Containment Through Firestopping
Fire detection, containment and suppression systems are all elements which work together to provide a comprehensive fire protection system to help protect lives and property from the direct and indirect losses incurred as a result of a fire. Under fire conditions, fire and toxic gases can pass through unsealed or improperly sealed openings in and around penetrations and construction joints. Firestopping is a key component of the containment system within the overall fire protection system. Firestopping is a method of passive fire protection that serves to help contain the fire and toxic gases to the area of origin by sealing around penetrations and construction joints in fire-rated floors and walls. Firestop systems consist of a fire-rated assembly or assemblies (e.g., a fire-rated floor or wall), a penetrating item or construction joint, and the material used to seal that opening or joint. Increased awareness and knowledge of having a comprehensive fire protection system in place, which includes detection, containment and suppression systems, has led to the development of innovative firestop products and solutions. There are many firestop product solutions on the market today to address various applications for through-penetrations and construction joints in fire-rated walls and floors. Firestop sealants, sprays, collars, wrap strips, foams, cast-in devices, mechanical products and numerous other materials offer a variety of solutions to handle a wide range of containment applications.
Testing and ApprovalFirestop systems are tested and listed by independent testing laboratories such as Underwriters Laboratories and Omega Point Labs, and firestop products should display the approving agencies' classification mark on the package or container. However, the classification mark does not approve the product for use in all firestop applications. Firestop products are tested in accordance with various test standards depending upon the designed application use of the product. The two most common test standards for firestop products in the U.S. are ASTM E-814/UL 1479 "Test Standard for Through-Penetration Firestops" and ASTM E-1966/UL 2079 "Tests for Fire Resistance of Building Joint Systems." To receive an agency's classification mark, the firestop products must be tested in accordance with the applicable test standard for the specific application in question. With so many products available to provide firestop solutions, it is important to match the application with the appropriate listed firestop system for that application. The approved method of installation for each tested application can be found in the applicable independent testing laboratories' directory (e.g. UL Fire Resistance Directory).
Firestopping With SealantsThe most common method of firestopping is the use of sealant material to seal openings around penetrations and construction joints. There are various types of sealant materials for through-penetrations and construction joints. Sealants are typically categorized into two groups: (1) intumescent sealants and (2) non-intumescent sealants.
Intumescent-type sealants are designed to expand once the intumescent material reaches a pre-determined temperature range. Intumescent sealants are commonly approved for use around insulated and non-insulated metal pipes, combustible and glass pipes, cables and cable bundles, electrical busways, and around non-dampered hvac duct. Intumescent sealants typically provide the widest range for through-penetration firestop applications.
Non-intumescent sealants are commonly used in construction joints and some through-penetration applications. Non-intumescent sealants are ideally suited for construction joint applications where movement of the joint is expected. There are generally two types of non-intumescent sealants. The first is an acrylic-based sealant that cleans up easily with water and is paintable to provide a finished look in exposed areas. The second type is a silicone-based sealant. These silicone-based sealants are ideal for situations in which the applications may be exposed to weather elements such as water and are typically UV resistant. Non-intumescent sealants remain flexible once cured and provide various movement capabilities.
Firestop sealants are commonly packaged in tubes, foil packs or pails. Non-intumescent sealants come in various forms, ranging from a caulk gun-grade form to self-leveling forms that require no additional tooling once applied.
Other types of firestop sealants are sprayable mastics for joint applications where speed and ease of application are desired (i.e. top of wall/curtain wall applications). Firestop joint sprays can be quickly applied using a variety of industrial airless spray equipment. When used in conjunction with pre-formed mineral wool deck plugs (such as Hilti's CP 777 Speed Plugs), spray-applied firestop sealants can reduce the time and labor of firestopping top-of-wall applications involving fluted metal deck. These spray-applied sealants are ideal for large joint applications where large joint runs exist, and joints where maximum movement capabilities are needed. Most firestop spray materials and spray equipment readily clean up with water once the job is completed.
Intumescent Collars and Wrap StripsDue to their combustible nature, vented plastic pipes present a far more challenging fire hazard compared to metal pipes or conduits. If not properly firestopped, these pipes may melt or burn, leaving a passage for fire to spread quickly into adjoining rooms or floors above. Fortunately, there are several firestopping products available to handle such a situation.
Due to the natural flammability of the penetration itself, intumescent materials installed around combustible pipes must be capable of closing down and sealing the opening created when the penetration burns away. Larger combustible pipes exceed the capabilities of intumescent sealants to properly seal the openings and maintain the desired fire rating. When dealing with larger combustible pipes, intumescent collars or intumescent wrap strips are needed to maintain the required fire rating.
Intumescent collars are usually constructed of galvanized steel bands with specially designed intumescent material inlaid into the band. These collars will have either fixed or adjustable mounting tabs for attachment to the wall or floor assembly. Intumescent collars come in a variety of sizes to handle various sizes and schedules of combustible pipes. Most intumescent collar systems will incorporate a smoke seal utilizing a sealant material within the annular space of the penetration.
Intumescent wrap strips are long strips of highly intumescent material in various widths (usually 1" or 2" in width) that are wrapped around the penetration a pre-determined number of times. The wrap strips are then slid into the annular space within the floor or wall assembly or held in place with a pre-fabricated steel band or retaining collar. Intumescent wrap strips can be slid into the annular space on corrugated metal deck applications, make firestopping combustible pipe penetration easier. There is no need to attach a steel plate to the underside of the metal deck as is required when utilizing intumescent collars.
Large openings and openings with multiple penetrations pose challenges in regard to firestopping. The firestop material should be designed and tested to function properly with various types of penetrations. Large multiple penetration openings can contain combustible penetrations, such as plastic pipes and cables, insulated pipes, cables and cable bundles, cable trays and a wide variety of metallic penetrations. Firestop products for these types of applications include fire blocks, pillows, mortars, composite sheets and innovative fire-rated foams. Many of these products afford the user the ability to re-penetrate the opening with new penetrations or to remove penetrations that may be taken out of service. The ability of the material to easily be removed and reshaped around the new penetrations is extremely beneficial, especially in telecom applications where mining of new cables is an ongoing process.