EU CLASSIFICATION OF CONSTRUCTION PRODUCTS FOR RESISTANCE TO FIRE - EXCLUDING VENTILATION SERVICES - AN OVERVIEW OF EN 13501-2.

Why the need for a new system?
In the past, the fire testing of construction systems for Resistance to Fire has varied in different EU member states. This is because each country has evolved its own methods, using furnaces of different sizes, with different fuels, and different characteristics. While the nominal fire exposure has been similar, these variations mean that test results from different countries are difficult to compare. Some countries have different requirements to others.

The new Euroclass system for Resistance to Fire, prEN 13501 -2, reflects new fire test provisions for these differences, not by changing the design of furnaces, but by rationalising the method by which the temperatures in the furnace are measured, using new 'plate thermocouples', higher pressurisation of the furnaces and other adjustments.

In general, this means that test results are comparable across the EU, regardless of the national location of the fire test laboratory. For the UK, it means that the test exposure is a little more severe than before, and some products may be 'rated' or classified at a slightly poorer level than previously. This is partly due to new harmonised Resistance to Fire test methods and the new EU classification of fire resistance data provided by these tests.

New Fire Classification Methods
When compared to existing UK nomenclature and that of some other countries, the way the EU expresses the classification of the test results is different. Despite the changes, requirements already used in most EU member states will still be available in the overall classification.

EU member states will be permitted to select the particular performance appropriate to national requirements, and may well ignore some parts of the classification. However, manufacturers will be required to use the entire classification system when supplying construction systems into other EU countries.

Fire Exposure Level
In most system applications, the fire exposure conditions will be the same, but some applications require different fire exposures to be evaluated. Fire tests will be made selecting from 5 fire exposure scenarios:

5 FIRE EXPOSURE SCENARIOS
[1] The standard temperature-time curve (post flashover)
[2] The slow heating curve (smouldering fire)
[3] The 'semi-natural fire'
[4] The external fire exposure curve
[5] Constant temperature attack

................

[1] The standard temperature-time curve (post flashover fire)
This is defined by:

Temperature T = 345log10(8t +1) +20

Where t = time for exposure [minutes], T = 0C. This is the generalised fire scenario that most construction systems will be subjected to, representing a fully developed fire in a compartment.

[2] The slow heating curve (smouldering fire)
This exposure is only suitable when heat reactive elements may be susceptible, or reduced by exposure, in the growth stage of a fire below 500 0C. Further details are given in the test document EN 1363-2

[3] The 'semi-natural fire'
In this fire exposure, the fire gas temperatures adjacent to the soffit of a ceiling shall reach 1000 0C within 10 to 20 minutes of the start of the test, and is usually provided by fire from a softwood timber crib. Further detail is available in test method prENV 13381-1

[4] The external fire exposure curve.
This is a time-temperature relationship representing the exposure of the external face of a wall to a fire emerging from a window in the building, or from a free burning external fire. Further detail is available in test method EN 1363-2

[5] Constant temperature attack.
Some elements will be evaluated by a notional constant value of temperature. For example -
20 0C for evaluating the leakage rate of smoke control doors at ambient temperature.
200 0C for evaluating the leakage rate of medium temperature smoke control doors.
500 0C for evaluating the fire performance of raised floors.
1000 0C for evaluating soot fire resistance of chimneys and chimney related products.

Resistance to Fire Characteristics
EC document Interpretive Document2 requires the assessment of the characteristic

'Load-bearing capacity and/or Integrity in fire and/or Insulation in fire'.

Other characteristics are also named, as indicated in the following table. Many of these characteristics will only be used according to particular member state requirements. However, manufacturers who export goods to other EU Member States will be required to have data available on all the 'characteristics'.

Summary of Resistance to Fire characteristics :

Classification Periods of Fire Resistance
The classification period is declared in minutes, using one of the periods 15, 20, 30, 45, 60, 90, 120, 180, 240 or 360. The requirement may vary between different EU member states.

Declaration of Performance
Combinations of 'designatory letters', as appropriate to the application, are used as part of the classification of performance for Resistance to Fire, supplemented by the time, 'tt' in minutes, of the nearest lowest class satisfied. When characteristics are combined, the time declared will be that for the characteristic having the shortest time.

