Abstract: Particle produced pulses are evaluated on an individual basis for shape symmetry, with significantly asymmetric pulses, becoming subject to editing, i.e. exclusion. Pulse symmetry is determined by measuring the areas under the pulse before and after the first pulse amplitude peak and then by comparing those pulse areas with respect to pre-established limits which are not based upon any of the pulses then being evaluated.

Abstract: A porosimeter comprises a gas supply, a gas pressure regulator for the gas supply, a sample holder having an inlet and an outlet, said inlet being connected to the gas pressure regulator, a gas pressure sensor connected to the gas pressure regulator for measuring the pressure of gas supplied to the sample holder, and a gas flow sensor wherein the gas flow sensor is disposed to measure the gas flow between said gas pressure regulator and said sample holder. Both pressure and flow-rate readings are taken directly from the respective sensors to an automatic recorder which draws mechanically the output in the form of a graph, or may feed them to, for example, an integrating computer.