FOERFARANDE OCH ANORDNING FOER KONTINUERLIG MAETNING AV POROSITET.

摘要

The porosity of a strip of material is continuously computed by causing air to be drawn through the material as the strip moves across a perforated head situated atop a chamber in which the pressure is reduced by suction. In one embodiment, the reduced pressure is held substantially constant while the amount of air drawn through the chamber is measured and the porosity is determined by a computer whose inputs include the measured volume of air flow through the chamber and the speed at which the strip moves across the head, in addition to other inputs. In another embodiment, the volume of air flowing through the chamber is held substantially constant while the pressure in the chamber is measured and used as an input to the computer. In both embodiments, the speed at which the strip moves across the head is employed as a factor in the porosity computation.