ABB PGC5000 Series gas chromatographs
Introduction
For a classified Ex zone 1 area, the rationale behind this “Zone 2 by design” analyzer is that the analyzer must remain safe when operated in an abnormal condition. In the event of a fault, the PGC5000 provides continual protection:
• Should a failed component become ignition capable, the pressurization system prevents the components from being exposed to flammable gases or vapors.
• Should a failed pressurization system expose the internal components to flammable gases or vapors, the analyzer’s alarm provision will alert the user of the failure.
Neither of these single faults would present a hazard to the potentially explosive atmosphere; therefore, electrical power interlock is not required for this type of pressurization protection. Enclosure doors are not required to be interlocked so that the electrical supply is disconnected automatically when doors are opened.
The requirement is simply an alarm provision since there are no hazards inside the enclosure when in normal operation. The zone 1 certified PGC5000 analyzer offers simple pressurization protection, commonly referred to as Ex ‘py’ or “Y-purge”. This enclosure pressurizing technique is made possible by ensuring that the internal components within the analyzer are not capable of causing an ignition in normal operation, thus allowing for a reduction in classification within the protected enclosures from zone 1 to zone 2
PGC Certification
This simple pressurization technique for the PGC5000 is considered an improvement to the process gas chromatograph analyzer by allowing for a continual operation without possible disruption caused by interlocking the electrical power to the pressurization system. When operated in a zone 1 area, the user of the PGC5000 analyzer is simply responsible for:
• Operating the analyzer within the manufacturer’s established parameters, as described in the product manuals and the CE conformity declaration’s special conditions for safe use • Providing a reliable supply of protected air for the enclosure purge and pressurization system
