Fire Detectors – Infrared Flame Detectors

Fire Detectors - Infrared Flame Detectors

Flame detectorsOpens in a new tab. are devices that use special optics to detect firesOpens in a new tab. from long distances without heat or smoke to get to the flame detector first. Hazardous industries and manufacturing plants require high tech flame monitoring equipment to prevent fires.

Generally, there are four different types of optical flame detecting devices. Each of them is based on online-on-sight detection of radiation given off by red flames and heat.
Below are some common types of flame detectors:

  • Visual flame imaging
  • Ultraviolet detectors
  • Ultraviolet and Infrared detectors

Infrared Detectors

These detectors use optical sensors, working in a special range and record radiation at a selected wavelength. The signals recorded by each sensor are carefully analyzed using some special techniques. Below are some of them:

  • Correlation to memorized spectral analysis.
  • Flickering frequency analysis.
  • Mathematical ration and correlation between different signals.
  • Comparator techniques.
  • Threshold energy signal comparison.

It is important to consider the following factors when any of the above flame detectors are being configured.

  • Self-diagnostic.
  • False alarm immunity.
  • Response time.
  • Field of view.
  • Detection range

The focus of this article is going to be on Infrared flame detectors, with a view to learning about how they work, the various types that are available and their application, how to choose an IR flame detector and some advantages of IR flame detectors.

What are infrared flame detectors

An infrared optical detector is a device that locates flame by deploying a high-tech infrared sensor to accurately identify their unique spectral pattern emitted by live fire.

Infrared detectors are embedded with a pyroelectric sensorOpens in a new tab. that can easily detect thermal radiation and are sensitive to a variation of the light signal it receives.

IR detectors are suitable for areas where combustion sources can produce intense and smoky fires. They can operate within the range of sixty meters from the fire sources. Unlike other detectors that can only be used indoorsOpens in a new tab., IR detectors can be used in both indoor and outdoor environments. IR detectors are immune to radiation produced by sunlight, welding, and other hot objects that might be present in the environment it is installed in.

To prevent IR detectors from false alarms, they are embedded in multiple high tech detectors. To crown it up, IR detectors are more reliable and cheaper than other detectors in the market.

Advantages of infrared flame detectors

IR flame is suited for a cold and rugged environmentOpens in a new tab.. It has a special heat optical window that enables it to perform well in snow or icing conditions. Since they are weather resistant and likely the most durable flame detector available, they can easily be programmed for all environments, applications, and requirements. This can easily be done by changing the configuration parameter in the device. Conducting various monitoring tasks and modifying these parameters and maintenance is possible by means of the Highway addressable remote transducers.

Since infrared detectors have extended coverage, you won’t need to buy a lot of them. They are highly reliable and fairly expensive to purchase and maintain. Generally, infrared detectors are designed to work as a stand-alone unit connected to an automatic fire suppressing systemOpens in a new tab. or an alarm.

Types of IR detectors

1. Single IR flame detector

Single IR flame detectors are designed to detect gas fire and hydrocarbon-based fuel using a special flame sensing tool. They are affordable durable and can work perfectly in extreme conditions.

Method of operation

Single IR detectors use high tech pyroelectric sensors that have a 4.4 micron optical and an electronic bandpass filter to gas fires and carbon-based fuel. The device is also sensitive to CO2 emissions. The reason why they are so effective is that they use various mathematical techniques and parameter analysis to distinguish between flame spectral signatures and other infrared sources.


Single IR flame detectors can be used in the following areas:

  • Chemical plants.
  • Waste disposal facilities.
  • Gas and offshore oil installations.
  • Onshore oil and gas installations.
  • Warehouses.
  • Power generation facilities.
  • Storage Tanks.
  • Pharmaceutical industry.

Main features of the device

  • Manual and automatic built-in-test.
  • The device can operate as a stand-alone unit.
  • It can also be connected to a fire suppression system or a fire alarm.
  • The device is reliable and can work for a minimum of 150,000 hours.
  • It utilizes RS-485 and HART for digital communication.
  • It has a quick response time
  • It can be used in a harsh environment.

2. Multiple IR flame detector

Multiple IR flame detector is specially designed to detect hydrogen flames and hydrocarbons at long distances. It can detect a hydrogen flame at 30 meters, a gasoline pan fire at 65 meters in less than 5 seconds. What makes this detector stand out is that it is reliable, can detect flames a long distance away, and is immune to false alarms. The device is suited for locations where combustion sources create smoky flamesOpens in a new tab..

