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

OSH ACT of 1970 Section (5)(a)(1): 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 combustible rice bran extract dust fire, deflagration and explosion, hazards while working at or near an indoor spray dryer system (main drying chamber, fines recovery cyclone, baghouse, and connecting ductwork). The system operated in a manner where uncontrolled fire, deflagration propagation, and explosion hazards were present from the processing of combustible rice bran extract dust. The system was operated without a means of fire protection (detection, shutdown, and suppression) to prevent the development of a fire condition, without means of deflagration propagation protection (isolation systems) to prevent the spread of a pressurized flame between the equipment within the spray dryer system, and without a means of explosion protection for the fines recovery cyclone to prevent an overpressure of that vessel: On or about July 24, 2020, the indoor spray dryer system (main drying chamber, fines recovery cyclone, bag house, and connecting ductwork) handling combustible rice bran extract dust, presented combustible dust fire and deflagration propagation hazards as the system was operated without: a) a means of fire protection (detection, shutdown, and suppression) to prevent the development of a fire condition; b) a means of deflagration propagation protection (isolation systems) to prevent the spread of a pressurized flame between the equipment within the spray dryer system; and c) a means of explosion protection for the fines recovery cyclone to prevent overpressure of that vessel. Among other methods, one feasible method to correct the hazards would be to follow the guidance in the National Fire Protection Association's (NFPA) Standard 61 "Standard for the Prevention of Fires and Dust Explosions in Agricultural and Food Processing Facilities (2020)"- Section 9.3.17.5.2 (Spray Dryer System Safety Controls); 9.3.17.5.3 (Spray Dryer Operation); 9.3.17.5.4 (Fire Detection); 9.7.4 (Equipment Isolation); 9.3.17.5.5 (Spray Dryer System Explosion Protection); and 9.3.4.1 (Air-Material Separator Explosion Protection). Specifically: For fire protection- Provide the dryer with the means for detecting abnormal conditions that indicate the presence or potential of a fire. The detection of conditions should activate an alarm, automatically shutdown the equipment, and activate means for extinguishing the fire within the drying chamber. For deflagration propagation protection - Provide means of deflagration propagation protection (isolation) between connected equipment (i.e. the main drying chamber, the fines recovery cyclone, and the baghouse). Numerous methods of isolation (i.e. active and passive systems) can be found in NFPA 69 "Standard on Explosion Prevention Systems". For explosion protection on the fines recovery cyclone - Provide means of explosion protection such as: (1) Deflagration detection and chemical suppression system in accordance with NFPA 69, (2) Deflagration venting to a safe outdoor location in accordance with NFPA 68 "Standard on Explosion Protection by Deflagration Venting", or (3) Deflagration venting indoors through a listed dust retention and flame-arresting device in accordance with NFPA 68. For ignition source prevention - Ensure appropriate cleaning and maintenance of systems to minimize the change of internal product layers forming and being exposed to a heated surface or hot air stream. In addition, provide safety controls so that the spray dryer and auxiliary equipment such as: (1) Excess temperature detection (for the airstream between the air heater and drying chamber air inlet & for the airstream at the discharge of the cooling and heating sections), alarms, and automatic shutdown of key systems (heating system fuel, flow of product out of the dryer, airflow from fans into the dryer), and (2) Operating controls that maintain the temperature of the drying chamber within prescribed limits. In consideration of the abatement methods outlined above, a Dust Hazards Analysis (DHA) should be performed on the spray drying system. The purpose of a DHA is to thoroughly evaluate the fire, deflagration, and explosion hazards present in a facility/operation and to provide recommendations to managed confirmed hazards. Chapter 7 of NFPA 61 (2020) outlines the general requirements, criteria, documentation, methodology, necessary material evaluations, etc. for conducting a DHA.