ASTM E662 Standard Test Method for Specific Optical Density of Smoke Generated by Solid Materials

Get Certified ASTM E662 Testing for Reliable Smoke Generation Assessment

Smoke reduces visibility during a fire, and materials differ in how much smoke they produce as they decompose or burn. ASTM E662 defines a standard test method that enables engineers to determine the optical density of the smoke that a material produces under defined exposure conditions. The results enable manufacturers to make informed material selection and design decisions for products that involve smoke generation in buildings, transport, and other applications.

The scope of ASTM E662 includes:

• Material type: Solid materials and assemblies mounted in the vertical position, in thicknesses up to and including 25.4 mm (1 in.).
• Purpose: Determination of the specific optical density of the smoke that a specimen generates under specified fire exposure conditions.
• Properties evaluated: Attenuation of a light beam by smoke that accumulates in a closed chamber, expressed as specific optical density.
• Testing method: Technicians expose a vertically mounted specimen to a radiant heat source under nonflaming and flaming conditions while a photometric system measures the light that passes through the smoke.
• Results: Specific optical density, which the analyst derives from a geometrical factor and the measured optical density, a measure of smoke concentration.
• Test limitations: Values apply only to the specimen form and thickness tested and do not represent inherent properties of the material. The standard gives no basis for predicting smoke density under other fire conditions, and it does not by itself incorporate all factors required for fire hazard or fire risk assessment.
• Use conditions: Results are valid only for the fire test exposure conditions that the method describes. The standard regards inch-pound values as standard, and the SI values in parentheses are for information only.
• Applications: Comparison of the smoke-generating behavior of materials and assemblies, product development, and quality control.

What are the Uses of ASTM E662 Testing?

ASTM E662 testing supports engineers in assessing the amount of smoke that a solid material or assembly produces under controlled conditions. Manufacturers can use the results for comparing materials and supporting product development.

• Determines the specific optical density of the smoke from solid materials and assemblies.
• Measures the smoke-generation properties of solid materials and assemblies under nonflaming and flaming exposure conditions.
• Compares the smoke-producing characteristics of materials, thicknesses, and assemblies.
• Supports material selection and product development where smoke generation matters.
• Assists manufacturers in quality control of materials and assemblies.

Which Materials Can Be Tested Under ASTM E662?

ASTM E662 applies to solid materials and assemblies that technicians can mount in the vertical position in thicknesses up to and including 25.4 mm (1 in.). The values that the test method produces apply only to the specimen form and thickness that the technician tests. Therefore, the specimen should be representative of the material or assembly under evaluation. Before testing, the technician prepares a specimen of the specified size and mounts it in the holder.

Why is ASTM E662 Important?

ASTM E662 is essential because it provides manufacturers with a standard procedure for measuring the amount of smoke that a solid material produces on one particular photometric scale. The photometric scale that the standard uses is similar to the optical density range for human vision, but the test method does not involve physiological response. The values that the test method produces depend on the specimen thickness and density, among other factors, and they respond to variations that other test methods may mask completely. ASTM E662 defines the specimen form, exposure conditions, and measurement procedures that relate the optical density to the smoke produced by the specimen. This enables engineers to compare the materials based on the results of the test method.

ASTM E662 Testing Process and Data Collection

Technicians mount the specimen vertically in the holder and close the chamber. The technician then exposes the specimen to the radiant heat source with or without the additional flaming exposure to cause the specimen to pyrolyze or burn. As the specimen produces smoke, the photometric system measures the amount of light beam that passes through the chamber. The analyst calculates the specific optical density from the measured optical density and the geometrical factor and records the values for each exposure condition. The analyst also records the specimen form and thickness because the values apply to this particular specimen only.

Common Challenges and Troubleshooting

Accurate ASTM E662 results depend on a consistent specimen form, correct mounting, and a controlled radiant exposure. The standard describes the test as complex, and the data respond to variations that other test methods may treat as insignificant. Specimen thickness and density affect the result, so technicians record both and compare only specimens of the same form and thickness. Technicians also standardize the radiant heater output with the radiometer and follow the specified mounting and exposure steps closely.

• The analyst reports the specific optical density that results from the geometrical factor and the measured optical density.
• The analyst reports the specific optical density at the specified times and the maximum value that the test reaches.
• The analyst records the exposure condition, nonflaming or flaming, for each result.
• The analyst records the specimen form and thickness with each result.
• The analyst treats the results as valid only for the exposure conditions of the test and not as inherent properties of the material.

Link to ASTM E662