JP4107970B2 - Leak inspection method for water purification cartridge - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a leak inspection method for a water purification cartridge containing at least a porous agent.
[0002]
[Prior art]
In order to purify tap water or the like, a water purifier 2 having a water purification cartridge 1 as shown in FIG. 4 may be used. As the water purification cartridge 1 of the water purifier 2, for example, a hollow fiber membrane module 12 in which a large number of hollow fiber membranes 11 are converged in a U-shape and their ends are fixed, a porous agent 13 such as activated carbon, And integrated with the case 14 and the lid 15. In this water purifier 2, raw water flows into the water purification cartridge 2 from the inlet 17, passes through the porous agent 13 and the hollow fiber membrane module 12 in this order, then flows out from the outlet 18, and from the outlet 19 of the water purifier 2. Discharge as treated water.
However, in such a water purification cartridge 1, a gap may be formed if the case 14 and the lid 15 are incompletely joined. In the case where a gap is formed in the joint portion 16 between the case 14 and the lid portion 15, the raw water does not pass through the hollow fiber membrane module 12 and the porous agent 13 and passes through the gap in the joint portion 16 into the treated water. There was a possibility that the water would be insufficient due to contamination. Therefore, normally, after producing the water purification cartridge 1, the leak inspection is performed.
[0003]
As a conventional inspection method (for example, see Patent Documents 1 to 3), as shown in FIG. 5, the water purification cartridge 1 in which air is sealed from the air introduction pipe 41 is submerged in the water tank 42, and the presence or absence of bubbles 43 is generated. As shown in FIG. 6, there is a soaking method for visually confirming the presence of bubbles 44 by applying soapy water to the joint 16 of the water-purifying cartridge 1 filled with air. Can be mentioned.
As another inspection method, supply the inspection gas to the water purification cartridge, measure the leakage amount of the inspection gas with a micro flow meter, set the inside of the water purification cartridge to positive or negative pressure, and change the pressure after that. Examples include a pressure method in which leakage is detected by measuring with a pressure gauge, a pressure sensor, a pressure switch, etc., and comparing the amount of change in pressure with a threshold value for presence or absence of leakage.
[0004]
[Patent Document 1]
JP-A-9-75690 [Patent Document 2]
Japanese Patent Laid-Open No. 10-15059 [Patent Document 3]
Japanese Patent Laid-Open No. 2002-236102
[Problems to be solved by the invention]
However, in the above-described submersion method and soap solution application method, since the operator makes a visual decision, the generation of bubbles may be overlooked, and the accuracy is low. Furthermore, since the water purification cartridge gets wet in the submersion method or the soap water application method, it has to be dried before shipping as a product, which requires time.
Further, the flow rate method and the pressure method have the following problems. That is, since the porous agent accommodated in the water purification cartridge has many voids, it takes time for the inspection gas to fill the void when the inspection gas is supplied to the water purification cartridge. Therefore, since air flows for a long time, the flow rate method sometimes misidentifies that it is leaking. Further, in the pressure method, even if it is determined that the pressure is stable, the air is actually not completely filled, and the pressure may be further lowered, which may be mistaken as a leak.
That is, it is difficult to distinguish between the entry of air into the void of the porous agent and the leakage of air, and the inspection accuracy is low. On the other hand, if the air is completely filled in the air gap, there will be no misidentification, but there is a problem that the inspection time becomes very long. Moreover, in recent years, since the water purification cartridge has been increased in size, the above-mentioned tendency has become stronger, and inspection by the flow rate method and the pressure method has become more difficult.
[0006]
From the above, an inspection method suitable for quality control of the water purification cartridge has been desired. Furthermore, a simple inspection method has been desired from an industrial viewpoint.
The present invention has been made in view of the above circumstances, and provides a method for inspecting a water purification cartridge that can be easily and highly accurately tested for leakage of a water purification cartridge in a short time and can be easily applied to quality control. Objective.
