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Volume 31, Issue 1

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Electronic and Computer Equipment areas are found in every local community across America. They may range from a small computer in one office area to a large mainframe computer room with raised flooring and isolated power and climate controls. The primary purpose of this article is to address the specific construction principles and fire protection standards related to large data centers.

The NFPA has reported more than one thousand fires erupting in computer equipment across the U.S. on an annual basis. Beginning in 1980 through 1991 the number of fires has been on a downward trend while 1991 to the last year of the report, 1996, has shown an upward trend in fire incidents . This trend can be attributable to the proliferation of home personal computers as well as the quantity of computers found in businesses today.

Fires involving data centers, whether they originate inside the computer room or extend to the area from an adjacent room, brings special hazards to the firefighter that cannot be overlooked.

Businesses today spend multi-million dollars in computer equipment to manage their information systems and rely on sophisticated controls, detection and suppression systems to protect this large investment. As businesses expand or divest, the need for computer equipment changes as well. As a result, the original sound installation of wiring, and fire-resistant construction is left to the hands of employees who have no knowledge of fire growth and flame spread.

General Principles

Location

A new tenant looking for space to house a critical infrastructure such as a computer room will look for several key factors in their search.

Businesses today spend upwards of $150 per square foot of floor space for a high-tech facility. Some of the requirements for a computer room include the following:

 

R Secure location with minimum exposure to the outside environment
R Sufficient ceiling height
R A location away from sources of water leaks
R Adequate floor load capacity

Based on this criteria, you can expect to find computer rooms away from exterior windows and doors, toward the center of the building. Ceiling heights must be sufficient to support a raised floor and equipment dimensions. The minimum height for this purpose would be 10 ft. slab to slab clearance. This provides for a 1 foot raised floor height and 1 foot above the ceiling space.
In high rise structures the most appropriate floor location would be equally distributed between the top most and bottom most floor. In a ten floor building look for the computer room to be on the 5th floor. This design provides for the minimum distance from computer area to computer user in efforts to reduce communication problems and cable lengths.

In single story office buildings computer locations will most likely be in the center of the building, away from windows and doors, but may not be centrally located otherwise. Many office buildings house warehouse as well and the majority of the computers would not be found there.

Therefore, the main computer area would be found within the office environment.

Security

Computer rooms house a significant investment in equipment as well as sensitive business data. As such, a higher security level is placed on this area with limited access. If constructed properly, this access restriction should not be a problem when the fire alarm is activated. In this case, all doors should be automatically placed in an un-locked position to allow for the rapid exit of occupants and ease of entry by firefighters.

Void Spaces Raised floors in computer rooms provide a large void space that allows fire to spread undetected. The raised flooring usually runs the entire span of the enclosed room and should not extend beyond the fire rated walls. Floors of this type are generally constructed of wood surrounded by a fire resistant material. In some cases, they may even be made out of concrete.

The 2x2 foot sections of tile lay on top of a metal frame, generally 1 to 1.5 ft. in height. The metal frame is supported by metal posts at the corners of the tile. A tile remover is required to lift the tile from the frame, as shown in Figure 2.

Fire Load

Nearly half of all fires originating in electronic equipment rooms have been caused by the electrical distribution system, resulting in over $8 million in damage and 22 civilian injuries. The use of fire resistive materials in the construction of computer rooms does not prevent fires from occurring. Whether the fire originates in the computer room or extends to the room from an adjacent space, fires will occur and may overwhelm the automatic suppression systems. The live loads placed in the data center are primarily made of plastics and will burn at double the Rate of Heat Release as wood and paper products, as much as 16,000 BTU/lb. Adding to the load of computer equipment is the tape and microfiche stored in the room. This adds to the hazard as tapes will burn much more readily than the sturdier construction of the computer enclosures.

The amount of paper products found in computer rooms is much less today than was found nearly 10 years ago. The majority of printing occurs outside the data center, closer to the users who need it. This has eliminated the need to store large amounts of paper in the computer room.

