| 摘要 |
899,973. Photo-electric fluid analysers. DISTILLERS CO. Ltd. Sept. 7, 1960 [Oct. 9, 1959], No. 34223/59. Class 40(3). A radiation fluid analyser comprises a source of radiation producing a beam which is split into two beams sequentially chopped and passed in sequence to a detector system comprising means s for discriminating between t h e signals induced at the detector by each beam, and means for amplifying and converting each of the signals to a D.C. signals and means for measuring the ratio of one of said D.C. signals with respect to the other. As shown for an arrangement to detect the measurement of water in acetone, light from a tungsten lamp 1 is passed through a collimator 2 and filter 3 passing infra-red radiation of wavelength 1.45Á for which water has a characteristic overtone absorption, but acetone has only a small background absorption. The collimated parallel beams are passed through a double aperture plate 4 to a chopper cylinder 5 having apertures 6, 7 disposed at right angles and driven via gearing 10, 11 from a synchronous motor 8. The beams pass to a cell 13 containing pure acetone and to a cell 14 containing the sample under test and are focused by a lens 15 on to a scrambler device comprising a ground glass screen 16 placed in front of a cylindrical brass tube 17 of highly polished internal surface, behind which is located a lead sulphide cell 18. The signals from the cell 18 are passed via an amplifier 19 and a synchronous switch 20 to an integrating and ratio-detecting circuit 23 controlling an indicator 24, which may be calibrated to show the percentage of water in the acetone. The switch 20 is controlled by an A.C. generator 21 driven from the synchronous motor 8, and in order to provide chopped radiation pulses at the frequency of the motor 8, the gear wheels 10, 11 are in the ratio of 1:2. In a modification, using a reference wavelength, the acetone / water mixture is circulated through the cells 13, 14 in series and the filter 3 is removed from its position shown in the Figure and placed at any point between plate 4 and lens 15 in the path of the beam passing through cell 14. Another filter placed at any point between the plate 4 and lens 15 in the path of the beam passing through cell 13 must be such as to pass radiation in the overtone region but to exclude the overtone wavelength at which water absorbs strongly and any overtone wavelength at which acetone absorbs strongly, so that this beam becomes the reference wavelength beam. Visible or ultra-violet radiation or infra-red radiation in the fundamental wavelength region may be employed. Specification 781,972 is referred to. |