[0007]
[Means for Solving the Problems]
The method for inspecting leakage of a water purification cartridge according to the present invention includes introducing a gas connected to the water inlet and outlet of the water purification cartridge into a reference water purification cartridge that contains at least a porous agent and is confirmed not to leak. A first measuring step of measuring a pressure change in the reference water purification cartridge after introducing a test gas having a predetermined pressure by a pipe for use ;
An inspection gas having a predetermined pressure equivalent to that of the first measurement step is connected to the water purification cartridge to be inspected having the same configuration as the reference water purification cartridge by a gas introduction pipe connected to the water inlet and outlet of the water purification cartridge. And a second measuring step for measuring a pressure change in the water purification cartridge,
Based on the pressure change measured in the first measurement step and the pressure change measured in the second measurement step, the presence or absence of leakage of the water purification cartridge to be inspected is inspected.
In the method for inspecting a leak of a water purification cartridge according to the present invention, it is preferable to use a sealed inspection gas having a predetermined pressure as a reference for pressure change.
In addition, when introducing the inspection gas into the water purification cartridge, it is preferable to introduce the inspection gas from all the openings formed in the water purification cartridge.
Furthermore, it is preferable that the predetermined pressure of the inspection gas is in the range of 0.01 to 0.7 MPa.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
One embodiment of a water purification cartridge leak inspection method (hereinafter abbreviated as a leak inspection method) of the present invention will be described with reference to the drawings. The water purification cartridge used in this embodiment is shown in FIG.
In the leak inspection method of the present embodiment, first, after introducing the inspection gas of a predetermined pressure into the reference water purification cartridge that is confirmed not to leak in the first measurement step, the reference water purification cartridge Measure the pressure change. The pressure change measured here is a phenomenon resulting from the filling of the inspection agent gas into the voids of the porous agent and the hollow fiber membrane.
Next, in the second measurement step, after introducing a test gas having a predetermined pressure equivalent to that in the first measurement step into the water purification cartridge to be inspected having the same configuration as the reference water purification cartridge, the pressure change of the water purification cartridge is changed. taking measurement.
And based on the pressure change measured at the 1st measurement process, and the pressure change measured at the 2nd measurement process, the presence or absence of the leak of a water purification cartridge is test | inspected.
[0009]
A method for measuring a pressure change in the above-described leak inspection method will be described.
In FIG. 1, the schematic diagram of the pressure change measuring apparatus 20 used when measuring a pressure change is shown. The pressure change measuring device 20 includes an air supply means 21 such as a pump for supplying an inspection gas, a gas introduction pipe 22 connected to the air supply means 21, and a reference pressure container 23 that can store the inspection gas. A first connection pipe 25 that connects the gas introduction pipe 22 and the water purification cartridge 1, a second connection pipe 26 that connects the gas introduction pipe 22 and the reference pressure vessel 23, and a first connection pipe 25. And a pressure measuring means 27 for measuring a differential pressure between the test gas on the reference pressure container 23 side and the test gas on the water purification cartridge 1 side.
[0010]
In the pressure change measuring device 20, opening and closing valves 28 a and 28 b are installed in the first connecting pipe 25 and the second connecting pipe 26.
Moreover, all the openings formed in the water purification cartridge 1 are connected to the first connecting pipe so that the inspection gas is introduced. That is, the inlet 17 for taking in raw water at the time of use and the outlet 18 for discharging treated water are connected to the first connecting pipe 25. In this way, if the inspection gas is introduced from all the openings formed in the water purification cartridge, the introduction time can be shortened and the pressure can be easily stabilized, resulting in a longer inspection time. Can be shortened.
