A contractor is setting up a temporary fuel storage area holding 200 gallons of diesel (Class B combustible). OSHA rules require one 10B-rated extinguisher within 50 feet. If they have 600 gallons, they need larger protection. Calculate the minimum rating for 600 gallons.

A welding operation is taking place. It generates a radiant heat flux of 100 kW/m² at a distance of 1 meter from the arc. A stack of dry cardboard packaging is sitting 4 meters away. Estimate the radiant heat flux reaching the cardboard.

A confined space contains methane gas. The LEL of methane is 5% by volume in air. A gas monitor reads the methane concentration at 25,000 parts per million (ppm). Determine if the atmosphere is explosive.

A welder is cutting steel brackets directly above a lower floor using an oxy-acetylene torch. Sparks fall through a small gap around a pipe penetration. The welder finishes the job at 3:00 PM, packs up, and leaves. At 3:45 PM, a smoldering piece of slag ignites foam insulation on the lower floor, burning down the building.

Painters using linseed oil to finish architectural woodwork pile their soaked rags into a corner of a poorly ventilated room at the end of the shift. Hours later, the rags burst into flames without any external ignition source (no sparks or open flames).