GB1240991A - Photosensitive apparatus for measuring and for comparing the transmission of light through a fluid - Google Patents

Abstract

1,240,991. Photo-electric apparatus. MECTRON (FRIGISTOR) Ltd. Oct.14, 1968 [Sept. 8, 1967], No.41084/67. Heading G1A. [Also in Division H3] Photo-electric apparatus, particularly suitable for determination of the cloud point of an oil, comprises two pairs of light guides, the gaps between the end surfaces of the guides in each pair being within a liquid under test, and means for comparing the intensities of respective light beams transmitted through the guides of each pair and through the liquid in each gap. In the arrangement shown, light from prefocused lamps, 1, 1A, passes through the pairs of light guides 3, 7 and 3A, 7A and gaps 4, 4A to photo-transistors 9, 9A. The light guides are arranged in mountings 11, 11A so as to be adjustable in position. The container 13 which is light-proofed may be heated or cooled by a two stage thermo-electric system 19-22. In determination of the cloud point of an oil in the container, the oil is heated and then cooled at about 20‹F. per minute. The cloud point of the oil (separating out of the solid particles) is reached first at the lower gap 4A, due to convection currents in the oil. The photo-transistors are in a differential circuit arrangement, Fig.2 (not shown), which is balanced by the adjustment of a potentiometer and the source intensities before the oil has been put into container 13, and the effect of crystallization of oil in the gap 4A causes a reduction of the intensity reaching transistor 9A and an imbalance of the circuit results. The imbalance signal is amplified to actuate a relay to give a visible and/or audible alarm. At this instant, the temperature indicator 16, receiving the output of temperature sensitive resistor 14, is read as the cloud point. Alternative constructions. The relay can be coupled to a temperature recording device so that automatic recording of the cloud point is obtainable. The apparatus can be adapted by the addition of a second temperature sensitive device so that the cooling process is reversed on reaching the cloud point to repeat the test. The apparatus may be modified to monitor intermittent samples of oil diverted from a flow-line, being in this instance provided with input and output valve means. Only one light source may be used instead of separate ones 1, 1A. The light guide pairs may have their gaps at right angles to one another and be in a fixed relationship, Figs. 3, 4 (not shown). One gap may be larger than another. Applications, Besides cloud point determination, other applications mentioned are sedimentation studies, monitoring the mixing of viscous solutions, measuring the haze point of beer and breakdown of transformer oils.