Demystifying IT room protection requirements
Information technology (IT) equipment area/room designs must balance the needs for security, cooling, and fire protection.
- Illustrate NFPA 75: Standard for the Fire Protection of Information Technology (IT) Equipment and how it affects data center design.
- Make use of NFPA codes and standards in IT equipment room design.
- Consider fire suppression systems appropriate to IT equipment rooms.
Most of us use computers daily, but we generally don’t think much about the infrastructure necessary to keep them connected and safe. Dedicated information technology (IT) equipment areas (not to be confused with other general areas, such as offices that contain desktops and laptop computers) are often misunderstood in this respect, as the requirements contained in NFPA 75: Standard for the Fire Protection of Information Technology Equipment can be confusing.
NFPA 75 contains the following definitions:
Section A.1.2 of NFPA 75 provides some insight on what actually constitutes an IT room or area:
NFPA 75 essentially applies to areas that house large server racks or equipment, sometimes operating up to 30 kW per rack. These areas are what we would refer to as "server rooms" or "data farms." Thus, it is clear that NFPA 75 generally doesn’t apply to office areas or small rooms. However, there are some cases where computing equipment may be subject to higher risks, which may require protection beyond that found in a typical office environment.
Each facility or organization is different, and not all applications benefit from a one-size-fits-all fire protection approach. Some applications may warrant risk analysis to establish the level of desired protection. For example, air-traffic control centers may require a more stringent approach, separation requirements, and additional suppression capabilities (or all of the above) because the occupants cannot immediately leave the premises. The designer must account for these factors in the analysis. For these reasons, a fire risk analysis should be used to determine the construction and fire protection and fire-detection requirements for IT equipment, IT equipment rooms, and IT areas, where permitted by NFPA 75.
NFPA 75 defines fire risk analysis as follows:
Where risk analysis is used, the following factors must be considered:
- Life safety aspects of the function (e.g., process controls, air-traffic controls)
- Fire threat of the installation to occupants or exposed property
- Economic loss from loss of function or loss of records
- Economic loss from value of equipment
- Regulatory impact
- Reputation impact
- Redundant offsite processing systems.
Building construction requirements
NFPA 75 requires the IT equipment area to be housed in a fully sprinklered building, located in a building that complies with NFPA 220: Standard on Types of Building Construction Type I or II construction, or in a single-story building of Type II construction. These construction types roughly correspond to types I and II construction, as defined by the International Building Code (IBC). NFPA 75 also requires the IT equipment area to be separated from other occupancies within the building, with a minimum separation of 1 hour. Again, risk analysis may determine that higher separation requirements are necessary.
Security needs, mechanical system design, and other considerations also play a role in the location of the IT equipment room or area. NFPA 75 requires the IT equipment area to be housed so it is not above, below, or adjacent to areas containing hazardous processes. While NFPA 75 does not clearly define hazardous processes, it can be assumed that higher-risk areas are to be avoided when selecting a location for an IT equipment room/area. For example, it would be imprudent to locate a critical IT equipment area adjacent to a flammable liquids storage area.
The structural members used for raised floors must be noncombustible to avoid collapse during a fire. Additionally, all decking must be noncombustible or fire-retardant wood, having a flame spread index of 25 or less.
Penetrations through rated barriers must be properly firestopped to an equal rating of the barrier through which they pass. This includes cable, conduit, and other similar penetrations. Firestopping classifications must employ the use of approved firestopping materials and the appropriate UL classifications. Most manufacturers of firestopping products are happy to assist designers with their designs and can provide details for drawings.
Other openings, such as pass-through windows and service counters, must be protected by rated shutters, rated windows, or rated service-counter fire doors, meeting the requirements of NFPA 80: Standard for Fire Doors and Other Opening Protectives. These openings must operate automatically by the presence of smoke or fire on either side of the protective opening. Smoke detectors and fusible links are often used to actuate these protectives. Smoke detectors used for this purpose may be area detectors (those found on the ceiling) or duct-type smoke detectors.
IT equipment generates a large amount of heat, and there are several methods used to make cooling more efficient. One commonly used method is aisle containment, where supply or return air is contained by barriers, sometimes called collars. These collars guide the hot air from the racks back to the cooling units. Aisle-containment systems can be factory-packaged systems or field-constructed. However, the materials must have a maximum flame spread index of 50 and a maximum smoke development of 450 in accordance with ASTM E84 or ANSI/UL 723.
Where the application of aisle-containment systems or hot-air collars creates obstructions to proper operation of sprinkler systems, the sprinkler system must be modified as necessary to comply with NFPA 13: Standard for the Installation of Sprinkler Systems to avoid the obstruction. Where gaseous suppression systems are present, they must be designed to develop the required concentration of agent for the entire volume they serve, in accordance with NFPA 2001: Standard on Clean Agent Extinguishing Systems. NFPA 75 may not require modification of suppression systems in some cases, such as where obstructions are removed upon actuation of smoke detectors in the space.
Fire protection systems
The fire protection system’s main goal is to detect and alert occupants and operators of fire in the early stages, then bring the fire under control without disrupting the flow of business and without threatening the personnel in the facility. Halon gas is no longer in use because it has been proven environmentally unfriendly (ozone depleting) and unsafe for humans. Modern IT rooms typically use combinations of gaseous suppression systems. However, wet, dry, and pre-action sprinkler systems are also widely used and generally required.
