Explosion at a storage area of a chemical plant

One employee was injured in an explosion in a chemical plant storage area containing ammonia, acetone, and hydrogen.

storage area, ammonia, acetone, hydrogen

The fire department requested that the facility was not shut down but rather to continue operations, to reduce the hydrogen inventory in the tank.
(1) A checkpoint was established near the tank side of the building where hydrogen level readings were taken and reported every 5 minutes. Employees of the plant were notified to exit the front of the building in the event of an evacuation signal.
(2) As hoses were turned on by the fire department, a drop in water pressure tripped the internal alarm, causing an evacuation of the plant. All employees were accounted for and were asked to return to work, as this was a false alarm condition.
(3) Two local streets were closed, radios, cell phones, and other electronic devices were shut down within a 500-foot safety zone to eliminate any static electricity that could ignite the hydrogen gas,
(4) Airplanes were diverted from their normal flight path to the local airport.
(5) Firefighters set up combustible gas monitors inside the building, but no gas was detected.
The incident lasted approximately two hours.