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A new vacuum society
VACUUM Classified A b s t r a c t s
I
xo
General Science and Engineering
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--
VACUUM
ENGINEERING
(GENERAL)
--
I
-- :o
A New V a c u u m Society United Kingdom. I n a recent issue of this j o u r n a l it was tentatively suggested to form a v a c u u m working group u n d e r t h e auspices of t h e v a r i o u s interested professional institutions in this country. The a u t h o r of t h e p r e s e n t letter s u p p o r t s this suggestion and states t h a t in his experience the d e v e l o p m e n t of v a c u u m technology h a s reached a stage, where the existence of such a working group would be of decided a d v a n t a g e to f u r t h e r progress. Sommaire: D a n s cette lettre r6f6rence est faite de l'6ditorial du premier n u m 6 r o du Volume No. I I I de ce journal, et on a conseill6 de former u n groupe d'6tude du vide.
O
Descriptive T e r m s for V a c u u m Fumigation United Kingdom. I t is suggested t h a t the £erms n o r m a l l y used to designate the various techniques employed in v a c u u m f u m i g a t i o n should be altered to give a more accurate description. There are four different methods: (1) The pressure in t h e c h a m b e r is reduced. S u b s e q u e n t l y the f u m i g a n t is introduced. T h e v a c u u m is maintained for the whole length of the t r e a t m e n t . This m e t h o d is k n o w n as ' sustained v a c u u m ' fumigation. No change of n a m e is suggested. (2) The pressure in tile c h a m b e r is raised to atmospheric immediately after i n t r o d u c t i o n of the f u m i g a n t and r e m a i n s at this value for the rest of the processing time. This method, h i t h e r t o k n o w n as ' r e l e a s e d - v a c u u m ' m e t h o d would be b e t t e r described b y ' v a c u u m fumigation w i t h a t m o s p h e r i c pressure restored immediately after dosage '. (3) After admission of a m i x t u r e of air and vaporised fumigant, the c h a m b e r pressure is raised to atmospheric. This, the so-called ' F r e n c h released-vacuum ' m e t h o d should be t e r m e d ' v a c u u m f u m i g a t i o n w i t h s i m u l t a n e o u s admission of air and f u m i g a n t '. {4) After admission of the fumigant, the reduced pressure is m a i n t a i n e d for a while; t h e n air is a d m i t t e d and t r e a t m e n t continued at atmospheric pressure. This m e t h o d should be k n o w n as ' v a c u u m fumigation w i t h atmospheric pressure restored after a period '. I t is questionable w h e t h e r the general t e r m ' v a c u u m fumigation ' is a d e q u a t e as the operational pressures are never lower t h a n 5 cm. H g b u t no change of t e r m is proposed. Sommaire. On sugg6re que certains t e r m e s utilis6s en fumigation sous vide sont a m b i g u s et des n o u v e a u x termes d ' u n caract6re plus d6finitif sont rdcommendds.
V a c u u m Technique
O
187/I
Letter by D. W. Stops ~/acuum 3, July 1953 288
188/1
Letter by A. B. P. t'ago R. E. BlackiSh W. Burns-Brown & S. G. Heuser ('hem. & Industr. I I, April 1953 353-354
189/I
United Kingdom. l~ecent progress in v a c u u m e q u i p m e n t design and application is surveyed. The following new books are mentioned : ' V a c u u m Technique ' b y Reiman, ' Freezing and D r y i n g ' b y H a r r i s (Editor) and ' Miscellaneous Physical and Chemical T e c h n i q u e s ' b y Snyder and Lipkin. The a u t h o r describes a r o t a r y p u m p a t t a c h m e n t for the r e m o v a l of volatile solvents entrained in the p u m p oil. The oil is b r o u g h t to the top of a pipe, 3 ft. high and 4 inch. in diameter, b y m e a n s of a special gear p u m p . F r o m there it flows d o w n w a r d s over a s t e a m - h e a t e d copper coil which causes the volatiles to evaporate. After cooling the oil is r e t u r n e d to the r o t a r y p u m p . Some details are given of a newly developed self-cleaning fraetionating three-stage diffusion p u m p . Various gauge developments are discussed. The new design of a r o t a r y McLeod gauge b y A x e l b a n k is described and s h o w n in a sketch. The gauge is m a d e of glass and covers the range of 10 -2 to 10 -6 m m . Hg. The circuit of the s t a n d a r d a l p h a t r o n gauge has been redesigned to facilitate its use in conjunction w i t h a recorder unit. A similar gauge, especially developed for use in corrosive gas mixtures, has a polonium-on-nickel source and covers the range of 0.1 to 100 m m . Hg. A tetrode ionisation gauge with t w o grids and a thin silver ion collector on the glass wall has been proposed b y V~rarmholtz which has a range d o w n to 10 -s m m . Hg. Some details are given of Leek's investigation into the performance and range of the Pirani gauge. (See Vol. I I A b s t r a c t No. 132/II.) N e w