Application of the directive 94/9/EC to Bucket Elevators
How are bucket elevators to be treated within the framework of Directive 94/9/EC especially in respect that in the surrounding area of bucket elevators potentially explosive areas are not necessarily present?
In addition to Chapter 4.1.2 of the Guidelines the following can be said:
The intention of Directive 94/9/EC is to avoid the ignition of potentially explosive atmospheres by equipment, protective systems and components. According to the potential hazards and the prevention measures the products are divided into categories.
Directive 94/9/EC defines a potentially explosive atmosphere as an atmosphere, which could become explosive due to local and operational conditions. This means that the potentially explosive atmosphere is either present from the beginning or develops during the working process (e.g. in relation with the conversion of energy or the processing of materials).
In bucket elevators the potentially explosive area is limited in general by housings and/or sheathings, whereby a multiplicity of potential ignition sources can become effective due to construction, for example by rubbing and flapping sparks or by inadmissible heating.
A manufacturer of bucket elevators has to analyse all potential ignition sources (e.g. belts, buckets, angle wheels, drive units, regulating devices) and preventive measures according to design, transported material, transport speed etc. under the aspect of the intended use of the equipment.
The necessary level of protection of equipment and components inside the housing (e.g. category) depends on the frequency and the occurrence of the explosive atmosphere inside this housing.
According to the necessary level of safety, depending on their incorporation in the housing and the disturbances or equipment faults which have normally to be taken into account, some components (presenting a higher risk) might be assigned to categories different to the entire category of the bucket elevator.
If some ignition sources can not be avoided by the design of equipment or components, the manufacturer of the bucket elevator has to avoid the transmission of explosion to all the process.