JPS63200032A - Detecting method of leak in vessel - Google Patents

Abstract

PURPOSE:To simplify a structure by a construction wherein a holding substance holding a vaporizable liquid and having vent holes is disposed outside a vessel, the pressure inside the vessel is reduced by suction and the presence or absence of the component of the liquid is measured by a gas sensor. CONSTITUTION:An apparatus A is constructed of a case 2 fixing a vessel 1, a liquid holding substance (cotton) 3 fitted on the inner surface of this case 2, and a gas sensor 4 which sucks a gas in the vessel 1 from port 1a of the vessel 1 so as to reduce the pressure thereof and measures the component of the gas. In the state wherein a packing 11 is put on the port 1a of the vessel and thereby the vessel is sealed up, a suction pump 12 is driven to suck the gas until an internal pressure in the vessel 1 becomes about 0.1-2.0kg/cm<2>. In the case when any pinhole exists in the vessel 1, flow channels of the gas are formed of through holes 13 of the case 2, vent holes of the cotton 3 and the pinhole, and the vapor of ethyl alcohol impregnated in the cotton 3 flows into the vessel 1 through the pinhole and is sent, together with the gas in the vessel 1, into the gas sensor 4 through a hose 14. Therefore, the vapor of ethyl alcohol is detected by the sensor 4.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to various containers, such as containers for canned goods, spray containers for insecticides and hair styling, gasoline tanks for automobiles, oil storage parts of kerosene heaters, and air conditioners. This invention relates to a method for detecting the presence of small holes or pinholes in the peripheral wall, top, bottom plate, etc. of a refrigerant storage pressure-resistant container, high-pressure gas container, etc. of a refrigeration system.

[Prior Art] Conventionally, methods using nonflammable helium gas and methods using nonflammable Freon gas have been proposed for inspecting the presence or absence of small holes and pinholes that occur during the manufacturing of containers.

An example of a method using helium gas as the test gas is disclosed in Japanese Patent Application Laid-Open No. 61-246644, for example. This method supplies a small amount of helium gas into a vacuum container, maintains a reduced pressure state for a certain period of time, then sucks the helium gas in the container and measures the components in the helium gas. As a method for inspecting holes and the like, and as a method using the Freon gas, a method generally referred to as the FID method is conventionally well known.

However, in both of the above measurement methods, substances that are in a gaseous state at room temperature are used as test gases, so they must be stored in legally mandated pressure-resistant containers, which is problematic in terms of cost and safety. In addition to the problems, the cost of the gas itself is also high. Furthermore, to continuously inspect containers for pinholes, etc., an inexpensive and sensitive gas sensor is required, but the FID method requires an expensive gas sensor using the ionized hydrogen flame method, and the measurement of helium gas requires an expensive gas sensor. The reality is that there are no highly sensitive sensors available.

Therefore, the present applicant has proposed a container leakage testing method using alcohol gas as a gas that is safe, inexpensive, and has extremely sensitive sensors (for example, Japanese Patent Application No. 196500/1983 Patent application 1986-2525
(See Publication No. 04). .

[Problems to be Solved by the Invention] However, in the above method, the container is housed in a closed chamber, and the space inside the chamber or container is
After filling alcohol gas in one space and air in the other space, air is sucked from one space to create a pressure difference in the rain space, and whether or not there is alcohol gas present in the sucked air. Since this method detects alcohol gas using an alcohol gas sensor, it requires a closed chamber and piping for charging the gas in the chamber, resulting in a complicated structure.

The present invention has been made focusing on the above-mentioned circumstances, and
Not only is it safe and has high detection sensitivity, and continuous testing is possible, it does not require a conventional chamber, so the structure does not become complicated, and it can be done at a lower cost than conventional methods. The purpose is to provide a detection method.

[Means for Solving the Problems] That is, the characteristic configuration of the container leakage detection method according to the present invention is that a holder having a ventilation hole in which an evaporable liquid is held is disposed on the outside of the container; The present invention is characterized in that the presence or absence of components of the liquid in the container is measured by a gas sensor by suctioning the inside of the container under reduced pressure.

Here, the holding body may be made of natural fibers such as cotton, synthetic resin fibers, mineral fibers such as glass wool or rock wool, or natural resin foams such as rubber, sponges, etc., with ventilation holes communicating between the front and back surfaces. A resin foam with continuous foaming to form a resin foam, or a synthetic resin such as silicone resin, fluorocarbon resin, polypropylene, etc., or a natural resin such as rubber, etc., which has a porous structure through which gas can pass. Can be used. In addition, evaporable liquids include lower alkanes such as pentane, lower alkenes such as pentene, lower alcohols such as methyl alcohol, ethyl alcohol, propatool, butanol,
Ketones having a lower alkyl group such as acetone, ethers having a lower alkyl group such as ethyl ether, etc. can be used.