developments in v a c u u m p l u m b i n g are mentioned. F o r example, K n u d s e n has found t h a t 1/16 inch rings, made from indium sheet 0.007 inch thick, m a k e efficient seals between m e t a l and other surfaces and can be used in place of gaskets made from organic materials, where use of the latter is undesirable. H o w ever, on opening the seal the ring is destroyed. Stanier's design of a greaseless v a c u u m stopcock is described and s h o w n in a sketch (See Vol. I I A b s t r a c t No. 108/II.). Several v a c u u m processing m e t h o d s in m e t a l l u r g y axe briefly described w i t h particular reference to m o l y b d e n u m , t a n t a l u m , t i t a n i u m and zirconium. V a c u u m axc-furnaces working on the consumable-electrode principle have been built to give m o l y b d e n u m ingots of up to 1,000 lb. w i t h an o x y g e n c o n t e n t of less t h a n 0.003%. V a c u u m - s i n t e r i n g t a n t a l u m b y passing c u r r e n t t h r o u g h t a n t a l u m p o w d e r pressed into bars at t e m p e r a t u r e s of 2,500°C in a furnace continuously p u m p e d at 10 4 m m . Hg, p r o d u c e s a material which can be rolled into sheets. I t m a y be necessary to v a c u u m - a n n e a l the sheets at 1,500°C. The p r o d u c t i o n of titanium, believed to be p e r m a n e n t l y dependent on v a c u u m methods, increases steadily. The largest ingots cast to date are 2 tons. Details are given of the final stages of zirconium production, freeing the zirconium sponge from excess m a g n e s i u m and m a g n e s i u m chloride. Sommaire: U n article de portde g6n6rale sur les applications de la technique du vide p o r t a n t en particulier sur les mod61es de pompes, d'appaxeils de mesure et sur le d e v e l o p p e m e n t du t r a i t e m e n t des m 6 t a u x sous vide.
Apparatus for E v a c u a t i n g H o l l o w Articles See A b s t r a c t No.: 173/II
October 1053
Abstr~e~ ~o. and References
Article by S. L. Martin Chem..Process Eng,ng. 34, Sept;. 53 276-279
19ofl
Vacuum Vol. I I 1 No. ,~
434
I
xo
General Science and Engineering
--
--
VACUUM
ENGINEERING
(GENERAL)
--
I
-- :o
A New V a c u u m Society United Kingdom. I n a recent issue of this j o u r n a l it was tentatively suggested to form a v a c u u m working group u n d e r t h e auspices of t h e v a r i o u s interested professional institutions in this country. The a u t h o r of t h e p r e s e n t letter s u p p o r t s this suggestion and states t h a t in his experience the d e v e l o p m e n t of v a c u u m technology h a s reached a stage, where the existence of such a working group would be of decided a d v a n t a g e to f u r t h e r progress. Sommaire: D a n s cette lettre r6f6rence est faite de l'6ditorial du premier n u m 6 r o du Volume No. I I I de ce journal, et on a conseill6 de former u n groupe d'6tude du vide.
O
Descriptive T e r m s for V a c u u m Fumigation United Kingdom. I t is suggested t h a t the £erms n o r m a l l y used to designate the various techniques employed in v a c u u m f u m i g a t i o n should be altered to give a more accurate description. There are four different methods: (1) The pressure in t h e c h a m b e r is reduced. S u b s e q u e n t l y the f u m i g a n t is introduced. T h e v a c u u m is maintained for the whole length of the t r e a t m e n t . This m e t h o d is k n o w n as ' sustained v a c u u m ' fumigation. No change of n a m e is suggested. (2) The pressure in tile c h a m b e r is raised to atmospheric immediately after i n t r o d u c t i o n of the f u m i g a n t and r e m a i n s at this value for the rest of the processing time. This method, h i t h e r t o k n o w n as ' r e l e a s e d - v a c u u m ' m e t h o d would be b e t t e r described b y ' v a c u u m fumigation w i t h a t m o s p h e r i c pressure restored immediately after dosage '. (3) After admission of a m i x t u r e of air and vaporised fumigant, the c h a m b e r pressure is raised to atmospheric. This, the so-called ' F r e n c h released-vacuum ' m e t h o d should be t e r m e d ' v a c u u m f u m i g a t i o n w i t h s i m u l t a n e o u s admission of air and f u m i g a n t '. {4) After admission of the fumigant, the reduced pressure is m a i n t a i n e d for a while; t h e n air is a d m i t t e d and t r e a t m e n t continued at atmospheric pressure. This m e t h o d should be k n o w n as ' v a c u u m fumigation w i t h atmospheric pressure restored after a period '. I t is questionable w h e t h e r the general t e r m ' v a c u u m fumigation ' is a d e q u a t e as the operational pressures are never lower t h a n 5 cm. H g b u t no change of t e r m is proposed. Sommaire. On sugg6re que certains t e r m e s utilis6s en fumigation sous vide sont a m b i g u s et des n o u v e a u x termes d ' u n caract6re plus d6finitif sont rdcommendds.