Compartmentation

Computer Rooms are designed to be an enclosure surrounding the vital electronic equipment and sensitive data supporting the enterprise. The walls which define this enclosure are required to have two hour minimum fire ratings and must extend from slab to slab. Any openings, such as doors, must be properly constructed to create an environment sufficient to contain a release of a total flooding system and maintain the pre-determined concentration of gas of a minimum length of time.

The infrastructure supporting this enclosure is typically isolated from the remaining facility's equipment. Separate Heating, Ventilation, and Air Conditioning (HVAC), electrical supply, water chillers, and fire detection/suppression systems are designed and used for the computer room only. Many times you will find a diesel or natural gas powered generator that will be dedicated to supporting the computer equipment in the event of a power failure.

The enclosure, regardless of its location within building, becomes a city unto itself.

Detection and Signaling Systems

Sophisticated electronic equipment requires sophisticated protection. Modern fire protection systems incorporate heat, smoke, and water detection devices, both at the ceiling (except water) and at the floor level. The systems are usually wired to a control panel as well as a monitoring station within the computer room. The information provided below describes a typical fire protection system within a data center.

When a smoke or heat detection occurs, it activates visual warning (strobes) and initiates a communication to an off-site, 24-hour alarm center. No audible warning is received unless two detectors activate. The monitoring station within the control room will display the location of the activated detector to aid in the investigation. The system is also linked to the sprinkler system which is usually a dry pipe system. Some may be a combination of dry and pre-action which results in a safe environment from water leaks. The first stage of the alarm system would not activate the pre-action system.

When the 2nd stage activates it issues an audible warning along with the strobes. This audible warning alerts the occupants that the total flooding agent is ready to discharge. The occupants can activate the abort button, if so equipped, but must reset the alarm before releasing the abort button. Events at this point may vary but could include the shutdown of HVAC systems, the power distribution systems, and finally discharge of the flooding agent.

Suppression Systems

The suppression systems located in computer areas are a part of a complex system of detection and suppression equipment that is designed specifically for the hazards involved. They typically employ a clean agent fire extinguishing agent flooding system to protect the large investment of electronic equipment from post-fire damage. The NFPA defines total flooding systems as systems that are designed to discharge into, and fill to the proper concentration, an enclosed space or enclosure about the hazard. Clean agents, per the NFPA, are electrically nonconducting, volatile, or gaseous fire exstinguishant that does not leave a residue upon evaporation.

Any confined area, such as a computer room, that has in place a clean agent suppression system must identify the material by signs or placards at the entrance to the confined area. The more popular clean agents are detailed below.

Halon -1301 (bromotrifluoromethane) is a colorless, odorless, electrically non-conductive gas that is an effective medium for extinguishing fires. It was the most popular clean agent fire extinguishing system, prior to the adoption of the Montreal Protocol in 1987, when the US EPA ordered a phase-out of Halon production by 1993 due to the ozone depletion properties.

However, there was no requirement for existing installations to remove and upgrade to another fire extinguishing agent. Therefore, many Halon-1301 fire extinguishing systems are still in existence today.

Halon-1211 is used in portable extinguishers to supplement to total flooding system. In areas protected by Halon-1301, all portable extinguishers in the area should be of the Halon-1211 type.

Carbon Dioxide

Carbon Dioxide is a colorless, odorless, electrically nonconductive inert gas that is a suitable medium for extinguishing fires. Carbon Dioxide is 1.5 times heavier than air and extinguishes fire by reducing the concentrations of oxygen, the vapor phase of the fuel, or both in the air to the point where combustion stops.

As carbon dioxide displaces oxygen, occupants of any enclosure where CO2 is used must evacuate immediately upon activation of the system. Be aware of collecting pools of carbon dioxide as it will flow to a low area and build up concentrations. Warning signs for carbon dioxide are required to be at the entrance, inside the occupied area, and in any possible locations where the CO2 may collect after activation.

FM-2007

M-2007 is the trade name for heptafluoropropane and is distributed by Great Lakes Chemical company as a replacement to Halon-1301. The use of FM-2007 is covered by NFPA Standard 2001-Standard on Clean Agent Fire Extinguishing Systems.

