Hydrogen, as a promising clean energy source, is increasingly used in various industrial sectors. However, its highly flammable nature represents a safety risk. Early detection of hydrogen flames is essential to minimize the risk of fire, and ensure the safety of installations and people. 

Hydrogen, an energy source

Hydrogen (H2), also called dihydrogen when it is made up of two hydrogen atoms, is created by a chemical reaction with other atoms that can be produced in 3 different ways, such as :

  • gasification
  • electrolysis of water
  • steam reforming of natural gas (mainly methane)

This element is not very toxic to the health of those exposed to it, but it is extremely flammable and reactive, and can cause considerable damage (explosions, fires). Although not very toxic to health at first sight, in very high concentrations there is a potential risk of asphyxiation.  


This gas has no odor or color, and is much lighter than air, making hydrogen leaks very difficult to detect. Classified as R12 (flammable), its explosive limits are very wide, ranging from 4 to 75% volume. Hydrogen fires are invisible to the human eye.   

Hydrogen leak detection

Undetectable by smell, only an H2 gas detector can accurately detect and measure concentrations of this gas. Hydrogen can be detected in two ways: either in terms of toxicity, measured in ppm (rare cases), or in terms of explosiveness, measured as a percentage of LEL (explosive gas detector). The H2 explosimeter is widely used on the hydrogen detection market, with Oldham Simtronic's OLCT100 ATEX gas detector among our best-sellers. 


Optical hydrogen flame detection

Optical flame detectors are made up of sensors working in invisible radiation, i.e. ultraviolet (UV) or infrared (IR). The most powerful flame detectors generally have several sensors (UV, UV/IR, IR3 or IR4). Just like a fixed gas detector, a flame detector generally works in conjunction with a central gas detection system

The different types of flame detectors

  • UV flame detector: Consists of a sensor sensitive to UV radiation. Generates a radiation output signal, compared with a carefully calculated reference. 
  • IR flame detector: Consists of a sensor sensitive to the IR radiation emitted by the CO2 produced by combustion of the product in flame. 
  • UV-IR Flame Detector: This detector combines a UV sensor and an IR sensor to detect hydrocarbon, hydrogen and metal fires, with very fast response times (<150 msec). Requires simultaneous response from both sensing elements. 
  • IR3 flame detector: Three pyroelectric sensors detect IR radiation from different emission peaks. The IR3 sensor for detecting hydrocarbon flames is not sensitive to solar radiation. 
  • Flame Detector IR4: Combination of 4 infrared sensors for detection of hydrocarbon and hydrogen flames from 5 to 65 meters, with high immunity to nuisance alarms. 

Spyglass IR3-H2 hydrogen flame detector

Most hydrogen fires are detected using UV-IR optical flame detectors. This technology has been tried and tested for many years, but has a few minor drawbacks, such as a slightly shorter detection distance than IR3 technology, and a certain sensitivity to light or sparks, which in some cases can lead to false alarms. 

The Spyglasss IR3-H2 is a triple-wavelength (IR3) hydrogen flame detector designed to detect non-hydrocarbon fires. It detects long-distance methanol or hydrogen fires with unrivalled response times, while guaranteeing high immunity to false alarms. It can be fitted with an optional high-definition video device.  


As an option, they can be fitted with near-infrared video to detect flames invisible to the human eye, such as hydrogen fires.