Keep in mind that flame detection isn’t always the best choice for identifying a fire. For instance, flame detectors may not be wholly effective in protecting zones due to high levels of congestion, interference from flare activities or environmental conditions. In such cases, other methods like heat and smoke detectors and pneumatic detection systems may do a better job.
Also, always remember that flame detectors don’t negate the need to consider ways to prevent fires in the first place. Identify adequate safeguards using engineering standards and process hazards evaluation methods like event tree and layer of protection analysis .
Make The Right Choice
Successful performance of fire detection systems depends on the early and reliable identification of fire. Key to this is the careful choice of flame detectors in the process area. Base your device selection on an analysis of the characteristics of potential fires, their causes and the environment. UV detectors offer fast response and good sensitivity while UV/IR and multispectral IR models provide increased false alarm immunity over UV models and operate at moderate response speeds. Multispectral IR detectors offer the largest area coverage per device of any detector type and boast versatility and strong false alarm rejection; so, plants prefer them for a whole host of uses. CCTV detectors, which can provide images of the area under scrutiny, may serve for event management in case of a fire. In practice, their singular advantage is discrimination of flames produced by process flares.
No flame detector technology is best in all situations; usually a combination of thermal, flame and smoke detectors or several flame detector types is necessary. Bear in mind that some operations such as raw material receiving, sorting and storing as well as reaction and product generation may involve a variety of fuels. In addition, regulatory bodies in certain jurisdictions (e.g., the Bureau of Safety and Environmental Enforcement in the Gulf of Mexico) mandate the installation of pneumatic fusible-loop heat detection systems as an additional and complementary layer of protection.
EDWARD NARANJO is director of Rosemount fire & gas systems, Emerson Automation Solutions, Shakopee, Minn. Email him at Edward.Naranjo@emerson.com.
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