3700 Series Flat Panel Industrial PC
Chapter 2 – Installation
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143311 (H)
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Ignitable concentrations of Class I vapors or gasses are normally
prevented by positive mechanical ventilation, but which may become
hazardous due to mechanical failure of those ventilation systems.
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Location is adjacent to a Division 1 location.
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Class II combustible dust is not normally in the air in quantities
sufficient to produce explosive or ignitable mixtures. Dust
accumulations are normally insufficient to interfere with normal
operation of electrical equipment or other apparatus. Combustible dust
may be in suspension in the air as a result of the following:
malfunctioning of handling or processing equipment; combustible dust
accumulations on, or in the vicinity of electrical equipment; may be
ignitable by abnormal operation or failure of electrical equipment.
Groups
All electrical equipment that is approved for use in Hazardous Locations must
include a group rating. Various flammable and combustible substances are divided
into these groups as a function of their individual maximum experimental safe gap
(MESG), explosion pressure, and ignition temperature.
Component temperatures and the potential for spark based upon voltage, current,
and circuit characteristics, within electrical equipment, will determine what the
equipment group rating will be. A device approved for installation within Class I,
Group A locations may also be used in Groups B, C, or D.
Note
Approved Class I equipment may not be suitable for Class II installations. Class
I includes Groups A, B, C, and D. Class II includes Groups F, and G.
Enclosures
The systems are designed for installation within a clean and dry enclosure for both
ordinary and Hazardous Locations. The front panel meets the requirements of UL
and CSA Type 4, 4X, and 12 enclosures. The enclosure used for Class I Hazardous
Locations should have a minimum rating of Type 12 (NEMA 12, IP 5X). However,
Type 4 (IP 6X) enclosures are strongly recommended.
Panel flatness and rigidity are important if a proper panel seal is to be maintained.
If non-metal type enclosures, such as plastic or fiberglass, are to be used, install a
rigid metal stiffener behind the front panel. Failure to do so may result in an
inadequate panel seal due to flexure of the front panel material between the stud
mounts. Tighten the nuts on the mounting studs to 25 inch-pounds.
The requirements for enclosure fittings, conduit, and wiring vary according to the
specific rating of the location and the type of flammable or combustible material
involved. Those requirements are beyond the scope of this document and it is the
responsibility of the customer to ensure that the installation is compliant with
codes and regulations that apply to their specific location. Refer to NFPA 70,
Article 500 for specific regulations in the United States.
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