| 摘要 |
1,155,443. Photo-electric flow measurement. BECKMAN INSTRUMENTS Inc. Sept. 12, 1967 [Oct.27, 1966], No.41670/67. Heading G1A. [Also in Division G3] In a system for maintaining a constant flow of gas through a conduit, the pressure differential across a capillary inserted in the conduit is measured by a liquid manometer having a reflecting light-sensitive pick-off controlling a pump conveying gas through the conduit. In Fig. 1, a flow of gas, e.g. for analysis, is produced by a pump 26 through a capillary 20. Variations in the rate of flow are detected by changes of the level of oil 28 in a manometer 10. Such changes vary the amount of light transmitted from a lamp-36 and reflected from the inclined end of a light conducting rod 32 through a slit 40 on to a photo-cell 42. Photo-cell controls through line 46 the A. C. energization of a coil arranged in a resonant circuit (not shown) to vary the output of pump 26 and thereby maintain the flow of gas constant. The rate of flow is indicated by the level of oil against markings 46 on transparent leg 14. Use of a manometer having concentric legs is referred to.
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