S-World.com CLEAN AGENT IRE PROTECTION OR COMPUTER ROOMS By Mark L. Robin Mark L. Robin, Ph.D., is Technical Services Consultant for Specialty luorochemicals with DuPont luoroproducts and has over 20 years of experience in the fire suppression industry, including the development, testing and approval of clean agent fire suppression systems. INTRODUCTION In recent years the dependence on computers and other electronic equipment has increased significantly in both the business sector and in households throughout the world. Along with this increased reliance on computers and electronic equipment, the importance of providing fire protection for these critical assets has also increased. Throughout numerous industries there are countless processes and systems which are controlled by computers. Computers control semiconductor fabrication, steelmaking processes, petrochemical production facilities, and local and global telecommunication systems. In many instances it is critical that the operation of these computer and electronic systems is not interrupted. or example, the financial impact of service disruptions can be significant in both telecommunications facilities and in data processing centers. The estimated downtime impact per minute for various business applications is shown in Table 1. The downtime impact for a typical computing infrastructure is estimated at $42,000 per hour. Downtime impacts for companies relying entirely on telecommunications technology, such as online brokerages or e-commerce sites, can reach $1 million per hour or more. ire & Safety Magazine Spring 2008 64
S-World.com TABLE 1. DOWNTIME IMPACT PER MINUTE OR VARIOUS BUSINESS APPLICATIONS Business Application Estimated Outage Cost per Minute Supply Chain Management $11,000 Electronic Commerce $10,000 Customer Service Center $3,700 ATM $3,500 inancial Management $1,500 Messaging $1,000 Infrastructure $700 Source: Alinenan ROI Report, January 2004 or data processing facilities, the loss of data due to a fire can have devastating results. In addition to the problems associated with the loss of the data itself, for many types of businesses new federal regulations require that organizations ensure that their data is current, accessible and searchable at all times. Therefore, a data center that has been damaged by fire may be unable to provide access to important information, putting it in violation of the federal regulations and resulting in potential lawsuits, costly audits, and SEC fines. IRE DAMAGE: THERMAL DAMAGE Computers and electronic equipment are particularly susceptible to damage due to the heat, steam and combustion products (e.g., smoke, soot) which accompany a fire. Magnetic tapes, flexible discs and similar storage media are susceptible to thermal damage when exposed to sustained ambient temperatures above 38 C. Damage to hard disks can occur at sustained ambient temperatures of 66 C and above. Electronic component failure can occur at temperatures as low as 79 C and at temperatures in the range of 149 to 200 C major component failures are common. Damage to paper products occurs at temperatures in excess of approximately 177 C, and microfilm is damaged at temperatures exceeding 107 C. IRE DAMAGE: COMBUSTION PRODUCTS Combustion products formed during a fire include steam (water vapor), smoke, soot, and various species depending upon the material involved in the combustion process, and electronic components are susceptible to damage due to exposure to these combustion products. Hydrogen chloride (HCl) is a commonly encountered combustion product in computer facilities due to the widespread use of polyvinyl chloride (PVC) cable insulation in these facilities. Upon exposure to elevated temperatures, PVC produces gaseous HCl, which reacts with the galvanized zinc encountered in most electronic circuitry and components, resulting in the formation of a layer of zinc chloride (ZnCl 2 ) on the surface of the equipment. This zinc chloride layer then reacts with moisture from the surrounding air to form an extremely corrosive zinc chloride solution which attacks the metallic components. Additional corrosive combustion products frequently encountered in computer room and data processing fires include hydrogen fluoride (H), from the decomposition of the various fluoropolymers employed in cabling, and hydrogen bromide (HBr) from the decomposition of flame retardant chemicals employed in cable and in electronic components and housings. Damage to electronic components can also result from their exposure to smoke, soot and the corrosive particulates which are produced by a fire. Disk drives can be damaged by particulates as small as 0.5 microns in diameter. ires in computer rooms and data facilities are typically smoldering or slow growth fires, and these types of fires produce nonconductive soots which deposit out horizontally on equipment and form an insulating layer on equipment which interrupts electrical contacts. IRE DAMAGE: EXTINGUISHING AGENT The use of certain fire extinguishing agents on fires occurring in computer rooms or data processing facilities can result in damage caused by the suppression agent itself, and in many cases the secondary damage resulting from the suppression agent can exceed the damage from the fire itself. Water-based extinguishing systems such as sprinklers or water mist systems will leave an electrically conducting residue (water) which can lead to shorts and can also cause water damage to electronic equipment and other assets which exceeds the damage due to the fire. Dry powder agents or foam agents will leave a residue on equipment, and their use will require equipment shutdown and an extensive cleanup. CLEAN AGENTS The original "clean agents" were Halon 1301 and Halon 1211, which were extensively employed for the protection of computer rooms and data processing facilities. These agents are "clean" agents, which leave no corrosive or abrasive residues after their use. As a result of this property, the use of these agents eliminates the problem of secondary (non-fire) damage associated with ire & Safety Magazine Spring 2008 65
