Meeting OSHA Recommendations for Combustible Dust

Transcription

1 1 Meeting OSHA Recommendations for Combustible Dust

2 Table of Contents Introduction: Definition of Combustible Dust 1 Introduction: Hazards of Combustible Dust 2 Organic Dust Fire and Explosion: North Carolina Metal Dust Fire and Explosion: Indiana Related Experience in the Grain Handling Industry 5 Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions Scope of OSHA Oversight (and the General Duty Clause) 6 Elements of a Dust Fire and Explosion 7 Facility Dust Hazard Assessment 8 Facility Analysis 9 Electrical Classification 10 Other Hazard Considerations 11 Dust Control 12 Ignition Control 13 Damage Control 14 Training Employees 15 Training Management 16 DEMARCO Industrial Vacuum Systems 17 Portable 18 Stationary 19 Custom Engineered 20 Nilfisk CFM Explosion-Proof Vacuums 21 OSHA Voluntary Protection Programs 22 OSHA Combustible Dust Poster 23 Resources 25 Contact Us 26

3 Introduction: Definition of Combustible Dust To begin, let s start with the legal definition of combustible dust. The U.S. Occupational Safety and Health Administration (OSHA) follow the definition set forth by the National Fire Protection Association (NFPA). NFPA standard 654 defines combustible dust as: Any finely divided solid material that is 420 microns or smaller in diameter (material passing a U.S. No. 40 Standard Sieve) and presents a fire or explosion hazard when dispersed and ignited in air. The same definition is used for combustible metal dust in NFPA 484, Standard for Combustible Metals, Metal Powders, and Metal Dusts. There are too many sources of combustible dust to catalog on this page, but a full list can be found on the OSHA Combustible Dust Poster found at the end of this booklet. Some typically well-known sources of combustible dust include: wheat grain, powdered sugar, lactose, powdered aluminum, and plastic resins. 1

4 Introduction: Hazards of Combustible Dust The dangers of combustible dust have been well documented over the years. OSHA points to a number of recent industrial accidents that have focused national attention in the United States on the potential hazards that different forms of combustible dust have caused when ignited. 2

5 Introduction: Hazards of Combustible Dust Organic Dust Fire and Explosion: North Carolina In January 2003, devastating fires and explosions destroyed a North Carolina pharmaceutical plant that manufactured rubber drug-delivery components. Six employees were killed and 38 people, including two firefighters were injured. The U.S. Chemical Safety and Hazard Investigation Board (CSB), an independent federal agency charged with investigating chemical incidents, issued a final report concluding that an accumulation of a combustible polyethylene dust above the suspended ceilings fueled the explosion. The CSB was unable to determine what ignited the initial fire or how the dust was dispersed to create the explosive cloud in the hidden ceiling space. The explosion severely damaged the plant and caused minor damage to nearby businesses, residential property, and a school. 3

6 Introduction: Hazards of Combustible Dust Metal Dust Fire and Explosion: Indiana Finely dispersed airborne metallic dust can also be explosive when confined in a vessel or building. In October 2003, an Indiana plant where auto wheels were machined experienced an incident that was also investigated by the CSB. A CSB news release told a story similar to the previously discussed organic dust incidents: aluminum dust was involved in a primary explosion near a chip melting furnace, followed by a secondary blast in dust collection equipment. 4

7 Introduction: Hazards of Combustible Dust Related Experience in the Grain Handling Industry In the late 1970s, a series of devastating dust explosions in grain elevators left 59 people dead and 49 injured. In response to these catastrophic events, OSHA issued a Grain Elevator Industry Hazard Alert to provide employers, employees, and other officials with information on the safety and health hazards associated with the storage and distribution of grain. In 1987, OSHA promulgated the Grain Handling Facilities standard (29 CFR ), which remains in effect. This standard, other OSHA standards such as Emergency Action Plans (29 CFR ), and updated industry consensus standards all played an important role in reducing the occurrence of explosions in this industry, as well as mitigating their effects. The lessons learned in the grain industry can be applied to other industries producing, generating, or using combustible dust. 5

