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Gas Suppression in a nutshell

Gas Suppression in a nutshell

Gaseous fire suppression, or Clean Agent Fire Suppression, is a term used to describe the use of inert gases and chemical agents to extinguish a fire. These gaseous mixtures leave no residue behind and are designed to protect enclosures where there is a need for quick reaction to extinguishing a fire. A fire detection system is needed to trigger the gas suppression system.

The agents are governed by SANS 14520 part 1, the Clean Agent Gas standard for South Africa, with different standards and regulations in other parts of the world.

A gas suppression system typically consists of the fire detection system, along with the specific agent used, the agent storage containers, agent release valves, agent delivery piping (if it is an engineered system and not modular), and agent dispersion nozzles.

Engineered system

Modular system

There are four means used by gaseous agents to extinguish a fire. They act on the “fire tetrahedron”.

1. Reduction or isolation of fuel. No agents currently use this as the primary means of fire suppression.
2. Reduction of heat. Agents used include NAF S 227, FM-200 / Eckoshield HFCC227ea
3. Reduction or isolation of oxygen. Agents used include Argonite,CO2, Pyroshield and Inergen,
4. Inhibiting the chain reaction of the above components.

How does inert gas suppression work?

Why use inert gas suppression?
Gaseous fire-extinguishing agents are often used to effectively extinguish fires in special hazards that cannot be adequately protected by fire-sprinkler systems. These extinguishing agents are also utilised when the application of water may cause excessive collateral damage or an interruption of critical operations.

Inert gasses have become a good choice as they are the most green of all of the Clean Agents. They are defined as consisting of gases occurring naturally in the atmosphere, and consists of Nitrogen, argon, or helium, or a combination of these. CO2 is also found in one of the inert gas blends. Inert gasses work by removing the oxygen in the hazard to a point where it will not support a fire, but still high enough to support life. Pressure venting and volume need to be considered when designing the system, and it is critical to design it in such a way that the correct concentration is reached, without removing too much oxygen in the room.

The right gas will be safe to use around people, while efficiently suppressing the fire. Unlike foam and water, a gas discharge is cleaner and causes less downtime and disruption to businesses. It also causes less damage to electronic equipment and other assets. To view a demonstration of an Inergen gas discharge, click here.

The most common uses for gas fire suppression systems are in server and computer rooms, MCC cabinets, museums, libraries, art galleries, archives, document stores, and medical and pharmaceutical applications.

Broadly speaking, there are two methods for applying an extinguishing agent:
• total flooding and
• local application

Systems working on a total flooding principle, apply an extinguishing agent to a three dimensional enclosed space in order to achieve the concentration of the agent (volume percent of the agent in air) needed to extinguish the fire. These types of systems may be operated automatically by detection and related controls or manually by the operation of a system actuator.

Systems working on a local application principle apply an extinguishing agent directly onto a fire (usually a two dimensional area), or into the three dimensional region immediately surrounding the substance or object on fire. The main difference in local application from total flooding design is the absence of physical barriers enclosing the fire space.

At Secutron Fire & Integrated Systems, gaseous fire suppression is one of our company’s areas of expertise. For more information on and/or assistance with your fire protection system, please contact us on +27 12 997 3139.