MD 15116 - 2006 Computer Room Air-conditioning Systems
Appendix B - Fire Protection Systems
B1.0 Type of Fire-suppression System
Based on fire risk analysis, the installation of a single-interlocked preaction fire-suppression system is recommended for all Level III EDP rooms. The installation of a gas-fired suppression system is not recommended.
The fire-protection systems in EDP rooms are governed mainly by three regulations: the National Building Code, the National Fire Code and the Occupational Safety and Health Manual as issued by Treasury Board Secretariat (Chapter 3-3 Fire Protection Standard for Electronic Data Processing Equipment).
The National Building Code's main focus is with life safety, and it refers to NFPA Standards for further details. In the case of fully sprinkler red buildings, NFPA Standard 13 requires the installation of a wet pipe sprinkler system throughout the entire building including the EDP rooms (NFPA 13 Appendix A-4-2: "A dry pipe system should be installed only where heat is not adequate to prevent freezing of water in all parts of, or in sections of the system").
The Treasure Board Regulation's main focus is property protection and therefore, the requirements for Level III installations are as follows: "A halon 1301 system or other acceptable gaseous fire-suppression system shall be installed in the computer room where a fire-risk analysis concludes that, in addition to sprinkler protection, a gaseous fire-suppression system is necessary to minimize potential fire damage to the EDP equipment".
The use of any halon product, including Halon 1301 has been effectively banned under the Montreal Protocol; therefore, to conform to the federal governments sustainability policy, the use of any fire suppression system using halon is not permissible. In order to comply with the Treasure Board requirements to protect the EDP equipment on large computer room projects, the COE commissioned several fire code consultants to review all the relevant regulations and provide recommendations. Based on the reports findings and recommendations, the COE recommends installation of strictly single-interlocked preaction fire- suppression systems for all the Level III EDP rooms.
Fires originating within the computer room are expected to yield products of combustion, which will be corrosive and damaging to live electrical equipment. The quantity of smoke necessary to result in permanent damage depends on the properties of the combustible materials exposed to elevated temperatures. As large quantities of smoke can be produced in advance of visible flame or the subsequent sprinkler activation, it is generally accepted that the principle risk to sensitive computer equipment is from the corrosive, hot, smoke particles.
In order to protect the computer equipment from exposure to excessive quantities of smoke, early warning smoke detection should be installed in order that building occupants, supervisory staff and security staff can take appropriate action to suppress a small fire and implement smoke venting. This action may be sufficient to negate the operation of any further automatic fire suppression, whether sprinklers or gaseous suppression system. In the event that a fire is found to be too large to be suppressed by manual intervention, the manual release lever for the preaction valve can be activated in order to fill the sprinkler piping with water and await operation of the sprinklers. By this time, the quantity of smoke is expected to be so great as to result in widespread damage to the computer equipment within the room. It is to be noted that even small quantities of smoke can cause sensitive computer equipment to become unreliable. In these cases, the damage is done in advance of any activation of gaseous suppression or sprinkler systems.
Sprinkler operation within the computer room is expected only after the temperatures have risen to above 74 dec.C. The preaction valve will prevent sprinkler operation without the operation of at least two smoke detectors, thereby protecting the room and equipment from water damage in the event of physical damage to the sprinkler or accidental activation of a sprinkler. Otherwise, the sprinklers are extremely reliable fire-suppression systems with proven suppression capabilities.
The provision of a supplementary gaseous-suppression system could be an added value; however, there are limitations.
The discharge of gaseous-suppression systems (such as FM 2000 or Inergen) must occur within a short period of time to achieve good mixing with the air; therefore, the gas is discharged with great force. Anything in the room that is not fixed may be picked up and tossed about. Any dust in the room will become airborne which will reduce visibility. Visibility will be further reduced by the creation of a fog. Expanding gases discharging from the nozzles cause considerable cooling of the air to the point where the humidity contained within the room air condenses and creates the fog. The high gases discharge noise coupled with the fire alarm add to the overall confusion.
The gases utilized for fire suppression do not cause adverse reactions on skin contact, and are generally non-toxic in prescribed concentrations and durations of exposure. However, the gases are heavier than the air; therefore, a room filled with the gas will very soon, after discharge, have a heavy concentration of gas near the floor and virtually no gas at the higher levels. This may create two problems:
- Should anyone be trapped in a room after a gas discharge, there is a possibility of asphyxiation if anyone should fall and lie on the floor, as the gas will collect at the floor level.
- Fires located at higher levels above the floor may re-ignite within minutes after the gas discharges and the gas pools at the floor level.
The early warning smoke detection and preaction sprinkler protection systems are generally considered sufficient for the protection of computer and communications facilities when the rooms are occupied.
Suitable protocols must be developed and appropriate training is required for all computer room staff, supervisory staff, building maintenance personnel and security staff with respect to a response to alarm conditions. The implementation of appropriate procedures and training in combination with early warning smoke detection are expected to provide appropriate protection for the computer room and its equipment.
As such, the value added by implementation of a supplementary gaseous-suppression system is not considered to be sufficient to offset the added system maintenance costs, the potential system complications and the risks to room occupants in the event of activation
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