The hazards of an operating conveyor belt are not always recognised. Accidents often occur during fault repairs or cleaning work, either because the conveyor has not been stopped or it is turned on unexpectedly.
Always stop the conveyor belt safely by locking the safety switch before cleaning or servicing the conveyor.
Accident example 1
A summer worker was cleaning a conveyor belt with solvent. After a moment, he asked the operator to move the belt forward. The operator answered that it would take a while, after which the summer worker continued cleaning, assuming that the conveyor belt had a pre-start alarm feature which would sound an alarm before the belt began to move. However, this was not the case, and when the operator eventually started the belt, the worker’s left cuff was caught between the belt and a drum, pulling his left arm into the inrunning nip. The summer worker’s left arm had to be amputated.
Accident example 2
A stoker working in a thermal power plant had been informed by an automatic alarm system that there was a failure in the conveyor of the supplying fuel system. This failure was probably caused by fuel which had frozen under the conveyor. The operator and a maintenance man started to clean the area below the conveyor belt and the folding end. However, the conveyor was not stopped in order to attend to the failure. The inrunning nip guard of the conveyor’s folding end had been removed and placed on the floor beside the folding roll. Then, the operator fell near the conveyor belt’s folding end and his arm was caught between the running conveyor belt and the folding roll. His arm had to be amputated.
Safety starts with design
- A good and safe conveyor belt has, for instance, the following characteristics:
- It is possible to operate, adjust and maintain the conveyor from outside the dangerous area.
- If the conveyor belt must be operated within the dangerous area during, for instance, adjustment work, it must be possible to do this safely through, for instance, forced operation, slow speed or jog operation.
- It is possible to cut off the power with a locking safety switch.
- A light or sound alarm is given before the conveyor belt is started.
- An emergency stop is available along the entire length of the conveyor.
- Before the conveyor is taken into use, it is equipped with access ways enabling safe use and maintenance.
Safe use and maintenance
It is possible to increase conveyor safety through the following measures:
- Risks related to the use and maintenance of the conveyor are evaluated, moving parts are protected and the remaining risks are taken into account in work instructions.
- Conveyors are stopped and accidental starting prevented during fault elimination, cleaning and servicing.
- The smooth flow of information and communication is ensured during conveyor use, fault elimination, cleaning and servicing as follows:
- It is ensured that the conveyor is in a safe state before cleaning, fault elimination or service work is initiated.
- It is ensured that the operator is aware of the cleaning, fault elimination or service work underway (“Do not switch on – men at work” or an equivalent note).
Jaana Salo
Kari Häkkinen
Source: Risto Parikka, Kimmo K. Mäkelä, Janne Sarsama & Kimmo Virolainen, Improvement of the safety and reliability of the use of belt conveyors, Technical Research Centre of Finland (VTT), 2000, (in Finnish, with an English abstract).
