Surface Area Display Marking, Minimum Height of Lettering
Square inches | Inches |
Under 5 | 1/16 |
5 or more and under 25 | 1/8 |
25 or more and under 100 | 3/16 |
100 or more and under 400 | 1/4 |
400 or more | 1/2 |
Surface type (see § 1505.6(g)(2) ) | Thermal inertia type1 | Temperature | |
Degrees C. | Degrees F. | ||
C | 1 | 65 | 149 |
C | 2 | 75 | 167 |
C | 3 | 85 | 185 |
C | 4 | 95 | 203 |
D | 1 | 55 | 131 |
D | 2 | 70 | 158 |
D | 3 | 80 | 176 |
D | 4 | 90 | 194 |
1 Thermal inertia types are defined in terms of lambda as follows:
Type 1: Greater than 0.0045 (e.g., most metals).
Type 2: More than 0.0005 but not more than 0.0045 (e.g., glass).
Type 3: More than 0.0001 but not more than 0.0005 (e.g., most plastics).
Type 4: 0.0001 or less (e.g., future polymeric materials).
The thermal inertia of a material can be obtained by multiplying the thermal conductivity (cal./em./sec./degrees C.) by the density (gm./cm.3) by the specific heat (cal./gm./degrees C.)
16 C.F.R. §1505.3