According to Bureau of Labor Statistics (BLS, 2010b) data, machines were the primary or secondary source of 604 work-related fatalities in 2008. That same year, machinery was the source of 64,170 cases involving days away from work (BLS, 2010b). More than 25% of all machinery- related injuries that involved days away from work resulted in more than 31 days away from work (BLS, 2010a). OSHA (2010) has estimated the total cost of an amputation injury (indirect costs plus direct costs) to be $101,467. Clearly, machine-related injuries take a heavy toll on employers and employees. The ANSI B11 Accredited Standards Committee for Machine Safety Standards oversees more than 30 standards and technical reports. The standards are organized in an A-B-C manner. Type-A standards are known as basis standards and identify basic concepts, principles for design and general aspects that are applicable to machinery in general. Type-B standards are known as generic safety standards; they deal with safety aspects or safeguards that are applicable to many machine types. Type-C standards are known as machinery- specific safety standards and contain guidelines that are germane to certain specific machine types. Specific equipment covered by C-level standards such as ANSI B11.1, Safety Requirements for Mechanical Power Presses, or ANSI B11.3, Machine Tools: Safety Requirements for Power Press Brakes, should be guarded according to those specific standards. If the machines are interfaced with another machine or process, then ANSI B11.20, Safety Requirements for Integrated Manufacturing Systems, would be appropriate, as would be using B11.0/B11.19. C-level standards can have machine-specific exceptions to the rules in B11.19, but generally they should follow the rules of B11.19. This article concentrates on aspects of ANSI B11.0 and ANSI B11.19 that concern risk assessment and machine guarding. In addition, applicable sections of select international standards, as they relate to ANSI B11.0 and B11.19, also are briefly discussed.
James R. Harris, Ph.D., P.E., Research Safety Engineer, NIOSH, Protective Technology Branch, Division of Safety Research, Morgantown, WV