'Cause Unknown' Chicken Restaurant Fire, Reenactment Experiment Reveals... Surprising Results

Daejeon Police and Fire Department Joint Experiment Conducted
Investigation of Spontaneous Combustion in Fried Residue

A fire of unknown origin that occurred at fried food establishments such as chicken restaurants was revealed through a reproduction experiment to have been caused by the spontaneous combustion of frying residue.

On the 26th, Yonhap News reported that this fact was identified through a joint experiment by the police and fire authorities. On that day, the Fire Investigation Team of the Scientific Investigation Division at Daejeon Police Agency and the Fire Investigation Team of Daejeon Fire Headquarters confirmed through a joint fire reproduction experiment that spontaneous combustion occurred in the frying residue collected after cooking.

The interior of the business completely burned down due to spontaneous combustion of fried residue. Provided by Daejeon Police Agency.

The two agencies explained that over the past three years, about ten fires that occurred at fried food establishments such as chicken restaurants in the Daejeon area were presumed to be caused by spontaneous combustion, but the exact cause had not been identified. In particular, on October 3rd, a fire presumed to have been caused by the ignition of frying residue broke out at a chicken restaurant in Daedeok-gu, completely burning down the entire commercial building. On the 20th of the same month, at a restaurant in Galma-dong, Seo-gu, Daejeon, a fire broke out when heated frying oil was being discharged from a fryer, igniting the frying residue, but the fire was extinguished within six minutes. Recently, fires have occurred consecutively at restaurants that prepare fried food. At the time of the fires, all these establishments reportedly stored frying residue in containers made of highly flammable materials such as plastic.

Step-by-step process of fried residue ignition reproduction experiment. Provided by Daejeon Police Agency.

Accordingly, the police and fire authorities conducted reproduction experiments to determine the exact cause of the fires. They created an environment similar to the actual situation and conducted two reproduction experiments. As a result, they confirmed that the frying residue spontaneously combusted, producing smoke, and after 1 hour and 30 minutes of the experiment, flames appeared in the adjacent container. The oil components in the frying residue combined with oxygen, causing heat to accumulate and smoke to be produced without flames. The plastic container holding the residue deformed due to the heat, which then ignited. Therefore, both businesses and households can prevent fires simply by disposing of frying residue daily or by changing the containers used to hold the residue from plastic to metal materials.

A representative from the Daejeon Police Agency recommended, "Since it has been confirmed that fires caused by spontaneous combustion can occur in frying residue, fried food establishments should dispose of frying residue immediately after cooking." A representative from the Daejeon Fire Headquarters also advised, "If frying residue is generated, disposing of it daily or cooling it slightly with a fan can reduce the possibility of spontaneous combustion. Using metal containers rather than plastic ones or covering the containers with lids can block oxygen inflow and prevent the fire from spreading into a large blaze."