METHOD AND APPARATUS FOR DETERMINING THE PRESENCE AND/OR CONCENTRATION OF PREDETERMINED PARTICULATE MATERIAL IN LIQUID

摘要

1,248,738. Monitoring metal particles in liquids. ROLLS-ROYCE Ltd. 7 May, 1969 [8 May, 1968], No. 21744/68. Heading B1D. [Also in Division G1] The presence and/or concentration of a particulate material in a liquid is determined by first separating any such material from the liquid and then irradiating it using a radioactive source and measuring the emitted radiation stimulated by this irradiation. The invention is described with reference to the determination of solid particles in lubricating oil (e.g. steel particles from bearing balls, rollers or track or phosphor-ibronze particles from the cage), but is applicable also to the determination of gold particles in water. In the apparatus of Fig. 1, oil is directed from inlet pipe 14 tangentially onto a cylindrical filter element 11 e.g. of paper, supported by disc 12 and rod 13. Oil passes through and out via pipe 15. Solid particles drop and are guided by baffle 21, through a trough 20 whose boundary is surrounded by a ring 17 of X-ray emitting radioactive material which causes the particles to emit characteristic X- radiation. A particular characteristic spectral line e.g. that of iron is investigated by the use of a pair of detectors 22, 23 (of the scintillation counter-type using thallium-activated sodium iodide crystals provided with respective radiation filters, one adapted to pass radiation of energies up to just below the characteristic spectral line of interest and the other to just above. Subtraction of the counts obtained at 32 provides an indication of the presence or quantity of the element and can operate an alarm 35 if a predetermined quantity is exceeded. In alternative arrangements, one detector with two radiation filters, carried on a rotatable mount and used sequentially, may be used; three radiation filters may be used to investigate two elements; the ring 17 may be substituted by a coarse mesh of radioactive substance. Means may be provided to knock the solid particles off the filter element e.g. the vibrations provided by a gear pump connected to the outlet 15.