FM-2007 is a compound that consists of carbon, fluorine and hydrogen. It is colorless, odorless, electrically non-conductive, and suppresses fire by interrupting the combustion process and removing heat energy from the fire to the extent that the combustion process cannot sustain itself. If exposed to temperatures greater than 1300' F, toxic products of decomposition (hydrogen fluoride) are formed. Most materials contained in areas protected by FM-2007, such as aluminum, brass, rubber, plastics, steel, and electronic components, are unaffected when exposed to FM-2007.

The US EPA has approved its use at up to 9% concentration volumes without mandatory egress times, or up to 15% with mandatory egress times. The design concentration for FM-2007 in computer equipment areas is generally around 7%, therefore requiring no mandatory egress times.

Sprinkler Systems

Sprinkler systems are also used in electrical and computer areas to supplement the gas flooding systems. The sprinklers found in these areas are typically dry systems, to minimize any leakage and water damage to expensive equipment. Upon activation of a single detector, the system will pre-activate and fill the pipe with water. There will be no discharge of water until a sprinkler head is exposed to appropriate temperatures.

Abort Mechanisms

Abort mechanisms are not recommended but are provided in large data centers to provide the occupants the ability to withhold the flooding system from activating. This is a manual process and once a person depresses the abort button, they must remain in contact with the button until another individual can de-activate the system. Failure to keep the button depressed will result in release of the flooding agent.

For carbon dioxide extinguishing agents, abort mechanisms are not allowed.

High Hazards for Firefighters

Electrical

Computer systems for large corporations cannot be turned-off quickly. A normal shutdown procedure may take several hours. Because of this, most data centers have a UPS, or un-interruptible power supply, to provide power in the event of an electrical utility failure. Many times a company will use a generator for their critical operations and will continue to supply power for as long as the generator has fuel.

UPS systems designed for data centers will usually be located nearby, but isolated by fire resistive walls from the main equipment it is protecting. What may appear to be a closet could well be a set of batteries connected to the electrical system for the data center. Equipment of this nature is designed to automatically activate in the event of a power interruption. A request to the utility company for removal of electric supply to the building does not necessarily provide a safe environment for the firefighters.
It is imperative in these situations that the Incident Command coordinate activities with the building management and/or engineer to account for all possibilities.

Cable Distribution

For data centers to be effective, they must send and receive information. This requires the use of cables to be physically connected between the two points of information sharing. The point of origin is the data center with the raised floor to protect this cabling. All cables are run underneath the floor to a distribution panel.

The second point of information sharing occurs in the office areas where people operate their computers. Their personal computers are attached by cabling to the data center. In a single story office building, this cabling will usually be found above the drop ceiling. Any cables that are utilized for data transmission, such as these, are supposed to be suspended and not simply laid on the top of the ceiling tiles. However, in many cases this is exactly what you find.
In High-Rise buildings cables must be run through several floors. This requires a conduit to be placed between floors. The building codes require these conduits to be sealed after all the cable has been run. If an occupant decides not to seal this area, it becomes an excellent location for the heat and smoke to travel and extend through the building vertically.

Conclusions and Recommendations

Organizations that require expensive high technology solutions to computer services will build a state of the art computer room with complex fire detection and suppression systems. The systems are capable of handling the incipient fires that occur within the enclosed room. If the total flooding agent is not capable of extinguishing the flame, the generated heat will activate the sprinklers and control the spread of fire.

Although the walls surrounding the data center are fire rated, they are not fire proof, and will not prevent a fire that originated in an adjacent room from spreading into the sensitive area. The fire fighter faced with a battle within a computer room environment must understand the hazards he may encounter. Raised floors, miles of cabling, and high heat should be expected and understood by the firefighter.

The only way to understand the potential problems is to visit the offices and buildings in your jurisdiction and ask questions. The security director and/or computer manager should be glad to meet with you and discuss the fire protection mechanisms in place. Approach the business as a partner in their business continuity process and establish a relationship that will last a lifetime and prevent a disaster for both the fire department and the business when things go bad.


Timothy F. Joo has been an emergency service volunteer for over 20 years. He has certification as a Firefighter/EMT and Instructor qualifications in the Incident command System and Hazardous Materials Operations. He currently serves as the Manager of Systems Integrity at a large chemical company.