JPS6355647B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting vacuum leakage, and particularly for detecting leakage locations such as material joints that affect the degree of vacuum during the manufacturing process of large vacuum containers, etc., and detecting the degree of leakage. The present invention relates to a method of locally detecting the presence or absence of leakage by selecting a portion where there is a possibility of leakage without taking any means to evacuate the entire container such as a vacuum container.

Conventionally, the method for detecting vacuum leakage in a vacuum container is to evacuate the vacuum container to a predetermined degree of vacuum, and then
The presence or absence of leakage and the extent of the leakage were ascertained using helium detectors, etc. However, in recent years, chemical plant equipment and the like have become larger, and along with this, vacuum containers have also become larger, and a high degree of vacuum has been required.

In the conventional leak detection method, it takes a long time to evacuate the entire container to a predetermined degree of vacuum, and furthermore, the leakage area cannot be predicted in advance, so the amount of leakage is relatively large. If the object to be detected is a container having multiple parts, it will take an unnecessary amount of time to reach a predetermined degree of vacuum. Further, there are cases in which the predetermined degree of vacuum is not reached, resulting in failure to detect vacuum leakage.

An object of the present invention is to provide a method for detecting vacuum leakage by evacuating a vacuum container locally without evacuating the entire vacuum container, and by reaching a predetermined degree of vacuum in an extremely short time, as a means of eliminating the above-mentioned problems. It is in.

The present invention provides a vacuum container formed by joining a plurality of materials, with a flexible,
In addition, an inner cylinder and an outer cylinder surrounding the joint part are provided in close contact with each other, and a contact plate having a size that covers the joint part is installed, and the sealed space formed between the outer cylinder and the inner cylinder is closed. evacuate with a vacuum pump, and then evacuate the sealed space formed inside the inner cylinder with a vacuum pump to form a closed chamber surrounding the joint part on the other surface of the material joint part of the vacuum container. It is characterized in that a detection gas is sealed and a leakage detector detects that the detection gas has leaked into a sealed space formed inside the inner cylinder.

An embodiment of the present invention will be described with reference to the drawings. 1st
The figure shows the structure of a large vacuum container.
The nozzle 2 and the nozzle 2 are each formed by welding steel plates, and the main body 1 and the nozzle 2 are also connected by welding, and the two constitute one vacuum vessel. When evacuating this vacuum container and also detecting vacuum leaks, assuming that there is no vacuum leak in this vacuum container, the vacuum required according to the evacuation capacity of the vacuum pump is required to evacuate the entire vacuum container. The time is set.
Of course, if the cleanliness of the inner surface of the vacuum container is poor, outer gas will be generated and the time required for vacuuming will be longer.
That is, the evacuation time is determined by the volume of the part to be evacuated and the cleanliness of its inner surface, and if the cleanliness is constant, the smaller the volume, the shorter the evacuation time.

FIG. 2 shows an embodiment in which the present invention is applied to the nozzle 2 shown in FIG. The inner tube 3 and the outer tube 4 are made of non-porous sponge rubber, for example, and one end is adhered to the sealing plate 5, and the other end is made to match the shape of the main body 1. The sealing plate 5 is provided with a roughing nozzle 6 and a vacuum nozzle 7, and each nozzle is connected to the roughing pump 1 via vacuum hoses 8 and 9, respectively.
1 and a leak detector 12 with a vacuum pump. Therefore, the roughing nozzle 6 is connected to the inner and outer cylinders 3,
The vacuum nozzle 7 is opened in the inner tube 3 between the two, and the contact surfaces between the inner tube 3 and the outer tube 4 and the main body 1 are left freely without using any adhesive or the like.

Now, when the roughing pump 11 is operated, a negative pressure is created between the inner and outer cylinders 3 and 4, that is, in the space C, and the contact surfaces h and h' are brought into close contact with each other due to the outside air pressure. After space C has been evacuated to some extent,
When the pump of the vacuum pump-equipped leak detector 12 starts operating, the pressure in the space B becomes negative. The air leaking into space B is due to passing through the contact surface h' from space C, but since space C has reached a relatively high degree of vacuum, the amount of air leaking is negligible.
Space B quickly reaches a predetermined degree of vacuum. Since space A is the same space as space B, it naturally reaches the same degree of vacuum as space B.

On the other hand, there is some kind of defect in the nozzle 2 and the space A
Assuming that there is a vacuum leak in space A, space A will not reach the predetermined degree of vacuum, and if you know in advance the time required to reach the predetermined degree of vacuum in the volume of space A, it is possible to prevent leakage from some part of nozzle 2. It can be determined that there is a vacuum leak. Even if there is a vacuum leak from the nozzle 2, the defect may be small enough that the amount of vacuum leakage may be small enough to reach a predetermined degree of vacuum.
0 to form a space D by covering the outer periphery of the nozzle 2, and filling this space D with an appropriate amount of gas for detection,
The presence or absence of a vacuum leak can be confirmed by the leak detector 12 with a vacuum pump.

If the method described above is applied to the entire inner surface of the vacuum container, the time required will be greatly reduced compared to when detecting leaks by evacuating the entire vacuum container.
Moreover, it is possible to reliably grasp the presence or absence of leakage and the leakage part.

As described above, the present invention has the following effects.

(1) Since it can be carried out sequentially starting from the parts where the possibility of vacuum leakage is high, leakage points can be discovered at an early stage.

(2) Since the time required to detect a vacuum leak in the entire vacuum container can be greatly shortened, the cost required for the detection can be greatly reduced.

(3) It is possible to reliably detect the presence or absence of a vacuum leak, which allows for appropriate leak repair, thereby preventing accidents caused by vacuum leaks after the vacuum container has started operating.

[Brief explanation of the drawing]

FIG. 1 is an overall view of a large vacuum container, and FIG. 2 is a sectional view of an embodiment of the present invention applied to a nozzle portion. 1...Main body, 2...Nozzle, 3...Inner cylinder, 4...
... Outer cylinder, 5 ... Sealing plate, 6 ... Roughing nozzle, 7
...Vacuum nozzle, 10...Vinyl sheet, 11
... Roughing pump, 12 ... Leak detector with vacuum pump.

Claims (1)

[Claims] 1. A vacuum container formed by joining a plurality of materials has an inner cylinder and an outer cylinder that are flexible and are provided in close contact with one side of the material joint part to surround the joint part and cover the joint part. A close contact plate having a certain size is installed, the sealed space formed between the outer cylinder and the inner cylinder is evacuated with a vacuum pump, and then the sealed space formed inside the inner cylinder is vacuumed with a vacuum pump. A vacuum is drawn, and the other surface of the material joint part of the vacuum container is
A closed chamber surrounding the joint portion is formed and a detection gas is sealed therein, and leakage of the detection gas into the sealed space formed inside the inner cylinder is detected by a leak detector. Vacuum leak detection method.