Metal cans are not normally associated with static electricity problems, but there is one area where they can produce bad shocks for operators. Empty printed cans are transported at speed by conveyors to the filling stations. There are wide accumulator sections in the conveying system before the filling stations. These act as storage areas to hold cans ready for filling. This is shown in the plan view below:

The plastic conveyor below the cans continues to move while the cans are stationary in the accumulator. This generates a charge in the cans. This charge cannot escape because the walls of the conveyor are made of nylon or similar insulating material. The cans in the accumulator touch each other which allows the charge to be mobile. When an operator or inspector touches one can in the system the charge from all the touching cans can be dumped into his body. This can be very unpleasant and possibly dangerous.

This application is not limited to the food and drinks industry. It also exists in the aerosol industry where the propellant gas (e.g. hydrocarbon gas such as propane) can add an additional safety and fire risk.

Static discharges from cans can also interfere with electronic sensors on the conveyor. The solution is to place a 976 or 915 Bar above the cans on the conveyor immediately before the sensor.

Relevant Product Data Sheets 915  976

Relevant Product Data Sheets Bottle conveying line