Things to Consider before Purchasing a Point-type Infrared Flame Detector

Figure 1: Point-type infrared flame detector.

Point-type infrared flame detector does not cause false alarms for interference such as sunlight, artificial light sources, and thermal radiation, and works stably and reliably. It can be used in large spaces where flames are the mainstay in the early stage of fire, both indoors and outdoors. However, the application of a point-type infrared flame detector is not without limits.
Before we talk about the limits, we need to first learn about how a point-type infrared flame detector work.

The Working Principles of Point-type Infrared Flame Detector

In a nutshell, this detector judges the fire by detecting the light signal of the flame in two wavelength bands in the infrared light region. It usually selects infrared radiation with a wavelength near 4.35um as the detection band. Because natural gas alcohol, gasoline and other hydrocarbon substances will generate a large amount of CO2 gas when they are burned, and the radiation intensity of these hot CO2 gases is the largest near 4.35um.
Due to the absorption of C02 and water vapor by the surface, the infrared light at 2.7 and 4.35um in the spectrum of solar radiation hardly exists, so the infrared radiation generated by the flame can be received to the greatest extent near the 4.35um band.

Figure 2: Marine point-type infrared flame detector.

This can be understood in this way: the detector reacts as long as there is flame radiation. In addition, its response to open flame is way faster than that of heat and smoke detectors. Therefore, the flame detectors are especially suitable for large oil tank storage areas, petrochemical operation areas and other places where open flames are prone to burning or where the spread of open flames may cause major dangers.

Where should a Point-type Infrared Flame Detector be Installed?

Point-type infrared flame detector is not appliable everywhere. Here are its requirements for operating conditions.
The front end of the point-type infrared flame detector is a visual mirror window, so there must be a clear field of view from the flame detector to the detected area. And this detector is not suitable for the initial smoldering stage in which thick smoke is spreading. This is because the spreading smoke will block the front window screen, greatly reducing the accuracy of the detector.

Similarly, in places with high relative humidity and many suspended particles in the air, the lens of the detector is easily polluted. A point-type infrared flame detector cannot function well, either.

Figure 3: Plenty of water vapor during car-washing.

What’s more, materials like oil mist, oil film, thick smoke, hydrocarbon vapor, water film or ice can suppress the transmission of light. In refrigerators, car washes, paint workshops and other places where oil mist, smoke, water mist, etc. appear frequently, significantly reducing the intensity of the optical signal, the flame detector is not recommended.

As discussed above, there are limits for the operating conditions of the point-type infrared flame detector. Please consider them before purchasing one to make sure it functions well during usage.

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