A trained operator was blending water, sand, anhydrite, lime, cement, pulverized fly ash, and powdered aluminum in a mixing chamber to produce material for making concrete building blocks. In the blending process, sand and water are mixed to form a slurry, and then the powders are dispensed automatically into the mix by a computer-controlled system. Finally, a slurry of glycol-coated aluminum powder is added in the last few seconds before the mix is discharged into a car, and then molds are filled from the car. Adding aluminum to the mixture results in a small amount of hydrogen gas evolution, which disperses from the car into the surrounding ventilated area and out through roof vents. In addition to being an ingredient of the mix, water also helps to keep the mixture cool.
A sealed, unclassified electrical control enclosure, part of a listed and certified force-ventilated commercial hydrogen processing unit enclosure, exploded when the equipment manufacturer’s technician pressed the machine stop switch to complete factory commissioning procedure. The technician was forcefully hit by the flying metal panel holding the switch and sustained serious injuries requiring lengthy hospitalization and rehabilitation. Two were hospitalized. Two others were injured. Significant damage to the indoor facility also occurred.
An independent investigation found that drain lines from the external hydrogen vent stack drain trap and the electrical control enclosure cooler/condenser drain were interconnected into a single external sealed floor drain, in a manner not view more