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|3. Safety cage
|4. Access to downstream equipment
Big Bags are getting more and more common as factory owners try to get efficiency in their process. Such large packaging however present some specific safety risks that it is necessary to manage. Bags can indeed weight 500-1000 kg and sometimes more. If a Big Bag that was lifted is falling down on the operator, it can lead to a fatality.
This page is summarizing the precautions to be taken during design and operation to have a safe handling of Big Bags.
The whole station must be designed to handle the load of the
heavier Big Bag that will be tipped. It is important to re-validate
this load during trials or change of suppliers as different Big Bags
weight may be used.
The area below the lifted Big Bag must be protected to make sure that nobody is standing below the load when lifted. It is important to have in mind that accidents where the Big Bag falls do exist : it can be caused by a defect in the hoist, a defect in the traverse, Big Bag hanging loops not properly attached or a re-used Big Bag that finally breaks.
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For permanent stations, a cage should be installed with proper dimensions to make sure that nobody can get in when the Big Bag is lifted. It is also recommended to interlock the door of the cage to the position of the hoist : it should not be possible to open the door if the hoist is not in safe position, and it should not be possible to move the hoist if the cage is opened.
For temporary lifting, some barriers should be installed and a
safety officer should overview the lifting to make sure nobody
enters the hazardous area.
Another aspect to take into consideration for the overall safety of the dumping station is to make sure there is no access to rotating equipment below the tipping point. A typical safety risk is happening if the powder is not flowing well in the downpipe of the station : the operator reaches inside to unblock the powder and can get into contact with a rotating equipment that may be positionned below, like a screw conveyor or lump breaker.
This risk should be taken into consideration by the factory with possible measures including : positionning the rotating equipment downpipe out of reach, welding a grid in the downpipe (efficient, but may create flow issues), or having a cage with a proximity switch cutting off the power on the rotating equipment if opened.
Additonally, Big Bag dumpting stations are often equipped with a mechanism to clamp the spout of the Big Bag during discharge. This mechanism should be designed to avoid that the operator gets fingers squeezed by the clamping mechanism. Having a manual lock can be sufficient, while an automatic system will need that the command buttons be activated by the 2 hands of the operator.