ABB PGC5000 Series gas chromatographs Introduction

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.