8 Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions Scope of OSHA Oversight (and the General Duty Clause) The latest Safety and Health Information Bulletin (SHIB ) from OSHA on combustible dust, Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions, lays out the agency s oversight scope in the regulation of combustible dust in the workplace. It states in part: This Safety and Health Information Bulletin is not a standard or regulation, and it creates no new legal obligations.... Pursuant to the Occupational Safety and Health Act, employers must comply with hazard-specific safety and health standards promulgated by OSHA or by a state with an OSHA-approved state plan.... Employers can be cited for violating the General Duty Clause if there is a recognized hazard and they do not take reasonable steps to prevent or abate the hazard. 6

9 Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions Elements of a Dust Fire and Explosion 1. Combustible dust (fuel) 2. Ignition source (heat) 3. Oxygen in air (oxidizer). Additional Elements Needed for a Combustible Dust Explosion: 4. Dispersion of dust particles in sufficient quantity and concentration 5. Confinement of the dust cloud. The addition of the latter two elements to the fire triangle creates what is known as the explosion pentagon (see Figure 1). If a dust cloud (diffused fuel) is ignited within a confined or semi-confined vessel, area, or building, it burns very rapidly and may explode. The safety of employees is threatened by the ensuing fires, additional explosions, ejected debris, and collapsing building components. 7

10 Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions Elements of a Dust Fire and Explosion (cont d) A primary explosion (see below) in processing equipment or in an area were fugitive dust has accumulated may shake loose more accumulated dust, or damage a containment system (such as a duct, vessel, or collector). As a result, if ignited, the additional dust dispersed into the air may cause one or more secondary explosions (see below). These can be far more destructive than a primary explosion due to the increased quantity and concentration of dispersed combustible dust. If one of the elements of the explosion pentagon is missing, a catastrophic explosion cannot occur. Two of the elements in the explosion pentagon are difficult to eliminate: oxygen (within air), and confinement of the dust cloud (within processes or buildings). However, the other three elements of the pentagon can be controlled to a significant extent. 8

11 Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions Facility Dust Hazard Assessment A combustible dust explosion hazard may exist in a variety of industries, including: food (e.g., starch, flour, feed), plastics, wood, rubber, furniture, textiles, pesticides, pharmaceuticals, dyes, coal, metals (e.g., aluminum, chromium, iron, magnesium, and zinc), and fossil-fuel power generation. The vast majority of natural and synthetic organic materials, as well as some metals, can form combustible dust. NFPA s Industrial Fire Hazards Handbook states: Any industrial process that reduces a combustible material and some normally noncombustible materials to a finely divided state present a potential for a serious fire or explosion. 9

12 Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions Facility Analysis Facilities should carefully identify the following in order to assess their potential for dust explosions: Materials that can be combustible when finely divided Processes which use, consume, or produce combustible dusts Open areas where combustible dusts may build up Hidden areas where combustible dusts may accumulate Means by which dust may be dispersed in the air Potential ignition sources. Applicable federal, state, and local laws and regulations must be identified and followed. The two predominant model fire codes that have been adopted by many jurisdictions in this country are the International Code Council s International Fire Code and NFPA s Uniform Fire Code. Both of these model codes reference many of the NFPA consensus standards related to dust explosion prevention and mitigation. In the absence of a legal mandate to comply with these consensus standards, they should be considered a very useful source of guidance on this topic. 10

13 Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions Electrical Classification A facility analysis must identify areas requiring special electrical equipment classification due to the presence (or potential presence) of combustible dust. The OSHA Electrical standard (29 CFR Part 1910 Subpart S) contains general requirements for electrical installations in hazardous areas. Detailed requirements for equipment and wiring methods are in NFPA 70, the National Electrical Code. However, NFPA 70 does not define combustible dusts. Further guidance on area classification is contained in NFPA 499, Recommended Practice for the Classification of Combustible Dusts and of Hazardous (classified) Locations for Electrical Installations in Chemical Process Areas. This document uses the same definition of combustible dust as NFPA 484 and NFPA 654. The overall dust hazard designation for electrical requirements is Class II. This is further broken down into divisions that represent the probability of dust being present at any given time. Additionally, each dust is assigned a group (E, F, or G), representing the dust types (metal, carbonaceous, and other, respectively) with different properties. For instance, group E dusts are electrically conductive and electric current can pass through a layer of such dust under favorable circumstances, causing short circuits or arcs. 11

