Abstract: At approximately 11:05 a.m. on July 31, 1990, Employees #1 and #2 were attempting to stop the flow of fuel gas to the Unifiner heater charge by turning off the valves that controlled the gas and by flooding the burner section with steam. As they were doing this, a pipe containing hydrogen burst, resulting in an explosion and fire. Employees #1 and #2 were blown approximately 10 to 20 feet from where they were standing. Employee #1 suffered second-degree burns on his back and arms, and third-degree burns on his arms and one ear. Employee #2 suffered first- and second-degree burns on his back, arms, neck, and face. Employee #1 was hospitalized at the Sherman Oaks Burn Center for skin grafts on his arms.