A porosimeter includes a pressurizable sample chamber with a membrane
located directly below the sample. The membrane pores have a smaller size
than any of the sample pores of interest. A fluid reservoir is located
below the membrane such that the reservoir and the membrane form a seal.
In operation, as fluid enters the fluid reservoir through the membrane or
a reservoir inlet, fluid already in the fluid reservoir is displaced
through a reservoir exit. An inlet in a fluid displacement reservoir
receives the fluid displaced from the fluid reservoir. A recirculation
line receives fluid from the exit of the fluid displacement reservoir and
circulates the fluid into the inlet of the fluid reservoir. In a preferred
embodiment, a pump recirculates the fluid through the recirculation line.
Fluid returned to the reservoir circulates over the bottom of the
membrane, and sweeps air bubbles out of the reservoir.
