What is a Flame Sensor?
A flame sensor (or flame detector) is a device that detects and responds to the presence of a flame or fire. These sensors can distinguish between visible flames and invisible combustion sources such as smokeless liquids.
Flame detectors are commonly used in boiler furnaces and other combustion systems since they can detect fire, smoke, and heat effectively. Based on the air temperature and velocity, these sensors can identify the presence of flames in less than a second using ultraviolet (UV) or infrared (IR) technology.
When a flame is detected, the sensor responds depending on its installation setup — it may trigger an alarm, cut off the fuel supply, or activate a fire suppression system.
Types of Flame Sensors
Flame detectors are classified into three main types based on the technology they use:
1. Ultra-Violet (UV) Flame Detector
This type of flame detector operates by detecting ultraviolet rays emitted at the source of ignition. Almost all fires emit UV radiation, so when a flame appears, the UV sensor picks up these rays and sends pulses to the detector electronics, which then generate an alarm output.
2. Infra-Red (IR) Flame Detector
An infrared flame detector senses specific IR radiation patterns emitted by hot gases during combustion. However, since other sources like lamps and ovens also emit IR radiation, this sensor may occasionally produce false alarms. For accurate detection, the IR sensor requires the flame to flicker.
3. UV-IR Flame Detector
This detector combines both UV and IR sensors, allowing it to detect both ultraviolet and infrared radiations simultaneously. The combination enhances detection reliability and reduces false alarms, as the system verifies both UV and IR signatures before confirming the presence of a flame.
Pin Configuration of Flame Sensor Module
The Flame Sensor Module has four pins, as shown below:
- VCC: +5V DC power supply
- GND: Ground connection
- DO: Digital Output
- AO: Analog Output
Features and Specifications
- Operating Voltage: 3.3V to 5V DC
- Operating Current: 15 mA
- Comparator Chip: LM393
- Sensor Type: YG1006 Light-sensitive transistor
- Sensitivity: Adjustable via potentiometer
- Outputs: Digital and Analog
- Indicators: Power (Red LED) and Output (Green LED)
- Detection Spectrum: 760 nm to 1100 nm
- Detection Angle: 0° to 60°
- Operating Temperature Range: -25°C to +85°C
- PCB Dimensions: 3 cm × 1.6 cm
Applications of Flame Sensors
- Hydrogen refueling stations
- Combustion monitoring systems for burners
- Oil and gas pipeline safety systems
- Automotive manufacturing facilities
- Nuclear power plants
- Aircraft hangars and maintenance areas
- Turbine enclosures and power stations
Flame sensors play a crucial role in ensuring safety in industrial, commercial, and domestic environments. Their quick detection capability helps prevent fires and safeguard equipment and human lives.