JP2000136977A - Method and device for inspecting leakage of container utilizing differential-pressure change rate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make quickly measurable the leakage of an inspection container by measuring the change rate of the differential-pressure data of a reference container and a container under inspection immediately after a transient response period and comparing the change rate with a immediately after a transient response period and comparing the change rate with a reference value. SOLUTION: Compressed air is introduced to a reference container 1 and a container under inspection 2. By a pressurized line 4, connection to a pressurized pipe 3 is made, a solenoid valve 6 with a pressurized line is provided, and the pressurized air is supplied from an air source 7. A differential pressure gauge 8 is connected so that a pressure at both the sides of a solenoid valve 5 with the pressurized pipe is measured, and the output of the differential pressure gauge 8 is connected to a judging device 10 consisting of a computer. A manometer 9 is mounted to the container under inspection 2. When the solenoid valve 5 with the pressurized pipe is open, the pressure of the reference and inspection containers 1 and 2 is measured. On the other hand, when the solenoid valve 5 is closed, the pressure of the container under inspection 2 is measured. Then, the change rate of the differential pressure of a specific period after transient response period passes is obtained. The change rate corresponds to a leakage area, thus comparing the change rate with a reference value, and hence detecting the presence or absence of the leakage area. For judging the presence or absence of the leakage, the inclination of the differential data of the container is measured in advance, and the leakage is judged to be allowable when the inclination is equal to or less than a preset value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a container leakage inspection method and apparatus for detecting leakage of a container by a differential pressure from a reference container.

[0002]

2. Description of the Related Art A differential pressure method is used as a method for detecting leakage of a container. The differential pressure method measures the differential pressure between a reference container without leakage and the inspection container to be inspected to the same pressure, and then measures the differential pressure between the two. If the differential pressure exceeds the reference value, the inspection container has a leak. If not, there is no leakage.

[0003]

In the initial period when a pressure difference is generated between the reference container and the test container, the pressure difference fluctuates greatly because the air in both containers and the pressurized air are mixed. FIG. 3 is a diagram showing the time course of the differential pressure. A1 to A3 show the time course of the differential pressure in the case of a test vessel having the same leak area, and B1 to B3 show the time course of the differential pressure in the case of a test vessel without leak. If there is leakage, the time required to reach the threshold value for detecting the presence or absence of leakage varies depending on the initial transient response even if the leakage area is the same. For this reason, it is necessary to measure whether or not the threshold value is exceeded after a certain period of time after the occurrence of the differential pressure. When detecting a large number of containers, if the detection time per one container is long, it is often difficult to detect all the containers. It takes a long time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a method and an apparatus for inspecting a container leak in which the measuring time of the differential pressure is shortened.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, a reference container having no leakage and an inspection container to be inspected are pressurized to the same pressure, and then the pressure difference between the two is measured. Then, the rate of change of the data within a predetermined period after a lapse of a predetermined time from the occurrence of the differential pressure is obtained, and leakage is detected from the change rate.

[0006] The differential pressure between the reference container and the inspection container to be inspected fluctuates greatly immediately after the occurrence, and it may take time to reach the threshold value for judging the presence or absence of leakage. Therefore, detection of whether the differential pressure has reached the threshold value is performed after a certain time T from the occurrence of the differential pressure. The differential pressure in the case of leakage is stable after the elapse of the initial transient response period, and the rate of change of the differential pressure within a predetermined period after the transient response period is substantially the same when the leakage area is the same. Therefore, by detecting the rate of change, it is possible to detect the presence or absence of leakage, and moreover, the detection of the rate of change is
Since it can be obtained from data measured during a predetermined period immediately after the transient response period, the time t at which this detection ends is shorter than the time T at which the differential pressure reaches the threshold, and the presence or absence of leakage is reduced. It is possible to measure time.

According to a second aspect of the present invention, there is provided a pressurizing pipe connecting a leak-free reference container and a test container to be inspected and having a shut-off valve in the middle, a pressurizing line for supplying pressurized gas to the pressurizing pipe, A differential pressure gauge for measuring a differential pressure between both ends of the shutoff valve of the pressurizing pipe, and a determining device for detecting leakage of the test container from a measured value of the differential pressure gauge, wherein the determining device has passed a predetermined time since the generation of the differential pressure. The rate of change of data within a predetermined period later is obtained, and leakage is detected from the rate of change.

First, the shutoff valve of the pressurizing pipe is opened, and pressurized gas is supplied from the pressurizing line to the reference container and the inspection container. When a predetermined pressure is reached, the shutoff valve is closed and the connection with the pressurizing line is also cut off. I do. The differential pressure of the differential pressure gauge after this time is measured and set as differential pressure data. The judging device does not use the data for a predetermined time after the occurrence of the differential pressure as data for a transient response period in which the value fluctuates greatly. It is compared with a predetermined reference change rate for leakage determination, and if it is larger, it is determined that there is leakage. This makes it possible to determine the leakage in a shorter time than in the conventional method of comparing the pressure difference with the threshold value of the pressure difference.

According to the third aspect of the present invention, the rate of change is:
Data within a predetermined period after a predetermined time elapses from the occurrence of the differential pressure is approximated by a straight line, and the gradient of the straight line is used.