[0011]
In the pressure change method using the pressure change measuring device 20, the opening / closing valve 28 a of the first connection pipe 25 and the opening / closing valve 28 b of the second connection pipe 26 are opened, and the air supply means 21 An inspection gas having a predetermined pressure is introduced into the reference pressure vessel 23 and the water purification cartridge 1 from the gas introduction pipe 22. Next, the opening / closing valve 28a of the first connection pipe 25 and the opening / closing valve 28b of the second connection pipe 26 are closed, and the inspection gas on the reference pressure container 23 side and the inspection gas on the water purification cartridge 1 side are changed. Isolate and leave. While being left, the pressure measuring means 27 measures the differential pressure between the inspection gas on the reference pressure container 23 side and the inspection gas on the water purification cartridge 1 side. Here, since the fluctuation range of the pressure value is large immediately after the introduction of the inspection gas, it is preferable to wait for the fluctuation range of the pressure value to decrease before measuring the differential pressure. The waiting time varies depending on the size of the water purification cartridge 1, the amount and physical properties of the contained porous agent, and the inspection conditions, but is preferably about 0.2 to 5 seconds. If the standing time is less than 0.2 seconds, the fluctuation range of the pressure value may not be sufficiently small. If the standing time exceeds 5 seconds, the influence of the inspection gas entering the voids of the porous agent and the hollow fiber membrane is affected. It may not be negligible.
[0012]
When measuring the differential pressure, the test gas on the reference pressure container 23 side is sealed, so that the pressure of the test gas on the reference pressure container 23 side does not change, and the pressure at the time of introduction is the same. It remains. On the other hand, on the water purification cartridge 1 side, the pressure drops due to the filling or leakage of the inspection gas into the voids of the porous agent and the hollow fiber membrane. Therefore, by measuring the differential pressure between the inspection gas on the reference pressure container 23 side and the inspection gas on the water purification cartridge 1 side, the pressure change of the inspection gas in the water purification cartridge 1 can be measured.
In addition, it is preferable to shorten the measurement interval of a pressure change at the initial stage of measurement with a large pressure change, and to make it long at the latter stage of a measurement with a small pressure change.
Here, the introduction of the inspection gas is simultaneously performed in the reference pressure vessel 23 and the water purification cartridge 1 here, but may be performed separately.
[0013]
Such a pressure change measurement method can be applied to both the first measurement process and the second measurement process. Further, in such a pressure change measuring method, the pressure change measuring means 27 measures the pressure difference between the pressure of the inspection gas at the time of introduction and the pressure in the water purification cartridge to obtain a pressure drop, and the change in the pressure always changes. Since it has a reference, it can be measured with higher accuracy.
[0014]
In the pressure change measuring method described above, the inspection gas is not particularly limited, and for example, air can be used. The predetermined pressure of the inspection gas can be appropriately selected in consideration of the size and structure of the water purification cartridge, deformation during pressurization, etc., but is within the range of 0.01 to 0.7 MPa. It is preferable. If the predetermined pressure of the inspection gas is within a range of 0.01 to 0.7 MPa, it is possible to easily determine the presence or absence of a leak, and an equipment corresponding to a high pressure becomes unnecessary.
[0015]
The presence or absence of leakage of the water purification cartridge is determined from the pressure change in the first measurement process and the pressure change in the second measurement process measured by the pressure change measurement method described above. Hereinafter, an example of the determination method will be described. In this determination method, the pressure change measured in the first measurement step is plotted, and a master curve A as shown in FIG. 2 is created, and an allowable pressure drop is taken into account based on the master curve A. A threshold curve B is created. Then, a change in pressure measured in the second measurement step is plotted to create a measurement value curve C. When this measurement value curve C is located above the threshold curve B, there is no leakage. On the other hand, if the measured value curve C is located below the threshold curve B (illustrated example), it is determined that there is a leak. 2 can also be determined based on the magnitude relationship between the pressure drop amount of the inspection target product at the predetermined time T and the threshold value on the threshold curve B. FIG.
In this determination method, the allowable pressure drop is determined by the required performance, the structure of the water purification cartridge, the predetermined pressure amount, and the like.
[0016]
In the determination method described above, a determination device 34 having a storage unit 31, a comparison unit 32, and a display unit 33 as shown in FIG. 3 may be used. When the determination device 34 is used, the pressure change measured by the pressure change measuring means 27 in the first measurement process is stored in the storage unit 31. Then, the comparison unit 32 compares the pressure change stored in the storage unit 31 with an allowable value and the pressure change measured by the pressure change measuring unit 27 in the second measurement step. The comparison result (determination result) is displayed on the display unit 33. If the determination device 34 is used in this way, the determination can be made in a very short time. In this case, when performing a leak inspection of a water purification cartridge of the same shape, the stored master curve A can be used for comparison, so the first measurement step must be repeated each time a leak inspection is performed. Also good.
