Plastics Smoke generation Part 1 Guidance on optical densitv testing (BS EN ISO 5659-1:1999 This standard was drawn up by Technical Committee PRI/26
The standard was approved by CEN on May 6 1999.
This short guidance standard discusses smoke testing particularly in relation to testing to ISO 5659 Part 2, which is a static, cumulative single-chamber test procedure. This development of the original smoke chamber test (BS 6401, ASTM E662 etc) enables a better assessment to be made of smoke generation from materials in a horizontal orientation and under a wider range of heat fluxes using a truncated cone heater similar, but smaller, to that used in the cone calorimeter and in the ignitability test apparatus, designed to ISO 5657 and BS 476 Part 13.
The standard opens with a discussion on different fire scenarios and on fire models with reference to the classification given in ISOITR 9122-1. A treatment of the principles of smoke density measurements comes next, in which the point is well made that some test methods report smoke simply in terms of light transmission, which is inadequate and can lead to false conclusions being drawn. The point is also well made that there are no means provided for predicting the ability of the human eye to see through smoke, nor to evaluate the effect of irritants in further restricting the visual range. It is suggested that eye irritants could reduce vision by anything between 50 to 95%.
The next section looks at factors which affect smoke production. There are sub-sections dealing with the mode of decomposition, ventilation and the burning environment, time and temperature effects and lastly removal mechanisms for smoke particles.
Finally the standard addresses the applicability of results. The point is made that an isolated test can only indicate the response of a material in the particular fire model selected. Thus ISO 5659-2 should not be the only criterion for assessing the potential smoke obscuration hazard of the product in use.
The standard can be purchased from Customer Services, BSI Tel: 44(0) 20 8996 9001 or by Fax: 44(0) 8996 7001.