What is infrared flame detector?

What is an infrared flame detector?

An Infrared (IR) Flame Detector is a specialized fire protection device designed to detect the presence of a fire by sensing the infrared radiation emitted by flames. Unlike smoke or heat detectors, which detect the byproducts or effects of a fire, flame detectors "see" the fire itself by recognizing the unique optical patterns (flickering frequencies and spectral bands) of burning materials.

They are critical for safeguarding high-value assets and hazardous environments where rapid, reliable fire detection is essential.

How Does an Infrared Flame Detector Work?

IR flame detectors operate on the principle that all flames emit specific patterns of infrared radiation. Here's a breakdown of the process:

1. Sensing IR Radiation: The detector's sensor, typically a photodiode tuned to specific infrared wavelengths, receives electromagnetic radiation from its field of view.

2. Spectral Analysis: The most common and advanced type is the Multi-Spectrum (or Multi-Band) IR detector. It doesn't just look at one wavelength; it simultaneously analyzes multiple infrared wavelengths (e.g., 2.7µm, 4.3µm, 4.0µm, 5.0µm). This is crucial because:

• The 4.3µm wavelength is a strong emission band for hot carbon dioxide (CO₂), a key byproduct of hydrocarbon fires (e.g., gasoline, diesel, natural gas, propane).

3. Flicker Frequency Analysis: Most flames flicker at a characteristic frequency between 1-25 Hz. The detector's microprocessor analyzes the incoming signal for this flicker to distinguish a real flame from other steady-state IR sources.

4. Signal Processing & Algorithm: The detector's built-in intelligence (a 32-bit MCU and sophisticated algorithms) compares the signals from the multiple IR channels and the flicker frequency against stored "signatures" of real fires.

5. Alarm Decision: If the signals match the predefined criteria for a genuine fire, the unit triggers an alarm within seconds (typically 3-5 seconds, but can be as fast as milliseconds), sending a signal to the fire alarm control panel.

Key Features & Advantages

Applications (Where are they used?)

IR flame detectors are essential in industries where fast-spreading, hazardous fires can occur:

• Oil & Gas: Offshore platforms, refineries, pipelines, wellheads.

• Chemical & Pharmaceutical: Processing plants, solvent storage, spray booths.

• Power Generation: Turbine halls, hydrogen cooling systems.

• Aerospace: Aircraft hangars, engine test cells.

• Automotive: Paint shops, fuel testing areas.

• Warehousing & Logistics: For high-bay storage areas.

Infrared vs. Ultraviolet (UV) Flame Detectors

Modern best practice often uses UV/IR Combos or Multi-Spectrum IR detectors, which combine technologies to leverage the strengths and mitigate the weaknesses of each.