Conveyors | Safeguarding for Specific Types of Machinery

Conveyors are used in many industries to transport materials horizontally, vertically, at an angle, or around curves. Types include non-powered and powered, live roller, slat, chain, screw, and pneumatic. Conveyors eliminate or reduce manual material handling tasks, but they present amputation hazards associated with mechanical motion.
Conveyor hazards
Add a note hereConveyor-related injuries typically involve a worker’s hands or fingers becoming caught in nip points or shear points on conveyors and may occur in these situations:
§  Add a note hereCleaning and maintaining a conveyor especially when it is still operating.
§  Add a note hereReaching into an in-going nip point to remove debris or to free jammed material.
§  Add a note hereAllowing a cleaning cloth or an employee’s clothing to get caught in the conveyor and pull the worker’s fingers or hands into the conveyor.
*       Other conveyor-related hazards include improperly guarded sprocket and chain drives. Overhead conveyors warrant special attention because most of the conveyor’s drive train is exposed. Employees have also been injured while stepping or walking on or near conveyors.
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Case History 
Add a note hereWhile removing a cleaning rag from the ingoing nip point between the conveyor belt and its tail pulley (non-powered end of the conveyor), an employee’s arm became caught in the pulley, which amputated his arm below the elbow.


Figure 1: Chain driven live roller conveyor
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Engineering controls
Add a note hereSome general controls you might use for conveyors include the following:
§  Add a note hereInstall guards for all sprockets, chains, rollers, belts, and other moving parts. Guarding by location — locating moving parts away from employees to prevent accidental contact with the hazard point — is one option for guarding conveyors. It is particularly difficult, however, to use this method when guarding the in-going nip points on certain conveyors such as roller conveyors because the exposed rollers are crucial to the function of the conveyor.
§  Add a note hereUse prominent warning signs or lights to alert workers to the conveyor operation when it is to install guarding devices because they interfere with the conveyor’s operation.
§  Add a note hereEnsure that all conveyor openings such as wall and floor openings, and chutes and hoppers, have guards when the conveyor is not in use.
§  Add a note hereEnsure that start buttons have guards to prevent accidental operation.
§  Add a note hereEnsure that conveyor controls or power sources can accept a lockout/tagout device to allow safe maintenance practices.
Add a note hereFor crossovers, aisles, passageways, you need to do the following:
§  Add a note hereEnsure that all accesses and aisles that cross over or under or are adjacent to the conveyor have adequate clearance and hand rails or other guards.
§  Add a note herePlace crossovers in areas where employees are most likely to use them.
§  Add a note hereEnsure that all underpasses have protected ceilings.
§  Add a note herePost appropriate hazard warning signs at all crossovers, aisles, and passageways.
§  Add a note hereConsidering emergency egress when determining placement of crossovers, aisles, and passageways.
Add a note hereFor emergency stops or shut-offs, you will need these engineering controls:
§  Add a note hereEquip conveyors with interlocking devices that shut them down during an electrical or mechanical overload such as product jam or other stoppage. When conveyors are arranged in a series, all should automatically stop whenever one stops.
§  Add a note hereEquip conveyors with emergency stop controls that require manual resetting before resuming conveyor operation.
§  Add a note hereInstall clearly marked, unobstructed emergency stop buttons or pull cords within easy reach of workers.
§  Add a note hereProvide continuously accessible conveyor belts with emergency stop cables that extend the entire length of the conveyor belt to allow access to the cable from any point along the belt.
Typical conveyor hazards and safeguarding methods
Add a note hereBelt conveyors
§  Add a note hereHazards: Conveyor take-up and discharge ends, where the belt or chain enters or exits the in-going nip point; where the belt wraps around pulleys; where the belt changes direction, such as take-ups; or where multiple conveyors are adjoined.
§  Add a note hereControls: Guarding of belt conveyors is not always feasible because guarding devices interfere with normal operation. Options for hazard control include guarding by distance as well as installing hazard warning signs and signals.
Add a note hereScrew conveyors
§  Add a note hereHazards: In-going nip points of turning helical flights for the entire length of the screw conveyor when the housing is opened.
§  Add a note hereControls: Screw conveyor housing should completely enclose the moving elements of the conveyor except for the loading and discharge points. If such guarding is not feasible, the entire conveyor should be guarded by railing unless it is guarded by location — the hazardous areas cannot be easily accessed by employees. Permanently affixed grids or Plexiglass can be installed to allow the operator to inspect the operation. Open troughs can be used if such covers are not feasible; but they should be guarded by location. Alternatively, the trough side walls should be high enough to prevent employees from reaching over falling into the trough.
Add a note hereChain conveyors
§  Add a note hereHazards: Moving chains since the chains can not be enclosed without impairing the function of the conveyor.
§  Add a note hereControls: Guarding of chain conveyors is not always feasible because guarding devices interfere with normal operation. Options for hazard control include guarding by distance and installing hazard warning signs and signals.
Add a note hereRoller conveyors
§  Add a note hereHazards: In-going nip points between the drive chain and sprockets; nip points between belt and carrier rollers; and nip points at terminals, drives, take-ups, idlers, and snub rollers.
§  Add a note hereControls: Roller conveyors should have permanent guards that can be adjusted as necessary to protect the worker. For example, when transporting small items on a roller conveyor that does not require the use of the entire roller width, the unused section of rollers closest to the workers should be guarded.
Add a note hereWork practices and administrative controls
§  Add a note hereDevelop and implement safe operating procedures for conveyors and conduct periodic inspections to ensure compliance.
§  Add a note hereAllow only trained individuals to operate conveyors and only trained, authorized staff maintenance.
§  Add a note hereTrain employees working with or near conveyors regarding the location and use of emergency stopping devices and the proper procedures for conveyor operation.
§  Add a note hereForbid employees to ride on conveyors.
§  Add a note hereInstruct employees to cross over or under conveyors only at properly designed and safeguarded passageways.
§  Add a note hereInstruct employees to lubricate, align, and maintain conveyors when the conveyor is stopped. If this is impractical, advise workers to perform this work at a safe distance from any ingoing nip points or pinch points. Installing extended oiler tubes and adjusting screws will help in these instances.
§  Add a note hereProhibit employees working with or near conveyors from wearing loose clothing or jewelry, and require them to secure long hair with nets or caps.
§  Add a note herePerform servicing and maintenance under an energy control program in accordance with §1910.147.

2 comments:

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