ISO 11907-4:1998

Overview

ISO 11907-4:1998 - Plastics - Smoke generation - Determination of the corrosivity of fire effluents - Part 4 specifies a laboratory dynamic decomposition method using a conical radiant heater to quantify the corrosive effect of combustion effluents from plastic materials. The test measures metal loss (corrosion) on standardized targets by monitoring the increase in electrical resistance of a metal circuit exposed to combustion products. Results are intended for material evaluation, product development and research - not as a standalone measure of real-fire hazard.

Key topics and technical requirements

• Test principle: Two-stage test - (1) preliminary mass-loss tests under a set irradiance to determine combustible mass loss; (2) dynamic exposure where combustion products are routed through an exposure chamber holding corrosion targets until 70% of the measured mass loss is reached.
• Irradiance and heating: Recommended irradiance 50 kW/m², with capability up to 100 kW/m², provided by a conical radiant heater (heater element rated ~5 000 W/240 V).
• Specimens: Five specimens, nominally 100 mm × 100 mm, thickness up to 12 mm (typical 6 mm).
• Corrosion measurement: Change in electrical resistance of target circuits is converted to metal thickness loss. Instrument resolution specified to permit thickness-change detection of not worse than 5 nm.
• Sampling and flow: Gas-sampling system channels a portion of decomposition products to a corrosion-resistant exposure chamber; sample pump flow monitored (≈ 4.5 l/min noted in the standard).
• Exposure timing and conditioning: Targets exposed to combustion products for 1 hour, then conditioned 24 hours in an environmental chamber at about 23 ± 2 °C and 75 ± 5 % RH before final measurement.
• Apparatus elements: Cone heater, temperature controller, thermocouples, load cell for mass-loss monitoring, exhaust and filtering, gas-collecting funnel, rigid/flexible heated tubing, and a Kelvin-bridge-type corrosion-measuring instrument.
• Safety and limitations: The standard warns against using results alone to appraise real fire risk and stresses operator safety (ventilation, PPE, handling hot components).

Applications and users

• Practical uses: Material selection, comparative corrosivity screening, product development, research on fire effluents, and supplemental data for fire-safety assessments.
• Typical users: Fire safety engineers, materials scientists, testing laboratories, plastics manufacturers, and regulatory bodies involved in product design, qualification and safety evaluation.

Related standards

• ISO 11907 series (Part 1 Guidance; Part 2 Static method; Part 3 Dynamic decomposition using a travelling furnace)
• ISO 5660-1 (Cone calorimeter method) - cone calorimeter equipment can be used if fitted with the required gas-sampling system.

Keywords: ISO 11907-4:1998, plastics smoke generation, corrosivity of fire effluents, conical radiant heater, dynamic decomposition method, corrosion by metal loss, exposure chamber, cone calorimeter.