| 摘要 |
768,767. Automatic density control systems. QUEEN'S UNIVERSITY. April 13, 1955 [May 20, 1954], No. 10595/55. Class 38 (4). To control the density of a liquid, a sample stream is continually passed through a control chamber in which its temperature is controlled to maintain its density constant, the temperature variations being measured and used to adjust the density of the main part of the liquid. In the embodiment described the sample stream is led from conduit 10 to the top of the control chamber 1 through a coil 13 immersed in boiling liquid 3a in the lower part of a surrounding chamber 2, containing an electric heater 3. The sample stream leaves the lower end of chamber 1 through conduit 14 and the level-control device 15. The vapour of the boiling liquid in chamber 2 is condensed in condenser 18 and returned to the chamber 2. The density of liquid in the chamber 1 is indicated by the position of a floating bob 5 which sinks when the density decreases, to allow light from a source 19 to energize a photo-cell 20. The current in cell 20 is caused to operate an amplifier and relay 22 to actuate a vacuum pump 21 connected to the space above the boiling liquid 3a, by a pipe 23, through the condenser 18. The lowered pressure causes the temperature of the liquid 3a to fall and hence that of the sample liquid in chamber 1. The resulting increase in density causes the bob 5 to rise and cut off the light falling on cell 20 so that the pump 21 is shut down. A thermocouple 7 immersed in the sample liquid actuates a potentiometer &c. 8 connected to effect the required density control in the main part of the liquid. Alternatively, movement of the bob 5 may be used to vary an inductance or capacity to operate the relay, Figs. 3 and 4 (not shown).
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