Inergen® Gaseous System

Inergen® Gaseous System

What is INERGEN?

INERGEN is a mixture of nitrogen, argon and carbon dioxide, and has been specially developed to provide fire protection for sensitive electrical and electronic instruments and equipment.
How does INERGEN work?

INERGEN extinguishes fire by reducing the oxygen level in a room to below 15% (the point at which most combustibles will no longer burn). Simultaneously the patented carbon dioxide in INERGEN protects anyone that may be trapped in the fire area from the effects of the lowered oxygen levels, by increasing the rate of respiration.

Gas suppression systems are extensively used in electronic data protection and electrical system switch environments. Systems comprise electrical detection linked to a bank of cylinders where the gas is stored ready for discharge into the fire area

Inergen is a mixture of three inert gases:

  • Nitrogen – 52%
  • Argon – 40%
  • Carbon Dioxide – 8%

It offers excellent protection of personnel and equipment by providing a safe, clean and efficient fire suppresion agent. The agent works by lowering the oxygen content within the protected environment to a level below that which combustion can take place.

People Friendly

In addition to this extinguishing feature, people are still able to function normally in the atmosphere into which Inergen has been injected. This is attributed to the increased carbon dioxide level, which typically increases to between 2.5% to 5% of the room volume.

This increased level of carbon dioxide stimulates the rate of respiration and increases the body’s oxygen use efficiency. This compensates for the lower oxygen levels that are present when a fire is being extinguished.

As a result, the brain continues to receive the same amount of oxygen in an Inergen atmosphere as it would in a normal atmosphere, even if the oxygen concentration falls to below 10%. Hence Inergen can be used in automatic total flooding systems in areas that are normally occupied.

The physiology of breathing in a reduced oxygen-increased carbon dioxide environment has been understood since the 1930’s and the Inergen respiratory concept has been approved by Occupational Health and Safety organisations Worldwide.

People can breathe within a correctly designed Inergen atmosphere without any long-term ill effects. Inergen is non toxic, so it has been possible for the agent to be medically tested on people in both Europe and the USA. This is not true for Halocarbon based products, which are all lethal at high concentrations and still toxic even at low concentrations, hence tests on these agents have been limited to laboratory animals.

Exiting during a Inergen discharge situation is made safer as the agent does not fog the atmosphere and no impairment of vision occurs.

Environmentally Perfect

Since Inergen is composed of natural components that exist in the air (Nitrogen, Argon and Carbon Dioxide) its components simply resume their normal role in the earth’s life cycle following a discharge, so Inergen presents no environmental impact:

  • Ozone depleting potential (ODP) is zero.
  • Global warming potential (GWP) is zero.
  • Thermal decomposition products (TDP) are zero.
  • Atmosphere lifetime (ALT) is zero.

In summary there are never any environmental restrictions on use.

It should be noted that although many other Halon replacement agents have a zero ODP, they may not have zero values for GWP, TDP and ALT. This may see restrictions placed in the future with changes in environmental legislation.

Equipment Safe

Many other agents break down in the combustion process forming by-products that are corrosive to electronic components and cards. Inergen does not form any corrosive by-products.

Inergen is discharged into the protected area in a “single phase” so there is no thermal shock or large temperature drop associated with the discharge. Discharge tests conducted by Wormald demonstrate that the temperature drop is typically less than 2ºC in room temperature.

Engineering Design

Inergen exists in a “single phase” throughout the discharge process, that is cylinder storage, pipework distribution and nozzle discharge. This single-phase situation simplifies pipework design and computer software design (pipe friction losses etc). Inergen is stored at high pressure (200 bar) so this allows for long pipe runs, remote cylinder location, and the option of storing the cylinders horizontally.

Extinguishing Properties

In addition to this extinguishing feature, people are still able to function normally in the atmosphere into which Inergen has been injected. This is attributed to the increased carbon dioxide level, which typically increases to between 2.5% to 5% of the room volume.

This increased level of carbon dioxide stimulates the rate of respiration and increases the body’s oxygen use efficiency. This compensates for the lower oxygen levels that are present when a fire is being extinguished.

As a result, the brain continues to receive the same amount of oxygen in an Inergen atmosphere as it would in a normal atmosphere, even if the oxygen concentration falls to below 10%. Hence Inergen can be used in automatic total flooding systems in areas that are normally occupied.

The physiology of breathing in a reduced oxygen-increased carbon dioxide environment has been understood since the 1930’s and the Inergen respiratory concept has been approved by Occupational Health and Safety organisations Worldwide.

People can breathe within a correctly designed Inergen atmosphere without any long-term ill effects. Inergen is non toxic, so it has been possible for the agent to be medically tested on people in both Europe and the USA. This is not true for Halocarbon based products, which are all lethal at high concentrations and still toxic even at low concentrations, hence tests on these agents have been limited to laboratory animals.

Exiting during a Inergen discharge situation is made safer as the agent does not fog the atmosphere and no impairment of vision occurs.

System Description

The proposed Gas Flood System would have both automatic and manual operation capabilities.

Automatic Operation

Within the proposed protected zone, smoke detectors would be distributed throughout the ceiling on two separate electrical circuits. Following “first circuit” detection or operation of the manual “gas start switch”, the following warning devices would be activated:

  • Operation of “first circuit” bell
  • Indication on the gas flood control panel
  • Indication on the main fire alarm panel (if required)
  • Air conditioning shutdown

Following “second circuit” detection, the following alarms would be activated:

  • “Second circuit” audible horn would operate
  • Time delay would be initiated
  • Shut down power supply (if required)

At the completion of the time delay, an electrical signal would be relayed to the solenoid valves. This device would trigger the Inergen valves, releasing the gas contained within the cylinders. Inergen gas would be distributed through the discharge pipework and nozzles.

The “gas released” signs would be illuminated following the system activation.

Manual Operation

Manual activation could be achieved by operating the “gas start switch” or the manual actuator located on the cylinder.

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