Pressurisation ductwork

Pressurisation ductwork is a fire protection system. It is used to supply a steady stream of fresh air to any area of refuge or designated emergency evacuation or egress route.

Purpose

* To ensure a positive pressure environment of clean outside air, free from smoke to enable people to either hold out until rescued or to escape with a minimum of dangerous smoke exposure.

Requirements

Typically, pressurisation ductwork is subject to demonstrable product certification on the basis of fire testing (for eampmple, ISO 6944). In the United States, additional hose-stream testing is required to achieve product certification, as the system includes not just a section of ductwork tested in a full scale floor furnace, but also a firestop, which must survive the hose.

Pressurisation systems are evaluated for exterior fire exposure. Grease ducts, on the other hand, are evaluated for interior fire exposures.

ystems

There are two means of providing fire-resistance rated ductwork:

*1. an inherently fire-resistant duct, or proprietary factory assembled chimney pipes, which tend to be made of sheet metal shells filled with mixtures of rockwool, or ceramic fibre and silicon dioxide

:"or"

*2. ordinary ductwork equipped with exterior fireproofing materials, such as blanket rockwool, ceramic fibre or intumescent paint.

History

Grandfathering

The use of drywall shaftwall systems has been common for many years. 3-D full scale fire testing (e.g., ISO 6944) resulted in the first certification listing for an inherently fire-resistant duct. Drywall systems were tested as flat walls and a three-dimensional solution surrounding a real duct with four corners was never done, but are currently accepted in construction.

In Europe, where ISO 6944 originated, rockwool systems, calcium silicate and sodium silicate bound and pressed vermiculite as well as the proprietary DuraSteel systems, have been in use for decades .

ee also

* Heat and smoke vent
* Fire protection
* Passive fire protection
* Duct (HVAC)
* Smoke exhaust ductwork
* Grease duct
* Emergency evacuation
* Area of refuge
* Fireproofing
* Firestop
* Underwriters Laboratories

External links

* [http://www.iso.org/iso/en/CatalogueDetailPage.CatalogueDetail?CSNUMBER=13488&ICS1=13&ICS2=220&ICS3=50 ISO 6944 Abstract]
* [http://www.ul.com/fire/wrapping.html UL treatise on "Wrapping Systems"]