Basics of Fire Protection - the Passive Fire Protection

Fire is one of the leading causes of accidental deaths worldwide - but one of the most preventable! A little precaution goes a long way.

A fire in your building could mean total devastation - get the facts on passive fire protection to minimize the spread of fire in your facilities. While every facility professional will do what he or she can to ensure that a fire never begins in the first place, the next step is knowing how to minimize its spread.

 

Most people are familiar with the basics of fire suppression (sprinklers, fire extinguishers, etc.), but the passive fire protection that actually contains a fire at its point of origin can be invisible and nearly forgotten - until the day you come to truly appreciate and depend on it.

Passive fire protection (PFP), despite its name, is always at work. Based on compartmentation of fire and preventing collapse through structural fire resistance, when properly installed and maintained, your building's passive fire protection can save lives and assets, and the building itself.

What we have learned from the devastating fires across the globe is that the construction systems, especially Fire Protection Systems, must be properly Designed, Installed, Inspected and Maintained (DIIM). This philosophy for passive Fire Protection has an important role to play in the safety of buildings and their occupants many years from now. Basic elements of Passive Fire Protection

1. Structural fire protection:

Structural fire protection guards essential structural components (such as structural steel and joint systems) from the effects of fire. This is accomplished with a fireproofing material (spray-on thin-film intumescents, endothermic materials like gypsum-based plasters and cementitious products, mineral wool wraps and insulation, and firepro ofing cladding) or building the structure out of concrete products. "When structural fire protection is designed and applied properly, the building's structural integrity should be maintained when it's exposed to fire."

2. Compartmentation:

Fire barriers, firewalls, fire partitions, and smoke barriers are all included in compartmentation. Fire barriers include fire-rated walls, floors, and ceilings (often made of concrete, combination wood, gypsum, or masonry). These barriers are used to limit the spread of fire in a building and allow safe egress. Walls extend from a fire-rated floor to the fire-rated ceiling above, and continue into concealed spaces for full protection.

"Fire walls as defined by the International Building Code are built structurally stable, so even if there is collapse of a building on either side of the wall, the wall will remain standing",

"The window of evacuation time is maximized when the barriers effectively contain the fire

3. Opening protection:

FIRE DOORS and windows are installed in an opening of a fire barrier to maintain its fire resistance.  "Doors, builders' hardware, and frames work together with the fire or smoke barrier to finish effective compartmentation". Fire-rated glazing/glass and framing are tested as a complete assembly that maintains the protection of the fire barrier. Additionally, fire and smoke dampers (often used in duct systems) are considered "opening protection" and complete the fire barrier where air ducts penetrate fire-rated and/or smoke-resistant assemblies.

4. Firestopping materials:

These materials are used to limit fire spread through penetrations in a fire barrier. It's not uncommon to see a fire barrier penetrated during a minor building alteration, and then the penetrating item isn't protected by firestopping. It can leave hidden holes in the barriers.

Other elements of PFP that warrant mentioning are cable coating (the application of fire retardants to wire and cable), joint systems (which include changes in direction between fire-separating elements and the spaces surrounded by those elements), and perimeter fire barriers (which deal with the perimeter of the floor and the exterior curtain-wall).

While passive fire protection can successfully prevent the spread of fire, it's important to note that most professionals recommend redundancy in fire protection. In other words, a fire-sprinkler system, alarms and detection systems, and occupant education, in conjunction with passive fire-protection systems, are a safer, more balanced approach to protecting your building and the people inside.

Which codes regulate firestopping?

Passive Fire Protection Clauses in NBC 2005

Revised Building Codes of India Firestop Guidelines (excerpts from part 4: Firestop Life safety)

Openings in separating Walls and floors

Clause 3.4.8 At the time of designing openings in separating walls and floors, particular attention shall be paid at all such factors as will limit fire spread through these openings and maintain fire rating of the structural member.