For example, an element with a load-bearing capacity of 155 minutes, integrity of 80 minutes, and insulation of 42 minutes will be classified as R 120 / RE 60 / REI 30.

For load-bearing elements, the classes shall be expressed as -

REI tt, - where 'tt' is the time satisfying the load bearing capacity, integrity & insulation criteria.
RE tt - where 'tt' is the time satisfying the load-bearing capacity & integrity criteria.
R tt - where 'tt' is the time satisfying the load-bearing capacity criterion alone.

For non load-bearing elements, the classes are -

EI tt - where 'tt' is the time satisfying the integrity and insulation criteria
E tt - where 'tt' is the time satisfying the integrity criterion alone.

Other Classification Parameters :

ADDITIONAL CLASSIFICATION PARAMETER

W - when the radiation criteria is required and has been satisfied, the designatory
Letter W is used in a similar way to R, E and I criteria, e.g. REW 30 or EW 30.

EXPANDED PERFORMANCE PARAMETERS
Similarly, the classification may be expanded, according to requirements, as

M -	used as REI 30-M
C -	for doors and shutters equipped with a self-closing device, the expansion is EI2 30-C0, where the classes 'C0 to C5' are defined in test document prEN 13916.
S -	for elements with requirements on smoke leakage, as EI2 60-Sm when the classification is determined under ambient conditions Sa and/or medium temperature conditions Sm.
IncSlow -	where the response to the slow heating curve has been additionally evaluated, as EI 30-IncSlow.
sn -	where the semi-natural fire is an additional regulatory requirement to the standard time-temperature exposure [ only relevant for lightweight horizontal protective membranes with low thermal inertia ], and expressed as R 60-sn.
ef -	where performance against external fire exposure instead of the standard time-temperature exposure is determined, and expressed as EI 60-ef.
r -	where performance against constant temperature attack of 500 0C [reduced temperature exposure] instead of the standard time-temperature exposure is determined, expressed as RE 30-r.

PARTICULAR PERFORMANCE PARAMETERS

G - The performance parameter G will be used for chimneys and chimney related products designed to be resistant to soot fires, as tested in prEN 13216-1.

K - The performance parameter K, Fire Protection Ability, will be used for any covering which provides fire protection to products behind it, as tested in prEN 14135 for various periods.

Presentation of Classification
The combination of R, E, I and W shall be deduced from test data. Expanded performance parameters shall be added when relevant.

The classification shall be presented according to the following template, and for load-bearing elements the applied load and/or load level shall be included in the classification report.

R

E

I

W

t

t

-

M

C

S

IncSlow

sn

ef

r

The document EN 13501-2 also lists the tests to be carried out per application.

Other Dedicated Classifications:

Other classification terminology is used for particular applications, as indicated in the following list:

CLASSIFICATION OF FACADES (CURTAIN WALLS) and EXTERNAL WALLS (INCLUDING GLAZING)

Relevant tests include prEN 1364-3 and prEN 1364-4 for parts of curtain walls.
When the elements are tested from both sides, with standard-time temperature curve from inside, and external fire exposure curve from outside, the lowest time determines the classification

Tests and classifications may be performed from 1 side only, inside or outside, and in these cases, identified by -

i --> o when classification is envisaged from inside to outside.

o --> i when classification is envisaged from outside to inside.

o <--> i when classification is envisaged from inside to outside and outside to inside.

i.e. compare EI 60 (i -->o) with fire on inside only, with EI 60 (o <--> i) for fire exposure from both outside and inside.

CLASSIFICATION OF CEILING MEMBRANES WITH INDEPENDENT FIRE RESISTANCE
Tests are conducted to EN 1364-2 and could be for fire exposure above the ceiling [a], or from below the ceiling [b], or from both above and below the ceiling [ a and b].

So for a ceiling membrane providing 30 minutes integrity and insulation, the possibilities are respectively expressed as -

EI 30 (a -->b) or EI 30 (b --> a) or EI 30 (a <-->b)

CLASSIFICATION OF PENETRATION SEALS [FOR PIPES]
When penetration seals for piped services are to be classified, 4 different pipe end configurations are defined in the test standard prEN 1366-3, with ends capped or uncapped inside/outside the fire test furnace.
The classification is specified for the relevant condition as

EI 30 U/U or similar

In accordance with the table below, which defines the Pipe End Configuration