[0017]
In the leak inspection method described above, since the test gas having a predetermined pressure is introduced into the reference water purification cartridge that has not leaked in the first measurement step, the pressure change in the reference water purification cartridge is measured. It is possible to grasp the pressure change due to the entry of air into the pores of the material and the hollow fiber membrane. Then, taking into account this change in pressure, a criterion for determining whether or not there is a leak is determined and compared with the measurement result of the second measurement step, which is highly accurate. Moreover, since it is not necessary to wait until the inspection gas completely fills the voids of the porous agent and the hollow fiber membrane, the inspection time is shortened. This inspection method is simple because it does not require a special device.
[0018]
【Example】
A water purification cartridge was produced as follows. First, a polyethylene hollow fiber membrane (manufactured by Mitsubishi Rayon Co., Ltd., fractionation performance: 0.1 μm, outer diameter: 380 μm), the total surface area of the hollow fiber membrane is 0.6 m ^2. , 7500 hollow fiber membranes were converged so as to have a length of 65 mm when folded back into a U shape, and loaded into a cylindrical case having a bottom surface. Next, a fixing resin made of polyurethane resin was filled in the vicinity of the bottom surface of the case, and the fixing resin was solidified to form a fixing portion for fixing the hollow fiber membrane. Next, at a position 10 mm from the bottom surface of the case, the fixing portion was cut in parallel to the bottom surface to open the hollow fiber membrane, thereby producing a hollow fiber membrane module integrated with the case.
Next, 200 g of granular activated carbon which is a porous agent is filled in a case integrated with a hollow fiber membrane module, and a lid is joined to the case, so that a large number of hollow fiber membranes 11 as shown in FIG. The water purification cartridge 1 which has the hollow fiber membrane module 12 by which these were converged in the U-shape and the edge part was fixed, and the activated carbon which is the porous agent 13 was obtained.
[0019]
(Example 1)
First, in the first measurement step, the first connecting pipe 25 of the pressure change measuring device 20 as shown in FIG. 1 is connected to the inlet and outlet of the reference water purification cartridge that has been confirmed not to leak. did. Next, the opening / closing valve 28a of the first connecting pipe 25 and the opening / closing valve 28b of the second connecting pipe 26 are opened, and the air supply means 21 allows the inside of the reference pressure container 23 and the water purification cartridge from the gas introduction pipe 22. 1, air of 150 kPa was introduced as a test gas in 60 seconds.
Next, the opening / closing valve 28a of the first connection pipe 25 and the opening / closing valve 28b of the second connection pipe 26 are closed, and the air is separated into the air on the reference pressure container 23 side and the air on the water purification cartridge 1 side and left as it is. did. Then, the pressure change was measured by measuring the change in pressure difference between the air on the reference pressure container 23 side and the air on the water purification cartridge 1 side for 30 seconds by the pressure measuring means 27 while left unattended. In addition, since the fluctuation range of the pressure value was very large immediately after the introduction of air, the pressure value was left for about 0.5 to 2 seconds until the fluctuation range of the pressure value became small. By such a first measurement step, the pressure change due to the entry of air into the hollow fiber membrane and the activated carbon gap in the water purification cartridge was determined. In addition, the measurement interval in the pressure change measurement was shortened at the initial stage of measurement where the pressure change was large, and was increased in the latter stage of measurement where the pressure change was small. Further, the first measurement step was performed a plurality of times to obtain an average pressure change, and this average pressure change was stored in the storage unit 31 of the determination device 34 as shown in FIG.