Clause 3.4.8.1 Every wall opening shall be protected with fire-resisting doors having the fire rating of not less than 2 h in accordance with accepted standard. All openings in the floor shall be protected by vertical enclosures extending above and below such openings, the walls of such enclosures having a fire resistance of not less than 2 h.

Clause 3.3.1 & 3.3.2 - Fire Test Requirement – General It is required that an element / component shall have the requisite fire resistance performance when tested in accordance with the accepted standard.

Clause C-9 Compartmentation

The building shall be suitably compartmentalized so that the fire and smoke remain confined to the area where the fire incident has occurred and does not spread to the other part of the building.

Clause 3.4.8.3 Fire Stopping

Openings in walls or floors which are provided for the passage of all building services like cables, electrical wiring and telephone cables etc., shall be protected by enclosures in the form of Ducts / Shafts with a fire resistance of not less than 2 hours.

 Clause 3.4.8.4 Fire Stopping

Every vertical opening between the floors of a building shall be suitable enclosed or protected as necessary to provide reasonable safety to the occupants while using the means of egress by preventing spread of fire,  smoke or fumes through vertical openings from floor to floor, thus allowing occupants to complete their safe use of the means of egress.

Service Ducts/Shafts

Annex Clause C1.9 Fire Stopping Service Ducts & Shafts

Service ducts and shafts shall be enclosed by walls of 2 hour and doors of 1 hour rating. All such ducts / shafts shall be properly sealed and fire stopped at all floors.

Annex Clause C1.12 Fire Stopping Cable Ducts Penetrations

The electric distribution cables / wiring shall be laid in a separate duct. The duct shall be sealed at every floor with non-combustible materials having the same fire resistance as the fire rating of the cable duct.

Annex Clause C1.17 Fire Rated Ducts

Where the duct passes through fire walls, the opening around the duct shall be sealed with fire resisting materials having the fire resistant rating of the compartment. Where the duct crosses the compartment which is fire rated, the duct shall be fire rated for same fire rating. Further, depending on the services passing around ductwork, which may be affected in case of fire temperature rising, the ducts shall be insulated.

Annex Clause C1.12a Cable Ducts

The electric distribution cables / wiring shall be laid in a separate duct. The duct shall be sealed at every floor with non-combustible materials having the same fire resistance as the fire rating of the duct.

Annex Clause C1.16a Transformer Substation

The outside walls, ceiling, floor, opening including door and windows to the transformer substation area shall be provided with fire resistance of 2 hours rating.

Annex Clause C1.16C Transformer Room

When housed inside the building the transformer shall be of dry type and shall be compartmentised from the other portion of the premises by walls / doors / cut-outs having fire a minimum fire resistance of 4 hours.

Smoke Venting

Claus 3.4.12.3 Where smoke venting facilities are installed for purpose of exit safety these shall be adequate to prevent dangerous accumulation of smoke during the period of time necessary to evacuate the area served using available exit facilities with a margin of safety to allow for unforeseen contingencies.

Every opening in a fire barrier shall be protected to limit the spread of fire and restrict the movement of smoke from one side of a barrier to the other. (NFPA 101 8.2.3.2.3)

Fire/smoke barriers shall be continuous in accordance these specifications: Fire compartments shall be formed by fire barriers that are continuous from outside wall to outside wall, from one fire barrier to another or a combination of the two. This continuity must continue through all concealed spaces such as those above the ceiling. (NFPA 101 8.2.2.3*)

Penetrations for cables, conduits, pipes, tubes, exhaust vents, wires, etc, that are created to accommodate electrical, mechanical, plumbing, and communications systems, must be protected by a firestop system or device if they pass through a wall or floor/ceiling assembly constructed as a fire barrier.(NFPA 101 8.3.5.1* Firestop Systems and Devices Required.)

Firestop systems and devices shall have an F rating of at least 1 hour, but not less than the required fire-resistive rating of the fire barrier that has been penetrated. (NFPA 101 8.3.5.1.3)