The classification and grading of dangerous goods is a technical guarantee and basic requirement for its convenient transport globally. The recommendations on the transport of dangerous goods: model regulations and recommendations on the transport of dangerous goods: manual of tests and criteria edited and complied by UN Economic and Social Council, Committee of Experts on the Transport of Dangerous Goods has made a general regulation on the classification and grading. The fireworks and firecrackers are divided into 1.1G, 1.2G, 1.3G, 1.4G and 1.4S. As there is a great variety of fireworks and firecrackers, the classification of a specific item should be identified through test. Due to the high cost of the experiment on grading and classification, some European countries proposed a default table list by deduction based on the limited test data from a few experiments. The default table list is made by analogy, based on limited data, thus it is not exactly correct. Some countries accept it while some do not. Therefore, there rises a problem that the same product exported to different countries is not unified in its classification. This paper makes a brief introduction on the causes of the default table list and the grading results as well as the factors that influencing grading.

1.       The UN fireworks grading default table list

The 14th edition of the states that fireworks are usually classified into grade 1.1, 1.2, 1.3 , 1.4 by the experiment data of test series 6. However, due to the great variety of fireworks products and the limited experiment facilities, the classification can be made by analogy. The procedure regulates that fireworks is classified into UN number 0333, 0334, 0335 or 0336, which does not need to conduct a test series 6, the classification can then be made by analogy according to the designated fireworks classification default table list. The classification in the table list is only applicable to products that can be loaded in fiberboard cases. This classification must be made by the competent authorities. As the classification is quite complicated, the default is simplified into the following table for reference.

2.       Cause analysis for the inconsistence of grading results

Analysis shows that there are a great many reasons causing the blockage of trade due to hazardous grading, the main aspects are:

(1)    undefined grading standard with no specific targeting

The United Nations recommendations on the transport of dangerous goods: model regulations has given a defined distinction on the item names, UN numbers, the corresponding grade, etc of hazardous goods. As far as fireworks and firecrackers are concerned, the hazardous grades are 1.1G, 1.2G, 1.3G, 1.4G, and 1.4S while the corresponding UN numbers are 0333, 0334, 0335 and 0336. As for chemical hazardous goods, such as pesticide, different proportions for the same product can have different hazardous grade. As is known to all, there is a great many kinds of fireworks and firecrackers, and the formula for its powder composition and explosive effect varies from each other. By the above-mentioned standards, we can not specify the hazardous grade of each particular product. International hazardous goods marine rules as well as other relevant international covenant have listed corresponding requirements, but they still have not covered the whole categories of the fireworks and firecrackers products.

(2)    high cost of grading test, mainly adopting the results by analogy

 The United Nations recommendations on the transport of dangerous goods: manual of tests and criteria has listed 7 test series for hazardous grading of explosives. If all experiments conducted by the manual, it not only takes a rather long time but also cost much. It is reported in Japan that the three experiments in the 6 series concerning the specific hazardous grade on only two toy categories cost as much as 25,000 US dollars. The grading test in China for each sample costs also as much as 10,000 RMB. Thus, governments or administration institutions in different countries generally adopt the way of analogy, that is, infer the hazardous grade based on the essential factors of categories, fireworks powder type and amount of powder as well as its specification, some of its conclusions are not in compliant with the testing results.

(3)    There is a great difference in laws and regulations in different countries and it is hard to form a unified standard.

There is a great divergence on the definition and specific regulations in laws and standards in different countries. Take rockets and candles for examples, in the American market, the report powder for each individual rocket should not exceed 130 mg, the total powder amount should not exceed 20g. The main products are little rockets; for the Holland rockets, it is regulated that the powder for sound effect should not exceed 5g, the total amount should not exceed 25g(including the lifting charge). The main products are medium and large rockets. America regulates that report for roman candles should not exceed 130mg, the whole amount should not exceed 20g; while in Holland, the explosive composition for items with sound effect should be less than 40g, for item without sound effect, the explosive composition should be less than 100g. The above data indicates that the products exported to the US manufactured in China are usually small sized products of the ones in Holland. Therefore, the difference in hazardous grade, even with the same name, are obvious.

(4)    the grading results are not transparent enough, while the technology need improving

Different countries have not published their grading results in a timely fashion, or even when published, the differences concerning the specific items are not listed. We are short of an administration department or intermediary organs to collect, analyze and offer guidance for applicants, thus the manufacturers are hard to get the unified information. On the other hand, out of respect for trade, some importers deliberately demand the manufacturers to paste low hazardous grade labels, which makes the incorrectly graded products enter into the international markets. Meanwhile, due to the fierce competition in the market, the rising of raw materials and the maximization of profit by production factories, high-explosive powder is used in products such as rockets, roman candles, shells and cakes. The market has responded favorably because of its high explosiveness, height and visual and audio effect, however, at the same time, the products have become more dangerous.

3.       Factors that influencing grading results

The analysis of the standards of grading experiment can lead to the following results:

(1)    Whether exploded wholly: exploded wholly refers to explosion that leads to almost whole load in a very short moment. The sensitivity of the powder, powder amount and explosion force are the essential factors that determine the whole explosion. In finished grading experiments, because of its huge powder amount, shells that are above 8 inches are quite possibly exploded wholly, usually; they can be classified as 1.1G.

(2)    Ejection distance: the main factors that affect the grading are the ejection distance of flaming debris or effect stars. Under the condition of ignition of cakes and shells, stars can be ejected to a great distance by the propellant powder. A firing ball or flaming reaching outside the testing screen, or the flaming debris ejected from the products over 15 meters from the pack can be deemed as 1.3; A firing ball or flaming reaching over 1 meter, or the flaming debris ejected from the products over 5 meters from the pack can be deemed as 1.4G.

(3)    Heat flux: heat flux is also an important factor that classifies the grading. The reaction heat enthalpy and the density of loaded powder are factors that affect heat flux. The burning time of the tested products less than 35s/100kg net explosive quality, or if the product is low energy material, the radiosity of the products that are 15 meters away from the pack when burning is larger than 4kw/m2  of the flaming can be deemed as 1.3. The burning time of the tested products less than 330s/100kg net explosive quality can be regarded as 1.4G.

The above introduction has clearly shown that explosion hazardous, ejection hazardous and heat radiation hazardous are main reference factors in determining grades. The hazardous of explosion and ejection can be effectively controlled through improving product packaging; the ejection and heat radiation hazardous can be reduced through improving product construction and powder formula; the product hazardous can be comprehensively controlled by adopting new powders and lowering the powder amount. The fireworks industry need further strengthen its research, take appropriate steps to effectively control the hazardous and promote the healthy development of this industry.