JPS6063438A - Method and device for leak detection - Google Patents

Abstract

PURPOSE:To detect even slight leak very accurately and surely by sensing ultrasonic waves generated in accordance with break and movement of bubbles, which are generated when gas is jetted from a leak of an object to be examined, to detect the leak or the leak position. CONSTITUTION:One end of a feeding pipe 2' of a gas feeding mechanism 2 is linked to the inside space of an object 1 to be examined by airtight connection. A liquid l which generates easily bubbles is sprayed or applied to all of the surface of a welded part 1a by an applying mechanism 8. When air or gas pressurized to a prescribed pressure (including a negative pressure) is supplied into the object 1 to be examined through the feeding pipe 2' in this state, this pressurized air or gas is jetted from a leak if the leak exists in the welded part 1a. In case of this jetting, bubbles (a) are generated in the sprayed or applied liquid l. If the pressure in bubbles (a) is more powerful than the surface tension of bubbles (a), they are broken after a while to generate oscillating waves of gas (ultrasonic waves). Consequently, ultrasonic waves generated in accordance with break or the like of bubbles (a) are sensed by a sensor A to check presence/ absence of a leak and a leak position accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a leakage detection method and device for detecting leakage or leakage locations by sensing ultrasonic waves generated when bubbles burst, etc., and its purpose is to , Spraying or applying water, oil, or other liquid to the object to be detected, or immersing the object to be detected in water, oil, or other liquid, and pressurizing or depressurizing the object to be detected. By supplying a gas such as air or gas and detecting the ultrasonic waves generated when the bubble bursts or moves when the gas is ejected from the leak of the object to be detected, the leak or leak location is detected. , gas f that generates bubbles: not limited to a specific one,
It is possible to use an appropriate gas such as air, and it can be detected easily and inexpensively without being too dependent on the environmental temperature. It is possible to very accurately and reliably check even minute leaks that were often overlooked, greatly increasing reliability.
The present invention aims to provide a leak detection method and a device thereof which can be widely applied even in the case of leakage detection.

Next, the method of the present invention will be explained using a preferred embodiment shown in the drawings. This is the object to be detected.

When conducting a leak test for this object to be detected,
One end of the feed pipe 2' of the gas feed mechanism 2 is connected to the internal space of the object to be detected 1 in an airtight manner.

Then, a liquid that tends to form bubbles, such as water, oil, soapy water, or a liquid l thereof, is sprayed or coated over the entire surface of the welded portion 1a by the spraying or coating mechanism 8. In such a state, if a gas such as air or gas pressurized to a predetermined pressure (including the case of negative pressure) is fed into the inside of the object to be detected 1 via the feed qf 2/, this pressurized gas will If there is a leak in the welded part 1a, it will eject from the leak, but when this erupts, bubbles a will be added to the liquid l, such as water, oil, soapy water, etc. that was sprayed or applied.
occurs. When the pressure inside the bubble a is stronger than the surface tension of the bubble a, the bubble a bursts and generates gas vibration waves (ultrasonic waves) at its core. Therefore, if the ultrasonic waves generated due to the bursting of the bubble a are detected by the sensor A, the presence or absence of leakage and the location of the leakage can be accurately checked from the sensor K.

The illustrated example of the sensor is an example of an ultrasonic leak detector, which includes a main body 5 including an instrument indicator 3, a speaker 4, etc., a detection probe 6 connected to the main body 5, and a headset. 7, etc., and the detection probe 6
The device senses the ultrasonic waves generated when the bubble a bursts or moves, and the meter indicator 3 and speaker 4 or headset 7 alert the user.

The one in Fig. 3 detects leakage by catching ultrasonic waves from the burst sound of bubbles a, and the one in Fig. 4 shows a state tube for detecting bubbles outside or inside the container 9. Detected object 1
This device detects the movement of bubbles a (not plosive sounds h) generated by the bubbles using Doppler ultrasonic waves, and the tip of the detection probe 6 is placed in the liquid L and set on the side wall of the container 9. .

The one shown in FIG. 5 is almost the same as the one shown in FIG. 4, but the detection probe 6 is not placed in the liquid but is kept in close contact with the container 9 from the outside.

As described above, the leak detection method according to the present invention detects leaks by sensing ultrasonic waves generated when bubbles burst or move when gas is ejected from a leak. The gas is not limited to a specific gas, and any suitable gas such as air can be used.・
In this respect, conventional leak detection methods require a helium detector if helium gas is used, a halogen detector if halogen gas is used, etc., and prepare a dedicated detector corresponding to the type of gas used. However, in the method of the present invention, such conventional disadvantages and inconveniences are not present at all.

In addition, conventional leak detection methods, such as those using differential pressure, require certain temperature conditions. Therefore, differential pressure methods cannot be used immediately after welding, etc., and halogen In the case of a detector, halogen gas (such as Freon gas) is easily removed and remains, so it is necessary to blow off the halogen gas remaining in the vicinity before the next test.However, with the method of the present invention, this was affected by environmental temperature, etc. Leakage can be detected without being influenced by environmental temperature, etc.Furthermore, in the method of the present invention, although it depends on the degree of pressurization, the smaller the leakage caused by pressurized gas, the easier it is for bubbles to form, and therefore the leakage. Since it is easy to detect, it is possible to check even minute leaks, which were often overlooked in the past, extremely accurately and reliably, thereby greatly increasing reliability.

As described above, the present invention involves spraying or applying water, oil, or other liquid to an object to be detected, or immersing the object in water, oil, or other liquid, and adding water, oil, or other liquid to the object to be detected. A gas such as air or gas under pressure or reduced pressure is supplied, and when the gas is ejected from the leak of the object to be detected, the leak is detected by detecting the ultrasonic waves generated due to the bursting of bubbles or the transfer of IvJ, etc. Alternatively, since it is used to detect leakage points, the gas that generates bubbles is not limited to a specific one (in addition to being able to use an appropriate gas such as nitrogen, it is not affected too much by environmental temperature, etc.). Although it is easy and inexpensive to detect, the smaller the leak, the easier it is to form bubbles and therefore the easier it is to detect, so even minute leaks that were often overlooked in the past can be checked extremely accurately and reliably, increasing reliability. Not only can it be greatly improved, but it can also be applied to a wide range of fields without requiring any special technology or skill. It has extremely useful effects, such as being able to be used effectively from both sides.

[Brief explanation of the drawing]

Figures 1 and 2 are perspective views showing the state in which a leak test is performed at a welding location using the method and device of the present invention, respectively, and Figures 3 to 5 are respectively illustrative of the state in which the detected object is water, oil, or other In the figure, 1 is an object to be detected, 2 is a gas supply mechanism, 8 is a liquid spraying or coating mechanism, and ! is a liquid, a is a bubble, a person is an ultrasonic sensor, and 9 is a container.

Claims (1)

[Claims] (1) Spray or apply water, oil, or other liquid to the object to be detected, or immerse the object to be detected in water, oil, or other liquid, and pressurize or apply pressure to the object to be detected. Leakage or leakage is detected by supplying a gas such as reduced pressure air or gas, and detecting the bursting of bubbles that occur when the gas is ejected from the leak of the object to be detected, or the ultrasonic waves generated as the bubbles move. A leak detection method characterized by detecting a location. (2) A mechanism for spraying or applying water, oil, or other liquid to the object to be detected, or a round container for immersing the object to be detected in water, oil, or other liquid, and pressurizing the object to be detected. Or it consists of a feeding mechanism that feeds gas such as reduced pressure air or gas, and an ultrasonic detection mechanism that detects ultrasonic waves'6
Wet leakage detection device with f-makicho.