ASTM E662 Smoke Density Test

What Is ASTM E662 Testing?

ASTM E662 is a standard that gauges a solid material's smoke production during a fire. This standard is specific to solid materials and equipment up to 1 inch in thickness that rests in a vertical position.

Manufacturers must perform an ASTM E662 test to confirm that a material's smoke production falls within the standard's parameters. ASTM E662 testing is a test method that measures the specific optical density of smoke. The test weighs density rather than volume.

Optical density refers to a substance's ability to transmit light. A substance with high optical density transmits little to no light, while a substance with low optical density is mostly transparent.

Smoke detectors read a room's atmosphere to determine the optical density because the presence of smoke will increase a room's optical density. Reading optical density allows a smoke detector to alert occupants when there is danger.

ASTM E662 testing is a requirement in various industries. The test is one aspect of transportation codes that apply to trains and buses, such as National Fire Protection Association 130 and 49 Code of Federal Regulations Part 238. ASTM E662 testing also applies to military specifications like MIL-STD-1623 for Navy ships and submarines.

How Is ASTM E662 Testing Performed?

ASTM E662 testing occurs at a certified laboratory with the amenities to support each of the assessment's components. VTEC Laboratories has equipment and personnel capable of conducting accurate ASTM E662 tests.

The ASTM E662 test consists of four stages:

• Specimen preparation
• Preconditioning
• Non-flaming condition
• Flaming condition

Specimen Preparation

After scheduling your test, send at least six samples sample of the material in question.

With this type of smoke density test, we will examine a sample of no more than 3 inches by 3 inches by 1 inch. Each sample should be identical for the test's accuracy. If your material is available in multiple textures, we must test at least three of each variation.

Preconditioning and Conditioning

When we receive your specimen, it will undergo preconditioning and conditioning periods. These processes set each sample at a consistent moisture level according to its weight.

During preconditioning, the specimens rest in a preconditioning oven set within 5 degrees of 140 degrees Fahrenheit. After 24 hours of preconditioning, we will move the samples into a conditioning environment. The conditioning environment is within 5 degrees of 73 degrees Fahrenheit and within 5% of 50% relative humidity.

Non-Flaming Condition

Each specimen first undergoes non-flaming testing inside of what's called a smoke density chamber.

We'll mount the specimen inside the chamber, then expose it to an electrical radiant heat source that's rated at 2.5 watts per centimeter squared. A light beam is then shone through the chamber.

Exposure will last for 20 minutes or for three minutes after the optical density eclipses the required threshold. The smoke density can subsequently be calculated by measuring the obscuration of the light beam by the smoke using a photo sensor.

Flaming Condition

Next, we test the specimens under a flaming condition inside the same smoke density chamber with a light beam shining through. During this portion, we supplement the radiant energy source with evenly spaced flames from a tube burner. The flame affects the bottom of the substrate. Like the non-flaming portion, the flaming portion lasts for 20 minutes or until three minutes after the specimen's smoke reaches the required optical density.

How to Interpret the Results

The ASTM E662 test produces the following data for the non-flaming and flaming variations:

• Ds (1.5): Specific optical density after 1.5 minutes of exposure
• Ds (4.0): Specific optical density after four minutes of exposure
• Dm: Maximum specific optical density recorded during the examination
• Dm (corr.): Corrected maximum specific optical density during the examination

The compliant specific optical density figure a material must display varies with the substance and industry. Dm (corr.) accounts for soot that may obscure the glass and light source.

Your organization can compare the ASTM E662 test's findings with industry-specific requirements to verify compliance. Note that the results are specific to the material at its sample size. The material's performance may vary at smaller and larger sizes.