MSHA PE FoamThe Mine Safety and Health Administration (MSHA) reported a fire occurred in an underground coal mine on June 27, 2024, after a large quantity of polyurethane foam was injected into a roof cavity. This was the fourth uncontrolled heating event attributed to polyurethane foam application in four years, according to the agency. Polyurethane-based foam products produce heat from an exothermic chemical reaction. MSHA said injecting large quantities of polyurethane to fill voids can cause underground mine fires.

MSHA is recommending that underground coal operators develop a site-specific plan for void fills. It should address appropriate formwork (placement of foam), injection volume and rates, personal protective equipment for chemical exposures, temperature monitoring, fire watch, and storage and handling. The agency reminded coal operators to follow the manufacturer’s instructions and cautioned against filling large voids with polyurethane foam products that generate a hazardous amount of heat.

Miners deploying polyurethane foam should be trained in the hazards, safety precautions, and manufacturer’s safety data sheets.