THEORETICAL AND EXPERIMENTAL STUDY OF VARIOUS DIFFUSION PUMP OILS.
Final rept., 27 June 62-26 Mar 63,
IIT RESEARCH INST CHICAGO ILL
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DC 704, DC 705, and Convalex 10 diffusion pump oils were studied in baffled systems operating at 10 to the -7th power to 10 to the -9th power torr for periods up to 5 mos. The pumping stations, with fail-safe instrumentation, used 6-inch frac tionating pumps with water-cooled caps, and cooled optically tight baffles of either chevron traps or right-angle elbows. A sensitive analytical procedure involving ultraviolet absorption spec tra was developed to measure the quantity of oil deposited. The amount of backstreaming oil with both baffles and collection plate cooled with 5 C water varied from 1 x 10 to the -6th power to 10 to the -8th power mgsq cm min as follows DC 704 chevron DC 705 chevron Convalex 10 chevron DC 705 elbow Convalex 10 elbow. One-fifth as much backstreaming was obtained with Convalex 10 compared with DC 705 under comparable conditions and also one-fifth as much with the elbow baffle compared with the chevron baffle. While the exact mechanism of backstreaming was not determined, backstreaming undoubtedly is primarily a function of the erup tive boiling characteristics of the vaporizing process. Author