Since the differential pressure data after the elapse of the transient response period often changes almost linearly, the data is approximated by a straight line, and the gradient is obtained. If the gradient is equal to or more than the reference value, it is determined that there is a leak. This is because if the data is a straight line, the rate of change is the slope of the straight line.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a container leakage inspection device according to the present embodiment. Reference numeral 1 denotes a reference container having no leakage, and reference numeral 2 denotes an inspection container to be inspected. Reference numeral 3 denotes a pressurizing tube, which has a solenoid valve 5 with a pressurizing tube in the middle, and introduces pressurized air into the reference container 1 and the inspection container 2. Reference numeral 4 denotes a pressurizing line, which is connected to the pressurizing pipe 3 and has a solenoid valve 6 with a pressurizing line, and pressurized air from an air source 7 (a test pressure of 0.3 kgf / cm ² is usually used. Can be set arbitrarily). A differential pressure gauge 8 is connected so as to measure the pressure on both sides of the solenoid valve 5 with a pressure pipe, and the output of the differential pressure gauge 8 is connected to a judgment device 10 composed of a computer. A pressure gauge 9 is attached to the inspection container 2, and measures the pressure of the reference container and the inspection container when the solenoid valve 5 with the pressurized pipe is open, and measures the pressure of the inspection container 2 when the solenoid valve 5 is closed.

FIG. 2 shows a pressure gauge 9 and a differential pressure gauge 8 during operation of the apparatus.
Shows the measured values. FIG. 2A shows the measurement value of the pressure gauge 9, and FIG. 2B shows the measurement value of the differential pressure gauge 8. In (A), during the pressurizing period, the solenoid valve 5 with the pressurizing tube and the solenoid valve 6 with the pressurizing line are opened, and the case where the air pressure is applied to the test pressure from the air source 7 is shown. , 6 are closed. (B) shows the measurement value of the differential pressure gauge 9 during the inspection period.

FIG. 3 shows the measured data of the test container. The inspection containers A1 to A3 and B1 to B3 are containers having the same shape,
A3 have openings of the same leakage area size, and B1 to B3
3 is a container without a leak. Reference container 1 is inspection container 2
It has the same shape as. 0.3 kgf / cm ² as test pressure
Shows the change in the differential pressure when. The differential pressures of A1 to A3 change differently during the transient response period, but become almost stable after this period. Therefore, the rate of change of the differential pressure during a predetermined period (a period from t0 to t) after the elapse of the transient response period is obtained. The magnitude of the rate of change is a value corresponding to the leakage area. Then, the rate of change can be compared with the reference value to detect the leakage area and the presence or absence of leakage.
When the differential pressure data can be approximated by a straight line as shown in FIG. 3, the rate of change of the differential pressure is the gradient of the approximated straight line, so that it is possible to estimate the leakage area and the presence or absence of leakage from the magnitude of this gradient. become. When determining whether or not there is a leak, the gradient of the differential pressure data of the container having the allowable leak amount is measured in advance, and if the slope is equal to or less than this slope, the determination is made by the determination device 10 to be equal to or less than the allowable leak. Since this gradient measurement is performed in the period from the end of the transient response period t0 to t, it can be measured in a shorter time than the threshold pressure measurement time T of the differential pressure as in the related art, and leakage of many containers is detected. In this case, the detection time can be significantly reduced.

In the test containers B1 to B3 having no leakage, the differential pressure during the transient response period fluctuates, but after this period, the data is represented by a substantially straight line, the gradient thereof is substantially 0, and the line of the differential pressure 0 is sandwiched. It becomes a straight line. If the determination is made based on the case where the differential pressure exceeds the threshold value as in the prior art, the threshold measurement time T is set at the rate of change in order to enable detection of the case where the transient response period fluctuates greatly and rises slowly as in A3. It is much later than the measurement end time t.

[0015]

As is apparent from the above description, the present invention measures the leak rate of the test container by measuring the rate of change of the differential pressure data between the reference container and the test container immediately after the transient response period and comparing it with the reference value. Can be measured in a short time. By using the method of the present invention, the leakage inspection time of a large number of containers can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an apparatus according to an embodiment.

FIG. 2 shows measured values of a pressure gauge 9 and a differential pressure gauge 8 during operation of the present apparatus.

FIG. 3 shows measured data of an inspection container.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reference container 2 Inspection container 3 Pressurizing pipe 4 Pressurizing line 5 Solenoid valve with pressurizing pipe 6 Solenoid valve with pressurizing line 7 Air source 8 Differential pressure gauge 9 Pressure gauge 10 Judgment device

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshiaki Suzuki 1720 Kamai, Higashi-machi, Inashiki-gun, Ibaraki Pref.Ishikawajima Inspection Instruments Co., Ltd. Inside Kasumigaura Works (72) Inventor Takeshi Ishizaki 1720 Kamai, Higashi-machi, Inashiki-gun, Ibaraki Prefecture

Claims (3)

[Claims] 1. A pressure difference between a reference container having no leakage and a test container to be inspected is measured after the pressure is increased to the same pressure, and a change in data within a predetermined period after a predetermined time has elapsed since the generation of the differential pressure. A container leak inspection method using a differential pressure change rate, wherein a rate is determined and a leak is detected from the change rate. 2. A pressurizing pipe connecting a leak-free reference container and a test container to be inspected and having a shutoff valve in the middle, a pressurizing line for supplying pressurized gas to the pressurizing pipe, and a shutoff valve for the pressurizing pipe. A differential pressure gauge for measuring the differential pressure between both ends of the test container, and a determining device for detecting leakage of the test container from the measured value of the differential pressure gauge, wherein the determining device is configured to perform a predetermined period after a predetermined time has elapsed since the generation of the differential pressure. A container leak inspection device using a differential pressure change rate, wherein a rate of change of the data is obtained and a leak is detected from the change rate. 3. The differential pressure according to claim 1, wherein data within a predetermined period after a predetermined time has elapsed since the occurrence of the differential pressure is approximated by a straight line, and a gradient of the straight line is used as the rate of change. Container leak inspection method using change rate.