Fire on a hydrogen production facility

The fire developed on the hydrogen production unit of a subcontractor in a plant producing metallic wire articles. The cause was a malfunctioning of the hydrogen unit.
The production was stopped for 17 hours.

The INITIATING CAUSE was a fire was due to a malfunctioning of the electrolyser.

Hydrogen production unit

The electrolyser experienced an emergency shut-down and the factory production was stopped for 17 hours.

Restarting of installations was authorised only after the submission of a report proposing technical/organisational improvement to avoid such incident.

16:30 - The fire was reported. The fire-fighters found multiple hydrogen tanker trucks on fire in the facility yard. The fire department ordered an evacuation radius of ca. 450 m, (affecting an industrial area and few people working there at that time).
Once it was confirmed that no one was injured and the area was evacuated, the fire-fighters switched to defensive operations with multiple ladder trucks flowing water from aerial master streams, to cool the liquid hydrogen tank and surrounding equipment exposed to the residual fires.
17:40 - The fire was extinguished. It took firefighters an hour and at least three aerial water streams to put out the fire. Later firefighters made access to tanker valve and shut down while master streams flowed to cool the tanks and trucks previously impinged with Fire.
Firefighters used thermal imaging cameras from different vantage points to make sure that the hydrogen was not burning even after it appeared that it was shut down.

An internal accident investigation performed by the company reported:
"A hydrogen leak was detected during the trailer fill process. Per our fill procedures, the fill should have been stopped and the vehicle placed out of service for maintenance to be performed by trained technicians at one of our maintenance locations. Instead, an employee attempted to perform maintenance on the process equipment without authorization. This resulted in a release of high pressure hydrogen and the subsequent fire. We have inspected all trailers and leak checked the entire fleet, which resulted in the replacement of one O-ring."

The facility was allowed to restart only after the submission of a report regarding the circumstances of the accident and containing technical/organizational proposals to reduce the probability of its renewal.
Unfortunately, the report has not been made public.