Fire Fighting Enterprises Talentum IR3 Flame Detector - Manual (Page 2)

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Introduction to Intrinsic Safety
There are many places where an explosive mixture of air and gas or vapour is or may be
present continuously, intermittently or as a result of an accident. These are defined as
hazardous areas by BS EN 60079-0:2006, Electrical apparatus for potentially explosive
atmospheres – General requirements.
Hazardous areas are common in petroleum and chemical engineering plants and in factories
processing and storing gases, solvents, paints and other volatile substances.
Electrical equipment for use in these areas needs to be designed so that it cannot ignite an
explosive mixture, not only in normal operation but also in fault conditions. There are a number
of methods available to achieve this – oil immersion, pressurised apparatus and powder filling,
for example, but the two most common used are flameproof enclosures and intrinsic safety.
Flameproof equipment is contained in a box so strong that an internal explosion will neither
damage the box nor be transmitted outside the box. The surface must remain cool enough not
to ignite the explosive mixture.
When flameproof equipment is interconnected, flameproof wiring must be used. This method is
most valuable when high power levels are unavoidable but it is not acceptable for areas in
which an explosive gas/air mixture may be continuously present or present for long periods.
For this reason these flame detectors are made intrinsically safe rather than flameproof.
Intrinsically safe equipment operates at such low power and with such small amounts of stored
energy that it is incapable of causing ignition:
o In normal conditions
o With a single fault (for ib type of protection code)
o With any combination of two faults (for ia type of protection code)
In any of these conditions every component must remain cool enough not to ignite gases for
which it is approved. See Table 2
Classification of Hazardous Areas
EN 50014 states that electrical apparatus for potentially explosive atmospheres is divided into:
• Group I: Electrical apparatus for mines susceptible to fire damp;
• Group II: Electrical apparatus for places with a potentially explosive atmosphere,
other than mines susceptible to fire damp.
These flame detectors are designed to meet the requirements of Group II apparatus. For the
type of protection “i” intrinsically safe, Group II is subdivided into Equipment Categories, Type
of Explosive Atmosphere (Table 1), Type of Protection Code (Table 2), Temperature Class
(Table 3) and Gas Group (Table 4).
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