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Feedback from assessments of ExCBs and ExTLs – Areas where difficulties are experienced

Feedback from assessments of ExCBs and ExTLs – Areas where difficulties are experienced. Jim Munro Chairman IECEx Panel of Assessors. Scope of presentation. This training session will: Look at some common problems and how to overcome or avoid them

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Feedback from assessments of ExCBs and ExTLs – Areas where difficulties are experienced

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  1. Feedback from assessments of ExCBs and ExTLs – Areas where difficulties are experienced Jim Munro Chairman IECEx Panel of Assessors

  2. Scope of presentation • This training session will: • Look at some common problems and how to overcome or avoid them • Discuss IECEx and other documents ExCBs and ExTLs need to consider • Discuss some of the approaches that can be used to help bodies be accepted

  3. Types of issues/problems • Applying IECEx Procedures and IEC standards • System issues related to ISO/IEC Guide 65 and 17025 • Technical issues • Other Issues

  4. Applying IECEx Procedures and IEC Standards - ExCB • IECEx 02 IECEx Scheme rules of procedure • OD003 (Parts 1 and 2) IECEx Assessment procedures • OD009 Issuing of CoCs, ExTRs and QARs • OD005 Quality System requirements for manufacturers (Parts 1 and 2) • ISO/IEC 80079-34 : Explosive atmospheres – Part 34: Application of quality systems for equipment manufacture • Comparison document between ISO/IEC 80079-34 and OD005-1 is ExTAG/247A/Inf • F-001 and F-002 – QAR forms

  5. Applying IECEx Procedures and IEC Standards - ExCB • OD025 Management of assessment and surveillance programs for manufacturers • OD026 IECEx– Guidelines for the qualification of auditors • OD017 Drawing and documentation guidance • OD011 – Guidance on the on-line system • OD024 - Testing, or witnessing testing at a manufacturer’s or user’s facility • Other ODs • ExTAG Decision Sheets

  6. Applying IECEx Procedures and IEC Standards – ExTL • IECEx 02 IECEx Scheme rules of procedure • OD003 (Parts 1 and 2) IECEx Assessment procedures • IECEx Operational Document OD009 Issuing of CoCs, ExTRs and QARs • Other ODs • IECEx Technical Guidance Documents (TGDs)/Technical Capability Documents (TCDs) • ExTAG Decision Sheets • IEC standards corrigenda • IEC interpretation sheets (I-SHs)

  7. Applying IECEx Procedures - • Use of data, subcontracting and off site testing – application of OD024 • For third party laboratories - hierarchy: • IECEx • IECEE • Local accreditation • No accreditation • Identification of and contracts with subcontractors • Assessment and control is critical

  8. Applying IECEx Procedures - • Appeals – to IECEx • QARs • Manufacturing surveillance - adjustment where local system is different (not a Type 5 Scheme) • Application of ISO/IEC 80079-34 • Correct dates in QARs • ExTRs • Lack of supporting data • Errors • Referencing to ATEX component certificates – see Decision Sheets 2004/006 and 2006/002

  9. Applying IECEx Procedures - • Clear delineation of responsibilities of people within ExCB and ExTL, including: • Who makes certification decision • Who signs what • Deputies where necessary

  10. Guide 65 and 17025 • Using uncontrolled pieces of paper: • For recording results • For useful data such as conversion lookup tables • Capturing and retaining original data • Internal audits - Not always done to schedule

  11. Guide 65 and 17025 • Calibration • Instruments not in calibration • Extending calibration periods • Humidity calibration of environmental chambers • Checking of calibration certificates

  12. Guide 65 and 17025 • Inconsistencies in quality systems • Defining and recording competencies • Correction of errors when writing down readings

  13. Technical Issues • Technical issues related to: • Equipment • Procedures • Competency

  14. Technical Issues –Intrinsic Safety • Spark test apparatus • Inductors and capacitors • Periodic full calibration • Temperature classification • Measurement • Assessment • Small component ignition • Battery short-circuit tests

  15. Technical Issues –Intrinsic Safety • Outcomes from proficiency testing pilot • Inductance/resistance of connecting leads is critical. Needs to be as low as possible. • For factor of safety best option is the increase in FOS of gas mixture.

  16. Technical Issues –Intrinsic Safety • Outcomes from proficiency testing pilot • Advisable to monitor output values of test sample during STA test with oscilloscope. Current probe is best to use for this rather than current shunt. • Split tungsten wires are a problem. Tests done by PTB suggest this is more likely to cause ignition. Fusing wires is the best method to avoid split wires. • ExTAG/279/CD – full details

  17. Technical Issues – Flameproof • Version control of software where computers used • Condition and handling of measuring devices such as vernier callipers • Lack of calibrated thread gauges

  18. Technical Issues – Flameproof • Gas measurement • Calibration of oxygen analysers • Traceability of certificates for mixed gases • Flameproof pressure determination systems • Calibration approaches - static and dynamic • Noise or other interference on the system

  19. Technical Issues – Flameproof • Outcomes from proficiency testing pilot • Ensure that the measurement range is not too long, • Pressure transducer faces should be flush with the inside wall of the enclosures in which they are mounted. • To avoid affects of temperature on pressure transducers, the best approach is to coat the transducer faces with a thin smear of silicon rubber (allowing this to set) and then silicon grease.

  20. Technical Issues – Flameproof • Outcomes from proficiency testing pilot • Pressure transducers should be tightened to the torque recommended by the pressure transducer manufacturer. • When using digital oscilloscopes, DC coupling should always be selected. The problem with AC coupling is that it works like a high pass filter and hence removes some readings from the results • ExTAG/278/CD – full details

  21. Technical Issues – Temperature Measurement • Location of tests – drafts etc • Lack of attention to measurement techniques • Making of thermocouples • Thermocouple and system calibration • Thermocouple attachment • Measurement of ambient temperature • Hot spot location

  22. Technical Issues –IP Testing • Dust testing – keeping dust in circulation – see draft ExTAG decision sheet: • Humidity - heating • Vibrators – rappers – hoses • Slope of hoppers • Viewing windows - wipers • Chamber leaks • Measurement of volume changes • Pressure tests for Ex t

  23. Technical Issues –IP Testing • Water testing – • Temperature differential - control temperature or use of pressure balance • Nozzle calibration • Blocked nozzles

  24. Conclusion • Despite the seemingly long list of issues here – everyone seems to get there in the end!

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