Conveying Strategies for Safer Conveyor Operations
Trucks, trains, and other vehicles make it possible for humans to move large, heavy, or bulk items over great distances with far less effort. Conveyor systems are designed to serve the same purpose in smaller environments. Rather than force workers to make repeated manual moves of items — whether those items are bulky packages, heavy parts, or massive quantities of some material — conveyors tirelessly transport them from point A to point B.
That’s why you’ll find conveyors in manufacturing facilities, grain-handling businesses, logistics operations, bulk-material depots — basically, anywhere that products or material make repeated trips across the same paths. Regardless of the industry in which they are employed, workers are likely to use or interact with conveyors on a regular basis.
While conveyors do an excellent job of reducing labor, their designs create a variety of hazards. With moving parts like gears, chains, and belts and high-horsepower and high-speed power transmission systems, there are many places that present hazards for pinching, shearing, and similar situations. In particular, the risk for amputation of limbs is extremely high.
People who work around conveyors are most at risk in certain situations. A common source of injury is absent-mindedly reaching into a powered conveyor mechanism to remove an item that has jammed the conveyor. Another is trying to perform maintenance on a conveyor while it’s in operation. In addition, it’s far too easy for a worker’s clothing to get caught in an operating conveyor, dragging an arm or a leg into the mechanism. Finally, when the drive train of a conveyor is exposed, there’s the potential for breakage or other mechanical failure to release potential energy and strike someone who is working nearby.
As with many occupational risks, the hazards cannot be eliminated completely, but the danger can be reduced through engineering and safe work practices. Conveyor safety begins with an assessment of the hazards, which vary based upon the conveyor’s type, its location and installation, how workers interact with it, and the types of material it carries.
Safeguards for common conveyor types
Multiple engineered options are available for safeguarding workers, primarily mechanical guards and shields such as barriers and grates. Also important are properly lockout/tagout practices, to ensure that maintenance and repairs are never performed on energized equipment. Specific hazards associated with and options for safeguarding the major types of conveyors follow.
Belt conveyors are among the most common in industrial settings and what typically comes to mind when people think about conveyors. Potential hazards with this type of conveyor include locations where the belt goes around pulleys or over rollers, as well as nip points, where the belt slips under machinery, housings, or other assemblies. Another potential hazard are places where belts may change direction, or where objects are shifted to another belt.
Safeguards should be installed around any places that create a potential shear or nip point. Side guards can prevent accidental contact with the belt itself, the objects it carries, and any power transmission equipment. Additional measures can include railings that limit access to the belt and surrounding area and warning signage.
Screw conveyors involve a revolving shaft, usually with a twisted plate, typically placed inside a pipe or a trough. They’re usually used to draw bulk materials, such as flour, grain, or aggregates. Because the plate is constantly close to the surrounding pipe or trough, there is the constant possibility of nipping or pinching, and hands or arms being drawn in.
Enclosing a screw conveyor is the most effective way to protect workers, although the places where the convey is loaded and discharges will remain open. One option is to maintain grates or screens over these areas, so workers can observe the flow of the materials being conveyed without coming in contact with them. Where throughs are used, mechanical means such as high walls and railings can keep workers from accidentally being drawn into the screw.
Chain conveyors present hazards at every point in which the chain enters a sprocket. That can include take-ups, tension devices, terminals, and drives. The best way to minimize the hazard is to enclose the chains. If that’s not possible, install barrier guards around areas that create the most likely hazards.
Roller conveyors, which use a series of rollers that are placed parallel to one another and are often powered, create hazards along their length. Clothing, hair, or limbs can get pulled into the space between rollers. Guards or railings will minimize the opportunities to come in contact with the rollers.
As with any type of potentially hazardous equipment, only workers who have been properly trained should be allowed to work with conveyors. The conveyors should be inspected periodically to ensure that all component are in good working order, and that no hazards have been created by damaged or defective equipment. Powered conveyors should have highly visible and easily accessible stop controls for emergencies, and those controls should be installed to ensure that all conveyors in a series stop when one is stopped. All workers in the area should be trained in the location or controls and how to stop the conveyor. It’s important to ensure that they know they have the authority to use the stop controls without facing discipline, so they never hesitate inn an emergency situation.
People working in the vicinity of conveyors should not wear clothing with loose ends or dangling sleeves. They should also avoid wear jewelry that could get caught in machinery and keep long hair tied and tucked in.
Workers should never sit or climb on conveyors (and never engage is horseplay on or around them). In fact, they should never touch the conveyor system while it is in operation. If repairs or maintenance need to be made, no work should proceed until all energy sources have been properly disconnected and locked out so they cannot be inadvertently restarted.
Conveyors should never be operated if guards, railings, or other safety devices have been removed. They should never be overloaded, and should not be loaded when not operating, to prevent items from falling off or being damaged when the conveyor starts. Operations should not begin until all workers in the area have been warned, perhaps by the use of a horn that’s impossible to ignore. Incorporating these aspects into your safety plan will ensure that conveyors provide the convenience and productivity your worksite needs while minimizing the potential for damage or injury.