UN TEST N.4

Self-heating substances

Applicability: UN Test N.4 is the test method used to determine if a substance is a self-heating solid (UN Class 4, Division 4.2). The source for this test method is the UN Manual of Tests and Criteria, which is used by regulatory bodies such as the US Department of Transportation (DOT) to classify hazardous materials.

Purpose: UN Test N.4 determines a substance’s propensity for spontaneous combustion by exposing it to controlled temperatures and monitoring for exothermic activity.