Among these, ethyl alcohol is preferable because it has low toxicity and a low boiling point, and also shows high sensitivity to the gas sensor described below.

As the gas sensor, for example, an alcohol-selective gas detection element (see Japanese Patent Application No. 60-23541) is one that can be used particularly conveniently. This sensing element has the feature of being able to detect alcohols such as ethyl alcohol with high sensitivity and responsiveness even in the presence of hydrogen, carbon oxide, and methane, and is relatively inexpensive compared to conventional devices. It is.

The functions and effects of the above means are as follows.

[Function] When a vacuum suction is applied to the inside of the container with a holder having a ventilation hole holding an evaporable liquid placed on the outside of the container, the inside of the container is under reduced pressure compared to the outside, and the container is heated. Since a pressure difference is generated between the inside and outside, if a pinhole exists in the container, gas from outside the container is sucked into the container through the pinhole. At this time, since a holder holding an evaporable liquid is placed outside the container, the vapor of the liquid is sucked into the container through the pinhole as described above along with other gases (e.g. air). Ru. Therefore, if the gas in this container is measured with a gas sensor and a liquid component is detected, it can be determined that a pinhole exists, and if no liquid component is detected, there is a pinhole in the container. Therefore, it can be determined that it is not.

[Effects of the Invention] As a result, since it does not use a substance that is in a gaseous state at room temperature as in the past, it is convenient to handle, does not require a pressure-resistant container for gas storage, and does not use substances such as helium gas or Freon gas. It is now possible to use a cheaper and more sensitive sensor, which is not expensive, and it has become possible to perform continuous inspections.

Moreover, as mentioned above, since it is only necessary to place a liquid holder on the outside of the container, there is no need for a closed chamber like in the past, and the structure is simple, inexpensive, and easy to operate. Became.

[Example 1] Embodiments of the present invention will be described below based on the drawings.

Figure 1 shows a gas leak detection device (A) used in the container leak detection method according to the present invention.
consists of a case (2) for fixing the container (1), a liquid holder (3) attached to the inner surface of the case (2), and a container (1) housed in the case (2). It is configured to include a gas sensor (4) that sucks the gas in the container (1) under reduced pressure through the opening (la) and measures the components of this gas.

The case (2) is formed of a bottomed cylindrical synthetic resin molded product with an opening (2a) on the top surface.
A large number of through holes (I3) communicating between the inside and outside of the case (2) are bored in the peripheral wall and bottom of the case (2). The inner surface shape of the case (2) is formed approximately along the outer shape of the container (1) to be inspected, so that a slight gap is formed between the container (1) housed inside and the inner wall surface. In this case (2
) Cotton (3) as a holding body impregnated with ethyl alcohol is installed over almost the entire surface of the inner wall surface and the inner surface of the bottom, and a supply channel (6) is provided to replenish the cotton (3) with ethyl alcohol. is provided on the peripheral wall of the case (2).

The opening (2a) of the case (2) has a pair of left and right upper lids (7) driven by an air cylinder;
(7) is arranged to be able to open and close the opening (2a), and a piston rond (8) which is driven up and down by an air cylinder is arranged above the case (2). (8) At the bottom end of the container (1
) can be removed and installed freely. A nozzle (10) is provided at the lower end of the piston rond (8) with a flow path (9) that communicates with the lower and upper sides.
is attached, and a gasket (11) is attached to the lower end of this nozzle (10). A side opening of the nozzle (10) is connected to a suction pump (12) via a hose (I4), and an alcohol gas sensor (4) is connected to the middle of this hose (14).

Next, a method of inspecting the presence or absence of pinholes in the container (1) using the gas leakage inspection device (Δ) having the above configuration will be described.

As shown in Fig. 1, after setting the container (1) in the case (2) and tightening the upper M (7) by driving the cylinder,
The nozzle (10) is moved downward by the drive of the air cylinder, and the gasket (11) attached to the bottom 6a of the nozzle (10) is applied to the opening (la) of the container H3 (1) to seal it. Next, in this state, the suction pump (12) is driven to reduce the internal pressure in the container (1) to approximately 0.1 to 0.2 kg/
Aspirate gas gradually until cut. Here, if there is a pinhole in the container (1), the case (2)
As a result, a gas flow path is formed between the through hole (13) in the cotton (3) and the pinhole, so that the vapor of ethyl alcohol impregnated in the cotton (3) flows from the pinhole to the container (1).
) and is sent along with the gas in the container (1) from the hose (14) to the gas sensor (4), allowing the alcohol gas sensor (4) to detect the vapor of ethyl alcohol. After the inspection, return the inside of the container (1) to normal pressure, move the upper M (7), (7) from side to side, and move the piston rod (8) upward to remove the container (1) from the case. It can be removed from (2).

