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Intrinsically Safe Product Design Part 3: Production Quality Requirements

Part 1 of this series introduced the concept of intrinsically safe design for explosive environments. Part 2 described considerations for the definition of explosive environments and how geographic regions for device use can impact both explosive atmosphere characterization and product implementation. This blog describes regulatory and quality requirements for ongoing production and sale of an intrinsically safe electronic device.

An intrinsically safe device is designed and certified to accommodate specifically defined explosive atmospheres as defined by the governing standards in the geographic locations where the resulting product is to be sold and used. Given the risk of injury, death, and destruction in case of a product failure, it is critical to continually demonstrate that manufactured product conforms to the approved design. This is done by making the product in a regularly audited facility that has proven that its practices are repeatable within the intrinsically safe framework guidelines, including ISO 80079-34: Explosive atmospheres – Part 34: Application of quality management systems for Ex Product manufacture.

Most facilities who have been through ISO:9001 certification find they have the basic infrastructure and processes in place to take the next step for intrinsically safety device production compliance. The necessary certification requires both product-specific documentation, as well as regular and routine audit compliance by a nationally recognized test lab (NRTL), the topic for Part 4 of this blog series. There are two quality assurances most used for intrinsically safe production standards:

  • Quality Assurance Notification (QAN) – in accordance with the ATEX Directive for the EU and UK for equipment used in zones 1 and 0 (also 21 and 20). It is a mandatory Quality Assurance System for companies that apply for an ATEX EU-type examination and necessary to sell ATEX products on the European market.
  • Quality Assurance Registration (QAR) – in accordance with IECEx requirements. This too is a mandatory Quality Assurance (Manufacturing) System for companies that apply for an IECEx Certificate of Conformity.

Many of the requirements for ISO 9001 and EN 80079-34 overlap, although EN 80079-34 is more stringent. The IECEx QAR audit scheme does not differ much from the ATEX QAN audit scheme, so these are typically obtained together to save cost and time if both markets are to be served.

The holder of the QAN, QAR, and product certificate carries the responsibility, and hence liability, for the product sold. Therefore, the holder of these certifications is typically the organization with the design responsibility, who guarantees control of the bill of materials, assembly and test processes, and overall product quality. Invariably, over the production life of the product, certain questions arise where the design authority must provide expert guidance. For example, a specific part number may not be available for purchase during a production run. A replacement may require informed evaluation for appropriateness of inclusion within the product. It is the design authority’s responsibility to facilitate the evaluation, including any review by the NRT and update of design documentation in accordance with 80079-34.

Organizations who contract production services to a contract manufacturer (CM) may desire that the CM hold the QAN/QAR. This is possible, although highly unusual, since it is ultimately up to the design authority to ensure design control and address design-related issues as they arise. The design authority would provide product build documentation to the CM and require a certificate of conformance for delivered product. This, in combination with surveillance audits of the CM, are usually sufficient for the design authority (and holder of the QAN/QAR and product certificate) to assure compliance according to 80079-34.

The key for both the certification of an intrinsically safe product and its associated manufacturing processes is the NRTL. Part 4 of this blog series describes the role of and working with an NRTL in the design and delivery of intrinsically safe devices.

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