14 Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions Other Hazard Considerations The amount of dust accumulation necessary to cause an explosive concentration can vary greatly. This is because there are so many variables the particle size of the dust, the method of dispersion, ventilation system modes, air currents, physical barriers, and the volume of the area in which the dust cloud exists or may exist. As a result, simple rules of thumb regarding accumulation (such as writing in the dust or visibility in a dust cloud) can be subjective and misleading. The hazard analysis should be tailored to the specific circumstances in each facility and the full range of variables affecting the hazard. After hazards have been assessed and hazardous locations are identified, one or more of the following prevention, protection and/or mitigation methods may be applied. The references and information sources at the end of this document will assist in the decision process for the methods suitable to specific work sites. Additional guidance and requirements may be available from local or state fire and building code officials, as well as OSHA area or regional offices. 12

15 Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions Dust Control NFPA 654 (Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids) contains comprehensive guidance on the control of dusts to prevent explosions. The following are some of its recommendations: Minimize the escape of dust from process equipment or ventilation systems Use dust collection systems and filters Utilize surfaces that minimize dust accumulation and facilitate cleaning Provide access to all hidden areas to permit inspection Inspect for dust residues in open and hidden areas, at regular intervals Clean dust residues at regular intervals Use cleaning methods that do not generate dust clouds, if ignition sources are present Only use vacuum cleaners approved for dust collection Locate relief valves away from dust hazard areas Develop and implement a hazardous dust inspection, testing, housekeeping, and control program (preferably in writing with established frequency and methods). The OSHA ventilation standard, 29 CFR , contains ventilation requirements for certain types of operations (such as abrasives, blasting, grinding, or buffing) which involve dusts, including combustible dusts. Additionally, 29 CFR (a)(1) requires employers to keep work places and other areas clean, which includes the removal of dust accumulations. 13

16 Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions Ignition Control NFPA 654 also contains comprehensive guidance on the control of ignition sources to prevent explosions. The following are some of its recommendations: Use appropriate electrical equipment and wiring methods Control static electricity, including bonding of equipment to ground Control smoking, open flames, and sparks Control mechanical sparks and friction Use separator devices to remove foreign materials capable of igniting combustibles from process materials Separate heated surfaces from dusts Separate heating systems from dusts Proper use and type of industrial trucks Proper use of cartridge activated tools Adequately maintain all the above equipment. The use of proper electrical equipment in hazardous locations is crucial to eliminating a common ignition source. Once these areas have been identified, special Class II wiring methods and equipment (such as dust ignition-proof and NEMA 9 ) must be used as required. It is important not to confuse Class II equipment with Class I explosion-proof equipment, as Class II addresses dust hazards, while Class I addresses gas, vapor, and liquid hazards. 14

17 Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions Damage Control NFPA 654 contains comprehensive guidance to minimize the danger and damage from an explosion. The following are some suggested protection methods: Separation of the hazard (isolate with distance) Segregation of the hazard (isolate with a barrier) Deflagration venting of a building, room, or area Pressure relief venting for equipment Provision of spark/ember detection and extinguishing systems Explosion protection systems (also refer to NFPA 69, Standard on Explosion Prevention Systems) Sprinkler systems The use of other specialized suppression systems. 15

18 Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions Training Employees Workers are the first line of defense in preventing and mitigating fires and explosions. If the people closest to the source of the hazard are trained to recognize and prevent hazards associated with combustible dust in the plant, they can be instrumental in recognizing unsafe conditions, taking preventative action, and/or alerting management. While OSHA standards require training for certain employees, all employees should be trained in safe work practices applicable to their job tasks, as well as on the overall plant programs for dust control and ignition source control. They should be trained before they start work, periodically to refresh their knowledge, when reassigned, and when hazards or processes change. Employers with hazardous chemicals (including combustible dusts) in their workplaces are required to comply with 29 CFR , the Hazard Communication standard. This includes having labels on containers of hazardous chemicals, using material safety data sheets, and providing employee training. 16

19 Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions Training Management A qualified team of managers should be responsible for conducting a facility analysis (or for having one done by qualified outside persons) prior to the introduction of a hazard and for developing a prevention and protection scheme tailored to their operation. Supervisors and managers should be aware of and support the plant dust and ignition control programs. Their training should include identifying how they can encourage the reporting of unsafe practices and facilitate abatement actions. 17

