Chemical Engineering May 2016 - 71

Environmental Manager
Monitoring Flame Hazards In Chemical Plants
The numerous flame sources in CPI facilities necessitate the installation of
advanced flame-detection technologies
Ardem Antabian
MSA - The Safety Company
F
ire is a primary and very real
threat to people, equipment
and facilities in the chemical
process industries (CPI), especially
in the refining and storage of
petrochemicals. The consequences
of failing to detect flames, combustible
gas leaks or flammable chemical
spills can have dire consequences,
including loss of life and catastrophic
plant damage.
The monitoring of flame hazards is
mandated by the U.S. Occupational
Safety and Health Administration
(OSHA; Washington, D.C.; www.
osha.gov) through its comprehensive
Process Safety Management
(PSM) federal regulation. Internationally,
the European Union (E.U.)
splits gas and flame safety responsibilities
between E.U. directives and
European standards organizations,
including the European Committee
for Electrotechnical Standardization
(Cenelec; Brussels, Belgium; www.
cenelec.eu), the International Electrotechnical
Commission (IEC; Geneva,
Switzerland; www.iec.ch) and
several other bodies.
Many accidents are the result of either
failing to implement these standards
properly with suitable flamedetection
equipment or the failure
Ultraviolet
Visible
Infrared
FIGURE 2. Flame detectors, such as those shown here, implement ultraviolet and infrared detection
technologies
to train employees to follow related
safety procedures consistently. In
either case, it is important to understand
the many different sources of
flame hazards, the detection sensor
technologies that can warn of imminent
danger and the proper location
of flame detectors in today's complex
chemical plants.
In the petrochemical plant environSun's
energy
reaching
the
earth
300
nm 400 nm
800 nm
Wavelength
FIGURE 1. Flame detectors can detect light emissions
at specific wavelengths across the UV, visible
and IR spectrum to distinguish between actual
flames and false alarm sources
70
4-5 m
ment, the range of potential flammable
hazards is expansive and
growing as materials and processes
become more complex. These hazards
have led to the development of
more sophisticated combustible-gas
and flame-sensing technologies with
embedded intelligence that can better
detect the most common industrial
fire sources, some of which are
listed in Table 1.
Principles of flame detection
Industrial process flame detectors
detect flames by optical methods,
including ultraviolet (UV) and infrared
(IR) spectroscopy and visual
flame imaging. The source of flames
in CPI plants is typically fueled by
hydrocarbons, which when supplied
with oxygen and an ignition
source, produce heat, carbon dioxide
and other products of combustion.
Intense flames emit visible, UV,
and IR radiation (Figure 1). Flame
detectors are designed to detect
the emission of light at specific
wavelengths, allowing them to discriminate
between flames and false
alarm sources.
Flame-sensing technologies
The flame safety industry has developed
four primary optical flamesensing
technologies: UV, UV/IR,
multi-spectrum infrared (MSIR),
and visual flame imaging (Figure 2).
These sensing technologies are all
based on line-of-sight detection of
radiation emitted by flames in the
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Chemical Engineering May 2016

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