A man is dead following an explosion involving a pressurized nitrous oxide cylinder in Cecil County Friday night.Just before 8:30 p.m., emergency personnel responded to 75 Walnut Grove Road for a reported explosion with injuries.Investigators say a 10-pound nitrous oxide cylinder was at the rear exterior of a car parked at the home.The car had recently been purchased for racing purposes and contained a nitrous oxide system. For some unknown reas…