20 DEMARCO Industrial Vacuum Systems Currently, OSHA is still in the process of drafting an updated federal standard to systematically address the problem of combustible dust. While the agency continues to grapple with a new set of guidelines, manufacturers are turning to well-trusted industrial vacuum suppliers to meet their needs for mitigating fugitive dust in the workplace in order to meet current guidelines and recommendations. Although most manufacturers make every effort to keep their plants safe, accumulations of any amount of combustible dust can still lead to significant penalties and fines. OSHA recommends that you clean dust residue regularly using only vacuum cleaners approved for dust collection. Before cleaning, shut down all flame and ignition sources. Use a cleaning method that does not generate dust clouds (i.e., vacuuming instead of blowing). Establish a routine cleaning schedule to remove dust from floors, ledges, beams, equipment, and other surfaces. And clean regularly often enough to prevent dust buildup. DeMarco s innovative solutions are ready to work for you in handling almost any potential combustible dust hazard. We feature portable, stationary, customized, and explosion-proof vacuums for fugitive dust mitigation. 18

21 DEMARCO Industrial Vacuum Systems Stationary Stationary DEMARCO Bottom-Dump Hopper Vacuums are built for ultra heavy-duty use inside or outside your facility. This design allows for NFPA Compliant continuous dumping while maintaining hands-free filter cleaning for 24/7 operation. DEMARCO Industrial Vacuums range from 15 HP to 250 HP and easily handle the heaviest, most abrasive materials to the finest of powders, without interruption. Stationary DEMARCO Vacuums may be connected to a grounded central manifold system with multiple pick-up point connections. 19

22 DEMARCO Industrial Vacuum Systems Custom Engineered DeMarco s engineering capabilities reach far beyond standard industrial vacuuming applications. We provide our customers with unique solutions to even the most demanding cleanup requirements. Foundries, food processing, mills, mines, power plants, manufacturing and concrete facilities have all been seeking DEMARCO Industrial Vacuums for decades. We are not only known for our world-class customer support, but our customers loyalty is gained through our dedicated team of sales engineers that have one goal in mind: Customeroriented solutions. 20

23 OSHA Voluntary Protection Programs OSHA s Voluntary Protection Programs (VPP) recognize employers and workers in private industry and federal agencies who have implemented effective safety and health management systems and maintain injury and illness rates below national Bureau of Labor Statistics averages for their respective industries. In VPP, management, labor, and OSHA work cooperatively and proactively to prevent fatalities, injuries, and illnesses through a system focused on: hazard prevention and control; worksite analysis; training; and management commitment and worker involvement. To participate, employers must submit an application to OSHA and undergo a rigorous onsite evaluation by a team of safety and health professionals. Union support is required for applicants represented by a bargaining unit. VPP participants are re-evaluated every three to five years to remain in the programs. VPP participants are exempt from OSHA programmed inspections while they maintain their VPP status. 21

24 OSHA Combustible Dust Chart: For safety, review this chart to be certain your company is not at risk for a Combustible Dust explosion Agricultural Products Egg white Milk, powdered Milk nonfat,dry Soy flour Starch, corn Starch, rice Starch, wheat Sugar Sugar, milk Sugar, beet Tapioca Whey Wood flour Agricultural Dusts Alfalfa Apple Beet root Carrageen Carrot Cocoa bean dust Coffee dust Corn meal Cornstarch Cotton Cottonseed Garlic powder Gluten Grass dust Green coffee Hops (malted) Lemon peel dust Lemon pulp Linseed Locust bean gum Malt Oat flour Oat grain dust Olive pellets Onion powder Parsley (dehydrated) Peach Peanut meal and skins Peat Potato Potato flour Potato starch Raw yucca seed dust Rice dust Rice flour Rice starch Rye flour Semolina Soybean dust Spice dust Spice powder Sugar (10x) Sunflower Sunflower seed dust Tea Tobacco blend Tomato Walnut dust Wheat flour Wheat grain dust Wheat starch Xanthan gum Cabonaceous Dusts Charcoal, wood Coal, bituminous Coke, petroleum Lampblack Lignite Peat,22%H 2 0 Soot, pine Cellulose pulp Cork Corn Chemical Dusts Adipic acid Anthraquinone Ascorbic acid Calcium acetate Calcium stearate Carbox-methylcellulose Dextrin Lactose Lead stearate Methyl-cellulose Paraformaldehyde Sodium ascorbate Sodium stearate Sulfur Metal Dusts Aluminum Bronze Iron carbonyl Magnesium Zinc Plastic Dusts (poly) Acrylamide (poly) Acrylonitril (poly) Ethylene (low-pressure process) Epoxy resin Melamine resin Melamine, molded (phenol-cellulose) Melamine, molded (wood flour and mineral filled phenolformaldehyde) (poly) Methyl acrylate (poly) Methyl acrylate, emulsion polymer Phenolic resin (poly) Propylene Terpene-phenol resin Urea-formaldehyde/ cellulose, molded (poly) Vinyl alcohol (poly) Vinyl butyral (poly) Vinyl chloride/ ethylene/vinyl acetylene suspension copolymer (poly) Vinyl chloride/ vinyl acetylene emulsion copolymer 22

