Solvent spill in a paint preparation room with ventilation off
A furniture factory paint preparation room holds 12 × 20 L cans of xylene-based thinner, flash point about 25 °C, lower flammable limit 1.0% by volume. At 14:20 a worker decanting from a 20 L can into a 5 L bucket overturns it; about 8 L spreads over 6 m² of concrete. The room's exhaust ventilation was switched off at 13:00 because the fan belt was squealing. A pedestal grinder 4 m away is used intermittently, and an electric fan heater is running near the door. Two workers wear cotton overalls and safety shoes; one has a mobile phone. The spill is being mopped with rags into an open plastic bin. The shift supervisor says the smell is strong but 'it will air out' and production must continue until 18:00. You are the fire safety engineer called to the shop floor.
1. Identify the immediate fire and explosion hazards and decide whether work must stop.
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Stop work and evacuate the room. Eight litres of xylene-based thinner is a flammable liquid with a flash point near 25 °C and a lower flammable limit around 1.0% by volume; at room temperature it gives off enough vapour to form a flammable mixture near the floor and in low spots. The exhaust ventilation is off, so vapour accumulates instead of being diluted. The pedestal grinder, fan heater, mobile phone and static from cotton overalls and rags are credible ignition sources. The open plastic bin of rags adds a second fuel load and a spontaneous-heating risk. The supervisor's 'it will air out' is not a control. Use a calibrated gas meter: if the reading is above 10% LFL, evacuate and ventilate from a safe distance; do not energise or switch anything. Only trained personnel in appropriate PPE should contain the spill.
2. Describe the first 10 minutes of emergency response.
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First 10 minutes: sound the local alarm and stop production; move non-essential people out. Eliminate ignition – do not operate switches, grinders, the heater or a phone in the vapour area, and isolate power from outside. Ventilate by opening doors and windows and using explosion-proof portable fans only after the area is clear. Contain the liquid with inert absorbent or sand; never wash it into drains. Place used absorbent in a closed metal container. Close the room and restrict entry. Notify the fire service if vapour cannot be controlled and inform the factory fire safety officer. Do not mop with dry rags while vapour is present; use non-sparking tools and grounded containers. Re-enter only after gas testing confirms the atmosphere is safe.
3. What longer-term controls would prevent recurrence?
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Interlock the exhaust ventilation with the decanting operation and provide local exhaust at the decant point. Keep thinners in a closed metal cabinet with bunding and limit the quantity in the room. Bond and ground containers during decanting. Replace the fan heater with a fixed, explosion-protected heating system or remove it. Provide a spill kit, eye wash and fire extinguishers suitable for flammable liquids. Train workers on decanting, static and emergency actions; prohibit mobile phones in the zone. Review the room's fire and explosion classification with a competent engineer. Repeat gas testing after cleaning and before any hot work or power restoration.