Patent ID: 7928718

Claim:
An impedance particle counter for determining a particle size distribution in a sample containing the particles by determination of the corresponding pulse height distribution, the impedance particle counter having a controller that is programmed for a) controlling the impedance particle counter to count particles contained in a first part of the sample to determine the number of particles in each bin of a predetermined set of bins having different bin limits, b) adjusting bin upper and lower limits in accordance with the determined number of particles in each bin and based on a priori knowledge of a typical particle size distribution of the type of sample in question, and c) counting particles contained in a second part of the sample based on the adjusted bin upper and lower limits to determine the number of particles in each bin, wherein at least one of the bin limits are adjusted according to the formula: UpperLimit ⁡ ( B i ) = C 1 ⁢ a 0 · W 0 + a 1 · W 1 + … + a i · W i b 0 · W 0 + b 1 · W 1 + … + b i · W i + C 2 wherein C 1 and C 2 are constants, Bi is the i′th predetermined bin and Wi is the number of particle counts in the i′th bin, and UpperLimit(Bi) is the adjusted upper limit of the i′th bin.