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Classification by analogy

Explosives may sometimes be classified based on the results of tests carried out on other similar explosives. This is called analogy.

This route can be used in applications from the company holding the classification document for the analogous explosive.

It is for the applicant – not HSE – to demonstrate the analogy and provide the necessary technical justification, ie full details of the construction, packaging and test history of the original.

To establish an analogy the applicant will have to demonstrate similarity in terms of behaviour, explosive type, packaging, composition, net explosive mass (NEM), design features (if an article), method of packing, and density of explosives in the package.

Applying for classification by analogy

When applying for classification by this route, an analogy table, supported by a well-argued technical case, should be submitted to demonstrate that the claimed analogy is sound. Where the table is not supported by a technical case, HSE reserves the right not to process the application.

The analogy should  be based on an explosive previously classified by a Competent Authority of a Contracting Party to ADR, i.e. HSE or the Ministry of Defence’s Explosives Storage and Transport Committee (ESTC), on the basis of UN test data.

Where the new item contains a new explosive then evidence should be provided to show that the new explosive is comparable to the analogy in terms of sensitivity, stability, energy, burning rate, performance etc.

Where the NEC exceeds that in the analogous article, a valid technical justification must be provided to demonstrate that the hazard of the new article, as packaged for transport, is not increased.

The applicant is expected to have sufficient understanding of the products and the available technical resources to provide a credible technical justification in support of their application.

Presenting the information

The information should be presented in a clear and logical format to avoid the need for additional questions and to shorten the time taken to process the application.

The information supporting an application should allow a direct comparison of the new and analogous item, for example, by use of a table and technical explanation.


Two examples of possible formats for information submitted for classification by analogy are given below. The first is for a hypothetical gas generator and the second is for a pyrotechnic article.

Example 1 Hypothetical gas generator

Submission in support of an application for the classification of a Mk 49 Widget on the basis of analogy with the Mk 47 Widget.

  New explosive Analogous explosive
  Mk 49 Widget Mk 47 Widget
Original classification To be agreed UN No 0277, 1.3C – HSE Ref XI/5015/111/22
Basis of classification analogy UN Series 6 tests
Description see drawing xxx supplied see drawing yyy supplied
NEM 10 g 15 g
Explosive Acme Propellant 769 Acme Propellant 769
Packing method 6 units in fibreboard box, internal 6 units in fibreboard box, internal
Including packing instruction  fibreboard furniture. P130 fibreboard furniture. P130
NEM per box 60 g 90 g
Explosive density 0.29 kg/m3 0.44 kg/m3

Explanatory notes (mandatory):

Space for the applicant to prepare a technical justification, and provide additional information in support of the analogy.

Example 2 Pyrotechnic article

Notes regarding application reference ####
Application by analogy

The application is for the classification of a new product called New Widget. We are applying for a classification of 1.4G, UN0431 by analogy to the Widget (HSE Ref: XI/ABCD/E/F).

Widget Criteria New Widget
Articles Pyrotechnic Proper shipping name Articles Pyrotechnic
0431 UN number To be determined
1.4G HSE Ref XI/ABCD/E/F Classification To be determined
UN Series 6C Tests Basis of classification Analogy
See above Design See above
XXXXXXXX % Propellant (Example) YYYYYYYY %
Component A XX.X% Composition (Example). Additional compositions should be attached to a separate sheet Component A YY.Y%
Component B XX.X% Component B YY.Y%
Component C XX.X% Component C YY.Y%
Component D XX.X% Component D YY.Y%
Component E XX.X% Component E YY.Y%
Component F XX.X% Component F YY.Y%
0.016 kg Max. NEM per device 0.0045 kg
10 Devices per inner box 10
230 Devices per outer carton 230
3.68 kg Max. NEM per outer carton 1.035 kg
0.0514 m3 Volume of Transport Pack 0.0514m3
71.5 kg/m3 Net Explosive Packing Density 20.1 kg/m3
8.5 kg Max. gross mass of Transport Pack 6.5 kg
XYZ Packaging reference
(Drawings attached)

A technical discussion of the table contents should be included in the technical justification to describe, compare and contrast the analogous item with the previously tested item. The aim of this discussion is to show that the new explosive, when incorporated in its transport pack, would not increase in hazard if it were involved in a fire during carriage.

Updated 2016-12-10