GB1196374A - Improvements in or relating to the Measurement of the Properties of Fluids - Google Patents

Abstract

1,196,374. Photo-electric testing. WESTONMARLOW INSTRUMENTS Ltd. April 24, 1968 No. 19378/68. Heading G1A. [Also in Divisions B1, G2] In order to measure a property of a fluid, a sample of the fluid is introduced into a flexible cell, the quantity of the sample being insufficient to fully distend the cell, and the cell is then flattened between a pair of opposed rigid surfaces, so that a predetermined thickness of the fluid is formed in the cell and can be submitted to the required measurement. Fig. 3 shows a series of cells 34, to 44 made by joining two sheets of flexible plasticised polyvinylchloride along lines 45 by heat sealing, adhesive or preferably highfrequency welding. A sample of the fluid is introduced into the open top of each cell, and the tops are then secured by clamping the top edges between two rigid strips 46, 48. One end of the loaded package is introudced into the tapering gap between the faces of two rigid blocks 8, 10, of P.V.C. or polytetrafluoroethylene; and the package is drawn into position so that one of the cells, e.g. 42, is flattened between window 18 in block 10 and a corresponding window in block 8. When used as a spectrophotometer, radiation from a tungsten filament lamp directed through window 18, is transmitted through the fluid in the flattened cell, and emerges through the window in block 8 to be received by a suitable detector and recorder. Filters are provided to select the desired wavelength for study. In order to measure the conductivity of a fluid, the windows in blocks 8, 10 are replaced by electrodes; and the impedance between them is measured at two frequencies. Also described is an apparatus for taking fluorometric measurements. The cells may be made of polyethylene, polypropylene, polychlorotrifluoroethylene, or aluminium foil.