Application vs. Construction Standards
Light curtain standards fall into two categories: application standards and construction standards. Application standards reference how to use a light curtain for machine safety and guarding, for example, how to calculate the safe mounting distance. Although some may give condensed construction information, often the main thrust of machine safety application standard is how to apply a light curtain for the type of machine covered by the standard. For example, ANSI/RIA R15.06 discusses the use of presence-sensing devices (light curtains) for robot guarding. ANSI B11.1 provides information on how to use presence-sensing devices on mechanical power presses.
provide design, construction and testing information on presence sensing devices. There are currently no construction standards developed in North America and IEC61496, an IEC standard entitled Safety of Machinery - Electrosensitive Protective Equipment is generally accepted as the default.
IEC61496 covers specific items such as the number of outputs required, the need for a keyoperated switch, transformer construction, and failure conditions. Test specifications require that the equipment be subject to a battery of tests including moisture and dust intrusion, power supply transients, electrical interferences, electrostatic discharges, component failure mode analysis and object sensing capabilities.
Machine Safety and Guarding
In the United States, installation and use of machine safety and guarding is regulated by the Occupational Safety and Health Administration (OSHA). Some states have their own safety organizations with regulations that must be at least as strict as the federal OSHA standards.
In addition to OSHA, other organizations provide information on proper machine guarding. The American National Standards Institute (ANSI) publishes the B11 standards to provide information on the construction, care and use of machine tools. Certain standards are developed for specific types of machine tools. Standards in the B11 series include:
B11.1: Mechanical Power Presses
B11.2: Hydraulic Power Presses
B11.3: Power Press Brakes
B11.5: Iron Workers
B11.7: Cold Headers and Cold Formers
B11.8: Drilling, Milling and Boring Machines
B11.9: Grinding Machines
B11.10: Metal Sawing Machines
B11.11: Gear Cutting Machines
B11.12: Roll Forming and Roll Bending
B11.13: Single- and Multiple-Spindle
Automatic Bar and Chucking
B11.14: Coil-Slitting Machines
B11.15: Pipe, Tube and Shape Bending
B11.16: Metal Powder Compacting Machines
B11.17: Horizontal Hydraulic Extrusion
B11.18: Machinery and Machine Systems for
Processing Strip, Sheet, or Plate from
B11.19: Perfomance Criteria for the Design,
Construction, Care and Operation of
Safeguarding When Referenced by
other B11 Machine Tool Safety
Standards. B11.19 is considered one
of the best single sources of machine
tool guarding information for the
B11.20: Manufacturing Systems/Cells
Integrated Manufacturing Systems/Cells
An integrated manufacturing system is defined as a group of two or more industrial machines working together in a coordinated manner normally interconnected with and operated by a supervisory controller or controllers capable of being reprogrammed for the manufacturing of discrete parts or assemblies. This definition is provided by ISO 11161, Safety of Integrated Manufacturing Systems, an international standard covering requirements for the safe installation, programming, operation, maintenance or repair of these systems. A similar standard is ANSI B11.20, entitled Manufacturing Systems/Cells - Safety Requirements for Construction, Care and Use.
Both of these standards cover control. When machines in an integrated system operate separately or individually, or the safeguards are muted or suspended, the safety standards for the individual machines should be used as a supplement.
Robots and Robot Systems
Safety guidelines for applications using industrial robots result from the joint effort of ANSI and the Robotics Industries Association (RIA). In standard ANSI/RIA R15.06, an industrial robot is defined as a reprogrammable multifunctional manipulator designed to move material, parts, tools, or other devices. This standard does not apply to numerically controlled machine tools.
Ontario Regulation 7
Each Canadian province has created, or is developing its own specific safety regulations. The province of Ontario may have the most complete set. Of particular interest to users of industrial machinery is Regulation 7 of the Regulations for Industrial Establishments.
Regulation 7 outlines the requirements for a Pre-Start Health and Safety Review (PHSR). The intent of a PHSR is threefold:
1. Provide for a timely professional review to identify specific standards.
2. Ensure hazards are removed or controlled before start-up. 3. Ensure that worker protection the safety of multiple machines under some type of common protection as required under the applicable provisions of the Regulations for Industrial Establishments is provided.
What is a Pre-Start Health and Safety Review?
A PHSR is conducted upon the construction, addition or installation of a new machine, structure or protective element, or the modification of an existing installation.
The end result of a PHSR is a written report. This report details the actions, steps or engineering controls required to bring the subject application into compliance with the provisions of the Regulations for Industrial Establishments.
Benefits of a PHSR include:
Prevention of hazardous incidents Assurance of uniform quality inspections Reduced cost of protection Assurance that high risk areas are addressed Raises standards for OEM manufacturers
Although specific to the Canadian province of Ontario, Regulation 7 and the resulting PHSR report incorporate the risk assessment principals found elsewhere in this engineering guide.
The Canadian Standards Association (CSA) CSA is a Canadian laboratory that tests and certifies the electrical integrity and safety of products.
CSA is accredited by OSHA as a Nationally Recognized Test Laboratory (NRTL) which covers testing of all products under OSHAs jurisdiction.
The NRTL/C mark (Canadian/ US certification) on Omron Scientific Technologies, Inc. products indicates certification for Canada as well as the United States and is considered to comply with applicable CSA and UL requirements.
The NRTL/C mark is a counterpart to the Underwriters Laboratory C-UL mark. Both marks indicate that a product is in compliance with both CSA and UL standards.
The NRTL/C mark on Omron STI’s products precludes the necessity of having both CSA and UL agency logos. All Omron STI safety light curtains are CSA listed (file number LR90200).
In order to provide employees with a safe work environment, many corporations have authored their own standards for safety light curtains and personnel protection. These standards are frequently more stringent than those required by OSHA and can only be met by the most technically advanced products.