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Conveyor Guarding

  • Issued: May 15, 2017
  • Content last reviewed: May 2017
  • See also: Mining

Disclaimer: This resource has been prepared to help the workplace parties understand some of their obligations under the Occupational Health and Safety Act (OHSA) and regulations. It is not legal advice. It is not intended to replace the OHSA or the regulations. For further information please see full disclaimer.

Purpose

The purpose of this document is to help workplace parties understand the requirements for conveyors (including guarding and emergency stopping systems) in the Regulation for Mines and Mining Plants (Regulation 854) under the Occupational Health and Safety Act (OHSA). Current best practices for conveyor guarding are also provided.

Objectives

  • to provide guidance to assist in complying with legal requirements for guarding of conveyors, including preventing worker access to pinch points that are or may become accessible
  • to provide information on current best practices for engineering and design to provide optimum safety for workers

Legal requirements

Sections 196 and 196.1 of the Mining Regulation set out the key requirements for conveyors.

Background information

  • Conveyors are widely used in Ontario mines. Workers may be exposed to certain hazards if conveyor belts and related equipment are not properly guarded and maintained.
  • Ontario workers have been killed and injured when they came into contact with equipment or components, such as conveyor drive belts and improperly guarded pinch points.
  • This guideline supports other safety policies and practices in the workplace, such as locking and tagging procedures when repairs, adjustments or other maintenance work is performed on conveyors [Mining Reg. s. 196 (6)].

Requirements and best practices

Conveyor guards

As a general matter, accessible pinch points must be guarded at the head, tail, drive and deflection pulleys or if the lift of the belt is restricted, the return rollers and carry rollers [Mining Reg. s. 196 (3)]. An accessible pinch point is a place where it is possible for a body part, article of clothing or an object to be caught between moving machine parts or between moving and stationary machine parts.

Figure 1. Belt conveyor pinch points (Diagram is illustrative only and not to scale.)

Illustration showing belt conveyor pinch points.  A pinch point can be located at a head, tail, drive, deflection and tension pulley or, if the lift of the belt is restricted, at the return rollers and carry rollers.

View a larger version of the illustration

Guarding is normally provided in the form of:

  1. Fixed enclosure guards
  2. Fixed distance barriers
  3. Other devices

Fixed enclosure guard

A fixed enclosure guard is fastened in place (i.e. closed or attached to a fixed surface) either permanently (e.g. by welding) or by other means of securing (screws, nuts, locks, etc.) using a tool. A fixed enclosure guard prevents access to a hazardous location or other area.

Figure 2. Example of a fixed enclosure guard

Illustration showing an example of a fixed enclosure guard (guard must extend at least 0.9 meters from the pinch point as per subsection 196.3.1 of Regulation 854).

(Diagram is illustrative only. Other configurations may be appropriate)

Fixed distance barrier

A fixed distance barrier prevents access to a pinch point by its physical dimensions and distance from a hazard. It may take the form of a barricade or fence that prevents normal access to the danger zone.

A gate used with a fence or barricade must comply with Mining Reg. s. 196 (3.2)(c). It must have an interlock system with a manual rest switch that renders the conveyor inoperative when the gate is moved or opened.

Other devices

Other devices may include:

  • Interlocked fail-safe barrier guard: a fixed or movable guard attached and interlocked in such a manner that the machine tool (conveyor) will not cycle or will not continue to cycle unless the guard itself or its hinged or movable section encloses the hazardous area.
  • Adjustable barrier guard: a fixed guard that is adjustable as a whole or that incorporates adjustable parts. The adjustment to the guard remains fixed during operation and prevents access.

All of these should be installed, maintained and operated in accordance with the manufacturers’ instruction or based on competent instruction.

Guarding in the vicinity of pulleys

Head, tail, drive, deflection and tension pulleys must be guarded at any pinch point that is or may become accessible. Other accessible pinch points in the vicinity of these pulleys should also be guarded.

