A method and apparatus are provided for distinguishing microscopic size, elongated fiber-like particles from cubically shaped, irregularly shaped, or spherically shaped particles in a mixture... Show moreA method and apparatus are provided for distinguishing microscopic size, elongated fiber-like particles from cubically shaped, irregularly shaped, or spherically shaped particles in a mixture suspended in an electrically conducting liquid medium and for counting the fiber-like particles. In accordance with the method, an electrical zone sensing apparatus is provided with a screen means having microscopic openings therein of predetermined size to filter from the suspension particles having an effective area larger than the size of screen openings. Particles passing through the screen and through the sensing aperture of the zone sensing apparatus are separately sized by volume characteristics of electrical signals generated. The electrical signals having predetermined volume characteristics associated with the maximum spherical particles for passing through the screen openings are counted as non-fiber particles; whereas signals having larger volume characteristics are separately counted and designated as fibers. By the use of screens of successively smaller sizes, the larger particles including fibers having larger transverse cross sections may be successively filtered from the suspension and from reaching the sensing aperture. Therefore, smaller fibers having smaller cross-sectional area may be distinguished from particles having diameters approximating that of the smaller screen size openings. Show less
