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A controlled gas leak
VACUUM Classified Abstracts
I -
General
Scienceb;zd
Engineering
-
I
(luality of the zirconium. Samples supplied from four different sources have been tested by this method showing a weight loss of 10%. 20y0, 40% and 4.5% respectively. The behaviour of these materials was checked during production. It was found that the material showring a 10% weight loss produced no deposit on the valve envelope, whereas the remaining three materials did and, in addition, lengthened excessively the time required for pumping. .Sommoire
: Une m&hodr de contr6le de la qualit
The Formation
of Adsorbed Layers in Vacuum
des
’ getters
I
au zirconium.
Sorizmaire
Z/I
Chambers and Their Detection by Electrons
Germany. Adsorption phenomena in evacuated vessels are investigated. .Idsorbed layers of gas arc evident in metal vacuum apparatus and Drechsler and Hess have shown that the speed of their growth can serve as a measure of the quality of an operational vacuum. The nature and properties of adsorbed layers are discussed with particular reference to conditions in the electron microscope and diffraction camera. Adsorbed layers. normally originate from water vapour and hydrocarbons present in the residual atmosphere, the latter as a result of the use of greased joints or rubber seals in the construction of plant.
: Etude sur les ph6nomdnes d’absorption
.\rticlo by II. Figour & II. I%onnel. 1.r I*ide 8, >larch 1953 1305-13OG
,
Arbiclebv
ti. Ko& C’acsum 3, Jan. 19jd :c-1n
dans lcs enceintes B vide.
0 78/I
Evaluation of Vacuum Gasket Materials See Abstract No.
: 71 II i9/1
Sorbed Gases and High Vacuum Systems United St&s. The evolution of adsorbed, al)sru-bed and occluded gases from metals or glass can cause a virtual leak of some magnitude in a high vacuum system. 1)uring the casting of aluminium it was observed that as much as 17 cmJ. of gas, mainly hydrogen, may be trapped in 100 g. of the processed metal. Two experiments are briefly described. The first providing for an air pressure of IO micron Hg on one side of a cast plate and atmospheric pressure on the other indicated a ’ leakage ’ at the rate of 1 x IO-’ ft.$/inchp., hr. This was solely due to the liberation of occluded or absorbed gases from the metal as could be proved by the second experiment where helium was used on the high pressure side and a helium leak detector on the opposite side. No helium was detected by the instrument confirming that no real leakage existed. The rate of evolution of gases was found to rise exponentially with increasing temperature Sommnire
: Etude sur le dCgazage sous vide des pi&es en a)uminium could. 80/I
Rapid Graphical Procedure for Oven Design lYnifed States. in order to reduce the time and effort normally required to finalise the design of ovens such as bake-out ovens for vacuum systems, a graphical procedure has been devised which permits a rapid estimation of the heating power required. and the operational outer surface temperature of an oven, if the size of the oven the nature and thickness of the structural materials and the operational temperature in the oven are known. The uses of the method are demonstrated 1)~ application to a practical case.
0
Sommaire : On dPcrit un pro&d6 graphique permettant dc dbterminer rapidement requise et la temp6rature des surfaces estcricures du four.
la puissance de chauffe
Vacuum Bakeout Ovens See Abstract
No.
81/I
: 61 II
A Controlled Gas Leak
82/I
United States. .\ Leak-in assembly is described which facilitates the controlled admission of gas at a rate ranging from 10,000 to 1 to a system which is continuously pumped at a pressure level of about IO-“mm. Hg. The essential component consists of a rod made from porous porcelain of the type described by Hagstrum and Weinhart. The rod is situated in a container partly filled with mercury. Hy means of a magnetically operated plunger the level of the mercury can be raised or lowered as desired. Two such units, one with a large-diameter rod and one with a small-diameter rod are connected in series via a small reservoir fitted with a Pirani Gauge. A stopcock-controlled line between the gas bottle and system, by-passing the leak-in units is provided. In operation, the assembly is pumped down, the mercury level in the first unit lowered to expose the rod and the rod in the second unit left submerged. Then the tip of the gas bottle is broken off and the gas leaked through the first unit into the intermediate reservoir up to a pre-determined pressure. Then leak No. 1 is submerged and leak No. 2 exposed to the extent required for the desired rate of admission of the gas to the system. The arrangement allows the use of gas bottles filled to atmospheric pressure and ensures that any chosen leak rate is kept constant for several hours. Sommaire : Description d’un dispositif permettant d’introcluire une quantit6 do&e d’un gaz dans un syst6me B vide pour unr dur6e prolong& la fuite 6tant construite en porcelaine poreuse.
A$d,
1953
Article by A. T.Wntt Jr.
