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Application note: gas detection in boiler rooms

Application note: gas detection in boiler rooms

Date de l'actualité

Despite the heat of September, it's time to prepare for winter ... Have you checked that your boiler room complies with the amendment to article 2.16 of the decree of 03/08/2018? This was amended in December 2022 and states that boiler rooms that had a gas detection threshold of 60% of the LEL must reduce this threshold from 60% LEL to 30% LEL.

Gas detection in boiler rooms is an essential safety measure to prevent the risks of fire and explosion. In a boiler room, combustible gases such as natural gas, propane or fuel oil are used to produce heat and energy. However, these gases can present dangers if leaks or accumulations occur. To ensure reliable detection of combustible gases in boiler rooms, it is important to follow good boiler room safety practices and install gas detectors.


Modification of boiler room regulations

The regulations on gas detection in boiler rooms were amended last December.

According to Article 2.16 of Decree no. 2018-704 of 3 August 2018, amended on 8 December 2022, on gas detection - fire detection, all boiler rooms with a rated thermal output of more than 1MV must be equipped with a gas detection device and a fire detection device.

  •     For boiler rooms with a capacity of 2 to 20 MW:

PIC Order of 25 July 1997, amended on 10 August 1998: safety threshold set at no more than 60% of the LEL. According to the amendment of 8 December 2022, boiler rooms that had a gas detection threshold of 60% of the LEL must reduce this threshold from 60% LEL to 30% LEL in accordance with article 2.16 of the amended order of 03/08/2018.

  •     For boiler plants with a capacity of more than 20 MW:

GIC Order of 30 July 2003: safety threshold set at no more than 30% of the LEL.

For more information:

 Boiler room regulations

boiler room

What is an industrial boiler room?

Industrial boilers are used for heat exchange to produce steam for use by heat emitters or to heat heat transfer fluids. This type of heating is mainly found in medium and large power installations, district heating, apartment blocks, commercial applications and industry. In contrast to individual boiler rooms, industrial boiler rooms are used to operate all the equipment needed to run a factory or business.


Boiler rooms can present safety risks if they are not properly designed, installed and maintained. Prevention and protection measures, such as gas detection, are therefore necessary to ensure the safety of workers and building occupants.


Gas risks in boiler rooms

There are many risks associated with gases in boiler rooms, and they can be very dangerous for the health and safety of occupants and workers. Here are some of the most common risks:

  •     Risk of explosion: Boiler rooms can be potentially explosive environments due to the presence of combustible gases. If these gases are not detected, or if boiler room safety systems are not sufficiently reliable, an explosion can occur, resulting in major property damage, injury or even death.
  •     Risk of poisoning: Combustible gases such as carbon monoxide, methane or propane are odourless and invisible, which can make them dangerous for the occupants of the gas boiler room. Excessive concentrations of gas can lead to serious or even fatal poisoning.
  •     Risk of fire: In the event of a gas leak, there may be a risk of fire. Boiler room equipment, such as boilers and burners, can also present a fire risk if they are not properly maintained.
  •     Risk of equipment failure: Gas boiler room equipment, such as gas detectors, safety valves and ventilation systems, can fail, leading to dangerous situations for occupants and responders.
  •     Environmental risk: Gas leaks can also lead to environmental pollution, with serious consequences for flora and fauna.

The risks are as follows:

  •     Fuel storage: loss of tightness, poor condition of valves, etc.
  •     Fuel supply: cracking or rupture of expansion valves
  •     Burners: malfunctions, poor adjustment, leaking fittings, etc.
  •     Ventilation: poor evacuation

Accidents in a boiler room

Several types of accident can occur in a boiler room:

  •     Gas leaks that can lead to a fire or explosion in the industrial boiler room,
  •     Escape of polluting fumes, rich in carbon monoxide, which can lead to poisoning of personnel,
  •     Accumulation of gas due to poor combustion in the boiler, which can lead to poisoning of personnel or an explosion.

gas leak 1

gas leak 2

Gas detection in boiler rooms

Installing your detection system

The location of detectors is determined according to the risks and depending on the type of gas:

  •     For natural gas - composed in particular of CH₄ - is lighter than air : 
    >  the sensor is placed approximately 1.50 m above the burner and can be fitted with an optional gas manifold depending on the size of the installation to be protected.
  •     For LPG (heavier than air):   
    > the sensor is placed below the burner.
  •     To protect the premises from the risk of explosion :
    > the sensor should be placed in the air flow at ventilation level.
  •     In the case of toxic gases :
    > the detector will be placed at respiratory tract level in the case of CO, and 50 cm from the floor for H₂S.
fixed gas detection system

A specific study of the boiler room may lead to the installation of additional detectors in places where gas is likely to accumulate.

You must install :

  •     1 detection point per burner, 1 m or 1.50 m above it.
  •     1 detection point at high suction if the gas is light, at low suction if the gas is heavy.

Two boiler room safety levels are required:

  •     1st threshold: gas supply cut-off
  •     2nd threshold: general shutdown