Classifying Unknown Substances Under ADR

Understanding how to properly classify unknown substances is a fundamental skill for anyone involved in dangerous goods transport. While consignors bear primary responsibility for classification, drivers and transport managers need to understand the process to ensure safe and compliant operations.

The Basics of Classification

At its heart, ADR classification is about identifying the primary hazard that a substance presents. The regulations divide dangerous goods into nine main classes, from explosives to miscellaneous dangerous substances. However, when faced with an unknown substance, the process requires careful consideration and often professional expertise.

Starting with What You Know

The first step in classifying an unknown substance is gathering all available information. Safety data sheets, product information, or any documentation from the manufacturer can provide valuable clues. Physical characteristics like appearance, odour, and state (solid, liquid, or gas) offer initial insights. However, never taste or directly handle unknown substances to determine their properties.

The Hierarchy of Hazards

When a substance displays multiple hazards, ADR provides a clear hierarchy for classification. For example, if a substance is both toxic and flammable, specific rules determine which hazard takes precedence. The regulations specify that Class 1 (explosives) and Class 7 (radioactive materials) always take priority over other hazards, followed by self-reactive substances and organic peroxides.

Professional Testing and Analysis

For truly unknown substances, laboratory testing becomes essential. Chemical analysis can determine properties like flash point, toxicity, and corrosiveness. This testing must be carried out by accredited laboratories familiar with dangerous goods regulations. The Vehicle Certification Agency (VCA) in the UK maintains a list of approved testing facilities.

Common Classification Challenges

One frequent challenge involves mixtures of known substances. For these, ADR 2.1.3.3 specifies that classification should be based on the properties of the predominant substance. However, there are specific exceptions to this rule, particularly for substances that could become more hazardous when mixed.

Documentation Requirements

Once classified, proper documentation becomes vital. Transport documents must include the UN number, proper shipping name, hazard class, and packing group. For example, a newly classified corrosive liquid might be documented as “UN 1760, CORROSIVE LIQUID, N.O.S., 8, II,” where N.O.S. stands for “Not Otherwise Specified.”

The Role of Safety Advisers

When in doubt about classification, consulting a Dangerous Goods Safety Adviser (DGSA) is often the wisest course of action. DGSAs have specialised training in classification and can provide authoritative guidance. Under UK regulations, many companies must have access to a DGSA, though there are some exemptions for smaller operations.

Practical Implications for Drivers

While drivers aren’t typically responsible for classification, understanding the basics helps ensure safe transport. If you notice discrepancies between the documented classification and the apparent properties of a substance, raise your concerns. Better to delay a shipment than risk an incident due to incorrect classification.

Maintaining Compliance

Regular audits of classification procedures help maintain compliance and safety. Keep records of classification decisions and their justification, particularly for substances classified as N.O.S. When circumstances change—such as new information becoming available or regulations being updated—review and update classifications as needed.

By following these guidelines and maintaining a cautious, systematic approach to classification, transport operators can ensure both regulatory compliance and operational safety. Remember that when in doubt, it’s always better to seek expert advice than to make assumptions about dangerous goods classification.