Answer :
Final answer:
The student seems to be asking for the flame spread rating for a Class C finish but provides a scenario for calculating the rate of heat flow through a wall. The rate of heat flow can be found using the temperature difference, area, and thermal resistance of the wall's materials.
Explanation:
The question is asking for the flame spread rating for a Class C finish according to ASTM E84. However, the body of the question provided is actually about the rate of heat flow through a wall with specified materials and temperatures on either side. While the initial question is about building materials and fire safety, the provided information and subsequent details relate to a physics problem involving thermal conductivity and calculating heat transfer.
Heat Flow Through a Wall
To calculate the rate of heat flow through the wall, we would use the equation Q = U ext{A}(T_{inside} - T_{outside}), where:
- Q is the rate of heat flow (in Watts)
- U is the overall heat transfer coefficient (which is the reciprocal of the sum of the R values of the layers)
- A is the area of the wall
- T_{inside} and T_{outside} are the inside and outside temperatures in degrees Celsius respectively
For this scenario, the R values of all the layers would need to be summed to find the overall heat transfer coefficient (U), and then the area of the wall and the difference in temperatures would be applied to find the heat flow rate.