• • • HAZARDOUS AREA EQUIPMENT • • •
Ensuring electrical safety in hazardous areas
Darren Hugheston-Roberts, head of machinery safety at TÜV SÜD, a global product testing and certification organisation, says that many workplaces, gases, dusts or vapours can be found in the air, and if these materials ignite, an explosion could cause damage, injury or worse
S
pecific certification of equipment used in such environments is designed to minimise or prevent the potential risk of explosion. Therefore, if your production processes involve flammable liquids, gases, vapours or combustible dusts, or you provide equipment that’s used in such places, you may require expert guidance or product/system certification. CE or UKCA (UK Conformity Mark) marked equipment is safe when operated within a normal environment. However, due to the use of flammable gases, vapours or combustible dusts, some modern industrial environments pose an increased risk of fire and explosion, so equipment must meet the enhanced requirements of applicable regulations and standards. Increasingly, equipment is being used in potentially explosive environments to automate or control certain production processes, but the normal operation of equipment often involves actions or reactions that are a potential ignition source, such as:
Electric sparks – A poor quality component or electrical connection can fail, inadvertently producing an electric spark that can ignite gases or nearby materials.
High operating temperature – Depending upon the potentially explosive atmosphere present, hot surfaces of equipment could cause an auto- ignition. Process system heating effects by ‘work done’ i.e. pumping systems, must also be considered as these can elevate the ‘product’ above its flashpoint.
Electrostatic discharge – Some normal equipment operations can generate static electricity, which can serve as an ignition source at certain levels.
Friction sparks – Equipment operation may also involve repeated contact between materials, resulting in friction that can produce heated sparks and material contents must be considered as a potential ignition source.
To be able to eliminate the potential ignition sources, which can include considered faults, prior to manufacture and installation, a pre-assessment is recommended to understand the equipment design, operation and desired location and environment.
Tackling hazardous
environments In the UK, the UKCA Ex Regulation provides a detailed overview of the essential health and safety requirements applicable to equipment used in hazardous environments. However, the specific technical requirements to demonstrate compliance for various types of equipment and operating environments are found in nearly 100 individual harmonised standards.
Depending on the equipment and its intended use, this means that more than one harmonised standard may be applicable to the evaluation and certification process.
Under the provisions of the UKCA Ex Regulation, evidence of compliance is generally demonstrated by the issuance of a manufacturer’s or supplier’s Declaration of Conformity. The task of demonstrating compliance rests with the party responsible for introducing a product into the marketplace or putting into first use (i.e. not put onto the market but made in-house). External to Europe and the UK, the IECEx conformity mark is evidence that a manufacturer’s products have been independently assessed
against the additional requirements of the IECEx conformity mark licensing system. The mark license number is issued to a manufacturer by an accepted IECEx certification body (ExCB) that has entered into a mark license agreement with the IEC.
The primary goals of the IECEx Scheme are to reduce testing and certification cost, speed up market access for new products and equipment, and increase international acceptance of product assessment results. The Scheme achieves these goals through the issuance of an International Certificate of Conformity based on: Testing and assessment of equipment samples for compliance with applicable international standards;
Assessment and auditing of a manufacturer’s quality assurance system; and Ongoing surveillance audits to ensure continued compliance.
Poor installation
Ex-rated equipment has therefore been classified as safe for use in hazardous areas as it is designed to contain or prevent any sparks, flames, or explosions. However, poor installation of EX equipment can compromise its integrity. Conducting initial detailed inspections prior to first use will therefore help to identify potential installation quality issues, as well as ensuring the equipment is suitable for use. In the European Union, there are two ATEX Directives – one for the manufacturer and one for the user of the equipment. The ATEX 114 “equipment” Directive 2014/34/EU focuses on the responsibilities of manufacturers of Ex-rated machinery and other equipment. In the UK, it is implemented by The Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations 2016, which is law. The legislation’s function is to ensure that the design and manufacture of equipment intended for explosive atmospheres conforms with the Essential Health and Safety Requirements, so that these are met before anything is placed on the market. This is typically achieved by third-party testing and certification by an Approved or Notified Body. However, after machinery has been installed, how can you verify that conformity and compliance have been achieved? To ensure the installation quality and integrity of Ex-rated equipment post installation, an intrusive inspection by a competent person should be carried out. This is described within the requirements of EN60079-17 as an ‘Initial Detailed Inspection’. If carried out correctly, such an inspection will ensure that the equipment,
26 ELECTRICAL ENGINEERING • MAY 2023
electricalengineeringmagazine.co.uk
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