What Is Smoke Density?
Smoke density test is an experiment in which the sample is smoked under a defined heat flux in a closed room, and the rate of smoke reduction in light transmission is measured as specific optical density (Ds) or smoke density index.
Purpose of Smoke Density
The aim is to classify the smoke production of the material in terms of loss of visibility and difficulty in evacuation in case of fire.
Which Products Is Smoke Density Applied To?
- Railway and ship interior materials
- Cable insulation and sheaths
- Building interior coatings
- Aviation cabin supplies
In Which Sectors Is Smoke Density Used?
Standards Related to Smoke Density
- EN ISO 5659-2
- ASTM E662
- ASTM D2843
- EN 61034 (smoke density for cables)
- 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
Smoke Density Conditions
- heat flux
- Heat flux levels defined in the standard in EN ISO 5659-2 (e.g. 25 and 50 kW/m²)
- Alev
- Testing can be done in flame and flameless modes.
- Measurement
- Transmittance by light source and photodetector; Ds and VOF4 are calculated
- Specimen
- Size and thickness defined in the standard; represents the actual product
Equipment for Smoke Density
- Smoke density chamber (NBS type)
- Cone heater and heat flux meter
- Optical system and data recording
- 3 m cable smoke chamber (for EN 61034)
Sample Requirements for Smoke Density
- Sample thickness and surface should represent the actual product
- Conditioning is defined in the standard
- The optical system should be cleaned and reset before each experiment.
- The number of specimens is defined in the standard
Duration of Smoke Density
Typically 2–4 weeks.
Smoke Density Procedure
- 1Samples are prepared and conditioned.
- 2The heat flux is set and verified.
- 3The optical system is reset.
- 4The sample is smoked and the permeability is recorded.
- 5Ds and related quantities are calculated.
- 6Results are compared with the limits.
Smoke Density Acceptance Criteria
The acceptance criteria are the maximum smoke density values given in the relevant product standard (e.g. Ds limits in EN 45545-2).
Evaluation of Results
Heat flux and flame/flameless mode change the result significantly; Comparison cannot be made without reporting these parameters. If the optical windows remain dirty, it indicates the smoke density as falsely high.
Smoke Density Report
- Standard applied
- Heat flux and test mode
- Specimen thickness
- Measured quantities such as Ds, VOF4
- Assessment
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 authorisationsRelated Regulations
- EN 45545 (demiryolu)
- IMO FTP Kodu (deniz)
- Building fire regulations
Fire Testing — What Does This Testing Field Cover?
The section below describes the field that the Smoke Density 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 Smoke Density
According to which standard is Smoke Density made?
Smoke Density is executed in scope EN ISO 5659-2, ASTM E662, ASTM D2843 and EN 61034 (smoke density for cables). 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 Smoke Density apply to?
Mainly applied to Railway and ship interior materials, Cable insulation and sheaths, Building interior coatings and Aviation cabin supplies. Whether your product is included in the scope is determined by examining its technical specifications and intended use.
Under what conditions is Smoke Density done?
The determining parameters are: heat flux — Heat flux levels defined in the standard in EN ISO 5659-2 (e.g. 25 and 50 kW/m²), Alev — Testing can be done in flame and flameless modes. and Measurement — Transmittance by light source and photodetector; Ds and VOF4 are calculated. 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 Smoke Density?
Sample thickness and surface should represent the actual product, Conditioning is defined in the standard and The optical system should be cleaned and reset before each experiment.. The number of samples is determined according to the product standard and the scope to be reported.
How long does Smoke Density take?
Typically 2–4 weeks. 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 Smoke Density result called "appropriate"?
The acceptance criteria are the maximum smoke density values given in the relevant product standard (e.g. Ds limits in EN 45545-2).