Construction of Critical Spaces

When it comes to protecting your business from every aspect of fire damage, especially concerning your data center and telecommunication equipment, we believe our integrated systems approach represents the best value in protecting you from physical injury, data loss, and business downtime.

Recommended protection for critical spaces areas should be constructed where it is not subject to damage from external exposure. Critical spaces should be separated from other occupancies within the building, including atria or other open-space construction, by fire-resistant-rated construction.

The fire resistance rating should be commensurate with the exposure but not less than 1 hour for both. The fire-resistant-rated enclosures should extend from the structural floor to the structural floor above or to the roof. Every opening in the fire-resistant-rated construction should be protected to limit the spread of fire and to restrict the movement of smoke from one side of the fire-resistant-rated construction to the other.

This information has been prepared to assist anyone who must seal a room for a Clean Agent System.  In the majority of circumstances, if an Enclosure Integrity Test (as recommended by NFPA 2001) is to be performed, the room will need to be air tight to pass this test.  In extreme circumstances (where the enclosure cannot be properly sealed), an alternative qualitative testing method may be considered by the AHJ.  In either test case, the rooms must be properly sealed.  It is the nature of Clean Agent to suppress all flame and fire spread.  Therefore, it is critical that the Clean Agent remain in the protected area until emergency personnel have a chance to deal with a possible continuing source of ignition.

ALL DOORS leading from the Clean Agent protected areas or into another Clean Agent protected area shall have drop seals on the bottoms, weather stripping around the jams, latching mechanisms and door closer hardware.  In addition, double doors shall have a weather-stripped astragal to prevent leakage between doors and a coordinator to assure proper sequence of closure.  In general, doors shall be treated as though they are being weatherproofed for outside use with the least amount of light possible passing through all sides.  Doors, which for any reason cannot be kept normally closed, should be equipped with electromagnets designed to release on alarm.

ALL DUCTWORK leading from or into a protected area may be permanently sealed off, air tight, with metal plates caulked and screwed in place.  Ductwork left in service from the building air handling unit must have butterfly blade type dampers installed with neoprene seals.  Dampers must be spring loaded or motor operated to provide 100% air shut off.  It is further recommended that the building air-handling units be shut down to prevent the spread of smoke or Clean Agent into other areas of the building.

SELF-CONTAINED AIR HANDLING UNITS – As per NFPA 2001, Section 5.3.6: “Other than ventilation systems identified in 5.3.6.2, forced air-ventilating systems, including self-contained air circulating systems, shall be shut down or closed automatically where their continued operation would have an adversely affect the performance of the fire extinguishing system or result in propagation of the fire.  One must also consider the possibility that the air-handling unit could be the source of the fire.  Therefore, it is recommended to interconnect the systems to be shutdown. Self-contained air handling units may continue to run as long as they do not adversely affect the performance of the fire extinguishing system or result in propagation of the fire. This would be the decision of the owner.

PROTECTED AREAS shall be enclosed with wall partitions, which extend slab-to-slab.  This would be in accordance with NFPA 75.

ROOM CONSTRUCTION, that does not have full-height walls or a 1-hour enclosure, is not IAW NFPA 75.  If these conditions exist, and a clean agent system is desired, then an inert gas clean agent needs to be selected as the agent of choice, in leu of a HFC compressed gas clean agent.

As part of the design of an inert gas system, the following parameters become mandatory:

a. A dead air condition must be achieved in and around the protected space to achieve and maintain an acceptable level of inert gas concentration.  This can be accomplished with the shutdown of the following:

  • Dedicated CRAC units
  • Return Air unit above ceiling
  • Dampers, both supply and return
  • Exhaust Fans
  • Make-up Air Fans

b. Pressure Relief Vent Area (PRVA) requirements must be calculated to relieve pressure achieved during discharge so as not to cause any damage to walls/ceilings.  The PRVA quantity is part of the inert gas hydraulic flow calculations program which is provided to the General Contractor, Mechanical Engineer, and/or Mechanical Contractor so that pressure relief grills are designed and installed.

SUSPENDED CEILINGS should be clipped in place within 4 feet of any discharge nozzle when nozzle deflector plates are not used.  Suspended ceiling tiles shall also be provided with “mesh/perforated” type open vent tiles.

ANY HOLES, CRACKS, OR PENETRATIONS leading into or out of the protected area must be sealed.  This includes pipe cleaners and wire troughs.  All walls should be caulked around the inside perimeter of the room where the walls rest on the floor slab and where the walls intersect with the ceiling slab above.

IF A RAISED FLOOR continues out of a Clean Agent protected area into adjoining rooms, bulkheads must be installed under the floor directly under above-floor border partitions.  These bulkheads must be caulked top to bottom. If the adjoining rooms share the same underfloor air handlers, then the bulkheads must have dampers installed the same as required for ductwork.  See item #2

ALL FLOOR DRAINS should have traps, and those traps should be designed to have water in them at all times.

POROUS BLOCK WALLS must be sealed slab-to-slab to prevent agent from passing through the block.  Two or three coats of paint are normally required.  Unpainted block walls are totally unacceptable

IN GENERAL, the basic intent is to make Clean Agent protected areas as air tight as possible during and after Clean Agent discharge.  Clean Agent is heavier than air and therefore, openings below floors are usually more critical than those above a ceiling.  However, during discharge the room does get pressurized to some extent and any agent that can be pushed out of the room will not return.  Smaller rooms are much harder to seal than larger rooms because each little crack becomes much more significant as the surface area to volume ratio changes.

ONCE THE AGENT IS DISCHARGED, in most jurisdictions, it must remain in the room at its designed concentration for at least ten minutes.  The length of time that the agent will remain is directly proportional to the “air tightness” of the room.

These twelve (12) points, which are offered here, do not claim to be all-inclusive or to guarantee that the required tests will pass.  They are, however, presented as the most common items, which affect the Enclosure Integrity test and the Concentration test.  If, in addition to presenting a few specific areas of concern, they provoke thought about the overall “air tightness” of the enclosure, then they will have served a good purpose.

Fire protection is important to your business. Finding the solutions to your fire protection needs is something we have been doing since 1990. Our customers have found that they can trust the experience, knowledge, honesty, integrity and ethics of FPS team. We invite you to contact one of the members of this team to discuss how FPS can protect your employee’s life safety and your valuable assets for the continued operation and success of your company. Contact us at support@fpsys.com or 1-(714) 257-2244 for a Systems and Design Consultant to assist you with your needs.

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