GB1415311A - Method and apparatus for monitoring hyperfine particles in a fluid medium - Google Patents

Abstract

1415311 Electrostatic and magnetic separation TRANS-SONICS INC 25 Aug 1972 [25 Aug 1971] 39836/72 Heading B2J [Also in Divisions G1 and G2] Hyperfine particles in a fluid flow are monitored by utilising an electric or magnetic force field to deposit the particles on a substrate and then optionally monitoring selected characteristics of the deposited particles. As shown, Fig. 1, a magnet 14 having pole pieces 16, 18 defining a narrow gap produces a magneic field extending perpendicularly to a substrate 20 mounted on a tapered support 28. The substrate is provided with non-stick edging members 22 to define a flow channel down which is passed a sample of oil from an engine. Iron particles in the sample are precipitated by the magnetic field, the large particles first, followed by the smaller particles, thus producing a graded distribution according to particle size. Preferably the sample is mixed with a "developer" e.g. perchlorethylene, to break the oil-particle bonds. After deposition of the particles the substrate is flushed with developer to remove residual oil and then with a "fixer" (e.g. trichlorethylene) to remove the developer. The resulting slide may be viewed by a microscope, e.g. using the two colour illumination technique of the divisional Specification 1415312-see Division G2-or by a photoelectric densitometer which measures the transmissivity of the sample at a plurality of selected points along the distribution the results being presented as the individual concentrations, the first er second time derivatives of these concentrations or the ratio of the concentrations at two points. In an on-line system, Fig. 13, a minor bypass. in an oil line includes a transparent tube 92 subjected to a magnetic field by a magnet 98. A lamp 94 illuminates the particles deposited on the wall of the tube and measurements are made by a densiometer 100 which may utilise a plurality of photocells to monitor different parts of the particle distribution. It is preferable to utilise an electromagnet which is switched off between measurements to allow the particles to be washed away by the oil flow. An electrostatic embodiment is described with reference to Fig. 14 (not shown).