‘Nacho Typical Fire’

Spontaneously combusting tortilla chips provide laughs—and lessons about stored hazards BY ANGELO VERZONI

In July, a tortilla chip factory in Austin, Texas, tested a new method for disposing of chip waste that didn’t go very well. According to published reports, the method included grinding the waste into a powder, enclosing that powder in cardboard boxes, and placing those boxes outside.

Under the scorching summer sun, the boxes began spontaneously combusting, according to a July 18 Facebook post by the Austin Fire Department.

“On the evening of July 12, several of our B-shift crews responded to 6110 Trade Center Drive for the spontaneous combustion of tortilla chips,” the department said. “Yes, you read that right. Spontaneous combustion. Of tortilla chips.” Nobody was hurt in the blaze, which continued to ignite in numerous boxes after firefighters arrived on scene, and damage was confined to the exterior of the factory, according to the post. Three days later, firefighters were again called to the factory as more boxes of ground-up chips ignited.

Not surprisingly, many who saw the Facebook post got a kick out of it. One commenter wryly suggested dousing the next batch of burning chips with guacamole instead of water. Another wrote, “that’s nacho typical fire.”

As amusing as the situation might have been, it serves as a good example of how a seemingly innocuous material can become a combustible hazard, given the right conditions. According to Guy Colonna, senior director of Engineering at NFPA, the fires were caused by spontaneous oxidation of the frying oil that saturated the chips—the oil oxidized naturally, generating heat, and the mass of confined chip dust acted as insulation, retaining the heat and the allowing the temperature to gradually increase to the point of ignition.

“That kind of high edible-oil content can create problems,” Colonna said, and offered an example encountered by NFPA technical staff a number of years ago. Fires were taking place in commercial laundries and seemed to involve the linens used in restaurants, including aprons, table cloths, and napkins. The linens were collected by a laundry company, washed, and dried in commercial dryers, then folded and stored overnight for loading into trucks and delivery back to the restaurants the next morning. Fires were breaking out while the linens were stored after drying.

“The culprit turned out to be the cooking oil used in restaurants that accumulated on the linens,” Colonna recalled. “Because the linens were not cooled before folding and storing, they retained heat that reacted with the oil residue that had not been fully laundered out. The self-heating process continued until ignition occurred.”

For a related report on spontaneous combustion by NFPA’s Research, Data and Analytics Division, visit nfpa.org/spontaneous

ANGELO VERZONI is staff writer for NFPA Journal. Top Photograph: ISTOCKPHOTO