Air transit time is the measured time it takes a fixed volume of air to pass through the prepared powder bed between two reference levels. The apparatus uses that timing, together with the test setup, to calculate the material’s specific surface area and report the Blaine fineness value.

In practical terms, the transit time is the permeability signal. A longer time generally means the packed bed is resisting airflow more, which points to a finer cement sample, while a shorter time indicates easier airflow and a coarser sample. That is why consistent sample packing and porosity matter from one test to the next.

Need to match the timing method to your lab workflow? learn more about this system, or request a quote if you want help confirming the right setup for your cement fineness testing.