Standard Interpretations - Table of Contents|
| Standard Number:||1910.147; 1910.212; 1910.212(a)(1)|
July 7, 2005
Mr. Eric Frumin
Health and Safety Department
275 Seventh Avenue, 10th Floor
New York, NY 10001-6708
Dear Mr. Frumin:
Thank you for your January 31, 2005 fax to the Occupational Safety and Health Administration (OSHA). Your letter was forwarded to the Office of General Industry Enforcement for response. This letter constitutes OSHA's interpretation only of the requirements discussed and may not be applicable to any questions not delineated within your original correspondence. You had specific questions regarding robotic laundry shuttles.
1. Would training and strict enforcement of work rules prohibiting any employee from entering the working envelope of the shuttle while the shuttle is operating provide acceptable protection for the employees?
2. Could safety features such as warning lights, audible alarms, and emergency stops provide acceptable protection for employees who may be exposed to hazards from laundry shuttles?
3. Are barrier chains or fencing surrounding the working envelope of the shuttle system, but which are constructed of a height that provides easy, but conscious access to the hazardous area, an accepted protection for employees, if the employer has training and work procedures which prohibit employee access to the area while the shuttle is running?
4. Would any combination of warning lights, warning alarms, warning signs, awareness guards, training and enforcement of written rules, and emergency stop switches provide protection that complies with OSHA's machine guarding standards?
5. Would barrier guarding that only provides employee access to the shuttle area through unlocked, non-electrically-interlocked gates provide acceptable protection for employees?
6. Would barrier guarding with electrically-interlocked access gates that put the shuttle into manual mode when opened provide acceptable protection for employees?
7. Would barrier guarding with control-reliable, electrically-interlocked access gates that stop shuttle motion when opened provide acceptable protection for employees?
Responses: If an employee may be exposed to machine hazards during the machine's normal operation, the hazardous areas of the machine must be guarded. The Occupational Safety and Health Review Commission has found employee exposure where it is reasonably predictable, either by operational necessity or otherwise (including inadvertence), that employees have been, are, or will be in the machine's zone of danger. Employees may be exposed as they interact with the machinery, travel within a facility, or engage in other employment and comfort activities. While the answers to your questions depend in some cases on facts related to the particular machines and the manner in which workers interact with the machines, the methods described in your questions 1-5 generally would not provide adequate protection for workers exposed to machine hazards. On the other hand, in most situations the methods described in your questions 6 and 7 would provide adequate employee protection.
if an employee may be exposed to hazards, such as nip points or moving parts on a machine (e.g., a conveyor on a shuttle), OSHA's general machine guarding standard, 29 CFR §1910.212(a)(1), addresses guarding for the hazardous areas. The OSHA machine guarding standard provides that, if an employee may enter the working envelope of a laundry shuttle and be exposed to hazards associated with the operation of the laundry shuttle, the machine hazards must be addressed by: fixed barriers that are not easily defeated, barrier guards with interlocks that immediately stop machine motion, or presence-sensing devices that immediately stop machine motion.
The American National Standard for Industrial Robots Systems Safety Systems (ANSI/RIA R15.6-1999) and other non-ANSI sources address hazards specific to industrial robots, including some hazards not addressed in §1910.212. In 1987, OSHA issued an Instruction concerning industrial robots (STD 01-12-002 PUB 8-1.3 Guidelines for Robotics Safety (copy enclosed)), which references some of these sources and describes safety systems available to eliminate robotic hazards. The guarding methods listed in the Instruction encompass all of the methods listed in your seven questions, including: Interlocked Barrier Guards, Fixed Barrier Guards, Awareness Barrier Devices, Presence-Sensing Devices, Emergency Robot Braking, and Audible and Visible Warning Systems. However, in practice, the guarding system selected must effectively protect employees exposed to robotic hazards; merely because a guarding system is listed in the instruction does not mean the selected guarding system meets OSH Act requirements, either alone or in combination with other guarding systems for any particular machine. Selection of an appropriate guarding system depends on the hazards specific to the robot in question. However, the 1986 ANSI standard on robotics systems and the updated ANSI standard (ANSI/RIA R15.6-1999) provide guidance on the selection of guarding devices. While these standards provide some leeway for selection of guarding devices when risk and severity of injury are both slight, the standards clearly provide that awareness guards must be used in conjunction with, and not in place of, specific safeguarding devices (fixed barriers, two-hand control systems, and presence-sensing safeguarding devices) during normal operations in all cases where workers could be seriously injured. See e.g., ANSI/RIA 15.6-1999, Sections 8, 9, and 10.4.2.
Please be aware that guarding provisions discussed above protect workers from hazards when machines and robotic devices are used during normal production modes. If an employee is exposed to hazards while performing servicing or maintenance work on a machine, the lockout/tagout standard (29 CFR §1910.147) applies, and all sources of hazardous energy must be isolated.
Thank you for your interest in occupational safety and health. We hope you find this information helpful. Please be aware that the enforcement guidance contained in this response represents the views of OSHA at the time the letter was written based on the facts of an individual case, question, or scenario and is subject to periodic review and clarification, amplification, or correction. It could also be affected by subsequent rulemaking; past interpretations may no longer be applicable. In the future, should you wish to verify that the guidance provided herein remains current, you may consult OSHA's website at www.osha.gov. If you have any further questions, please feel free to contact the Office of General Industry Enforcement at (202) 693-1850.
Richard E. Fairfax, Director
Directorate of Enforcement Programs
|Standard Interpretations - Table of Contents|