Problem
Fatal accidents have occurred after employees have entered from the top into bins, hoppers and silos which contain dry bulk materials. Entry is often in response to the need to start the material discharging. Children on farms have also entered grain silos and tragically died from suffocation in moving grain.
It is virtually impossible for a person, adult or child, to maintain their face above grain which is moving downward. Once people are buried it is very difficult to pull them out. Even if a belt is attached as a lifeline, it may be insufficient to rescue that person if no other precautions have been taken.
Solution
The prevention of accidents involving moving grain can be best achieved by preventing access to the silo. An access guard inside the silo, under the centre grain loading opening and under the roof access door (if one is fitted) will prevent entry to the silo. The guard could consist of bars, strips, grates or mesh permanently attached to the silo.
Various regulatory authorities have produced Codes of Practice, guidelines and standards on bulk storage and silo safety. Farmers who were consulted believed that there was no reason for any person to enter the top of the silo. If required, grain samples can be obtained by using a sampling cup attached to a long rod.
There are many alternative ways to start grain discharging from a silo. Firstly, if grain is kept in in its driest possible state, blockages should not occur. If blockages do occur, vibrators attached to the sides of exit chutes will release the grain. Alternatively, compressed air is sometimes fired up the exit chute, which also causes release.
The maximum distance between the parallel sides or diameter of the guard mesh should not exceed 250 mm (i.e. should be substantially smaller than the cross-section of a 3-year-old child’s body).
The guard can be dished so that a person may insert their head inside to inspect the interior, and be deep enough to avoid silo roof glare.
Hierarchy of Controls:
Engineering
Benefits
- The cost of materials for the guard is low, and installation relatively simple.
- Given the many small and large silos throughout rural communities worldwide, this device has the potential to prevent may tragic accidents.