Regulators in new report urge safety improvements after 2018 hydrogen truck fire in Diamond Bar

First responders who tended to a fire that erupted on a truck carrying hydrogen tanks in Diamond Bar in 2018 lacked the proper training for dealing with the dangerous gas, placing firefighters at risk, said federal officials in a report released Tuesday.

There were no injuries reported in the Feb. 11, 2018 incident, but it caused the evacuation of more than 1,500 people from surrounding businesses and homes and $175,000 in damage to transportation equipment.

The National Transportation Safety Board report was released amid increasing use of hydrogen-powered fuel cell electric vehicles, drawing an increase in bulk hydrogen fuel shipments throughout the county.

The report offered recommendations aimed at government and private agencies on handling such incidents; and suggested more training for firefighters and first responders along with improvements in the inspection of hydrogen storage and transportation equipment.

Poor inspection of the tank equipment prior to the incident was found to be the likely cause of the fire, NTSB officials said in the report.

The day of the incident

On the day of the incident the truck, owned by Air Products and Chemicals Inc., was on its way to a fuel cell electric vehicle fueling station in Diamond Bar. The station is used to fuel electric vehicles that used hydrogen-powered fuel cells to power the vehicles, rather than rechargeable batteries.

At about 1:15 p.m., as the truck sat idle at a stoplight along Golden Springs Road near South Brea Canyon Road, the driver of the truck remembered hearing a loud pop and seeing flames coming from the front of the module trailer, according to the report. The module contained 25 hydrogen cylinders; a system in which the entire module would have been delivered to the customer.

Leaping from the vehicle, the driver ran to warn people to evacuate the area. Authorities would eventually direct between 1,500 to 2,000 people to evacuate the area out of concern of a possible explosion.

Firefighters with the Los Angeles County Fire Department arriving on scene had no idea they were headed toward a hydrogen tank fire. They had been fed a slew of faulty reports about a gas station explosion and a tanker truck fire.

“It was not until firefighters arrived on scene and from very close distance that they saw the placard and the burning trailer containing ‘individual hydrogen tanks,’” the report said.

It said emergency responders lacked familiarity with hydrogen tube trailer modules and “did not immediately recognize the presence of hazardous materials, had difficulty estimating the likelihood for severe outcomes, and had not received guidance about appropriate mitigating actions needed to reduce the potential for catastrophic gas cylinder failures.”

Hydrogen, a colorless and odorless gas that is 14 times lighter than air, is extremely flammable and may form explosive mixtures in the air, the NTSB said. Hydrogen flames are often invisible and may ignite if a cylinder valve is opened to the air.

“Upon exposure to intense heat or flame, gas cylinders can vent rapidly or rupture violently,” the report said.

Faulty guidelines and a faulty inspection

Firefighters backed off and began to shoot water into the burning trailer. For the next nine hours, firefighters shot water into the flames, on-and-off, only stopping to check thermal imagining that was able to track the flames.

The report said firefighters were using general guidelines provided by the Department of Transportation. NTSB investigators found these guidelines to be too vague and not specific to hydrogen-related incidents. For instance, firefighters did not know that spraying water directly on the fire, especially toward vent pipes, could cause the containers to rupture and possibly explode, the report said.

The report also recommended that guidelines be revised for evacuations. On the day of the incident, the evacuation zone may have been larger than necessary.

After the tanks had cooled, Air Products workers were able to vent out the rest of the hydrogen and transfer the trailer to its facility in Santa Fe Springs by about 3 a.m. the next day.

Later investigation would show that the wrong pressure-relief device had been installed in some of the cylinders during an inspection by a contracted agency in 2017. The faulty installation allowed the high-pressure hydrogen to leak from a tank, causing a device to pop from a cylinder, igniting flames within the trailer toward other tanks. The fire damaged 21 other cylinders, causing hydrogen to leak from six of them.

Growing industry of hydrogen-powered cars

Though the NTSB investigation zeroed in on the 2018 Diamond Bar incident, the probe’s broader intent was to evaluate the safety of using mobile hydrogen tube trailer modules as fueling stations for electric vehicles that use hydrogen fuel cells. These types of vehicles are a part of growing industry in California with automakers expected to make thousands of new fuel cell electric vehicles in the near future, officials said in the report.

“As of April 25, 2018, the California Fuel Cell Partnership reported that the state had 36 open retail and nonretail hydrogen fueling stations, with another 28 stations in various stages of construction and planning,” the report said.