V a c u u m Technique
O
187/I
Letter by D. W. Stops ~/acuum 3, July 1953 288
188/1
Letter by A. B. P. t'ago R. E. BlackiSh W. Burns-Brown & S. G. Heuser ('hem. & Industr. I I, April 1953 353-354
189/I
United Kingdom. l~ecent progress in v a c u u m e q u i p m e n t design and application is surveyed. The following new books are mentioned : ' V a c u u m Technique ' b y Reiman, ' Freezing and D r y i n g ' b y H a r r i s (Editor) and ' Miscellaneous Physical and Chemical T e c h n i q u e s ' b y Snyder and Lipkin. The a u t h o r describes a r o t a r y p u m p a t t a c h m e n t for the r e m o v a l of volatile solvents entrained in the p u m p oil. The oil is b r o u g h t to the top of a pipe, 3 ft. high and 4 inch. in diameter, b y m e a n s of a special gear p u m p . F r o m there it flows d o w n w a r d s over a s t e a m - h e a t e d copper coil which causes the volatiles to evaporate. After cooling the oil is r e t u r n e d to the r o t a r y p u m p . Some details are given of a newly developed self-cleaning fraetionating three-stage diffusion p u m p . Various gauge developments are discussed. The new design of a r o t a r y McLeod gauge b y A x e l b a n k is described and s h o w n in a sketch. The gauge is m a d e of glass and covers the range of 10 -2 to 10 -6 m m . Hg. The circuit of the s t a n d a r d a l p h a t r o n gauge has been redesigned to facilitate its use in conjunction w i t h a recorder unit. A similar gauge, especially developed for use in corrosive gas mixtures, has a polonium-on-nickel source and covers the range of 0.1 to 100 m m . Hg. A tetrode ionisation gauge with t w o grids and a thin silver ion collector on the glass wall has been proposed b y V~rarmholtz which has a range d o w n to 10 -s m m . Hg. Some details are given of Leek's investigation into the performance and range of the Pirani gauge. (See Vol. I I A b s t r a c t No. 132/II.) N e w developments in v a c u u m p l u m b i n g are mentioned. F o r example, K n u d s e n has found t h a t 1/16 inch rings, made from indium sheet 0.007 inch thick, m a k e efficient seals between m e t a l and other surfaces and can be used in place of gaskets made from organic materials, where use of the latter is undesirable. H o w ever, on opening the seal the ring is destroyed. Stanier's design of a greaseless v a c u u m stopcock is described and s h o w n in a sketch (See Vol. I I A b s t r a c t No. 108/II.). Several v a c u u m processing m e t h o d s in m e t a l l u r g y axe briefly described w i t h particular reference to m o l y b d e n u m , t a n t a l u m , t i t a n i u m and zirconium. V a c u u m axc-furnaces working on the consumable-electrode principle have been built to give m o l y b d e n u m ingots of up to 1,000 lb. w i t h an o x y g e n c o n t e n t of less t h a n 0.003%. V a c u u m - s i n t e r i n g t a n t a l u m b y passing c u r r e n t t h r o u g h t a n t a l u m p o w d e r pressed into bars at t e m p e r a t u r e s of 2,500°C in a furnace continuously p u m p e d at 10 4 m m . Hg, p r o d u c e s a material which can be rolled into sheets. I t m a y be necessary to v a c u u m - a n n e a l the sheets at 1,500°C. The p r o d u c t i o n of titanium, believed to be p e r m a n e n t l y dependent on v a c u u m methods, increases steadily. The largest ingots cast to date are 2 tons. Details are given of the final stages of zirconium production, freeing the zirconium sponge from excess m a g n e s i u m and m a g n e s i u m chloride. Sommaire: U n article de portde g6n6rale sur les applications de la technique du vide p o r t a n t en particulier sur les mod61es de pompes, d'appaxeils de mesure et sur le d e v e l o p p e m e n t du t r a i t e m e n t des m 6 t a u x sous vide.
Apparatus for E v a c u a t i n g H o l l o w Articles See A b s t r a c t No.: 173/II
October 1053
Abstr~e~ ~o. and References
Article by S. L. Martin Chem..Process Eng,ng. 34, Sept;. 53 276-279
19ofl
Vacuum Vol. I I 1 No. ,~
434