Inert v Chemical

The Advantages and Disadvantages of:

Chemical Systems (FM200/NOVEC/CO2) v Inert Systems (i3/Inergen)

Chemical Systems (FM200/NOVEC/CO2)

In contrast, Chemical systems, such as FM-200 are very different.

These are manufactered chemical extinguishing agents, normally HFC's, which work at low concentrations and attack the fire directly at a molecular level, rather than by reducing Oxygen levels.

They are low pressure systems, generally 25 bar, and the agent is stored as a liquid, super-pressurised with Nitrogen to "push" them along the pipework.

Benfits of Chemical Extinguishing Systems are:

  • Discharge within 10 seconds ensuring rapid knockdown of fire.
  • Low pressure storage (25bar)
  • Stored as a liquid meaning smaller footprint of hardware than Inert Gas Systems
  • Do not reduce Oxygen levels
  • Can be modular in design, enabling simple pipework installations
  • Easy to retrofit - Additional cylinders can be added, or levels "topped up" without risk of Over Pressurising the enclosure
  • Zero Ozone Depletion Potential

 The negatives with Chemical Systems are:

  • Some Global Warming Potential
  • Small possibility of breakdown products if in direct contact with large flame
  • Being low pressure, cylinders need to be stored as close to encloure being protected as possible
  • More difficult to retain once discharged, as agents are heavier than air

 All of the fire suppression systems both Inert and Chemical are approved for use all over the world by bodies such as UL, FM, LPCB etc and are recognised by Environmental Agencies like the EPA as being suitable for use in normally occupied spaces.

Inert Systems (i3/Inergen)

These systems, which are stored at a pressure of between 150bar and 300 bar, extinguish fires in a passive manner. They reduce the Oxygen content within the protected enclosure to a point where fire can no longer survive.

The benefits of these type of system are :

  • Being high pressure, they can be stored long distances from the risk being protected.
  • They have a zero ozone depletion potential
  • Very low Global Warming Potential
  • No possibilty of breakdown products
  • Discharge time is 60 seconds
  • Are able to be used in multi room engineered systems (many risks from one bank of cylinders)
  • Similar density to air, meaning easier to retain after discharge

The negatives with Inert Gas Systems are:

  • Being high pressure and the quantities of gas required, Pressure Relief Venting will always be required to prevent potential damage to the structure of the enclosure.
  • Because they are stored as a gas, many cylinders are required in comparison to Chemical agents
  • Complicated and high pressure pipework is required
  • Method of extinguishment is through Oxygen Reduction
  • Inert Systems cannot be modular in design