Measuring and testing – With fluid pressure
Reexamination Certificate
1999-02-10
2001-08-28
Williams, Hezron (Department: 2856)
Measuring and testing
With fluid pressure
C073S040700, C073S049200
Reexamination Certificate
active
06279382
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the structure of a vessel sealed with a double seal and, more particularly, to a sealed vessel whose air tightness property in each seal part can be easily checked and a method of testing the air tightness of the sealed vessel.
When an electronic apparatus is installed in the water such as on the sea bottom or in a river, the apparatus is usually housed in a pressure-proof sealed vessel. It is important to sometimes check the air tightness performance of the sealed vessel. In order to check the air tightness performance, an air tightness test using gaseous helium is usually carried out. A typical pressure-proof sealed vessel has a structure such that a lid is attached to an end face of a cylindrical vessel. The pressure-proof sealed vessel and the lid are usually sealed with a double seal. A through hole communicating the inside and outside of the pressure-proof sealed vessel is formed through the lid. A pin is inserted in the through hole and can be sealed by welding. In case of testing the vessel, a sealed vessel to be tested is placed in a pressure test vessel. A vacuum pump arranged outside of the pressure test vessel produces a near vacuum in the vessel via a pipe attached to the through hole. After that, the pipe is switched from the vacuum pump to a gas sensor and the gaseous helium is introduced into the pressure test vessel and is pressurized. When there is a leak in the seal part, the gas sensor senses the gaseous helium spread into the vessel. When the sealed vessel has the double seal, however, it is difficult to check the performance of each of the two seals. In the air tightness test, the pressure of the pressurized gaseous helium is applied to the outer seal and a pressure of about a normal air pressure is applied to the seal on the inside. It requires a long time air tightness test to verify that the gas is leaked from the inner seal part.
When a metal seal is employed as one of the seals, the gas does not permeate the seal part. In the conventional test, therefore, the air tightness performance of the other seal cannot be checked.
SUMMARY OF THE INVENTION
It is an object of the present invention to test each of seals of a sealed vessel having a double seal easily and in short time. In order to achieve the object, in a first sealed vessel of the invention in which a lid is fitted with a double seal, a first hole communicating the space sandwiched by the seals and the outside of the sealed vessel and a second hole communicating the inside and the outside of the sealed vessel are formed. Both of the first and second holes can be formed through either the lid or the vessel. It is also possible that one of the holes is opened in the lid and the other hole is opened in the vessel. According to a second sealed vessel of the invention, peripheries of opening parts of two vessels each having one opening are jointed via a double seal, a first hole communicating the space sandwiched by the seals and the outside of the sealed vessel and a second hole communicating the inside and the outside of the sealed vessel are formed. A method of testing the vessel comprises the steps of injecting a gas into a space sandwiched by the seals, setting the inside of the sealed vessel in a vacuum or low air pressure state, and sensing the injected gas in the sealed vessel. Another testing method comprises the steps of placing the sealed vessel in a pressure vessel, injecting a gas into the pressure vessel, setting the space sandwiched by seals of the sealed vessel in a vacuum or low air pressure state, and sensing the gas in the space sandwiched by the seals. A method of testing a sealed vessel obtained by jointing the peripheries of opening parts of two vessels each having one opening via a double seal comprises the steps of injecting a gas into a space sandwiched by the seals, setting the inside of the sealed vessel in a vacuum or low air pressure state, and sensing the gas in the sealed vessel. The testing method further comprises the steps of placing the sealed vessel in the pressure vessel, injecting the gas into the pressure vessel, setting the space sandwiched by the seals in a vacuum or low air pressure state, and sensing the gas in the space sandwiched by the seals. According to the above-mentioned sealed vessel and the method of testing the vessel, the sealing performance of the two seals can be individually checked and the test time can be shortened.
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NEC Corporation
Scully Scott Murphy & Presser
Wiggins David J.
Williams Hezron
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