Classification by analogy
Explosives: update
The UK has left the EU, and some rules and procedures have changed from 1 January 2021.
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 (also called the explosives packing density).
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, ie 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 net explosive mass (NEM) 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.
Examples
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.
| No column header | New explosive | Analogous explosive |
|---|---|---|
| No column header | 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 |
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.
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 (Transport Pack) | 230 | ||
| 3.68 kg | Max. NEM per Transport Pack | 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) |
XYZ | ||
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.