Scope:

ASTM E285-08 test method covers the screening of ablative materials to determine the relative thermal insulation effectiveness. This test method is used to measure and describe the properties of materials, products, or assemblies in response to heat and flame under controlled laboratory conditions.

Test Procedure:

In ASTM E285-08 test method, hot combustion gases are directed along the normal to the specimen until burn-through is achieved. The erosion rate of the material is determined by dividing the original thickness by the time to burn-through. The insulating effectiveness is determined from back-face temperature measurements. Insulation index numbers are computed by dividing the times for temperature changes of 80°C, 180°C, and 380°C, from the initial ambient temperature, by the original thickness. The insulation to- density performance is computed by dividing the insulation index by the density of the panel.

Figure 1: Schematic Diagram of Gas System

Specimen size:

The test specimen shall be a square, flat panel 6.35±0.41 mm (0.250 ±0.016 in.) thick.

The dimensions of length and width shall both be 101.6°+0.0°, -0.71mm (4.000+0.000,         -0.028in.).

Data:

The general characteristics of the oxyacetylene heat source are:

1. Heat Flux – 835 W/cm2 (cold-wall calorimeter).

2. Velocity – 210 m/s (cold, unreacted gases).

3. Neutral flame conditions.