Chapter Three - Installation
45
Division 1 Locations
A Division 1 location is one in which flammable or ignitable gasses, vapors, or combus-
tible dusts and particles can exist due the following conditions:
•
Normal operating conditions.
•
Because of repair, maintenance conditions, leakage, or where mechanical failure or
abnormal operation of machinery or equipment might release or cause explosive or
ignitable mixtures to be released or produced.
•
Combustible dusts of an electrically conductive nature may be present in hazardous
quantities.
Note
Xycom Automation
3515/3512KPM
systems are not suitable for installa-
tion within Division 1 locations.
Note
Electrical equipment cannot be installed in Division 1 locations unless
they are intrinsically safe, installed inside approved explosion-proof en-
closures, or installed inside approved purged and pressurized enclosures.
Division 2 Locations
•
Class I volatile flammable liquids or flammable gasses are handled, processed, or
used, but confined within closed containers or closed systems from which they can
escape only in cases of accidental rupture or breakdown of such enclosures or sys-
tems, or in case of abnormal operation of equipment.
•
Ignitable concentrations of Class I vapors or gasses are normally prevented by posi-
tive mechanical ventilation, but which may become hazardous due to mechanical
failure of those ventilation systems.
•
Location is adjacent to a Division 1 location.
•
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 in-
terfere with normal operation of electrical equipment or other apparatus. Combusti-
ble dust may be in suspension in the air as a result of the following: infrequent mal-
functioning 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), explo-
sion 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