Figure 3. Example of guarding in the vicinity of a tail pulley

Illustration showing an example of belt conveyor guards in the vicinity of a tail pulley. The head, tail, drive, deflection and tension pulleys are guarded at any pinch point that is or may become accessible. Other accessible pinch points in the vicinity of these pulleys are also guarded. Guards must extend at least 0.9 meters from the pinch point as per subsection 196.3.1 of Regulation 854.

(Diagram is illustrative only, other configurations may be appropriate)

A gravity take-up device is used to provide tension in a conveyor belt. Generally, a free weight is suspended on a tension pulley from deflection (bend) pulleys on the return side of the belt. This take-up travelling pulley with weight is free to lower, as needed, to remove any slack as the belt is operated.

Generally, all components of a take-up device with counterweight system must be guarded in accessible spots. This applies to components that can move during operation as well as to return and carry rollers if the belt’s lift is restricted. For more information, see deflection and tension pulleys [Mining Reg. s. 196 (3)] and counterweight [Mining Reg. s. 185 (4)]. Guarding should be provided for take-up devices that operate automatically. This is to prevent access to all components of a tension carriage or balance weight.

If the bottom of a gravity take-up is accessible, guarding protection must be provided to prevent injury to a worker as a result of the weight’s descent due to failure of a component [Mining Reg. s. 185 (4)]. Provision should be made for the removal or disposal of spillage in this area.

Suitably worded signs warning of stored energy should be visible at each point of access in the take-up and rope systems.

Figure 4. Example of guarding in the vicinity of take-ups and counterweights

Illustration of an example of guarding in the vicinity of take-ups and counterweights.

(Diagram is illustrative only. Other configurations are possible)

Guarding at carry and return idlers when belt lift is restricted

Carry (troughing) idlers or rollers are located on the carrying (top) side of the conveyor and are designed to make a conveyor belt curve into a cupped shape. This increases a conveyor’s capacity. Return idlers or rollers are used as support on the unloaded side of the belt.

Workers must be prevented from accessing pinch points where the belt’s lift is restricted on carry and return rollers (idlers) [Mining Reg. s. 196 (3) 2.].

Figure 5. Example of guarding in the vicinity of carry and return idlers at convex curves

Illustration of an example of guarding in the vicinity of carry and return idlers at convex curves. Guards must extend at least 0.9 meters from the pinch point as per subsection 196.3.1 of Regulation 854.

(Diagram is illustrative only, other configurations may be appropriate)

The areas of the belt that contact either carry or return rollers and change the angle of or deflect the belt must be guarded. It is important to guard at the convex curve due to the high pressures generated between the belt and the roller(s).

Guarding at hoppers and chutes

All openings to hoppers and chutes that constitute a hazard must be suitably guarded [Mining Reg. s. 59 (1)]. Hoppers or chutes should be provided with access or openings so any needed cleaning or inspection may be done outside the hopper or chute as much as possible.

Guarding at loading, unloading and discharge points

Guards should be installed to prevent injury whenever a worker has access to a loading, unloading, work station, transfer or discharge point.

Guarding at crossovers and underpasses

Crossovers or underpasses should be provided at appropriate locations when access to either side of a conveyor is required. This may include crossovers or underpasses at the head and tail ends, drive and other transfer points along the conveyor.

Guards must be provided under conveyors that pass over a worker or if there’s a risk of material or parts falling on a worker [Mining Reg. s. 196 (4)]. Consideration should be given to the height, mass and speed of the material being conveyed. The employer should designate appropriate crossovers and underpasses, in consultation with the workplace’s Joint Health and Safety Committee (JHSC) or health and safety representative (if any).

Construction and strength of guarding material

Generally, guards should be constructed of sheet metal, mesh or equivalent material. Guards should be sufficiently rigid, with openings that are sized and braced to ensure safe distances are maintained in case a worker inadvertently makes contact with the guard.

