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ISO 5660

SO 5660-1:1993

The Cone Calorimeter test is at present the most advanced method for assessing materials reaction to fire. The method follows the procedure given in international standard ISO 5660-1:1993(E). Additionaly, measurements of smoke production and production of toxic gases can be performed during the test.

The test gives a possibility to evaluate:

  • Ignitability
  • Combustibility
  • Smoke production
  • Production of toxic gases


The surface of the test specimen is exposed to a constant level of heat irradiance, within the range 0-100 kW/m2, from a conical heater. Volatile gases from the heated specimen are ignited by an electrical spark igniter. Combustion gases are collected by an exhaust hood for further analysis. This gas analysis makes it possible to calculate heat release rate and to assess production of toxic gases from the specimen. Smoke production is assessed by measuring attenuation of a laser beam by smoke in the exhaust duct. The attenuation is related to volume flow, resulting in a measure of smoke density called smoke extinction area [m2/s].

The specimen is mounted on a load cell which records the mass loss rate of the specimen during combustion.

A thorough analysis requires testing at several irradiance levels. Typical levels of irradiance are 25, 35, 50 and 75 kW/m2. According to ISO 5660-1:1993(E), three specimens shall be tested at each heat flux level.


The test report contains information about dimensions, pretreatment and conditioning of the test specimens, and information about the test conditions. The following test results are tabulated:

  • Time to ignition [s]
  • Total heat released [MJ/m2]
  • Maximum heat release rate [kW/m2]
  • Average heat release rate after 180 s and after 300 s [kW/m2]
  • Effective heat of combustion [MJ/kg]
  • Average smoke production [m2/s]
  • Production of CO (carbonmonoxide) [g]
Output data are recorded for mass loss, for oxygen, carbon monoxide and carbon dioxide concentrations, for smoke density and fire effluent flow as a function of time. The raw data is manipulated and heat release rates and effective heats of combustion are calculated together with averaged data calculated by oxygen consumption calorimetry. Fire gas and smoke yields per gram of sample burnt are also calculated. Typical output summaries may include:

Cone test parameter

Typical material values

Time to ignition

3 – 600 s

Flameout time

Up to 1200 s

Time to Peak Rate of Heat Release

Often shortly after ignition for non-FR materials but some may show two peaks

Peak Rate of Heat Release

~ 250 kW m-2 but up to 650 kW m-2

Ave (3 min) rate of heat release

~100 kW m-2

Effective heat of combustion

30 MJ / kg

Total Heat Release

~ 100 MJ m-2

It is also possible to measure production of other gas components, like HCN (cyanic acid).

The following results are given graphically for each of the applied irradiation levels:

  • Heat release rate [kW/m2]
  • Rate of smoke production [m2/s]
  • Rate of production of CO and HCN [g/s]
  • Specimen mass as a function of time [g/s]

 The unit m2 is related to specimen area


The surface of the specimens shall be essentially flat. The specimens shall be representative of the product, and as far as possible be similar to the final product. A complete test requires that at least 12 specimens are available.

Dimensions of the specimens:
Area: 100 mm x 100 mm (+0-5 mm)
Thickness: maximum 50 mm


Typical Operating Conditions

Range of Operating Conditions

Radiant Flux

15 - 75 kW m-2

10 – 100 kW m-2


Very well-ventilated

Controlled Atmosphere version available

Sample dimensions

10cm x 10cm x ~0.5cm

10cm x 10cm x 5cm



Horizontal or Vertical