What is the difference between reaction to fire and resistance to fire?

How do the two fire test methods relate to Rytons A1® Classified range?

As a leading manufacturer of non-combustible metal ducting kits for high-rise building projects, we often speak to clients unfamiliar with the difference between fire test methods reaction to fire and resistance to fire. Some common misconceptions are that the terms mean the same, are interchangeable, or that a construction product classified as one will automatically meet the requirements of the other.

Reaction to fire and resistance to fire are the results of two different fire testing methods. Here we outline those methods and how they relate to Rytons A1® Classified range.

Reaction to fire testing

This is the immediate reaction of a material in a fire, how it will ignite (its combustibility) and how it will contribute to the growth of the fire. For construction products, reaction to fire is expressed as a Classification, tested according to European Standard EN 13501-1:2018.

There are seven reaction to fire Classifications, grading products from non-combustible to easily flammable. Materials Classified A2 to D also obtain an additional Classification regarding the production of smoke and flaming droplets and/or particles.

Reaction to fire Classification without testing
Referenced in BS EN 13501-1, European Commission Decision 96/603/EC contains a list of materials that are considered to be Class A1 without testing. The decision states that reaction to fire testing is not required for Class A materials and products made from them.

Reaction to fire Classification of Rytons A1^® metal range
Rytons range of non-combustible metal construction products are made from materials considered to be Class A1 without testing. Additionally, all powder coating used on Rytons A1® Classified products is non-combustible achieving Class A2-s1, d0.  Note: Class A2-s1, d0 is the highest fire rating a coating can achieve due to the requirement for a minimum dry film thickness to be above 60 microns.

Non-combustible construction products in high-rise buildings
To resist the spread of fire over walls and from one building to another, materials forming part of the external wall of a high-rise relevant building must be non-combustible to A1 or A2-s1, d0 Classification.

Resistance to fire testing

This is how a material resists fire and how long it will prevent fire and smoke from spreading through the compartmentation system of the building.

Fire resistance is measured in duration (30, 60, 90 or 120 minutes), in three main categories:

• Supporting capacity (R)
• Integrity (E)
• Insulation (I)

Fire resistance and ventilation ducts
In the event of a fire, preventing the spread of fire, smoke and gases through ventilation ductwork is an essential fire protection measure. Depending on the size and shape of the ductwork, fire stopping can be achieved using various intumescent products such as grilles, wraps, collars or cuffs.

Fire stopping PVC ventilation ducts
This can be achieved using an intumescent grille, which allows air movement until, in the event of a fire, the intumescent louvres activate, expanding to seal the duct and prevent the spread of fire for a specified period. Alternatively, a fire wrap, collar or sleeve can be fitted around the plastic ductwork. These types of products expand in the event of a fire, crushing the PVC and preventing the spread of fire for a time period.

Fire stopping Rytons A1^® metal ventilation ducts
High-rise buildings require the use of non-combustible metal ducting. To fire stop Rytons A1^® metal ducting, we recommend placing intumescent products near the metal duct, but clear of it, within the attached plastic ducting. This is due to intumescent fire wraps, collars and cuffs not generating sufficient pressure to crush and seal galvanised steel, and no test evidence to show that an intumescent grille will perform in metal ductwork as it does in plastic.

For further information, or to discuss Rytons A1® Classified range, please do not hesitate to call our technical sales office on 01536 511874 or email admin@rytons.com.