As a guide, sheet metal guards should be at least 1.5 mm thick. Mesh guards should consist of at least 1.5 mm wire gauge or 3 mm wire gauge for 50 mm square mesh and more. If alternative guarding material (other than stated above) is used, it should resist a force of:

  1. 450 N (100 lbs) at a point on the guard applied over a square area of 50 mm x 50 mm
  2. 220 N (50 lbs) applied to selected points to test the strength of a guard that can be climbed or rested upon when a simultaneous mass of 90 kg is placed on the guard.

The required clearances from the danger zone should be maintained when a force of 450 N (100 lbs) is applied at points on a guard over a square area of 50 mm x 50 mm.

Non-metallic materials may have strength and flammability issues, fire/chemical damage or deterioration caused by long term UV exposure.

Repairs, adjustments and maintenance of conveyors

Generally, a conveyor must be stopped, de-energized, locked and tagged out when a conveyor is undergoing repairs, adjustments or maintenance. If removal of guards is required, they must be replaced before restarting the conveyor.

If a conveyor must be operated during such work, effective precautions must be taken to prevent worker injury from moving parts [Mining Reg. s. 196 (6)].

Precautions may include, but are not limited to, extending grease lines to outside the guards. As well, the conveyor belt adjusters can be moved outside the guards so guards do not have to be removed while maintenance is being carried out.

Inspection/maintenance doors in fixed guards

Inspection doors may be provided on fixed guards subject to certain conditions. For example, incorporating an inspection door must not expose workers to pinch points or moving parts or material. Also, an inspection door must not be used when the conveyor is running unless conditions are met in Mining Reg. s. 196 (6).

Fences, barricades and gates

Other means can be used to prevent worker access to pinch points (i.e. fences, barricades and gates equipped with interlocking devices) if it’s not practicable to guard a pinch point as required by Mining Reg. s. 196 (3.1). These alternative options are allowed under Mining Reg. s. 196 (3.2).

Fences and barricades can be used to isolate a general area where one or more pinch points are located. The difference between a fence and barricade is that a fence is generally used to enclose, contain or separate a conveyor or part of a conveyor from the surrounding area. A barricade is used to close, block or otherwise prevent access to an area where a conveyor is being operated.

Generally, a fence is a barrier or other upright structure that encloses an area of ground to mark a boundary, control access or protect workers. Fencing needs to completely enclose a dangerous area and prevent access to pinch points. The fence needs to be of sufficient strength and construction so workers have no access to pinch points if they reach under, over or through the fence.

Generally, a barricade is any object or structure that creates a barrier or obstacle to control, block passage or force the flow of traffic in the desired direction. A barricade is used to isolate a general area or otherwise prevent access into the area by virtue of its physical dimensions and its distance from the hazards. The barricade needs to prevent access based on the type of traffic that needs to be controlled. For example, cement block may be used to prevent vehicle traffic, but not pedestrian traffic.

Generally, a gate is a type of barrier that can be used at an opening or entrance in a fence or barricade to prevent access to a conveyor. Where a gate is used it must be equipped with an interlocking device with a manual reset switch that will render a conveyor inoperable until the reset has been activated [Mining Reg. s. 196 (3.2)(c)].

This safety feature does not take the place of lock and tag requirements in Mining Reg. s. 185, but may be used in conjunction with those requirements. Not every fence or barricade needs to have a gate. However, those that do must meet the requirements of Mining Reg. s. 196 (3.2)(c) to provide workers with a controlled access point.

Fences, barricades and gates all serve the same purpose of preventing worker access to a dangerous area when guarding is not practicable.

Equivalent protection

No additional guarding is required if a conveyor’s position or construction provides equivalent protection as guarding so that workers cannot access pinch points [Mining Reg. s. 196 (3.3)].

For example, pinch points may not be accessible depending on a conveyor’s height or its configuration.

Emergency stop pull cord or other emergency stopping system

An emergency stopping system (ESS) is a manual or automatic operated system designed to stop a conveyor system in an emergency. Examples of ESS include pull cords and e-stops. The purpose of pull cords and other ESS are to stop a conveyor in case of emergency. They are not intended as a substitute for a guard, fence or barricade.

