OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 25 Tools, Equipment and Machinery

Section 384 Robots

Subsections 384(1)

Robots are machines specifically designed and programmed to perform certain operations. They are part of today’s workplace and are used in a variety of applications such as spray painting, arc and spot-welding, materials handling, assembly, and machine loading and unloading.

CSA Standard Z434-03 (R2008), Industrial Robots and Robot Systems – General Safety Requirements, applies to the manufacture, remanufacture, rebuild, installation, safeguarding, maintenance and repair, testing and start-up of industrial robots and robot systems. The Standard also includes requirements for worker training.

Robot safety can be divided into three major areas:

(1) safety in the process of manufacturing, remanufacturing, and rebuilding of robots;
(2) robot installation; and
(3) safeguarding workers exposed to hazards associated with the use of robots.

A hazard assessment as required by section 7 of the OHS Code must be conducted to identify potential hazards and appropriate controls when working with robots. A sample risk assessment process is included in the CSA standard. A risk assessment for robot safety may consider:

(a) size, capability, and speed of the robot;
(b) applications and process;
(c) anticipated tasks that will be required for continued education;
(d) hazards associated with each task;
(e) anticipated failure modes;
(f) probability of occurrence and probable severity of injury; and
(g) level of expertise of exposed workers and the frequency of exposure.

The robot and robot system must be equipped with adequate safeguarding devices to protect workers against hazards. Safeguarding should eliminate or control the hazard. A hierarchy of safeguarding controls is recommended in the CSA standard and summarized in Table 25.4.

Table 25.4 Hierarchy of safeguarding controls

Most
effective

 

 

 

 

 

 

 

 

 

 

 

 

Least effective

(1) Elimination or substitution
  • eliminate human interaction in the process
  • eliminate pinch points (increase clearance)
  • automated material handling
(2) Engineering controls (safeguarding technology)
  • mechanical hard stops
  • barriers
  • interlocks
  • presence-sensing devices
  • two hand controls
(3) Enhancing worker awareness or hazards
  • lights, beacons, and strobes
  • computer warnings
  • signs
  • restricted space painted on floors
  • beepers
  • horns
  • labels
(4) Training and procedures (administrative controls)
  • safe job procedures
  • safety equipment inspections
  • training
  • lockout
(5) Personal protective equipment
  • safety glasses
  • ear plugs
  • face shields
  • gloves

Source: CSA Standard Z434-03 (R2008), Table A.1

Types of safeguards

Safeguards that prevent workers from entering a restricted work area include:

(1) barriers – a physical means of separating the worker from the hazards;

(2) interlocking safeguarding devices – the operation of one control or mechanism allows or prevents the operation of another. These devices may be mechanical or electrical and must

(a) have a key, plug or actuating device that is not easily duplicated,
(b) be tamper-resistant and not be defeated intentionally without tools,
(c) provide a means for secure attachment, and
(d) be provided with documents stating the standards the product meets, the standard the product is independently certified to meet, and their safety circuit performance;

(3) safeguarding devices that signal a stop – examples include

(a) safety light curtains, screens,
(b) area scanning safeguarding devices,
(c) radiofrequency (RF) capacitance safeguarding devices,
(d) safety mat systems,
(e) single and multiple bean safety systems, and
(f) two-hand control systems;

(4) safeguards that limit robot motion – a restricted space must be established by installing a limiting device that minimizes the total distance a robot can travel. Limiting robot motion may be accomplished be means integral to the robot or by external limiting devices. Limiting devices redefine the space for a robot to perform its task. The restricted area is made smaller than the maximum space. The robot’s movement zone should be restricted to the range of motion a particular operation or installation requires; and

(5) presence sensing safeguarding devices – are used to detect intrusion into an area where a hazard may exist and include

(a) photoelectric cells,
(b) pressure-sensitive mats, and
(c) light or sound curtains.

Subsections 384(2) through 384(8)

Repealed.