In a paint manufacturing plant, fire broke out inside the utility room of the used solvent regeneration unit, on the wet heating system at the expansion tank vent at a height of approx. 2.5 m. Flames reached the metal wall separating the heating unit from the distillation tank, as well as the corrugated metal roof on both sides of the wall. The presence of a solvent container depot at a distance of 20 m constituted an additional hazard. The flames rose above the cladding and were seen immediately, which enabled a quick and effective intervention by the team of first responders using a powder extinguisher before the fire-fighters arrived. The staff were evacuated. The regeneration plant was shut down, and used solvents were evacuated for treatment offsite (resulting in an additional cost of €7,500 to €10,000 per month). The installation had just started 10 minutes before the fire was detected; the regeneration tank contained 600 litres of solvent (75% xylene, 20% naphtha and 5% butanol and other components). The heating time before distillation had typically been 90 min. The regenerated solvents were being used to clean the circuits. The cause of this accident remained undetermined. The operator questioned both the oil supplier (who was changed in November 2006) and the regeneration plant manufacturer in order to understand the reasons for the (observed) coolant gelling or its spontaneous combustion (flash point above 212°C, whereas its operating temperature was 180°C). The analysis conducted by the operator eliminated the control and safety thermostats as the potential cause. Furthermore, the dismantled electrical heaters were intact and not short-circuited. No electrical fault or external heat source were detected. The oil froze in the system without anyone knowing if this was the cause or the consequence of the phenomenon. Fire-fighters did not find any temperature above 105°C. The operator identified areas for improvement in terms of: organising and managing evacuation, training staff, locating storage for potentially hazardous substances, and reviewing the risk analysis. Maintaining this sort of activity onsite was called into question, since the parent group favoured internal recycling in compliance with proper waste management practices. Meanwhile, the installation was shut down and a return to service could not be foreseen in the plant’s current state.