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NFX10-702 Determination of the opacity of smoke
NFX10-702 Determination of the opacity of smoke –Standard
NFX10-702: Fire test methods- Smoke emission- Test of measurement of specific optical density of smoke by the combustion or the pyrolysis of solid materials
NF X 10-702 Determination of the opacity of smoke-General
The NF X 10-702 standard is a test method for the evaluation of smoke opacity. This standard can be used whenever a smoke opacity measurement is required on any type of material with respect to the requirements given in other reference documents. The NFX 10-702 test is mainly used within the frame of the F classification which is described in the NF F 16-101/102 standards.
NF X 10-702 Determination of the opacity of smoke-Principle
The aim of this test method – NF X 10-702 – (“Test for measuring the specific optical density of smoke emitted by the combustion or pyrolysis of solid materials”) is to expose a material to specified thermal conditions of pyrolysis and combustion in a continuous procedure. The change in optical density of the smoke produced when dispersed within a fixed volume of air is recorded throughout the period of test. The smoke density is measured using a white light beam which runs from the base of the chamber to a detector in the roof of the chamber, as smoke is produced less of the light reaches the detector. The resulting smoke density / time curve is used to calculate the smoke index. The actual values we record are: VOF4 value = a measurement of the rate of smoke production during the first four minutes of the test.
VOF4 is calculated as follows: VOF4 = Ds1min + Ds2min + Ds3min + (Ds4min/2)
Where Ds1min, Ds2min, Ds3min and Ds4min are the values of the specific optical density recorded at the 1st, 2nd, 3rd and 4th minutes respectively. Dsmax is the maximum specific optical density obtained within the 20 minutes test period.
Calculation of F rating:
The CIT, VOF4 and Dsmax values are combined in a weighted calculation in order to determine a ‘Smoke Index’ S.I.. It is this value that is used to provide an F rating.
Smoke Index (S.I.) = Dsmax/100 + VOF4/30 + CIT/2
NFX10-702 Smoke emission test – Relative Standard
NFX70-100:Firebehaviourtests–Analysisofpyrolysisandcombustiongases-Pipestillmethod
NFF16-102:Railwayrollingstockfirebehaviourchoiceofmaterials-ElectricalEquipment
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