Technical Issues and Common Misconceptions
There are three types of firestop pillows:
- rockwool batts with intumescent resin inside plastic bags
- vermiculite with intumescent graphite inside of fibreglass bags
- intumescent foam rubber
A hose-stream test, which is mandatory for firestops in the United States and often used in Canada, qualifies the openings and firestop pillow combinations as effective against the force of a 30 psi water stream. The pillows are compressed to provide sufficient strength to withstand the hose stream impact of the test. To accommodate larger openings that can allow the pillows to become dislodged, wire mesh is sometimes used. As a particular compression rate is required for each for each hole, the area of the opening less the area covered by the penetrating items is calculated, resulting in the number and size of the pillows to be installed. Without this information, there is no evidence the installation conforms with the requirements of the certification listing. As penetrants are exchanged or removed, this calculation is redone to maintain compliance with the certification listing.
An installation that meets listing and approval use and compliance usually requires pillow coverage between cables. The type and size of the pillows used must be matched to the exact cabling per the certification listing. Smoke will migrate through the interior of a cable bundle if the bundle is not opened up and sealed on the inside during the installation of any firestop, regardless of whether the firestop is intumescent or not. If mesh is used, mechanical fasteners are required, potentially negating the perceived benefits of fast installation and "re-enterability" that is typically purported to be provided by this technology.
Intumescent foam rubber firestops utilize Bayer Fomox intumescent foam, which can be extruded into various shapes. For countries that use a hose-stream test, the Fomox is reinforced with intumescent graphite, whereas for those who do not use a hose-stream, this ingredient is omitted.
Read more about this topic: Firestop Pillow
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