How are densities determined according to API 936?

The determination of densities according to API 936 is performed at room temperature on specimens after they have been fired. This approach is crucial because firing changes the physical and chemical properties of the refractory material, leading to a more accurate assessment of its density in its final state.

When the specimens are subjected to high temperatures during the firing process, they undergo sintering, during which the particles bond together and the material reaches its intended microstructure. Measuring density after this process allows for an evaluation of the true characteristics and performance of the refractory material in service conditions.

Conducting density measurements at room temperature ensures that the evaluation reflects the refractory's properties under typical operating conditions, rather than influenced by high temperatures or other factors present during the manufacturing process. This procedure is essential for quality control and ensures that the materials meet the performance criteria set forth in industry standards.