Many IT professionals prefer dry or pre-action systems because they believe sprinkler systems leak. The truth is, they do not leak any more than other systems, like domestic water. That being said, it is a good practice to locate sprinkler branch lines over aisles rather than the equipment.
Because they generally involve a somewhat higher hazard than other parts of a typical building, IT equipment rooms and IT equipment areas located in a sprinklered building must also be provided with an automatic sprinkler system. Most designers will classify the IT equipment room as Ordinary Hazard Group 1, as defined by NFPA 13.
IT equipment rooms and IT equipment areas located in a nonsprinklered building also must be provided with an automatic sprinkler system, a gaseous clean agent extinguishing system, or both. Water-mist systems may also be considered. Therefore, locating an IT equipment room/area in a nonsprinklered building will necessitate the need to add new fire protection systems. In some cases, sufficient water supplies may not be available. This would require water storage and a fire pump.
NFPA 75 requires an automatic sprinkler system or a gaseous fire extinguishing system to be provided for the protection of the area below a raised floor in an IT equipment room or IT equipment area where one or more of the following exist:
- There is a critical need to protect data reduce equipment damage, and facilitate a return to service.
- The area below the raised floor contains combustible material.
Where a gaseous fire-extinguishing system is provided only under a raised floor, the gaseous system must be either carbon dioxide or an inert gas. Where a clean agent fire-extinguishing system is provided to protect the space above the raised floor, the space under the raised floor must be simultaneously protected by the clean agent fire-extinguishing system. While carbon dioxide was once the preferred choice, most designers now prefer clean agent systems.
Where there is a critical need to protect data reduce equipment damage, and facilitate return to service, consideration must be given to the use of a gaseous agent inside rack units or total flooding systems in sprinklered or nonsprinklered IT equipment areas. The power to all electronic equipment must be disconnected upon activation of a gaseous agent total-flooding system, unless risk analysis indicates the need for continuous power. However, in some rare cases, the need to continue operations may supersede the need to secure electrical power.
Hot- or cold-aisle containment systems cannot obstruct the free flow of gaseous clean agent suppression systems to the IT equipment or cooling system serving the contained aisle.
Gaseous agent systems must be automatically actuated by an approved method of detection meeting the requirements of NFPA 72: National Fire Alarm and Signaling Code and a listed releasing device compatible with the system. Most gaseous agent suppression systems are engineered systems, having their own standards, such as NFPA 2001 for clean agent systems. Most of these systems are supplied with their own controls, and using the main building fire alarm system to operate the suppression system is discouraged. In any case, system controls must be listed for releasing service.
Dilution of the agent can be problematic during a fire because concentrations of the agent must be sufficiently high to extinguish the fire. Where operation of the air-handling system would exhaust the agent supply, it must be interlocked to shut down when the extinguishing system is actuated.
Where continuous power is provided, signs must be posted at each perimeter entrance to the IT equipment areas warning that electrical equipment will remain energized. This applies either upon activation of the suppression system or disconnect of main electrical service.
Automatic detection equipment must be installed to provide early warning of fire. Automatic detection systems are often used to operate dampers or shut down HVAC equipment to prevent the recirculation of smoke. The equipment must employ listed smoke detection and must be installed and maintained in accordance with NFPA 72. Stand-alone detection can be used, but best practices will generally involve system-powered smoke-detection equipment.
Automatic detection systems must be installed in the following locations:
- At the ceiling level throughout the IT equipment area
- Below the raised floor of the IT equipment area containing cables.
In the IT equipment area, where the space above the suspended ceiling or below the raised access floor is used to circulate air to other parts of the building, automatic smoke detection must be installed in one of the following locations to operate smoke dampers:
- Throughout the above ceiling space or below raised access-floor space, respectively
- At each smoke damper
- At other approved locations to detect smoke entering or exiting the IT equipment area.
Temperatures above 100°F in hot aisles can occur during normal facility operations. Most smoke detectors are listed for a maximum operating temperature of 100°F. For this reason, smoke detectors located in hot aisles, or in the airstream exhausted from hot aisles, must have the appropriate listing for temperatures above 100°F.
Spot-type smoke detectors are frequently used to provide early warning of fire/smoke in IT equipment rooms. However, air-sampling (aspirating) smoke detection is far more sensitive and is somewhat easier to maintain. Aspirating smoke detection uses a piping network throughout the protected area. The piping is connected to a single detector, which is generally located inside the space. An aspirating smoke detector is connected to the fire alarm system controls, usually through dry contacts.
Power to operate critical systems must be supervised by the fire alarm system controls. At a minimum, the following must be supervised:
- Electrical power to the interlocks and shutdown devices
- Operation of the electrical power disconnecting means.
Supervision of these conditions is generally accomplished through the use of monitor modules connected to the fire alarm system. These modules will create supervisory signals on the fire alarm system.
Alarm, supervisory, and trouble signals of automatic detection or extinguishing systems must be arranged to annunciate at a constantly attended location. Constantly attended locations can include a guard’s desk, supervising station, or other location that is staffed 24/7. The insurance carrier and authority having jurisdiction should be involved with the approval of the location.
IT equipment area/room designs must balance the needs for security, cooling, and fire protection. There are a large number of choices and decisions that must be made related to the type of systems and equipment. Good communication between mechanical designers, architects, IT professionals, and fire protection system designers is critical for success. By working together, engineers, architects, and IT professionals can achieve all desired goals while providing a safer system.
Merton Bunker is a senior fire protection engineer with EYP Architecture & Engineering.