December 2009
ISA Certified Automation Professional (CAP) program
Certified Automation Professionals (CAPs) are responsible for the direction, design, and deployment of systems and equipment for manufacturing and control systems.
CAP question
What ISA RP12.4 (NFPA 496) defined type of pressurization system will reduce the classification within an enclosure from Division 1 to nonhazardous?
A. Type X
B. Type Y
C. Type Z
D. None
CAP answer
The correct answer is A, Type X.
A Type X pressurization system reduces the classification within the enclosure from Division 1 to nonhazardous and, therefore, permits the use of ignition-capable equipment inside the enclosure.
A Type Y pressurization system reduces the classification within an enclosure from Division 1 to Division 2. A Type Z pressurization system reduces the classification within an enclosure from Division 2 to nonhazardous.
Reference: Ernest Magison; Electrical Instruments in Hazardous Locations, 4th Edition; ISA Press, 1998.
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