A pull cord or ESS must be resettable. The reset should be available only at the location where the emergency stop command is initiated. The ESS command must be manually reset before the conveyor can resume operation. A separate action would be needed to then start the conveyor. This could include using a start button, switch or control room activation, etc.

Specific precautions should be followed when pull cords are used. The system should be designed and arranged to operate the switching device and generate the emergency stop signal when:

  • the pull cord is pulled in any direction,
  • a perpendicular pulling force of less than 200 N (45 lbs) is applied to the pull cord and
  • a perpendicular deflection of the pull cord of less than 400 mm (15 3/4”) occurs.

In addition, a pull cord should be able to withstand, without breaking, a tension force 10 times greater than is necessary to generate the emergency stop signal.

A visual indicator should be installed to show which device was operated when a long pull cord or more than one switching device is needed.

An ESS is required at any pinch point on a conveyor that is not set out in Mining Reg. s. 196 (3). This applies only if the conveyor is accessible to a worker [Mining Reg. s. 196.1 (2)]. Such pinch points may be located at carry or return rollers where the belt’s lift is not restricted. The ESS must be within easy reach of workers at each of these pinch points.

If the conveyor is accessible to a worker, an ESS must also be available at other locations along the conveyor to ensure the system is always within a worker’s easy reach.

The locations of an ESS must be determined in consultation with a workplace’s Joint Health and Safety Committee (JHSC) or health and safety representative (HSR) if a conveyor is inaccessible to workers [Mining Reg. s. 196.1 (3)].

Consultation

The Ministry of Labour expects an employer to meaningfully engage with a JHSC or HSR if the OHSA or its regulations require another party (such as the JHSC or HSR) to be consulted on an action. This interaction must include dialogue, discussion and providing all relevant information.

The JHSC or HSR must be given a genuine opportunity to comment. Those comments should be received and considered in good faith. This includes taking into account any feedback and responses from the JHSC or HSR before taking action such as implementing a plan or program, etc. It also includes responding to any recommendations arising from the consultation.

An employer does not meet the requirements for consultation if he or she simply informs the JHSC or HSR of a planned action.

Equipment incorporating conveyors

Belted conveyor systems in crushing and screening plants must comply with Mining Reg. s. 196 and s. 196.1. Other moving equipment parts in crushing and screening plants must be guarded [Mining Reg. s. 185].

More information

Available standards and information

  1. CAN/CSA Z432-16, Safeguarding of Machinery
  2. Australian Standard AS 1755-2000, Conveyors-Safety Requirements
  3. British Standard BS EN 620:2002, Continuous Handling Equipment and Systems – Safety and EMC Requirements for Fixed Belt Conveyors for Bulk Materials
  4. CAN/CSA Z1002-12, Risk Management: Guideline for Decision-Makers
  5. Workplace Safety North, Guarding Equipment - Belt Conveyor Guarding
  6. U.S. Department of Labor, Mine Safety and Health Administration, Guide to Equipment Guarding, 2004

Toll-free number

Call 1-877-202-0008 any time to report critical injuries, fatalities or work refusals. Call 8:30 a.m. to 5 p.m. Monday to Friday for general inquiries about workplace health and safety.

Always call 911 in an emergency.

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Disclaimer: This web resource has been prepared to assist the workplace parties in understanding some of their obligations under the Occupational Health and Safety Act (OHSA) and the regulations. It is not intended to replace the OHSA or the regulations and reference should always be made to the official version of the legislation.

It is the responsibility of the workplace parties to ensure compliance with the legislation. This web resource does not constitute legal advice. If you require assistance with respect to the interpretation of the legislation and its potential application in specific circumstances, please contact your legal counsel.

While this web resource will also be available to Ministry of Labour inspectors, they will apply and enforce the OHSA and its regulations based on the facts as they may find them in the workplace. This web resource does not affect their enforcement discretion in any way.