Text For Citation: 01 Item/Group: 001 Hazard: BURNS

Section 5(a)(1) of the Occupational Safety and Health Act of 1970: The employer did not furnish employment and a place of employment which were free from recognized hazards that were causing or likely to cause death or serious physical harm to employees in that employees were exposed to burn and explosion hazards: On August 16, 2000, an explosion took place in the Littleford mixer that was blending a batch containing Celogen OT, the principle ingredient of which is p,p'-oxybis (benzene sulfonylhydrazide), a flammable dust. The force of the explosion opened the product door on the right, spraying an employee who was walking in the aisle way next to the mixer. The explosion also vented up the explosion vent on the right, which discharged next to the hopper and the work platform. The deflagration venting and other aspects of the design of the Littleford mixer and its work area do not conform to NFPA 654, "Standard for the Prevention of Fire and Dust Explosions for the Manufacturing, Processing and Handling of Combustible Particulate Solids," 1997 Edition. a) The Littleford mixer used for blending Celogen OT was not segregated from other operations by dust-tight physical barriers or separated from other operations by at least 30 feet, including a loading dock, aisle ways for pedestrian and lift truck traffic, and other operations in rooms with open doorways. This is not in accordance with NFPA 654, Section 2-2, "Segregation, Separation, or Detachment of Combustible Dust Handling and Processing Areas," which states in relevant portions: 2-2.1 General: Areas in which combustible dusts are processed or handled shall be detached, segregated, or separated from other occupancies to minimize damage if a fire or explosion occurs. 2-2.2.1 Physical barriers erected to segregate dust hazards shall have all penetrations of floors, walls, ceilings, or partitions sealed dust-tight and, where structural assemblies have a fire endurance rating, the seal shall maintain that rating. 2-2.3.2 The required separation distance between the hazardous area identified in 2-2.3.1 and surrounding exposures shall be determined by an engineering evaluation addressing the properties of the materials, the type of operation, the amount of material likely to be present outside the process equipment, the design of the building, and the nature of surrounding exposures. In no case shall the distance be less that 30 feet (9 meters). b) The discharge of material from the explosion relief vent on the right near the hopper of the Littleford mixer and the work platform is not in accordance with NFPA 654, Section 2-4, "Deflagration Venting", and Section 2-5, "Relief Valves," which state as follows: 2-4.2 Vent closures shall be directed toward a personnel restricted area, or the vent closure shall be restrained to minimize the missile hazard to personnel and equipment. The fireball emitted from the vent opening shall not impinge upon personnel pathways. 2-5 Relief valves shall not be vented to a dust hazard area as defined by 2-2.3.1. c) The dust collection system did not have isolation devices to prevent the explosion from reaching the dust collector. This is not in accordance with NFPA 654, Section 3-1.2, "Equipment Isolation," which states in relevant part: 3-1.2.1 Isolation devices shall be provided to prevent deflagration propagation between pieces of equipment connected by ductwork. Isolation devices include, but are not limited to: (a) Chokes (b) Rotary valves (c) Automatic fast-acting valve systems in accordance with NFPA 69, "Standard on Explosion Prevention Systems" (d) Flame front diverters in accordance with NFPA 69, "Standard on Explosion Prevention Systems" (e) Flame front extinguishing systems in accordance with NFPA 69, "Standard on Explosion Prevention Systems" d) The Littleford mixer was not dust-tight. Specifically, it leaked dust around the shaft to the right chopper. This is not in accordance with NFPA 654, Section 3-6, "Mixers and Blenders," which states in relevant part: 3-6.1 Mixers and blenders shall be dust-tight. e) The dust collector is inside the building, in the same room as the Littleford mixer. This is not in accordance with NFPA 654, Section 4-1, "Dust Collection," which states in relevant part: 4-1.2 Dust collectors shall be located outside of buildings. This requirement does not apply to dust collectors equipped with one of the following methods of protection: oxidant concentration reduction, deflagration pressure containment, deflagration suppression systems, in accordance with NFPA 69, "Standard on Explosion Prevention Systems," or dilution with a noncombustible dust to render the mixture noncombustible. It also does not apply to dust collector located within 20 feet of an exterior wall and equipped with deflagration vents vented through ducts to the outside. f) The Littleford mixer was not maintained in a manner that minimized the escape of dust. Specifically, the sealing to the right chopper was not repaired to prevent dust from escaping around the shaft. This is not in accordance with NFPA 654, Section 4-2, "Housekeeping," which states in relevant part: 4-2.1 Equipment shall be maintained and operated in a manner that minimizes the escape of dust.g) Operating and maintenance procedures for the Littleford mixer and emergency plans for employees operating the Littleford mixer had not been reviewed annually. This is not in accordance with NFPA 654, Section 7-1, "Employee Training," which states in relevant part: 7-1.1 Operating and maintenance procedures and emergency plans shall be developed. These shall be reviewed annually, and as required by process changes. h) The Littleford mixer was not tested and maintained to ensure that it was operating as designed. This is not in accordance with NFPA 654, Section 8-1, "Inspection and Maintenance," which states in relevant part: 8-1.1 An inspection, testing and maintenance program shall be implemented that ensures that the fire and explosion protection systems and related process controls and equipment perform as designed, and that a change in process equipment does not increase the hazard. Note: Feasible and acceptable abatement methods include but are not limited to: 1) Place the Littleford mixer that processes Celogen OT in a room without other operations, with doorways that are sealed to be dust-tight, and walls of a fire-resistance rating of at least one-half hour and capable of withstanding the maximum possible pressure that could be generated by a deflagration; 2) Extend the explosion relief venting to discharge above the roof; 3) Place the controls that operate the Littleford mixer outside the room and create mechanisms for the remote addition of materials such as oil that are added after the blending begins; 4) Add explosion suppression systems in the duct collection ductwork and in the dust collector; 5) Move the dust collector to the outside of the building; 6) Inspect and maintain the Littleford mixer so that it is dust-tight, operates as designed, and so that excess heat is not generated; 7) Put revised operating and maintenance procedures in writing, and review them annually or whenever the mixing process is changed; 8) Improve the training of operators, assistants, maintenance employees and supervisors to ensure that they understand the procedures as written, the explosion prevention and suppression systems, emergency procedures, and the explosion potential of Celogen OT.