Flame Spread — ASTM E84 / ISO 5658-2 / IMO A.653(16)

What Is Flame Spread?

Flame spread test is the flame propagation speed measured on the material surface under a defined flame and heat flux; It is the test in which it is classified as flame spread index or critical heat flux.

Purpose of Flame Spread

The aim is to classify the contribution of the surface material to the spread of fire.

Which Products Is Flame Spread Applied To?

Interior surface coatings
Ship and train interior materials
Insulating surfaces
Cable and pipe coatings

In Which Sectors Is Flame Spread Used?

ConstructionConstructionDemiryoluElectricalConsumer Products

Standards Related to Flame Spread

ASTM E84 (Steiner tunnel)
ISO 5658-2
IMO A.653(16)
EN ISO 11925-2
UL 94flammability class in plastic materials test
EN 13501Fire classification of building products test
ASTM E84flame spread on the surface test
ASTM E119Fire resistance in building elements test

Flame Spread Conditions

ASTM E84: 10-minute experiment in horizontal tunnel; flame spread index (FSI) and smoke development index (SDI)
ISO 5658-2: Flame propagation under the heat flux gradient from the side surface; critical heat flux (CFE) is measured
Specimen orientation: Defined in the method; horizontal or vertical
Assessment: Classification as index or critical heat flux

Equipment for Flame Spread

Steiner tunnel (ASTM E84)
ISO 5658-2 flame spreader
smoke measurement system
Heat flux meters

Sample Requirements for Flame Spread

Sample size is defined in the standard according to the method
The sample must represent the actual end-use assembly
Conditioning is defined in the standard
The number of specimens is defined in the standard

Duration of Flame Spread

Typically 3–6 weeks depending on the method.

Flame Spread Procedure

1The method and target classification are determined.
2Samples are prepared and conditioned.
3It is installed in the experimental setup.
4Flame is applied and progress is monitored.
5The index or critical heat flux is calculated.
6Classification is given.

Flame Spread Acceptance Criteria

The acceptance criteria are the index or critical heat flux limits given in the applied standard and relevant regulation.

Evaluation of Results

ASTM E84 indexes and Euroclass or ISO 5658-2 results are not interchangeable; Different geometry, heat flux and duration are used. North American and European requirements require separate testing.

Flame Spread Report

Standard and method applied
Sample description and assembly
Test conditions
Flame spread index or critical heat flux
Classification

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

Building fire regulations
IMO FTP Code (marine applications)

Fire Testing — What Does This Testing Field Cover?

The section below describes the field that the Flame Spread test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Fire testing measures two different concepts, and confusing them is the most common mistake in the field. REACTION to fire describes how much a material contributes to the start and growth of a fire. RESISTANCE to fire is the ability of a building element to hold a fire back for a defined period. One is a material property, the other a property of an element.

On the reaction side, ignitability, flame spread, heat release, smoke production, flaming droplets and toxic gas release are measured. The result is translated into an EN 13501-1 class in Europe, ASTM E84 indices in North America and a UL 94 class for appliance plastics. These three systems cannot be converted into one another; their scales and set-ups differ.

On the resistance side, furnace tests are carried out. The element is exposed to a defined temperature-time curve and it is measured how long it maintains three functions: load bearing (R), integrity (E) and insulation (I). For a fire door, the designation EI 60 says the element maintains its integrity and insulating function for sixty minutes.

SCALE is decisive in this family and directly affects cost. Small flame tests are suitable for screening materials and are fast and inexpensive. But real fire behaviour changes with scale: a material that self-extinguishes on a small specimen may sustain a flame over a large surface. Large-scale set-ups such as the room corner test and full-scale facade tests are therefore indispensable in critical applications.

Facade systems have become the most sensitive subject in the field in recent years. The rapid spread of facade fires in tall buildings has led national regulations to require large-scale facade testing. What is assessed here is not a single material but the SYSTEM: insulation, cladding, air cavity, fixings and fire barriers are tested together.

Smoke and toxicity form a separate body of work, because most deaths in a fire are caused by smoke rather than flame. In rail systems and on ships, smoke density and gas toxicity measurements are mandatory items; in an enclosed space the time available for evacuation depends on these values.

Cables have a sub-body of their own. A cable bundle inside a building can form a serious path for fire to spread between floors; flame spread, smoke production, halogen content and circuit integrity are therefore assessed for cables under separate standards, and in Europe the EN 13501-6 classification is used.

Method groups in this field

Non-combustibility and calorific value
The EN ISO 1182 non-combustibility furnace and EN ISO 1716 gross calorific value; the determinants of classes A1 and A2.
Single burning item (SBI)
EN 13823; heat release, flame spread and smoke production are measured together in a medium-scale corner set-up.
Small flame
Ignitability with a single flame source to EN ISO 11925-2; UL 94 horizontal and vertical burning; needle flame and glow wire.
Cone calorimeter
ISO 5660 / ASTM E1354; heat release rate, total heat release and smoke production are measured. The most informative test in material development.
Fire resistance
Furnace tests with the standard temperature-time curve; separate set-ups for doors, walls, floors, glazing and service penetrations.
Large scale
Room corner test (ISO 9705, NFPA 286), facade fire tests and vertical flame spread tests on cable bundles.
Smoke and toxicity
Optical smoke density, smoke gas analysis and toxicity indices; mandatory in rail systems and marine.

Commonly confused in this field

Reaction to fire and resistance to fire are different concepts; the specification must be explicit about which is required.
UL 94, ASTM E84 and EN 13501-1 results cannot be converted into one another.
A small-scale result is not evidence of large-scale behaviour; large-scale testing is required in critical applications.
A class is valid together with the end-use installation of the product; a different substrate or air cavity changes the result.
For facade systems a result for a single material is not sufficient; the system must be tested as a whole.
The fire class of a product does not show the fire resistance of an assembly made from it.

Which decisions these results support

The fire class in the declaration of performance for construction products
Regulatory compliance in the selection of cables, flooring and interior linings
Approval of interior materials for rail vehicles, ships and aircraft
Approval of the facade system design
Meeting insurance and project specification requirements

Related Tests

Frequently Asked Questions About Flame Spread

According to which standard is Flame Spread made?

Flame Spread is executed in scope ASTM E84 (Steiner tunnel), ISO 5658-2, IMO A.653(16) and EN ISO 11925-2. The limit values and acceptance criteria to be applied are defined in the product standard; The version valid for your product is confirmed in writing at the offer stage.

Which products does Flame Spread apply to?

Mainly applied to Interior surface coatings, Ship and train interior materials, Insulating surfaces and Cable and pipe coatings. Whether your product is included in the scope is determined by examining its technical specifications and intended use.

Under what conditions is Flame Spread done?

The determining parameters are: ASTM E84 — 10-minute experiment in horizontal tunnel; flame spread index (FSI) and smoke development index (SDI), ISO 5658-2 — Flame propagation under the heat flux gradient from the side surface; critical heat flux (CFE) is measured and Specimen orientation — Defined in the method; horizontal or vertical. The full terms are in the "Test Conditions" section on the page and vary depending on the product standard.

What kind of sample is needed for Flame Spread?

Sample size is defined in the standard according to the method, The sample must represent the actual end-use assembly and Conditioning is defined in the standard. The number of samples is determined according to the product standard and the scope to be reported.

How long does Flame Spread take?

Typically 3–6 weeks depending on the method. This duration belongs to the experiment itself; sample preparation, queuing and reporting are also evaluated. A realistic schedule for your product is given in the offer.

What is the Flame Spread result called "appropriate"?

The acceptance criteria are the index or critical heat flux limits given in the applied standard and relevant regulation.