Journal . Fig. for Fixing the be placed. The pumps are of a mechanical and mercuryvapour type ; each one having a duplex head in place of thesingle head usually provided, and the pumping operation hasbeen reduced from about four hours to about one and one-halfhours by reason of a special treatment which has been arrivedat as a result of considerable experimental work. Althoughit has been possible to obtain the prescribed blue glow test bydirect pumping and freezing, the time involved militated againstthis method as a commercial one and the valves as treatedcomply with the
Journal . Fig. for Fixing the be placed. The pumps are of a mechanical and mercuryvapour type ; each one having a duplex head in place of thesingle head usually provided, and the pumping operation hasbeen reduced from about four hours to about one and one-halfhours by reason of a special treatment which has been arrivedat as a result of considerable experimental work. Althoughit has been possible to obtain the prescribed blue glow test bydirect pumping and freezing, the time involved militated againstthis method as a commercial one and the valves as treatedcomply with the tests. Incidentally, a pressure of over can be applied to the anode, but this pressure maybe modified as advisability dictates. After the valveshave been removed from the ovens they are subjected to aspecial treatment to ensure the absence of blue glow, indicating SOME MODERN ENGINEERING PRACTICE IN AMERICA. 49. Fig. 12. Part of the Testing Apparatus. All the valves tested showed a greater the nature of the extent ofthe vacuum. This is imme-diately followed by a test forvacuum consisting of a highpotential impress on the anode ;during this test the anode be-comes white hot due to theelectrical bombardment. Havingpassed this test the valves arebased (Fig. 11), and the wiressoldered on the the final electrical tests thenfollow. (Fig. 12.) Most of these tests are toospecialised for this Paper, but itis necessary that when the pro-per voltages are applied to theplate and filament, regular in-crements of grid potential willcause the values of valve cur-rent to fall on a straight linecurve within the limits of thecapacity of the valve. value than the specified minimum ; a typical curve is shownin Fig. 2. Several tests were made with valves speciallymade with errors of dimensions and others with faulty place-ment of the elements, some test results of these are shownin Table III. The mec
Size: 1286px × 1944px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade186, bookpublisherlondon, bookyear1861
