FM Approved Flame Detection

The Hazards

The risk of fire and explosion is a real and ever-present threat in many industries. From agriculture and textiles to petrochemical, automotive and semiconductor manufacturing, the need for fast detection and control of fire and sparks is an essential requirement for loss prevention.

While proper storage, use, and safety precautions can help reduce the risk of losses related to ignitable liquids and gases, accidents happen and the results can be devastating. Causes of fire are many, including hot work, smoking, electrical arcs, electrostatic discharge, lightning strikes, equipment failure, operator error, arson and vandalism.

Fire from ignitable liquids and gases many not produce much smoke initially, and/or the smoke produced may take too long to reach ceiling-mounted detectors in large open areas. For some fuels and gases, the flame produced may be invisible or barely visible to the naked eye.

Therefore, conventional smoke and heat detectors can be ineffective in the early detection of fires in large and open facilities where ignitable liquids and gases are frequently used. These facilities include aircraft hangars, turbine generator halls, manufacturing plants, refineries, pharmaceutical and food processing, and semiconductor fabrication.

To protect such facilities, flame and spark detectors typically are part of a three-part system designed to detect, control and, in many cases, suppress or extinguish fires. It is the job of these detectors to accurately and quickly detect fires or sparks and sound an alarm, trigger a system shutdown and/or initiate a fire extinguishing system such as CO₂, foam or water mist.

Testing Required for FM Approval

Flame detectors are often used in combination with gas, heat and smoke detectors to provide complete coverage for high-risk occupancies. There are four primary types of optical flame-sensing detection systems available today: ultraviolet (UV), ultraviolet/infrared (UV/IR), multispectrum infrared (MSIR) and video imaging using a charge-coupled device (CCD) sensor.

All of these systems work by seeing the fire develop by line of sight and detecting the radiant energy or recognizing the fire using live images and imaging algorithms. In many cases, multiple detectors are needed to provide adequate coverage for large, open areas.

FM Approved radiant energy flame and spark detectors are evaluated according to Approval Standard 3260, Radiant Energy-Sensing Fire Detectors for Automatic Fire Alarm Signaling. This standard is also an ANSI standard. Video-based flame detectors are evaluated using FM Approvals Standard 3232, Video Image Fire Detectors for Automatic Fire Alarm Signaling.

Approval Standards ANSI/FM 3260 (radiant energy) and FM 3232 (video image) both require four detectors to ensure consistent and repeatable results. The detectors are subjected to performance-based testing using the manufacturer’s specifications, including the specific types of fuel fires it will detect, the claimed range, fire size, field of view, and response time. A key part of the performance tests for both Standard ANSI/FM 3260 and FM 3232 is a series of full-scale fire tests using liquid, gas and solid fuels.

No other testing organization uses full-scale fire tests as a standard part of its evaluation of flame and spark detectors. Most testing organizations use small-scale bench-top fire tests and extrapolate the data. Years of research and testing experience has shown that full-scale fire tests are still the most accurate and reliable way to evaluate the performance of flame and spark detectors.

FM Approvals was the first organization in the world to develop a video imaging fire detector standard (Approval Standard 3232) which also uses full-scale fire tests.

Flame, spark and video image detectors submitted for evaluation must also meet a range of functional tests designed to simulate real-world conditions, including flame response, false stimuli, humidity, voltage variation, vibration, switching, voltage range and temperature extremes. False stimuli testing, for instance, ensures that FM Approved flame detectors will respond to radiant energy in the intended wave- length without false alarms due to direct or reflected sunlight, artificial light, arc welding and heaters. Electrical transients are another real and ever-present challenge in many installations. FM Approved flame detectors will not produce false signals or malfunction when faced with voltage surges and fluctuations from miscellaneous electromagnetic interference (EMI) and radio frequency interference (RFI) sources.

Benefits and Availability

FM Approvals performance-based testing (full scale fire and functional tests) is unique in the industry and assures the FM Approved flame, spark and video image detectors deliver the performance promised by manufacturer specifications. This level of detailed testing enables specifiers, designers and others to choose the FM Approved detector that best meets the application requirements. FM Approved flame, spark and video image detectors provide the highest level of performance assurance.

In addition to Approval Standards 3260 (radiant energy) and 3232 (video image), manufacturers may also choose to have their flame, spark and video image detectors optionally certified by FM Approvals for hazardous locations, including intrinsically safe, nonincendive, explosion-proof or dust ignition-proof.

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