Fact Checked

What is a Flame Detector?

Harriette Halepis
Harriette Halepis

A flame detector is a type of device that uses optical sensors in order to detect flames. Flame detectors are used mostly at hydrogen stations in order to prevent any fires from happening. Essentially, there are seven different types of flame detectors available. These types include ultraviolet, infrared, UV/IR, IR/IR, IR/IR/IR, visible sensors and video cameras.

Ultraviolet detectors have the ability to detect fires and explosions in three to four milliseconds. From the moment that a small flame has been ignited, an ultraviolet detector can distinguish the type of flame. While incredibly accurate, ultraviolet detectors can be fooled by sunlight, radiation, arc welding, and lightning.


An infrared flame detector works by using an infrared band. When hot gasses are released near an infrared detector, a small thermal imaging camera immediately picks up on the presence of these gasses. On occasion, other sources of hot gas that happen to be near an infrared flame detector can cause this type of detector to set off a false alarm.

UV/IR detectors use a combination of both ultraviolet and infrared technology to detect heat. These detectors gather information from an ultraviolet perspective and an infrared perspective. When these two technologies work together, false alarms are often minimized. Similarly, an IR/IR flame detector detects flames within two infrared frequencies. Thus, IR/IR detectors are also able to eliminate most false alarms.

Even more accurate than IR/IR or UV/IR detectors are IR/IR/IR detectors that use three different infrared frequencies in order to detect a flame. Since an IR/IR/IR detector works by comparing three wavelength bands, it is nearly impossible for this type of flame detector to detect anything other than a dangerous flame or fire. Frequently, visible sensors are added to a flame detector in order to detect any flames that may be visible. When combined with a highly accurate detector, a visible sensor tends to eliminate any type of false alarm.

Lastly, a closed circuit video camera may be able to detect any flame or fire. However, as is the case with any other kind of camera, these cameras can be triggered by any kind of smoke or fog, which makes this type of flame detector the least reliable. While all kinds of flame detectors are used in industrial settings, such as hydrogen stations, residential fire alarms are also considered flame detectors. Without these devices, fires would not be detected, which could lead to a massive explosion, fire, or other incident.

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Discussion Comments


@miriam98 - That’s a fascinating question. I think computer technology would in fact help. One area might be image analysis, where it could study a scene to determine if there is anything unusual about it.

I know image analysis is used in some motion detectors, so maybe this could be combined with an optical flame detector to produce something that is really accurate.


@everetra - I notice that in order to eliminate false alarms, the best flame detectors use “smart” technology.

The article mentions the IR/IR/IR flame detectors as being the most accurate because they compare the different wavelengths of light to determine if a dangerous flame has in fact been lit.

That’s why I call it smart technology, because it requires comparing different values. I wonder if these kinds of detectors have any computerized circuitry, and if not, would the insertion of computer technology make these or other detectors even more accurate?


@allenJo - Yes, by I think that the flame detector is more accurate. Remember, the fire detector doesn’t just detect the fires; it also detects the nearby gases.

Any flame that is ignited is bound to release gases into the atmosphere. I think smoke detectors work on gas smells as well so I think the principle between the two is similar.

Also remember that before there is smoke, there is a flame, so I think that the flame detector is the more accurate technology. It nips the problem in the bud, at the very instant that it happens.


My first impression is that a flame detector works differently than a smoke detector, if I understand correctly.

All of the different detectors that are described in this article rely on gases or flames, and the detectors use the light spectrum to detect them.

What if you have smoke without any visible flames? I think a smoke detector works differently, as it detects mainly the smoke.

I’ve had my smoke detector go off when something burned – but there were no longer any flames – and so I think the technology is different.

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