25 OSHA Combustible Dust Chart: For safety, review this chart to be certain your company is not at risk for a Combustible Dust explosion Dust Control Measures The dust-containing systems (ducts and dust collectors are designed in a manner (i.e., no leaking) that fugitive dusts are not allowed to accumulate in the work area. The facility has a housekeeping program with regular cleaning frequencies established for floors and horizontal surfaces, such as ducts, pipes, hoods, ledges, and beams, to minimize dust accumulations within operating areas of the facility. The working surfaces are designed in a manner to minimize dust accumulation and facilitate cleaning. Ignition Control Measures Electrically-powered cleaning devices such as vacuum cleaners, and electrical equipment are approved for the hazard classification for Class II locations. The facility has an ignition control program, such as grounding and bonding and other methods, for dissipating any electrostatic charge that could be generated while transporting the dust through the ductwork. The facility has a Hot Work permit program. Areas where smoking is prohibited are posted with No Smoking signs. Duct systems, dust collectors, and dust-producing machinery are bonded and grounded to minimize accumulation of static electrical charge. The facility selects and uses industrial trucks that are approved for the combustible dust locations. The facility selects and uses industrial trucks that are approved for the combustible dust locations. Prevention Measures The facility has separator devices to remove foreign materials capable of igniting combustible dusts. MSDSs for the chemicals which could become combustible dust under normal operations are available to employees. Employees are trains on the explosion hazards of combustible dusts. Protection Measures The facility has an emergency action plan. Dust collectors are not located inside of buildings. (Some exceptions) Rooms, buildings, or other enclosures (dust collectors) have explosion relief venting distributed over the exterior wall of buildings and enclosures. Explosion venting is directed to a safe location away from employees. The facility has isolation devices to prevent deflagration propagation between pieces of equipment connected by ductwork. The dust collector systems have spark detection and explosion/deflagration suppression systems. Emergency exit routes are maintained properly. 22

26 Resources United States. U.S. Department of Labor. Occupational Safety and Health Administration.OSHA Fact Sheet - HazardAlert: Combustible Dust Explosions. Web. < United States. U.S. Department of Labor. Occupational Safety and Health Administration.OSHA INSTRUCTION. U.S. Department of Labor, Web. < United States. U.S. Department of Labor. Occupational Safety and Health Administration.Hazard Communication Guidance for Combustible Dusts. U.S. Department of Labor, Web. < United States. U.S. Department of Labor. Occupational Safety and Health Administration.STATUS REPORT on COMBUSTIBLE DUST NATIONAL EMPHASIS PROGRAM. U.S. Department of Labor, Web. < United States. U.S. Department of Labor. Occupational Safety and Health Administration.Combustible Dust - An Explosion Hazard. U.S. Department of Labor, n.d. Web. < United States. U.S. Department of Labor. Occupational Safety and Health Administration.Firefighting Precautions at Facilities with Combustible Dust. U.S. Department of Labor, n.d. Web. < United States. U.S. Department of Labor. Occupational Safety and Health Administration.OSHA Voluntary Protection Program. U.S. Department of Labor, n.d. Web. < 23

27 Contact Us DeMarco Corporate Headquarters USA: DeMarco Industrial Vacuum Corporation 760 Industrial Drive Cary, IL USA Or: REMIT TO ADDRESS: P.O. Box 1138 Crystal Lake, IL Phone: (USA); Fax: Web: 24