Method of operation

The working principle of multi IR detectors is based on the new spectral analysis technology, which can easily identify the infrared signature of Co2 at an emission band of 4.2 microns and hot water at an emission band of 2.7 microns.

The device incorporates a couple of detection algorithms, mathematical ratios, flickering, and correlations between different signals. When all the parameters of the analysis meet the programmed values, a fire conditioned fire alarm is triggered.


Multiple IR flame detector can be used in the following areas:

  • Printing industry.
  • Explosive and munitions.
  • Chemical plants.
  • Hydroxyl propellant.
  • Space industry.
  • Offshore and onshore oil and gas industry.
  • Gas tank farms.

Main features of the device

  • Sensitivity selection
  • The device is immune to false alarms
  • 150,000 operational hours
  • It can be used in hazardous areas
  • 5 seconds of response time
  • The device has a detection range of 65 meters
  • It has a field view of 90°

3. Triple IR flame detector

IR3 flame detector uses a digital signal processing system to thoroughly examine the spectral and dynamic properties of infrared radiation, to accurately recognize fire events quickly with immunity to false alarms.

Method of operation

The Triple IR detector is designed to recognize the spectral signature that is present in Co2 at a wavelength of 4.2.

The device utilizes 3 high-tech detectors to establish the difference between non-fire radiations and also to identify flame emission. The IR3 flame detector implements a different algorithm taken by a sophisticated microprocessor that carefully analyzes radiation intensity, ratios, flickering and correlation signals, and threshold values from 3 sensors. The role of the first sensor is to detect Co2 flames, while the other two are responsible for non-fire radiation. Flame detection alarm will only be triggered when programmed condition from all 3 infrared wavelengths found in an active fire are satisfied.


IR3 flame detectors can be used in the following areas:

  • Warehouses
  • Aircraft hangers
  • Petrochemical plants
  • Power generation facilities
  • Chemical plants
  • Offshore oil and gas installations
  • Printing industry

Main features of the device

  • Response time of five minutes
  • 65 meters detection range
  • It is suitable for harsh environments
  • Sensitivity selection
  • Multiple spectrum designs- this makes it suitable for long-distance detection and immune to false alarms

Choosing an IR flame detector

Each type of flame detector can easily detect a flame source apart from sulfur and magnesium which can only be detected with a special flame detector. As you may know, all IR detectors may not be good for your facility. To choose a good one that will be able to protect your property, you first have to consider the type of flame that can be generated in your facility. Below are some types of the flame detector and their application. Having a firm grasp of their application will put you in a better position to determine if they will be good for you or not.


This detector is meant to be used indoor only and an area where quick detectionOpens in a new tab. is required. The device can also be used through glass (this may reduce the range of the detector). IR2 detectors are available in ExD and ARE versions.


IR3 detectors can be used outside and inside. They are best suited for a dirty or outdoor environmentOpens in a new tab.. Regardless of the fact that they can be installed in an open environment, care should be taken to protect them from direct sunlight, as this will cause a false alarm. Like the IR2, IR3 detectors can be used through windows. The IR3 is available in ExD and IS versions.


This flame detector is designed to be used outside. Unlike IR3 and IR2 detectors, the UV/IR2 flame detector can be used in sunlit areas (special care must be taken to ensure that sunrays don’t flicker directly on the flame detector). This device has the highest immunity to false alarms as it needs both the UV and IR to activate an alarm. The only downside of the UV/IR2 detector is that it cannot be used through windows and is available only in an EXD version.

To choose between the IR detectors stated above, you have to consider the nature and the needs of your facility. For example, if the fire-prone area in your property is sunlit, then an IR3 detector will be good for you. On the other hand, if the area you want to protect is indoors, then either the IR2 or IR3 will be a good choice.

Final note

After getting a clear picture of what IR flame detectors are, how they operate, and their application, you are likely in a better position to narrow down the one that will suit your unique need. Having a strong grasp of the area you want to install it is essential. For example, you should know the type of fuel, the size, and the correlation of the area you want to monitor. It is helpful to set up comparison charts of the requirements of your structures and review it against the flame detectors deviceOpens in a new tab. you plan to purchase.

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