Deep-fat fryer fire in the galley with a grease-laden exhaust duct
The galley of a bulk carrier has a single deep-fat fryer holding 18 litres of oil at 185 C. The thermostat has been sticking for a week. At 12:10 the oil reaches 240 C and ignites, producing a flame about 1.5 m high from the fryer and dense smoke. The cook throws a wet cloth onto the oil and the flame flares up. He then switches the fryer off at the wall isolator and shouts for help. The exhaust hood filter above the fryer is heavily grease-laden and the flue duct runs 6 m up through the accommodation to a fan on the boat deck. The messroom is next door and the four-strong galley team is panicking. Available in the galley: a water-fog extinguisher, a 9-litre water extinguisher, a 5 kg CO2 and a 6 kg dry-powder. The wet-chemical extinguisher is mounted at the far end of the galley, behind the fire. The duct fan is still running.
1. Classify the fire and explain why water in any form is the worst possible choice here.
Read the worked answer
Classification. Burning cooking oil is its own class, Class F in the European scheme (Class K in the American scheme), with some Class B behaviour. Its distinguishing feature is saponification: the hot oil reacts with an alkaline extinguishing agent to form a soapy crust that seals the surface and smothers the fire.
Why water is the worst choice:
- Any water that reaches the oil flashes to steam almost instantly. One litre of water produces roughly 1,700 litres of steam, an expansion of about 1,700 times, and throws burning oil out of the fryer in a fireball across the galley.
- Even a fine spray onto a 240 C oil layer causes violent spitting.
- The water-fog and water extinguishers here would carry the burning oil out of the pan, onto the cook and towards the messroom door and the accommodation.
The cook made it worse twice: the wet cloth added water and smothered nothing. Switching off at the wall isolator was right, but only because the isolator was not behind the fire. A CO2 extinguisher is also poor here because its blast can splash burning oil out of the pan, and dry powder does not cool the oil, so re-ignition is almost certain.
2. Give the correct sequence of action with the equipment actually available, including the duct.
Read the worked answer
- Raise the alarm and clear the galley; the messroom should be evacuated and its door closed.
- Stop the fryer (done) and stop the exhaust fan and close the duct damper. The duct is grease-laden and the fan is pulling flame up into the accommodation - this is the most urgent action after the alarm.
- If a lid is available, slide it on from the side, gloves on, arms covered, keeping the body back. Smothering is the cheapest and cleanest fix. A fire blanket large enough to cover the fryer works the same way, held so the flame cannot lick up the arms.
- Otherwise use the wet-chemical extinguisher, applied gently from 1-2 m so the agent falls onto the oil rather than blasting it; aim at the near edge and let it spread and saponify.
- The wet chemical is behind the fire, so do not walk past the fryer to reach it. Have a second person pass it, or use a short burst from the CO2 at the doorway to knock the flame down and allow access - accepting that the oil will stay hot and may re-ignite.
- If the duct is alight, treat it as a separate fire: fan stopped, damper closed, use the fixed duct system or CO2/dry powder through the access hatch. Never put water into a hot grease duct.
- Cool the surrounding steel and hood from outside and keep the fryer where it is.
3. What are the post-fire risks and actions, and what should be recorded and reported?
Read the worked answer
Immediate risks:
- Re-ignition of the oil. Keep the lid on and let it cool naturally; do not drain, move or open the fryer while the oil is above 200 C. A hot element or a spark will relight it.
- The duct is the hidden hazard. Heated grease can re-ignite hours later. Open the duct access hatches only after the fan is stopped and the duct cooled, and inspect the filters, the fan and the duct run with a thermal imager.
- Heat and smoke spread through the accommodation along the duct; check the spaces it passes through for hot bulkheads and smoke.
Before restarting the galley: confirm the fire is out, the duct cleaned or renewed, the thermostat replaced and a high-temperature cut-out fitted, and the filter cleaning interval brought into the PMS.
Record and report: time of ignition, the thermostat's history, the agents used and how many, the duct fan and damper actions, and the condition of the hood filters. Photograph the fryer, thermostat and duct before cleaning. Report through the SMS to flag State and class as required, preserve the faulty thermostat as evidence, and feed the findings into the next drill and the galley staff training.