Vacuum Vol. III No. 2
Sole IJ)
J. Morrison Hav. Sri. Inairuw. 14, y&c~3;953
176
I -
General
Scienceb;zd
Engineering
-
I
(luality of the zirconium. Samples supplied from four different sources have been tested by this method showing a weight loss of 10%. 20y0, 40% and 4.5% respectively. The behaviour of these materials was checked during production. It was found that the material showring a 10% weight loss produced no deposit on the valve envelope, whereas the remaining three materials did and, in addition, lengthened excessively the time required for pumping. .Sommoire
: Une m&hodr de contr6le de la qualit
The Formation
of Adsorbed Layers in Vacuum
des
’ getters
I
au zirconium.
Sorizmaire
Z/I
Chambers and Their Detection by Electrons
Germany. Adsorption phenomena in evacuated vessels are investigated. .Idsorbed layers of gas arc evident in metal vacuum apparatus and Drechsler and Hess have shown that the speed of their growth can serve as a measure of the quality of an operational vacuum. The nature and properties of adsorbed layers are discussed with particular reference to conditions in the electron microscope and diffraction camera. Adsorbed layers. normally originate from water vapour and hydrocarbons present in the residual atmosphere, the latter as a result of the use of greased joints or rubber seals in the construction of plant.
: Etude sur les ph6nomdnes d’absorption
.\rticlo by II. Figour & II. I%onnel. 1.r I*ide 8, >larch 1953 1305-13OG
,
Arbiclebv
ti. Ko& C’acsum 3, Jan. 19jd :c-1n
dans lcs enceintes B vide.
0 78/I
Evaluation of Vacuum Gasket Materials See Abstract No.
: 71 II i9/1
Sorbed Gases and High Vacuum Systems United St&s. The evolution of adsorbed, al)sru-bed and occluded gases from metals or glass can cause a virtual leak of some magnitude in a high vacuum system. 1)uring the casting of aluminium it was observed that as much as 17 cmJ. of gas, mainly hydrogen, may be trapped in 100 g. of the processed metal. Two experiments are briefly described. The first providing for an air pressure of IO micron Hg on one side of a cast plate and atmospheric pressure on the other indicated a ’ leakage ’ at the rate of 1 x IO-’ ft.$/inchp., hr. This was solely due to the liberation of occluded or absorbed gases from the metal as could be proved by the second experiment where helium was used on the high pressure side and a helium leak detector on the opposite side. No helium was detected by the instrument confirming that no real leakage existed. The rate of evolution of gases was found to rise exponentially with increasing temperature Sommnire
: Etude sur le dCgazage sous vide des pi&es en a)uminium could. 80/I
Rapid Graphical Procedure for Oven Design lYnifed States. in order to reduce the time and effort normally required to finalise the design of ovens such as bake-out ovens for vacuum systems, a graphical procedure has been devised which permits a rapid estimation of the heating power required. and the operational outer surface temperature of an oven, if the size of the oven the nature and thickness of the structural materials and the operational temperature in the oven are known. The uses of the method are demonstrated 1)~ application to a practical case.
0
Sommaire : On dPcrit un pro&d6 graphique permettant dc dbterminer rapidement requise et la temp6rature des surfaces estcricures du four.
la puissance de chauffe
Vacuum Bakeout Ovens See Abstract
No.
81/I
: 61 II
A Controlled Gas Leak
82/I
United States. .\ Leak-in assembly is described which facilitates the controlled admission of gas at a rate ranging from 10,000 to 1 to a system which is continuously pumped at a pressure level of about IO-“mm. Hg. The essential component consists of a rod made from porous porcelain of the type described by Hagstrum and Weinhart. The rod is situated in a container partly filled with mercury. Hy means of a magnetically operated plunger the level of the mercury can be raised or lowered as desired. Two such units, one with a large-diameter rod and one with a small-diameter rod are connected in series via a small reservoir fitted with a Pirani Gauge. A stopcock-controlled line between the gas bottle and system, by-passing the leak-in units is provided. In operation, the assembly is pumped down, the mercury level in the first unit lowered to expose the rod and the rod in the second unit left submerged. Then the tip of the gas bottle is broken off and the gas leaked through the first unit into the intermediate reservoir up to a pre-determined pressure. Then leak No. 1 is submerged and leak No. 2 exposed to the extent required for the desired rate of admission of the gas to the system. The arrangement allows the use of gas bottles filled to atmospheric pressure and ensures that any chosen leak rate is kept constant for several hours. Sommaire : Description d’un dispositif permettant d’introcluire une quantit6 do&e d’un gaz dans un syst6me B vide pour unr dur6e prolong& la fuite 6tant construite en porcelaine poreuse.
A$d,
1953
Article by A. T.Wntt Jr.
Vacuum Vol. III No. 2
Sole IJ)
J. Morrison Hav. Sri. Inairuw. 14, y&c~3;953
176