There are many industries, processes and applications that have a need to protect and save life and property. To that end, they need detection systems and detectors that will be highly immune to false alarms and of the highest performance and reliability.
As a result, flame detectors were developed to detect fire at all times and in all weather conditions and yet be highly immune to false alarms.
In recent years, communication, video image processing and data storage power technology have developed rapidly and so are readily available and easy to implement. They will contribute to the next generation of Flame and Gas detection systems and products.
There were many types of flame detectors used in the past but since the early 1990s, Triple IR flame detectors (IR3) were introduced to the market to address the critical need for low or no false alarms, coupled with high sensitivity and fast reaction time. This is especially important in high risk applications such as shutdown systems on offshore/onshore oil and gas installations, activation of fire suppression systems etc.
Response time:
For many of these applications, every second in response time may make a large difference in addressing the evolving fire threat. So, very fast and reliable response is key.
False activations:
Activations, for no real threat, result in a very disruptive and costly event. They may result in shutdown of critical processes, evacuation of personnel, activations of suppression systems and the incurrence of high costs etc.
In many cases, the actual damage from false alarms / activations are even greater than the immediate cost of activating unnecessary fire emergency procedures. Unacceptable false alarm rates lead to a loss of credibility of the safety system. Such loss in credibility sometimes leads to loss of confidence that may result in personnel ignoring future fire alarms or even to the disconnection of crucial fire detection elements, which are considered problematic. The consequences in case of a real fire could be disastrous.
It should be noted that the challenge of avoiding false activation is complex. Many techniques that might be used to prevent false activation will also significantly reduce the detection sensitivity for real fires. Under no circumstance can one allow a detector not to alarm when a fire is at its initial stage, while it is still small enough to be controlled and extinguished.
The Challenge
This defines the challenge and the target to be addressed and met by the fire detection industry, which strives to develop new technologies and detection methods.
To that end, the market requirements and needs are for the following core capabilities:
- Fast and 100% positive detection of fire in all cases of background radiation conditions
- Very high immunity to false alarms in all weather and background radiation conditions
- Fast and reliable detection of any types of fuel or gas ignition or outburst of fire or vapor explosion.
- Reliable at all operating conditions with very high mean-time-between-failure (MTBF)
In addition the desired features are:
- Ability to continuously monitor and view the protected area and to receive an alarm and clear image of the events, as they occur, at the control room.
- Immediate transfer of all vital information to enable the control room and the emergency team to select the best response
- Fast and reliable visual location of the fire event in the monitored area
- Diagnostic and prognostic capabilities of the detector operation including data – logger and HD video that enable pre/post event investigation into the causes of ignitions.
Background
Flame detectors have been extensively used for over 50 years to address the need for quick detection and, in many cases, also the response to fast growing fire.
These devices monitor the optical radiation emitted by the fire in the ultraviolet (UV), visible and/or infrared (IR) wavelengths and issue an alarm when their measurements indicate that a hazardous flame is present. For high-risk areas, particularly outdoors, optical flame detectors are the favored solution. This is because, unlike smoke and heat detectors, detection is ‘taken’ to the fire rather than waiting for the fire to reach the detector.
Flame detection technologies have come a long way since the first phototube (UV) and photo cells that detected the photons emitted by flames.
The ever-growing requirements of modern industry for higher performance and reliability i.e. to continuously detect fire as early as possible with the highest sensitivity, and in all weather conditions, yet to be highly immune to false alarms.
This was better addressed in the late 1970s by the introduction of the combined UV/IR detectors. Yet the inability to detect fire at long ranges without a high false alarm rate was still a problem – because increasing the sensitivity of the UV/IR detection system, e.g. by appropriately lowering the threshold level, increased the range of detection however it also increased the false alarm rate.
UV/IR detection range is limited to 65ft (20m) or less.
False alarms may be caused by spurious radiation sources, such as direct or reflected sunlight, black body radiations, artificial lights (particularly halogen lamps), welding, electrical heaters, ovens, etc. Some spurious radiation sources may not be large enough to activate short-range detectors but can be large enough to activate detectors whose sensitivity has been increased to extend their detection range.
The UV / IR detectors were very commonly used and today are still used in some onshore industries, mainly indoors where false alarm sources are less prevalent or long detection range is less important
To address the need to reduce false alarms and increase detection distances, the late 1990s saw the major breakthrough in flame detection which was the introduction of TRIPLE IR (IR3) technology. This technology revolutionized the field of fire safety by providing a flame detector with a much longer detection range, much higher sensitivity and with exceptionally improved false alarm immunity.
IR3 detectors can detect a standard 1ft2 (0.1 m2) gasoline fire at a distance of up to 200ft (60m) and operate in extreme weather and harsh industrial conditions, with a very low false alarm rate. This is done by concurrently monitoring the detection area with three IR sensors, one of them sensitive to infrared radiation emitted by the hot CO2 product of fire (wavelength around 4.3µ) and the other two reference sensors sensitive to background radiation (at longer and shorter wavelengths).
IR3 detectors have provided industry enhanced flame detection reliability with a longer detection range combined with unprecedented false alarm immunity that was required by the high-risk, high-value facilities and processes in general but in particular the Oil & Gas offshore and onshore industries.
Next Generation
Now the next generation of the IR3, e.g. the FlameSpec-IR3–HD, is being introduced to further enhance the protection and safety for high risk and high value industries.
The FlameSpec-IR3-HD will detect fires and explosions extremely fast thus allowing preventative action to be initiated even more rapidly and minimizing the consequences!
The unmatched Detection times and distances are:
- 40ms – for a fast fire burst or explosion
- 1s – for 1ft2 (0.1m2) n-heptane pan fire at up to 100 ft. (30m)
- <4s – for 1ft2 (0.1m2) n-heptane pan fire at up to 260 ft. (80m)
The integral HD quality video, with event recording, on top of the proven superior capabilities of Triple IR (IR3) flame detection, then provides a very powerful safety tool to protect personnel, plant and process.
The FlameSpec-IR3-HD flame detector provides ultra-fast response, high performance and reliable detection of all types of hydrocarbon fires (visible and non-visible). The detector addresses slow growing fires as well as fast eruption of fire using improved triple IR (IR3) technology. It operates in all weather and light conditions with the highest immunity to false alarms.
In addition, the detector provides high-definition (HD) video output of the monitored area with clear imaging of a fire event and of personnel at distances up to 100 ft (30m). This allows the rescue team to be aware of the exact situation before entering the hazardous area. The detector automatically records video of any fire event (1 minute pre- and up to 3 minutes post alarm initiation). These features, along with the built-in event logger, provide additional means to study the cause and development of fire events for “lessons learned” reviews.
Summary
So many situations, where the risk from rapidly growing fires on unmanned platforms and processes, plant areas where operators and other workers are present near unwanted hazardous discharges, can all benefit from today’s readily available well proven flame detection technologies. To that end, the fire detection industry can and should meet the challenge and develop the next generation of substantially more capable, reliable and better performing products.
The latest technology has now been applied to the proven IR3 flame detection technique to produce an ultra-high speed IR3 flame detector that can respond in 40 milliseconds, with even higher immunity to false alarms and even higher reliability. With integral HD video and data/event recording, it is difficult to see why such a detector is not always the first choice.
For more information, go to www.fg-detection.com
Yechiel Spector
Olden Carr
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