chief Explosives Chemical Engineer, Office of the Chief of Ordnance, War Department, 1919-1942 since early in 1942, Technical Director, National Fireworks, Inc.

U. S. War Department Technical Manual TM 9-2900 and the U. S. Bureau of Mines Bulletins on the analysis of explosives describe the standard heat tests in detail. Explosives, Matches, and Fireworks by Joseph Reilly, New York, D. Van Nostrand Company, Inc., 1938, pp. 71-83, describes about 40 different heat tests. 

Various mixtures of materials in fireworks were tested for deflagration. The results are shown in Table 3.27. Changes in the rate of pressure increase vary with the amount of sample tested, so that those known to deflagrate strongly were evaluated with lg samples. 

Potassium chlorate becomes quite sensitive in contact with red phosphorus and ignites very easily by friction. These properties are used in match. When it is mixed with sulphur or compounds of sulphur like realgar, antimony trisulphide etc., the sensitivity to shock or friction is highly increased. According to the late professor S.Yamamoto of Tokyo University, when a mixture of potassium chlorate and realgar was shaped into a small tablet in a hand press and left on a table, a little while later the tablet caused spontaneous ignition and burnt out. He tried the same tests sevejjral times and the results were the same. He concluded that it was caused by inner friction which occurs with the recovery of the stress produced by the press(s. Yamamoto Studies in safety in firework manufacture 1(1959)3 ... 

For,1 firework use the sulphuric acid content mu t be low especially if it is used in combination with chlorate. The acidity is tested with blue litmus paper to see whether the wash water of the sulphur changes its colour to red or not. /... 

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