the use of extinguishing agents such as water, dry chemicals or foams, which can in many cases cause more damage than the fire itself. Halon 1301 and Halon 1211 are non-conductors of electricity and hence can be employed for the protection of electrical and electronic equipment. Halon 1301 and Halon 1211 served as a nearly ideal fire suppression agents for over 30 years. However, due to their implication in the destruction of stratospheric ozone, the Montreal Protocol of 1987 identified Halon 1301 and Halon 1211 as two of numerous compounds requiring limitations of use and production, leading eventually to the halting of Halon production in 1994. In response to the ban on Halon manufacture, the fire suppression industry has responded with the development of alternative clean agents which pose no threat to the ozone layer. Two general classes of agents have emerged as Halon replacements: fluorocarbon-based agents and inert gas agents. The fluorocarbon-based agents extinguish fire primarily via the absorption of heat, whereas the inert gas agents extinguish fire via oxygen depletion. In general, the new clean agents exhibit the same important chemical and physical properties as the Halons. These agents are clean, leaving no significant amounts of residues following extinguishment, and as a result no cleanup is required following the discharge of the agents. Because the agents do not form significant amounts of corrosive or abrasive residues they are suitable for use on delicate, expensive assets that might otherwise be damaged or destroyed by non-clean agents such as foam or water (e.g., paper goods, paintings, artwork). The clean agents are also electrically nonconductive, and hence can be employed for the protection of electronic equipment. The new clean agents are nontoxic at their typical ire & Safety Magazine Spring 2008 S-World.com 66 design levels, and hence are acceptable for use in occupied areas. Clean agent systems are applicable to Class A, B and C fires. The clean agent marketplace is currently dominated by two agents: HC-227ea (tradenames M-200 and E-227, marketed by DuPont) and Inergen, an inert gas mixture of nitrogen, argon and carbon dioxide marketed by Ansul. Clean agents are employed in a myriad of applications, including pleasure boats, marine and military vessels, flight simulators, medical facilities, cellular sites, internet service provider (ISP) centers, TV and radio control rooms, microwave relay towers, anechoic rest chambers, clean rooms, flammable liquid storage areas, art galleries, libraries and museums. Worldwide, numerous high value items are protected by clean agent systems. or example, M-200 suppression systems protect the electrical systems of the Eiffel Tower, the first draft of the Declaration of Independence, and protected the Star Spangled Banner during its recent restoration. M-200 suppression systems also protect the US EPA's new supercomputing facility. Additional examples of facilities protected by M-200 suppression systems are shown in Table 2. CLEAN AGENT STANDARDS NPA 2001 and ISO 14520 specify requirements and give recommendations for the design, installation, testing, maintenance and safety of clean agent systems. Critical to the design of any clean agent system is the associated detection system. Rapid detection is employed to ensure the fire is extinguished while still in its incipient stage, thereby limiting the damage to valuable assets. or example, in telecommunications applications, detection is often desired at a fire size of 1 kw, or for extremely sensitive equipment, at a fire size of 0.1 kw. ISO 7240 and NPA 72 are the standards for fire detection and alarm systems. Both standards deal with the application, installation, performance and maintenance of detection and alarm systems. Clean agent system designs take into consideration the appropriate detection/alarm standard, the appropriate clean agent standard, and any other standards relevant to the
specific application. or example, the design of a clean agent suppression system for the protection of a specific facility would involve adherence to three standards: NPA 72 (or ISO 7240) for guidance on the design of the detection system, NPA 2001 (or ISO 14520) for guidance on the design of the clean agent system itself, and the standard applicable to the particular facility. In addition, any local codes or standards, and any requirements mandated by the local authority having jurisdiction (AHJ) must also be adhered to in the design of a clean agent fire suppression system. TOTAL LOODING SYSTEMS In the United States, the requirements for the protection of information technology equipment are specified in NPA 75. Given the high value and sensitivity of the electronic equipment involved, and the consequences of system interruptions, total flooding gaseous agent systems are often provided for the protection of computer rooms. The use of a gaseous total flooding agent is especially critical where there is the need to reduce S-World.com equipment damage and to reduce or eliminate system downtime. The primary objective of a gaseous clean agent system is to extinguish the fire quickly, limiting fire damage to the object(s) involved in the origin of the fire. Hence, the purpose of a gaseous clean agent system is to protect the valuable and/or sensitive assets within the enclosure. The primary advantages of