How Thermal Conductivity Is Calculated
For Mingfa LG-Standard (HCS-23) and LG-High Temp calcium silicate insulation boards, thermal conductivity increases linearly with temperature. The relationship follows this formula, established through decades of laboratory testing using the guarded hot plate method (ASTM C518 / GB/T 10294):
This formula applies to Mingfa's standard density grade (approx. 230 kg/m³). Different density grades (170-900 kg/m³) have slightly different conductivity curves. For project-specific thermal calculations involving other densities, contact our technical team.
Thermal Conductivity Calculator
Reference Values at Common Temperatures
The table below shows pre-calculated thermal conductivity values using the standard formula. These are laboratory-verified reference points for quick lookup.
| Mean Temperature (°C) | Thermal Conductivity lambda (W/m·K) | Notes |
|---|---|---|
| 100 | 0.0670 | Low-temperature industrial pipe insulation range |
| 200 | 0.0780 | Medium-temperature equipment insulation |
| 300 | 0.0890 | Typical for steam piping and process vessels |
| 400 | 0.1000 | Cement kiln preheater tower backup insulation |
| 500 | 0.1110 | Aluminum reduction cell thermal barrier |
| 600 | 0.1220 | High-temperature furnace backup lining |
Understanding the Formula
The linear conductivity model (lambda = 0.056 + 0.00011t) is the standard reference curve for Mingfa calcium silicate products with density around 230 kg/m³. Key points to understand:
- Intercept value (0.056): This is the extrapolated thermal conductivity at 0°C. In practice, measurement at very low temperatures introduces higher uncertainty; the formula is most reliable between 100°C and 650°C.
- Slope (0.00011): The rate at which conductivity increases with temperature. This is a material property of the xonotlite crystal phase.
- Higher-density grades (such as MF-HD at 800-850 kg/m³) have somewhat higher conductivity values because denser materials conduct more heat. Contact our technical team for grade-specific conductivity curves.
- Lower-density grades (such as HCS-17 at 170 kg/m³) have slightly lower conductivity but reduced compressive strength, trading off thermal performance against mechanical loading capacity.
Engineering Note
For thermal calculations, always use the mean temperature of the insulation layer, defined as (T_hot_face + T_cold_face) ÷ 2. This is not the same as the hot face temperature. For example, if the hot face is at 400°C and the cold face is at 60°C, the mean temperature is 230°C, giving lambda = 0.0813 W/m·K.