[0020]
Next, in the second measurement step, the pressure change of the water purification cartridge to be inspected was measured in the same manner as in the first measurement step. And using the determination apparatus 34, the pressure change which added the allowance to the pressure change memorize | stored in the memory | storage part 31 and the pressure change of the water purification cartridge of test object are compared in the comparison part 32, and the presence or absence of the leak was determined. . In addition, in the comparison part 32, the pressure value in the same elapsed time was compared.
When 20 water purification cartridges were inspected by such an inspection method, it was possible to determine the presence or absence of leakage with high accuracy and to distinguish between good and defective products. Also, the inspection time was extremely short.
[0021]
(Comparative Example 1)
The first measurement step is omitted, and a pressure drop amount (threshold value) is set as a criterion for determining whether or not there is a leak. The water purification cartridge was inspected in the same manner as in Example 1 except that In this way, when the amount of pressure drop for a given time after the lapse of a predetermined time is compared with the threshold value, the pressure in the water purification cartridge also drops after the lapse of the predetermined time. Therefore, even if the measurement was repeated a plurality of times, the presence or absence of the leak could not be determined with high accuracy. That is, even if the water purification cartridge determined as good or defective in Example 1 was inspected by the inspection method of Comparative Example 1, different results might be obtained, and the result was incorrect.
[0022]
(Comparative Example 2)
The water purification cartridge was inspected by the following water immersion method. That is, as shown in FIG. 5, the prepared water purification cartridge 1 in which air is sealed from the air introduction pipe 41 is submerged in the water tank 42, and the presence or absence of leakage is determined based on the presence or absence of bubbles 43 generated from the water purification cartridge 1 ( In the example shown, there is a leak). Even with such a submergence method, it was possible to determine whether or not there was a leak in about 1 minute, but it took time for the determination because the water purification cartridge 1 had to be dried for about 1 day after the leak test.
[0023]
【The invention's effect】
The water purification cartridge leak inspection method of the present invention is simple and highly accurate, and can inspect the leakage of the water purification cartridge in a short time, and can be easily applied to quality control.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of an inspection gas pressure change measuring device used in a method for inspecting a water purification cartridge leak according to the present invention.
FIG. 2 is a graph plotting an example of a change in pressure of a test gas in a water purification cartridge.
FIG. 3 is a schematic diagram showing a configuration of a determination device used in a method for inspecting a water purification cartridge leak according to the present invention.
FIG. 4 is a cross-sectional view showing an example of the structure of a water purifier.
FIG. 5 is a side view showing a submersion method which is a conventional method for inspecting a leakage of a water purification cartridge.
FIG. 6 is a perspective view showing a soapy water application method which is a conventional method for inspecting a leakage of a water purification cartridge.
[Explanation of symbols]
1 Water purification cartridge 13 Porous agent

Claims (4)

At least a porous agent is accommodated, and a test water having a predetermined pressure is supplied to a reference water purification cartridge that has been confirmed not to leak by a gas introduction pipe connected to the water inlet and outlet of the water purification cartridge. A first measurement step of measuring a pressure change in the reference water purification cartridge after introduction;
An inspection gas having a predetermined pressure equivalent to that of the first measurement step is connected to the water purification cartridge to be inspected having the same configuration as the reference water purification cartridge by a gas introduction pipe connected to the water inlet and outlet of the water purification cartridge. And a second measuring step for measuring a pressure change in the water purification cartridge,
Leak inspection of a water purification cartridge characterized by inspecting whether there is a leak in the water purification cartridge to be inspected based on the pressure change measured in the first measurement step and the pressure change measured in the second measurement step Method. The method for inspecting a leakage of a water purification cartridge according to claim 1, wherein a sealed inspection gas having a predetermined pressure is used as a reference for pressure change. The method for inspecting a leakage of a water purification cartridge according to claim 1 or 2, wherein when the inspection gas is introduced into the water purification cartridge, the inspection gas is introduced from all openings formed in the water purification cartridge. The method for inspecting a leakage of a water purification cartridge according to any one of claims 1 to 3, wherein the predetermined pressure of the inspection gas is within a range of 0.01 to 0.7 MPa.

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