China Advanced Instruments Co.,Limited latest company blog about ASTM D662 or ISO5659-2

September 3, 2026

ASTM D662 or ISO5659-2

1. What's the application of NBS smoke density test chamber?

The NBS smoke density chamber measures the specific optical density of smoke produced by solid materials under flaming or non-flaming thermal decomposition inside a sealed 0.51 m³ enclosure.

It evaluates how much smoke is generated when materials are exposed to thermal radiation, to assess visibility hazard in fire scenarios. Typical applications:

Cables, plastics, rubber, textiles and interior composite materials
Industries: rail transit, marine, aircraft, building interior materials
Used for material qualification, fire safety screening and quality control. Optional extension: can sample flue gas to test combustion toxic gas.

2. Difference between ISO 5659-2 and ASTM E662

Both standards use the same NBS closed chamber and photometric smoke measurement principle, but there are key differences:

Item	ASTM E662	ISO 5659-2
Specimen mounting	Vertical sample	Horizontal sample
Radiant heater	Flat panel radiant heater, fixed 25 kW/m²	Cone radiant heater; 25 kW/m² or 50 kW/m² selectable
Main scope	US standard, widely used for aircraft cabin materials, rail interior materials	International standard, mainly for plastics, cables & marine materials (IMO FTPC Part2)
Test result	Specific optical density Ds	Specific optical density Ds
Important note	Test results from these two standards CANNOT be directly compared, due to different heating geometry and sample orientation

ASTM D662 or ISO5659-2

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ASTM D662 or ISO5659-2

1. What's the application of NBS smoke density test chamber?

2. Difference between ISO 5659-2 and ASTM E662