total flooding clean agents are as follows: TABLE 2. ACILITIES EMPLOYING M-200 CLEAN AGENT SUPPRESSION SYSTEMS acility Type acility Casinos Cultural Sites Airports, Satellite Installations Health Care acilities MGM Caesar's Palace Harrah's Tropicana American Museum of Natural History Smithsonian Institute Library of Congress Eiffel Tower Alexandria Library (Egypt) North American DEW Line Radar system Lockheed Star-SAT Center Dusseldorf International Airport Madrid International Airport Charles de Gaulle International Airport Duke University Medical Center Washington Hospital Center Baylor University Medical Center Vanderbilt Medical Center Clean extinguishment - fires are extinguished without collateral damage due to agent discharge (no residues, no cleanup required) Rapid extinguishment during the early stages of fire growth Ability to extinguish shielded, obstructed or three-dimensional fires in complex geometries These characteristics render the clean agents especially suitable for the protection of electronic equipment areas. The absence of residues and subsequent lack of cleanup allow for minimum service interruptions, and extinguishment in the early stages of the fire limits fire damage to the object(s) involved in the fire. The three dimensional nature of the clean agents allows them to extinguish hidden or obstructed fires within the protected area, for example a fire inside an equipment cabinet. Although not prohibited by NPA 75, carbon dioxide systems are not a suitable choice for total flooding applications in computer rooms. This is due to the toxicity of carbon dioxide at the extinguishing concentrations required, and to possible equipment damage due to thermal-shock or due to the conductivity of carbon dioxide. ire & Safety Magazine all 2007 68
PORTABLE EXTINGUISHERS In accordance with current standards, computer rooms should be equipped with portable fire extinguishers. In the United States, the requirements for the protection of information technology equipment are specified in NPA 75, Standard for the Protection of Technology Equipment. NPA 75 requires the provision of listed portable fire extinguishers of the carbon dioxide or halogenated agent type, maintained in accordance with NPA 10, Standard for Portable ire Extinguishers. Acceptable halogenated type agents for these applications include Halotron I (American Pacific Corporation) and E-36 (DuPont). WATER SPRINKLER AND WATER MIST SYSTEMS The primary objective of a sprinkler system, whether wet-pipe or preaction, is fire control, with the goals of containing the fire to its place of origin and controlling ceiling temperatures sufficiently to prevent structural damage and/or collapse. Actuation of sprinkler systems does not occur until the temperature at the glass bulb or the fusible link of a sprinkler head exceeds its temperature rating, typically 135 or higher. As a result of these relatively high actuation temperatures, fires will be well-developed before the sprinkler system activates, with fire sizes of several hundred kw being typical. This contrasts with the case of clean agent systems, where the primary objective is not control but extinguishment of fire in its incipient stages where fire sizes may be as small as 0.1 to 1 kw. Sprinkler systems employ water, which has obvious disadvantages in application where electronic equipment is involved, require cleanup after activation, and in some cases can produce more secondary damage than the damage produced by the fire itself. Sprinkler systems are more suited to the protection of the facility itself, whereas the clean agents are more suited to the protection the ire & Safety Magazine all 2007 S-World.com assets located within the facility. Maximum levels of protection for a facility can be accomplished y employing both a clean agent system to protect the facility's assets and a sprinkler system to protect the facility itself. Water mist systems have also been considered for the protection of computer rooms. The extinguishing action of water mist is due predominantly to dilution of oxygen in the zone of burning with steam resulting from the evaporation of water droplets in the heated area surrounding the fire. As a result, the ability of water mist systems to extinguish fires increases with the fire size - the extent of evaporation, and hence the degree of oxygen dilution at the fire, increases as the fire size increases. Water mist systems perform well in the extinguishment of large fires, hence their use in marine applications, for the protection of machinery spaces. A major advantage of water mist systems over conventional sprinkler systems is that the water mist systems employ less water than conventional systems. The extinguishment of small fires with water mist systems can be problematic due to the limited evaporation of water droplets and hence limited oxygen dilution at the fire location. In addition, water mist is not a total flooding agent like the gaseous clean agents, and as a result 69 may experience difficulty in extinguishing obstructed fires, such as fires originating within an equipment cabinet. As water mist systems will leave a residue (water), many IT managers are reluctant to install water mist systems for protection of computer rooms. Therefore, water mist systems generally are not recommended for data processing facilities where water can cause significant damage. CONCLUSION Due to their unique set of properties, the clean fire suppression agents are ideally suited for the protection of computer equipment and computer rooms/data processing facilities. As society's dependence on computers and other electronic equipment increases, the importance of providing fire protection for these critical assets will also increase.