A device used to measure the porosity of a paper by measuring the length of time it takes for a specified volume of air (usually 100 cm3) to pass through a particular area (usually 1 in.2) of a paper sample under a constant temperature and pressure. A slowly descending piston forces the quantity of air through the paper at the bottom of the shaft, while a timing device times how long it takes for all the air to diffuse through the paper. (See also Porosimeter.)
|