Friday, February 26, 2010 Just before 1700 hours the Commercial Fire Alarm Box was struck for the 100 Block of Commerce Dr. in Chester Twp. Truck 63, E63 and R63 made the response. Units were advised while enroute of reports of a fire in the rear of the complex with the building being evacuated.  47-12 arrived on scene with smoke showing from side “C” Charlie and established the Command. Truck 63 arrived first and stretched in to the building with two hand lines. The crew from Truck 63 found a medium smoke condition inside and had additional crews from Q52 and R40 assist with locating the source. After determining the fire was extinguished and that there was need for ventilation crews began opening up and trying to determine what had actually been on fire. E63’s crew talked to the workers who reported the fire and were shown the source and room of origin of the fire which turned out to be a fire explosion caused by a rupture disk safety on a hydrogen reactor. The explosion and fire was controlled by a worker with eight fire extinguishers prior to the FD arrival. Crews ventilated the building and were released a short time later. Other Companies on scene were 47, 52, 40, 61, 57, RIT 39, RIT 23 M83-7. Brookhaven Car 1 was on scene for the investigation.