| 摘要 |
<p>1507747 Photo-electric determination of oil in water STANDARD TELEPHONES & CABLES Ltd 21 Aug 1975 34778/75 Heading G1A To measure the amount of a first liquid dispersed in a lower refractive index liquid with which it is not miscible, an unclad optical fibre is immersed in the liquids and its optical attentuation is measured; the fibre has a refractive index greater than that of the second liquid, but not more than 0À1 greater than the first, and is periodically cleaned to remove any build up of the first liquid on the fibre. The measurement may be used to determine the amount of oil dispersed in water. As seen in Fig. 2, an oil droplet 20 on the fibre 21 allows light propagating along the fibre to escape into the dispersion 22. by detecting the light passing to a photo-detector at the end of the fibre, the amount of oil can be found. A suitable light source is a Ga As laser, a He-Ne laser, or a quartz-halogen lamp; for oil in water measurements the fibre may be of silica. Fibres of differing refractive indices may be used to distinguish between oils. To prevent oil buld up on the fibre during continuous monitoring of liquids in a duct, the flow may be switched periodically to a second duct and fibre while the first one is flushed clean. Ultrasonic cleaning may also be used. To eliminate the effects of particles in the flow, the measurement may be compared with results produced by a flow from which the oil has been removed.</p> |
