Sprinkler Water and Acid Soot in a Machine Shop
A hydraulic press fire in a 12,000 sq ft machine shop was extinguished by two sprinkler heads. About two inches of water stands in the machining bay. CNC machines, tooling, and bare steel stock are in the affected area; power is locked out. Smoke residue is visible on machine cabinets and in the office area. The owner needs production restarted in 72 hours and says to “just dry it out and wipe the machines.” Outdoor humidity is 85% and the building is at 68°F. You have six air movers, two LGR dehumidifiers, a 500 CFM HEPA scrubber, and a wet/dry vacuum. An electrician is available in 24 hours. A floor drain is slow. The fire department cut a 4 ft by 8 ft ventilation hole in the roof, and rain is forecast in 18 hours.
1. What is your first 24-hour priority order, and why?
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Order: life safety and electrical lockout; temporary roof tarp and board-up before the rain; stop and extract water; then dehumidify and filter. The roof opening is a secondary-damage pathway. Rain on a fire-damaged shop will add water damage and raise humidity, which accelerates acid corrosion on machines and steel. Extract first because standing water slows drying and keeps relative humidity high. Then set LGRs and air movers, but do not blow air across contaminated machine surfaces before HEPA filtration and cleaning, or you will spread soot. Bring the electrician in as soon as the building is safe. Document each step with photos, moisture readings, and a time log.
2. How do you protect the CNC machines and steel stock, and what documentation supports your recommendation?
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The enemy is moisture plus acid soot. Extract and dry the slab, keep relative humidity below about 50% if possible, HEPA-vacuum and wipe machine cabinets with a cleaner appropriate to the surface, and oil bare steel. Do not use water-based cleaners on electrical enclosures or controls. If the machines cannot be energized, use temporary heat and dehumidification and consider corrosion-inhibiting oil. Document relative humidity and moisture content daily, with photos of bare steel and cabinets. Recommend that the owner have the machine manufacturer or a millwright inspect before power-up. If the owner refuses, record the refusal in writing.
3. The owner refuses the roof tarp because “the hole is good ventilation.” How do you respond?
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Explain that the roof hole is a ventilation opening, but it is also a weather opening. A tarp is temporary and does not stop drying; it prevents rain from adding a new loss. If the owner still refuses, document the refusal, the forecast, and the potential consequences, and notify the adjuster. Do not let the refusal stop you from extracting and drying. Get the direction in writing. This is a scope and liability issue, not a debate about ventilation.