Scene resembles “cotton candy machine gone haywire”

Chris McGinnis, Tim Jue, SFGATE

For a few minutes Friday morning, one of San Francisco International Airport’s largest hangars looked like the Niagara Falls of the West.

Thousands of gallons of fluffy white firefighting foam dropped from ceiling spigots inside the airport’s “super bay” hangar during a test of a new building fire suppression system. (The super bay is the one you see directly across the runways from airport terminals, used primarily by American Airlines.)

The airport shared video of the spectacular sight on its Facebook page which you can see below.

Workers lit a small controlled fire inside the huge hangar, located on the opposite side of SFO’s passenger terminals, to trigger the new system.

The moment one of the 48 foam release sensors sniffed out trouble, the emergency system kicked into action, releasing a deluge of foam retardant from above.

“It’s like a huge cotton candy dispenser that’s gone haywire right now!” said airport spokesperson Doug Yakel as he watched from inside the hangar and gave viewers a narration of the action.

In mere minutes, around six feet of retardant fell from the ceiling, easily burying the fire below in a white frothy mousse of high-expansion foam.

Engineers built big walls to create a basin around the perimeter of the building to catch the retardant, keeping it from seeping outdoors.

“It now looks when I was growing up in Wisconsin after a heavy snowfall that’s what it looks like right now,” Yakel said, “Unbelievable!”

The test was deemed a success.

In most commercial buildings, sprinklers help extinguish indoor fires by dousing fires with a steady stream of water from above.

In an airplane hangar with the potential for hundreds, or thousands of gallons of aviation fuel, the response is industrial-grade. Firefighting foam rapidly floods the entire hangar to smother the fire. And there needs to be a lot of it — fast — to protect workers and limit the fire’s spread elsewhere.

Many times when we hear of these releases, they’re usually accidental. In 2016, foam retardant spilled from a private jet hangar at Mineta San Jose International Airport onto city streets when the system was mistakenly activated. (More about that here.)

The mess one left behind is only temporary. The foam eventually dissolves into a non-toxic sludge of sorts, according to Yakel, which then can be squeegeed away.