BS 7990:2003

This standard BS 7990:2003 Tube furnace method for the determination of toxic product yields in fire effluents is classified in these ICS categories:

• 13.220.99 Other standards related to protection against fire

This British Standard describes a tube furnace method for the generation of fire effluent for the identification and measurement of its constituent combustion products. It uses a moving test specimen and a tube furnace at different temperatures and air flow rates as the fire model.

The method can be used to model a wide range of fire conditions by using different combinations of temperature, non-flaming and flaming decomposition conditions and different fuel/oxygen ratios in the tube furnace. These include the following types of fires, as detailed in BS 7899-2:1999, Table 8:

• Stage 1: Non-flaming:
  • Stage 1b) Oxidative pyrolysis from externally applied radiation;
• Stage 2: Well ventilated flaming (representing a flaming developing fire);
• Stage 3: Less well ventilated flaming:
  • Stage 3a) Small vitiated fires in closed or poorly ventilated compartments;
  • Stage 3b) Post-flashover fires in large or open compartments.

For each flaming fire type the minimum conditions of test are specified in terms of the equivalence ratio ϕ as follows:

• Stage 2: ϕ <0.75;
• Stages 3a) and 3b) ϕ = 2 ± 0.2.

NOTE 1 Guidance on choice of additional decomposition conditions is given in Annex A.

The test method described in this standard can be used solely to measure and describe the properties of materials, products or systems in response to heat or flame under controlled laboratory conditions. It is not suitable to be used by itself for describing or appraising the fire hazard of materials, products or systems under actual fire conditions or as the sole source on which regulations pertaining to toxicity can be based.

NOTE 2 Guidance on calculation of lethal toxic potency of combustion products is given in Annex B.

NOTE 3 Guidance on the application of data from the tube furnace test to assessment of toxic hazard in fires, to health and safety assessments of combustion products and to environmental hazard assessment of combustion products is given in Annex C, Annex D and Annex E, respectively.