ATEX DIRECTIVE 94/9/EC
Background
The ATEX Directive 94/9/EC applies to equipment and protective systems intended for use in potentially explosive atmospheres. It also applies to safety, controlling, and regulating devices for use outside potentially explosive atmospheres but required for or contributing to the safe functioning within that atmosphere.
Explosive atmospheres are when, under atmospheric conditions, air is mixed with flammable substances in the form of gases, vapours, mists or dusts and which, after ignition, combustion spreads to the entire unburned mixture.
A potentially explosive atmosphere is one that could become explosive due to local and operational conditions.
Warning ! Explosive atmospheres can occur during such common situations as vehicle refuelling, gas welding, hydraulic oil leaks, grinding certain materials, when fine powder is present and even in dusty atmospheres.
Exclusions
The exclusions listed in the ATEX Directive include:
- medical devices, and PPE,
- equipment intended for use in domestic environments where potentially explosive atmospheres may result from the accidental leakage of fuel gas,
- when the explosion hazard results exclusively from the presence of explosive or unstable chemical substances
- vehicles and their trailers intended solely for transporting passengers or goods by air or by road, rail or water networks, but vehicles intended for use in a potentially explosive atmospheres must be ATEX compliant.
Warning ! Manufacturers have a duty of care to ensure that no unacceptable hazards exist regardless of these exclusions.
Essential Requirements
The Essential Requirements listed in Annex II to the directive apply to all equipments included in the ATEX directive.
Categories of Equipment
Annex I to the ATEX Directive lists the categories of equipment:
- Category M1 & M2 apply to equipment exposed to mining hazards associated with fire damp and/or combustible dust.
- Group II categories are defined broadly for when explosive atmospheres exist as follows:
- Category 1 - are present continuously, for long periods or frequently.
- Category 2 - are likely to occur
- Category 3 - are unlikely to occur or, only infrequently and for a short period only
Annex I also specifies the requirements for protection for each category as follows:
- Category 1 - equipment must ensure protection, even for rare incidents to equipment, such that:
- either, if one means of protection fails, an independent second provides protection, or
- protection is assured in the event of two faults occurring independently of each other.
- Category 2 - equipment must ensure protection, even in the event of frequently occurring disturbances or equipment faults
- Category 3 - equipment must ensure protection during normal operation.
Compliance with the Essential Requirements
The manufacturer should ensure that equipment for use in explosive atmospheres meets the relevant Essential Requirements listed in Annex II of the Directive. The latest technical solutions should be applied immediately !
Integrated explosion safety
The key safety criterion is integrated explosion safety. This has three measures:
- The prevention of explosive atmospheres
- The prevention of ignition
- The halting of explosions and /or limit the range of flames and pressures to provide a sufficient level of safety.
Design and manufacture must consider misuse and operating faults. Remember to consider releases by the equipment as well as in the surrounding atmosphere.
Essential Requirements
The essential requirements are divided into
- Marking
- Instructions
- General Safety requirements
- Supplementary Requirements specific to a category of equipment
Risk Assessment
A risk assessment must be conducted. Two harmonised standards should be taken into account as well as the risks identified in the Essential Requirements: use both EN 1050:1996 and EN EN1127-1:1997. A competent person should conduct the risk assessment.
For guidance on how to conduct risk assessments, contact info@atlanticbridge.co.uk
Comment
Potentially explosive atmospheres are easily ignored, but an explosion can be devastating. Whole businesses can be destroyed and many people injured or killed. The ATEX Directive makes it quite clear that “Equipment and protective systems must be designed and manufactured after due analysis of possible operating faults in order as far as possible to preclude dangerous situations.” It is incumbent on manufacturers to ensure their equipments remain safe under all modes of operation. For more information contact info@atlanticbridge.co.uk