How to evaluate fire safety

Reaction to fire

Majority of ROCKWOOL stone wool insulation products are classified as Euroclass A1 – The highest class for non-combustible products that do not contribute to a fire.

The Euroclasses are linked directly to the perceived hazard in a reference fire scenario — a fire in a room —and the large scale test modelling of this scenario was chosen to be the ISO 9705 Room Corner test which is the type of test used also in some worldwide insurance approval schemes.

The reaction to fire class can be different for different products and materials.

Although Euroclass ratings provide information about smoke intensity and production of burning droplets, these are measured using a relatively small fire source (31 kW) and the tested constructions are positioned vertically – both conditions limit the usefulness of such information; the rating depends on the way the product is installed during the tests.

Evaluation of smoke toxicity is not part of reaction to fire classification criteria.

Smoke

Statistics for fire deaths tell a tragic story. Although the exact figures differ, it is obvious that most fire victims die from smoke inhalation*.

It is surprising, then, although some fire classification systems measure smoke intensity, they are almost solely concerned with how the smoke will influence visibility for occupants and fire fighters. The assumption, of course, is that the only concern is for the occupants to be able to see and follow an escape route, and for fire-fighters to be able to see where they are going as they enter a building that is on fire.

This, however, takes no account of the smoke’s toxicity or the fact that there is no direct correlation between the amount of smoke released and its toxicity. A material may give off only a small amount of smoke when it is burning, yet be highly toxic. Two major toxic substances originating from burning organic material – carbon monoxide (CO) and hydrogen cyanide (HCN) can be completely invisible to the human eye.

SMOKE AND FIRECLASSES

A typical example of this approach is the European classification system for reaction to fire of construction products and materials, where smoke opacity is the only smoke-related parameter which is measured and evaluated.
The SBI test —EN 13823 —on which the Euroclass system is based simulates pre-flashover and well ventilated conditions when smoke intensity is significantly lower compared to when a fire reaches or passes the flashover stage.
The resulting three sub-classes – s1, -s2, -s3 are based on smoke optical density measurements and bear no information about toxic threats of smoke and gases released. Although it is the toxic smoke and gases which are most dangerous at fire, current fire classes do not cover that risk.

The other major area of fire testing – fire resistance – provides no information whatsoever about smoke that can be generated by building structure and penetrate to safe parts of the building or contaminate the surrounding area.

* source: Firesafeeurope.org or DFV.org