Flame Sensor: Explore the Functionality, Variants and Interfacing Techniques

A flame sensor is a device that is used to detect the presence of flames. It is a safety device used in gas-burning furnaces and boilers to detect the presence of flames The main function of this is to check if the boiler is working properly or not. In comparison to a heat or smoke detector, the flame sensor’s response is faster and more accurate.

FLAME SENSOR WORKING PRINCIPLE

Flame sensors use two types of technology to identify flames: ultraviolet (UV) and infrared (IR). Depending on the installation, these sensor’s reactions to a detected flame can include turning on a fire control system, sounding an alarm, and cutting a fuel line.

The UV-enabled flame sensor operates by simply detecting UV rays. Since all flames, in general, produce UV radiation at the place of ignition, if a fire were to occur, the sensor would sense it, become alert, and produce a series of pulses that the detector’s electronics would alter to produce an alarm.

Furthermore, the infrared flame sensor operates by looking for certain ornamentation that hot gases release in the IR spectral range. However, this type of apparatus requires a flickering flame. Generally speaking, infrared radiation comes from lamps, ovens, and other sources in addition to flames. Thus, the likelihood of a false alert is considerable.
Because the UV-IR sensor can detect both UV and IR light, it has both sensors.

FLAME SENSOR MODULE

The 4-pin flame sensor module is:

Pin 1 (VCC): 3 to 5 volts is the voltage supply. 

Pin 2 (GND): This is a ground pin.

Pin 3 (AOUT): The analog output pin is AOUT.

Pin 4 (DOUT): It is a digital output pin.

FLAME SENSOR TYPES

UV flame sensors:

Most fires emit UV radiation, so UV frames or UV frame sensors are used to detect this radiation. These sensors are especially beneficial for services that are vulnerable to certain risks, such as hydrocarbons, metal fires, and halogens. As a result, these kinds of sensors function poorly at longer ranges, but they are very sensitive at shorter ones—between 0 and 50 feet. These sensors react to lightning-related electrical discharges.

Infrared flame sensors:

Infrared flame sensors monitor IR radiation. These sensors can also identify and examine infrared spectrum bands to find specific preset prototypes released by hot gases. Thermal imaging or thermographic cameras find these prototypes. These sensors use flame recognition technology, which uses a charge-coupled device (CCD) to detect near-infrared radiation.

Ultraviolet and infrared flame sensors:

Infrared and ultraviolet radiation sensors are added to ultraviolet and infrared flame detectors. All these two sensors do is operate independently. However, some had wiring and circuitry to support the detection process and assess both UV and IR signals. Besides, the technology used in the IPES-IR/UV Flame Detector is based on infrared and ultraviolet detection. offering a quick response time of under five seconds. An explosion-proof, approved enclosure is a feature of IPES IR/UV. International accrediting bodies have recognized IPES IR/UV for SIL-3 rating.

With optical filters set for optimal sensitivity to radiation from flames or fires, IPES IR/UV advanced detection technology enables quick flame recognition and alarm signalling.

Multi-Spectrum Infrared Flame Sensors:

To distinguish flame-producing radiation from non-flame-producing radiation sources, MSIR sensors use a wide range of infrared wavelengths. MSIR sensors react to fires very fast, whether indoors or outdoors, and up to a distance of 200 feet.

IP3 flame sensor:

IR3 flame sensors compare the radiation band ratio and emission patterns across three different infrared spectral bands. Moreover, these flame sensors are often configured to detect one radiation band in the 4.4-micrometer range and two bands that fall outside of and above the 4-micrometer range. As a result, without a doubt, this sensor can distinguish between radiations that affect the results but do not fire.

Advantages and Disadvantages of Flame Sensor

Advantages of flame sensors:

1. Response time: The sensors offer rapid response times, which helps to detect the fire and work on its diffusion.
2. Alarms: False alarms cannot activate these sensors. Flame sensors do not produce false alarms, which makes them trustworthy.
3. Fast response: Because of the mechanics it uses to detect the flame, this sensor often responds faster and more accurately than a heat or smoke sensor. The faster they perform, the better they are.

Disadvantages of flame detectors:

1. Poor adaptability:  Also flame sensors may not perform well in conditions such as humidity, fog, or smoke. Indoor conditions can affect their accuracy.
2. Carbon fires: Some flame detectors are manufactured to detect a specific type of fire. Such as carbon-based fires, due to which they may not be accurate in detecting other fires.
3. Maintenance: Flame sensors are important for fire detection, so their regular maintenance is also important. Dirty sensors can result in failures in flame detection.

Aside from their drawbacks, flame sensors are useful and accurate. The advantages of flame sensors often outweigh their drawbacks.

Applications

Moreover, flame sensors are used in different places, like hydrogen stations, industrial heating, fire detection, fire alarms, firefighting robots, drying systems, industrial gas turbines, domestic heating systems, and gas-powered cooking devices.