Gaseous fire suppression, also called clean agent fire suppression, is a term to describe the use of inert gases and chemical agents to extinguish a fire. Hegel provide design and installation of Clean Agent Fire Suppression System such as :

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• FM200 System

• Inergen System

• Intertec System

• IG55 System

• SR200 System

• Argonite System

• Novec 1230 System

• Water Mist System

• Carbon Dioxide Gas System

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Protected hazards

Gaseous clean agent systems, typically used to protect electronics, can be used to protect a wide variety of hazards. Some of these mission-critical hazards include:

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• Military and government facilities where the loss of equipment and a long downtime can lead to lapses in defence systems

• Control centres for national air space

• Missile-guidance centres

• Airline flight-control servers

• Consumer-product credit card transaction computers

• Intelligence servers

• Satellite communication systems

• Research and development computing data hubs

• Engine test cells with accompanying data.

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Types of clean agents

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NFPA 2001 provides two main categories of gaseous clean agent systems. Inert gases, such as IG-541, extinguish fires by depleting oxygen, and halo-carbon-based agents, such as HFC 227ea, extinguish fires on a molecular level in the presence of heat, fuel, and oxygen. Note that halo-carbons disrupt the chemical reaction in the fire tetrahedron. Both types of systems have their pros and cons when protecting mission-critical applications. When comparing systems, it is important to consider the cost to refill, shelf life, and environmental concerns.

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The weight and required storage area of the suppression agent cylinders are typically smaller with halo-carbon-based systems as compared with inert gas systems. Increased weight can have structural implications that should be accounted for during design. More inert gas cylinders will typically be required than when using halo-carbon cylinders for protection of the same volume. This can be a driving factor on, for example, lease space and building-use planning. It is also an important consideration in retrofit applications in existing buildings, where large areas for cylinder storage are often difficult to find.

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Cylinder pressures for halo-carbon-based clean agents are typically lower than for inert gas agents. While the agent pressure drops drastically during release, there are still piping implications to be considered. Some inert gas systems require higher pressure-rated piping and fittings. The increase of room pressure is also greater with inert gases. Pressure relief venting of the protected enclosure is more common with inert gas systems than with halo-carbon systems.

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Construction requirements

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While inert gases reduce oxygen to a level that humans can survive and fire cannot the halo-carbon-based agents extinguish fires while heat, fuel, and oxygen are present. NFPA 2001 and other standards require that the gaseous clean agent is maintained at a minimum concentration threshold within a room for the duration of protection; this is usually referred to as the “hold time.” The latest requirement is 10 minutes.

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The hold time is intended to allow the gaseous clean agent to extinguish the fire and reduce the potential for re-ignition due to the presence of heat, fuel, and oxygen. To ensure that the required hold time is achieved, the room must be sealed as much as possible to reduce areas from which gaseous clean agents can leak. Sealing of the room is referred to as room integrity. Typically, walls in the protected area are continuous to the roof or floor/ceiling assembly above, or to a “hard” gypsum ceiling. Dampers or HVAC equipment controlled by the fire alarm system may be necessary to maintain room integrity. Caulking to address holes and other leakage paths in walls is usually necessary. Finally, seals around doors equipped with automatic closer may be needed to minimize leakage.

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During construction, room integrity is measured by administering what is commonly referred to as a “door fan test.” This test uses specialized equipment to pressurize the enclosure and measure leakage rates, which then can be translated into hold times.

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