The series of operations described above can be performed automatically by driving the air cylinder under microcomputer control, sequence control, or the like.

[Example 2] As shown in Fig. 2, a gas sensor (4) is attached to the lower end of the nozzle (10), and a lead wire of the sensor is buried in the nozzle (10) to allow the gas to flow into the container (1). The gas sensor (4) may directly measure the alcohol vapor. Further, in this embodiment, a method that is not affected by atmospheric gas is adopted, and the inspection method is as follows.

First, in a position above the case (2), with the mouth (1a) of the container (1) in contact with the lower end surface of the gasket (11) attached to the lower end of the nozzle (10), the suction pump (12) The gas inside the container (1) is sucked by the drive of the container (1). Then, the pressure inside the container (1) becomes reduced and the gasket (11) is adsorbed to the lower end of the gasket (11).
1) and set the container (1) into the case (2) through the opening (2a) of the case (2). In this case, the degree of vacuum inside the container (1) is as follows:
) It is enough to just stick it to the lower end of the cylinder, and there is no need to reduce the pressure to a high vacuum state. Next, the upper lid (7) of the case (2) is tightened, and suction is continued by the suction pump (12) to gradually reduce the internal pressure until the internal pressure becomes about 0.1 to 0.2 kg/cut.

Here, if there is a pinhole in the container (1),
Since ethyl alcohol vapor flows into the container (1) in the same way as above, it can be directly detected by the alcohol gas sensor (4). After the inspection, move the upper lid (7) to the left and right, move the piston rod (8) upward together with the container (1), and then return the inside of the container (1) to normal pressure. ) can be removed. In addition, in the figure (
6) is an alcohol supply path formed on the inner surface of the case (2).

According to the above detection method, the gas in the container (1) is passed through the hose (14) to the gas sensor (4) as in the first embodiment.
Because it can be detected directly inside the container (1) without having to send it to the
There is an advantage that even liquid or gas that tends to remain at the bottom of 1) can be detected without any problem. In addition, the case (2) is constructed so that it can be divided into upper and lower and left and right parts, so that the case (2) can be divided into
There is also the advantage that even if the shape of (1) is complex, it can be set inside the case (2).

[Example 3] The container (1) was set in the case (2) and a nozzle was inserted into the mouth (1a) of the container (1) so that the gas sensor (4) was not affected by the atmospheric gas around the device (8). (10) is inserted with a slight gap formed, fresh air from outside is introduced from the nozzle (10), and then the opening (1) inside the container (1) is introduced.
The above operation may be performed by sealing a) with a packing (11).

The part to be inspected of the container (1) may be the entire circumferential surface of the container (1) as in the above example, or only the parts where pinholes are particularly likely to occur, such as welded parts and caulked parts. You can also target it. Alternatively, a large number of containers (1) may be placed in the case (2) at once to check for leakage, and the holder (3) or the case (2) may be slightly heated. The evaporation of the liquid may be promoted by Furthermore, the holder (3) itself may be configured as a case (2), and the evaporable substance may be a sublimable solid, a fragrance, or the like.

Further, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings by such entry.

[Brief explanation of the drawing]

The drawings show an embodiment of the container leakage detection method according to the present invention, FIG. 1 is a longitudinal sectional side view of a container leakage detection device, and FIG. 2 is a partially cutaway side view of another embodiment of the leakage detection device. . (1) Container, (3) Liquid holder, (4) Gas sensor.

Claims (1)

[Claims] 1. A holder (3) having a vent that holds an evaporable liquid is placed outside the container (1), and the inside of the container (1) is vacuum-suctioned to remove the container ( 1) A method for detecting leakage of a container, characterized in that the presence or absence of components of the liquid in the container is measured using a gas sensor (4). 2. The container leakage detection method according to claim 1, wherein the holding body (3) is a fiber. 3. The container leakage detection method according to claim 1, wherein the holding body (3) is a resin foam having continuous foaming. 4. The container leakage detection method according to claim 1, wherein the holder (3) is made of porous resin. 5. The container leakage detection method according to any one of claims 1 to 4, wherein the evaporable liquid has a low boiling point. 6. The container leakage detection method according to claim 5, wherein the liquid is ethyl alcohol.