3 FM quick reads on Halon
1. Multiple Halon Alternatives Exist for Fire Suppression
Halon and carbon dioxide were once the go-to extinguishing agents for protecting special hazards, but both fell from grace for this application. Halon has the problem of depleting stratospheric ozone. And carbon dioxide is not safe to use in enclosed spaces that have people in them.
Special hazard fire-extinguishing agent alternatives were developed to take their place. All told, about a dozen such agents exist. These agents put out fires, avoid collateral damage, and are safe for people and for the environment. In addition to protecting special hazards, these agents are used in spaces where dumping many gallons of water would cause too much collateral damage or would disrupt critical operations.
When considering which extinguishing agent to use in a fire suppression system, several variables have to be considered: What is the hazard? What kind of enclosure is it in? What are the life-cycle costs? What is the impact on the environment? What is its impact on building occupants? How will the agent be stored?
An alternative to the Halon alternatives is water mist. Water mist systems use a very fine water spray to extinguish a fire. Because water mist systems require less water than a standard sprinkler system to adequately control a fire, water mist is effectively being used to protect areas normally protected by fire sprinklers that have water supply limitations or where system weight is a factor. They are still gaining acceptance in commercial facilities and have so far been primarily used to protect hazards such as passenger ships, machinery spaces, museums and hotels.
2. Ways to protect data centers from fire
Today's tip is to make sure your data center is adequately protected from fire. In the past, of course, data centers could use Halon to put out an electrical fire. But, once it became known that Halon was destroying the ozone layer, it was phased out for new systems.
Halon alternatives generally fall into two categories: clean agent systems, many of which use halocarbons, and inert gases. Clean agent systems extinguish fires by removing heat. Inert gases essentially suffocate the fire by depriving it of oxygen. Both can be "excellent, reliable systems," if they are properly designed and commissioned, says Scott Golly, senior fire protection engineer at Hughes Associates. Inert gas systems use a higher concentration of gas to extinguish a fire than halocarbon systems, so they require more storage space.
Any facility using a "dry," gaseous product for fire suppression must also have a water-suppression system, according to Kevin J. McCarthy, vice president of engineering company EDG2. But using water in a data center "can cause catastrophic damage to equipment," Golly says.
The sensitivity of conventional sprinklers may justify a pre-action sprinkler system, which requires multiple events for pipes to flood with water. A pre-action sprinkler has a large valve at the back of the water supply, so the pipes are empty.
A double interact system uses a clean agent to put out a fire long before a smoke-head is set off. A pre-action system may also require the activation of two smoke detectors in two different zones before a deluge valve opens to fill the pipes. The clean agent or inert gas fire suppression is designed to put out the fire before the sprinkler head begins dropping water.
Facility managers must evaluate what would constitute an acceptable loss. "Can you afford to have all those computers taken off line for several weeks?" Golly says. "If you cannot, then you cannot rely solely on sprinklers." Other questions to consider include storage space and cost. Both clean agent and inert gas systems are more expensive than pre-action systems.
3. Critical Facility Fire Suppression Options
When it comes to protecting critical spaces like data centers from damage caused by electrical fires, facilities used to have the option of Halon systems. But once it was known how damaging Halon is to the ozone layer, these systems were phased out. Replacement tanks can still be purchased to supply existing Halon systems, but new Halon systems cannot be installed.
This leaves the Halon alternatives for fire suppression in critical spaces like data centers. Halon alternatives generally fall into two categories: clean agent systems, many of which use halocarbons, and inert gases. Clean agent systems extinguish fires by removing heat from them. Inert gases essentially suffocate the fire by depriving it of oxygen.
When considering Halon alternatives it is important to keep several issues in mind. One is space. Inert gas systems use a higher concentration of gas to extinguish a fire than halocarbon systems, so they require more storage space.
One thing to weigh with halocarbons is their potential environmental impact, particularly with regard to ozone depletion. In addition, once the halocarbon agent can make the air very corrosive once discharged, which can damage equipment. Different halocarbons have different environmental properties, so it's up to facility managers to decide which are a better fit for their facility and organization.
Enclosure is another factor to ensuring a Halon alternative fire suppression system works properly. The room has to stay tight to maintain the required concentration of the fire suppressant, both in the case of an inert gas or a clean agent. When the room's enclosure must be compromised, such as by cutting a hole in the wall to pass wires through, these must be properly sealed back up.
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