12. PERFORMANCE OF CONSTRUCTION MATERIALS UNDER FIRE
12.1 Mineral wool versus other types of insulation
Mineral wool is an insulation that has low thermal conductivity, minimizes heat conduction and is a key component used in many firestop systems as a backing material for the firestop sealant to be installed against when you have larger annular space.
The reason for its popularity as an ideal firestop backing material is that it does not conduct heat and can resist temperatures over 1,000 ° C. Since its density is over three times more than fiberglass insulation, mineral wool also offers better accoustic insulation properties. Other materials used on site for insulation purposes like foam, fiberglass insulation, backer rods, etc., usually burn easily and quickly in the event of a fire, thus are not suitable alternatives to mineral wool. When inspecting firestopping applications, it is imperative that the proper backing material is installed, including the proper orientation and compression, per the listed firestop system.
12.2 Combustible and non-combustible pipes
Combustible and non-combustible pipes differ when exposed to fire due to the difference in their flammable properties.
Combustible pipes like plastic pipes( PVC) burn away creating a hole / opening in place of the pipe. Combustible pipe penetrations generally require intumescent materials to properly firestop around the penetration. These could be an intumescent sealant or intumescent device such as a firestop collar or firestop cast-in device. Intumescent products consist of materials which rapidly expands when exposed to fire and seals or closes the annular space around the combustible pipe as it burns away.
Non-combustible pipes like metallic pipes does not burn. They melt leaving a char or residue behind. For non-combustible pipes, non-intumescent products such as flexible or elastomeric firestop sealants are generally sufficient to properly firestop a non-combustible pipe penetration. Always refer to a tested UL firestop system or engineering judgment which will identify the appropriate firestopping products to be installed for the specific application.
12.3 Compatibility with CPVC pipes
Chlorinated polyvinyl chloride( CPVC) is a thermoplastic produced by chlorination of polyvinyl chloride( PVC) resin. CPVC is significantly more flexible than PVC, has greater insulating properties than copper and can also withstand higher temperatures.
CPVC is easy to work with, including machining, welding and forming processes. It offers high corrosion resistance at elevated temperatures and it can be bent, shaped and welded, making it a better choice for wide variety of processes and applications. It also has fire-retardant properties.
When firestopping CPVC pipes, care must be taken not to allow the pipe to be exposed to any material that may result in a failure. Some sealant may contain phthalates and phosphate esters which can have an interaction with the CPVC pipe, which can then cause it to weaken, split or crack. Therefore, it is important that the products that are used in conjunction with these CPVC piping systems do not contain any of these components and are chemically compatible.
Inspection Guidebook 26 / 28