Inert gas extinguishing systems

Fixed fire extinguishing with nitroge (IG – 100)


Systems of inerting and fire extinguishing with nitrogen

Inerting installations and / or with nitrogen firefighting differ according to the following main criteria:

  • way of inerting action;
  • way of fighting action;
  • way of actioning the installations;
  • way of controlling the command.

In terms of the action of inerting, nitrogen installations can be:

  • through the siphoning – in which nitrogen is introduced into the vapor space of the enclosure or technological equipment as it drains fluid from inside or equipment;
  • through the vacuuming – in which nitrogen is introduced into the enclosure or equipment where there is flammable liquids technology in which mixtures of vapor – air pressure is lower than atmospheric pressure;
  • through pressure – at which nitrogen is introduced under pressure in enclosures or technological equipment;
  • in continuous flux – in which nitrogen is introduced inside the evacuated continuous flow or nitrogen flow making the technological equipment inside and / or equipment.

In terms of action, fighting, nitrogen installations are:

  • for total flooding extinguishing;
  • for local extinction (small areas).

Actioning the fixed installations firefighting nitrogen can be automated and / or manual.

The commands automatic operation of fixed fire-extinguishing installations with nitrogen can be:

  • pneumatic;
  • mechanical;
  • electrical;
  • mixed.

Inerting the enclosures and technological equipment with nitrogen can be achieved by:

  • continuous introduction of a constant flow of nitrogen or inside the equipment;
  • discontinuous introduction of a variable flow of nitrogen to maintain an upper-atmospheric pressures.

Extinction in volume (total flooding) or on the restricted area (local extinction) is achieved by nitrogen discharge in locations protected from pressure (4 … 6) bar through distribution networks and discharge nozzles.


For the nitrogen concentrations in normal air volume necessary for fire fighting (43.7%) there are not major risks to people. Index NOAEL (no observed adverse effect level) corresponds to a volume concentration of nitrogen in the protected area by 43%, resulted in a minimum volume of oxygen concentration of 12% and the LOAELindex (lowest observed adverse effect level) corresponds to a volumetric concentration of nitrogen in the protected area of 52% and a minimum volume of oxygen concentration of 10%.

At concentrations of nitrogen in air volume greater than 78%, the air becomes toxic and pose risks to people.


Fixed installations of fire extinguishing with nitrogen consist mainly of:

  • nitrogen supply source;
  • installation of pressure reduction;
  • drives;
  • distribution network with nitrogen discharge nozzles in the protected area;
  • warning devices of men;
  • dsignaling devices coming into the installation (entering the installation is done after warning and evacuating people).

Power sources with nitrogen fixed of fire extinguishing installations are:

  • storage tanks at a pressure of (6 … 8) bar (for air fractionation of nitrogen in technological equipment);
  • containers (bottles) of nitrogen at pressures of 135 and 200 bar.

The length of the nitrogen tanks or cylinders to the distributor should not exceed 200 m.


The percentage of volumetric concentration of nitrogen for fire fighting, determined for heptane, is 33.6% and the minimum volume design concentration (computing) fire extinguishing, is 43.7% [ISO / FDIS 14520-13:2000 (E)].

The time required to ensure the minimum nitrogen concentration necessary for fighting fires is 1.5 to 3 minutes, and the time to maintain this concentration is 20 minutes.

Fire extinguishing systems with INERGEN type gase(IG 541)

Fire extinguishing systems with INERGEN type gase (IG 541) can be made:

  • Total flooding
  • local extinction..

Total flooding system can be done for enclosed spaces where doors, windows, pipes can be closed before or simultaneously with the beginning of gas spill.

For fire extinguishing inside spaces through total flooding, the entire space must be filled with extinguishing agents type INERGEN (IG 541), so the percentage of oxygen decrease (in short), below the combustion maintenance.

At the total flooding systems for instantaneous and surface fires (flammable liquids triggered), the amount (mass) of discharged extinguishing agents must cover losses due to leakages. The total area (m2) of the openings can not be closed will be less than 3% of the volume (m3) protected enclosure, or 10% of the total area (m2) and lateral surfaces of the upper and lower chamber. in case of technical or technological reasons these conditions can not be achieved, it adopts the local extinguishing system.


The standard volumetric concentration fire extinguisher, up to 43%, type extinguishing agents INERGEN (IG 541) does not put people’s lives at risk.

After extinguishing the fire, access for people in those rooms is allowed only after evacuation harm by natural ventilation – organized or mechanical ventilation installation.


The components of the fixed installations of fire extinguishing with gas INERGEN type(IG 541)

The fixed installations of fire extinguishing with gas INERGEN type(IG 541) consist mainly of:

  • INERGEN type gas cylinders (IG 541), grouped in batteries;
  • Flexible couplings for connecting the collector;
  • collector;
  • electric drives and mechanical of the pilot cylinder;
  • devices and electrical detection signal (acoustic and optical) and order;
  • control equipment;
  • monitoring items closing state elements openings (doors, windows, hatches etc.).
  • piping for transport and distribution of extinguishing substance;
  • extinguishing substance with discharge nozzles in the protected area.

The gas type INERGEN (IG 541) is stored in cylinders at a pressure of 150 bar and 200 bar at a temperature of 15oC.