Own agent systems | Fire station

Clean agent systems are waterless systems that protect assets that are in specific occupancies, such as data/storage centers, document storage, imaging suites, and telecommunications centers. The systems use an inert gas to extinguish a fire that would be extinguished by a standard sprinkler and reduce smoke and water damage. Clean agent systems are regulated by NFPA 2001: Standard for Clean Agent Fire Extinguishing Systems and are defined as an “electrically non-conductive, volatile, or gaseous extinguisher that leaves no residue on evaporation”.

There are different eigenagents. FM-200 and FE-25 have zero ozone depletion potential, but have high global warming and atmospheric lifetimes. Halon is a legacy agent that is no longer installed due to its ozone depleting qualities. Novec 1230 has a very low global warming potential and a short atmospheric lifetime. Inergen and Argonnite have no ozone depletion potential, global warming, or atmospheric lifetime.

Each clean agent has advantages and disadvantages that are based on the hazard protected, environmental impact, cleanup required after a discharge, and human contact.

Clean agents suppress fires in three ways:

  • Inert agents deplete oxygen
  • FM-200/FE-25 absorbs heat and disrupts the combustion reaction
  • Novec 1230 absorbs heat

how they work

Clean agent systems are, essentially, a fire extinguisher that self-discharges. The source of the system is a high pressure storage cylinder (Figure 1) connected to nozzles (Figure 2) which discharge the agent. Piping is installed symmetrically to achieve equal head pressure and balanced dispersion. Smoke detectors (Figure 3) are provided to recognize a fire and initiate a discharge. A horn/strobe unit (Figure 4) is placed inside the room above the door to alert occupants of system activation, and a strobe is provided outside the room above door to indicate that a discharge has occurred. A manual interrupt/shutdown station (Figure 5) is located inside the room adjacent to the door and a keyed maintenance switch is provided outside the room to disable the system. All of these are wired to a control panel (Figure 6) usually located outside the space adjacent to the door. Signs identify various accessories and explain audio/visual device warnings.

When a fire breaks out, the activation of the smoke detector is indicated on the control panel, the horn/strobe in the room is activated and the building’s fire alarm system is alerted. A second activation of the smoke detector is displayed on the control panel. HVAC equipment shuts down or dampers close to isolate the space, the horn/strobe unit pulses faster, and a time-out sequence begins to allow occupants to exit.

When the timer sequence is complete, the agent is unloaded and the strobe light outside the room activates. The abort switch can be used to stop agent discharge during the delay sequence. The manual release starts the sequence as if the second detector had been initiated and overrides the abort switch or will activate an immediate agent release. The key maintenance switch can be used to prevent the system from discharging, but the detection system will remain active.

The fire code does not allow a clean agent system to be the only defense against a fire because it is a finite source. The cylinder discharges the agent until it is empty. If the fire is not brought under control, the fire will continue to grow, so an automatic sprinkler system is needed as backup. There are exceptions to this rule, but they require the approval of the local fire code official. Preaction systems are usually supplied, as they are also well suited for critical spaces.

Pre-planning tactics

Firefighters should conduct pre-incident planning for spaces protected by these systems and develop a set of tactics. It is important to know what is protected before responding to an incident, as the tactics for an event in a server room will be different from those for an event in a rare book library.

The way the space is protected is also essential. Detectors and discharge nozzles may not only be located on the ceiling. Many data centers have a raised floor and the area under the floor can also be protected. The presence of a raised floor is usually evidenced by a ramp at the entrance to the space. Detection could be accomplished with an air sampling system that constantly monitors the air in the space for the presence of smoke. I liken it to a five-gas meter with a wand, but on a larger scale.

The location of the control panel is critical, as it will be your source of information about what is going on inside the space. You need to know if a pre-action backup system is in place and where its components are. Although not necessarily critical, it is good to know where the agent storage cylinder is. You should also understand how the HVAC system works under normal conditions and the options available to use the system to help with ventilation if needed.

When sent to an event, go to the space and determine if the clean agent has been returned. The presence of fog could be smoke or could be the agent, so check the outside strobe, which will indicate a system discharge. Locate the control panel to determine which detectors have been activated.

Try to determine if the preaction system has discharged if there is one. If the clean agent did not contain the fire and you enter, be prepared for the sprinklers to activate. Enter the space wearing an SCBA. The agent is not toxic, but you are here because of a fire, so protect yourself as you would in the event of any other fire. Locate the source of the event and determine if the fire has been extinguished. If not, supplement the extinguishing with a fire extinguisher or a hand line. Firefighters should be familiar with the methods used at this stage. The extinguisher must be compatible with the hazard in the room to work properly. The wrong choice or use of a handline could further damage the contents.

Once the fire is under control, the room must be put back into service as soon as possible. This probably won’t be the fire department’s responsibility, but you may be asked to help. If ventilation of the space cannot be accomplished by facilities personnel manipulating the building’s HVAC system, you may need to use fans. Many modern buildings have fixed sash windows that cannot be opened for ventilation, complicating the task. Even if you ventilate the space to the surrounding areas, there will be no problem. The agents are non-toxic and operate at small concentrations in a confined space, so there is no risk to occupants. However, firefighters should be prepared to explain this to reassure occupants.

Infrequent events with serious consequences

Clean agent systems are a complex network of fire suppression components that are used to protect contents or critical spaces. Discharges are infrequent events with significant consequences. Even a minor fire in this type of space can be a major event for a building owner.

Firefighters must understand that these systems are safe and to mitigate the situation in a timely manner while protecting the space and its contents. There may be irreplaceable items or equipment critical to business operations, which will need to be brought back online quickly.

Identify areas with a clean agent during the plan review process. Once the system is installed, witness the commissioning process. This is the best time to coordinate with everyone. The engineer and installer will be there to discuss system operation, the building owner will be there to discuss the contents and nature of the space, and facilities personnel will be there to discuss your response efforts. .

Proprietary agent systems can work in several ways. This article only describes what I think are most commonly installed. Firefighters must ensure that they have an accurate understanding of the systems that are in their area of ​​intervention.

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