METHOD AND SYSTEM FOR CLEANING AN APERTURE IN A PARTICLE STUDY DEVICE

1521300 Analyzing particles electrically COULTER ELECTRONICS Ltd 28 Oct 1975 [4 Nov 1974] 44423/75 Heading G1N In order to remove debris clogging the aperture 14 of a particle detector pulses are applied to electrodes 16, 18, positioned on either side of the aperture from pulse generator 28. The energy of the pulses causes the fluid suspension 26 in the aperture to vapourize and the expansion of the gas so formed forces the debris out of the aperture. The pulses from generator 28 are in the form of repetitive pulses, pulse trains or sequence of pulse trains and they may be uni-directional pulses, modulated high frequency waves, or bi-polar pulses or bursts of high frequency the latter two avoiding polarization effects. Electrodes 16 and 18 are also connected to counting and sizing analyzer 20 via switch 25a which is gauged together with switch 25b. In operation when a clogged aperture is indicated switch 25a is opened to disconnect analyzer 20 and switch 25b closed to connect the generator 28 to the electrodes. The switches may be controlled manually or automatically by control circuit 34.