Abstract: On June 10, 1992, and July 8, 1992, the ethylene oxide (EtO) sterilizer became overpressurized due to polymerization of material in a gas cylinder, which caused the solenoid to stick and the safety relief to lift. When this occurred on June 10, 1992, Employee #1 had entered and turned off the gas cylinder. Medical aid was administered to Employee #1, who suffered no acute injury and was not hospitalized. After the incident, a cracked bushing was found, which had prevented the safety valve from resetting. The EtO unit was repaired. On July 8, 1992, the same incident occurred, but no cracked bushing was found. The fire department responded and shut down the gas cylinder. The gas was tested for particulate.