CN102445312B - Device and method for testing plastic air tightness - Google Patents

Abstract

The invention discloses a testing apparatus for plastic airtightness and a method thereof. The apparatus comprises an air pump, a pressure reducing valve, an air filter, an air inlet on-off valve, a high pressure element, a differential pressure measuring element, an air pipe, a testing chamber, a reference chamber and a three-way cutting sleeve ball valve. The testing chamber is composed of a high pressure chamber, a low pressure chamber, a sealing ring, and a plastic sample. The reference chamber consists of a high pressure chamber, a low pressure chamber, a sealing ring and a reference iron sheet sample. And the structural size of the testing chamber is identical with that of the reference chamber. According the above-mentioned technical scheme in the invention, the reference chamber is arranged and the size of the reference chamber is completely identical with that of the testing chamber, so that the two chambers can be contrasted and a system error can be reduced; besides, an initial testing pressure of the low pressure chamber is an atmospheric pressure, so that an occurrence of an air leakage phenomenon can be reduced; and there is no need for vacuum pumping, apparatus investment can be reduced, and energy can be saved.

Description

Device and method for testing plastic air tightness

technical field

The present invention relates to an airtightness measuring device and method for measuring the airtightness of, for example, plastic films, sheets, processed papers and the like.

Background technique

Due to the advantages of low cost, light weight and easy processing, flexible packaging materials such as plastic films and sheets are widely used in the packaging of various daily products such as food and medicine. According to the needs of different engineering applications, the barrier properties of flexible packaging materials such as plastic films and sheets are different. Sometimes a high barrier property against oxygen is required to prevent the intrusion of oxygen, and sometimes a low barrier property with good oxygen permeability is required. Facilitate the exchange of oxygen inside and outside the package. In order to better apply flexible packaging materials such as plastic films and sheets to different packaging industries, it is necessary to test the air permeability of flexible packaging materials such as plastic films and sheets.

At present, the methods for dealing with air permeability testing of plastic films include pressure method (pressure difference method and equal pressure method), concentration method, volume method, gas chromatography and heat conduction method. According to different test methods, different types of air permeability test devices for plastic films have been developed at home and abroad. Among them, the pressure difference method is the primary method in the air permeability test of plastic films. The international film air permeability test standards based on the differential pressure method include ASTM D1434, ISO15105-1, JIS K7126, etc. The standard implemented in my country is GB/T 1038-2000. The new paper air permeability measuring instrument launched by Finland can detect the air permeability of the paper web during the papermaking process online. Using this air permeability measuring instrument can replace the laboratory testing method of paper products, which can improve the testing efficiency and facilitate the testing Management; the GDP-C gas permeability tester produced by BRUGGER in Germany can not only detect the permeability of gas, but also detect the diffusion coefficient and solubility of gas; Japan's "Toyo Seiki" company has produced a plastic gas permeability tester . These test devices based on the differential pressure method all have the same shortcoming: the test container is composed of a test gas chamber and a test chamber. The test gas chamber is provided with a high-pressure chamber, and the test chamber is provided with a low-pressure chamber. The gas in the low-pressure chamber is evacuated, and the cost is high, and the leakage of the low-pressure chamber directly affects the test results of the test device.

Contents of the invention

The object of the present invention is to provide a plastic airtightness testing device and method, which can conveniently and accurately test the airtightness of plastic or other material samples.

In order to achieve the above objectives, the present invention adopts the following technical solutions: a plastic airtightness testing device of the present invention, including an air pump, a pressure reducing valve, an air filter, an air intake on-off valve, a high pressure measuring element, and a differential pressure measuring element , air pipe, test chamber, reference chamber and three-way ferrule ball valve, the test chamber is composed of high pressure chamber, low pressure chamber, sealing ring and plastic sample, the reference chamber is composed of high pressure chamber, low pressure chamber, sealing ring and reference iron sample Composition, the test room and the reference room have the same structural size, and the two are compared with each other to reduce system errors; the air pump outlet is connected with the pressure reducing valve, air filter, intake on-off valve, high-pressure pressure measuring element through the air pipe in turn, and the pressure reducing valve It can reduce the pressure of the gas charged into the device and make the air intake stable. The air filter can filter out the dust and impurities in the air before the air intake on-off valve, and separate the moisture in the air to avoid the influence of the test results. Interference, the intake on-off valve is used to block gas, and prevent gas leakage in the high-pressure chamber during the experiment. The test chamber and the reference chamber are connected in parallel. Set the differential pressure measuring element and the three-way ferrule ball valve in parallel, and connect the two low-pressure chambers through the air pipe. The three-way ferrule ball valve is used to communicate the low-pressure chamber of the test chamber and the low-pressure chamber of the reference chamber with the atmosphere before the experiment starts. , to ensure that the initial pressure is atmospheric pressure. During the experiment, the pressure difference between the low-pressure chamber of the test chamber and the low-pressure chamber of the reference chamber can be directly read through the pressure difference metering element; the high-pressure chamber and the low-pressure chamber of the test chamber are connected by threads, and Compress the plastic sample set in it, and seal rings are provided at the positions where the high-pressure chamber and the low-pressure chamber contact the plastic sample; the high-pressure chamber and low-pressure chamber of the reference chamber are also connected by threads, and the reference iron The sheet sample is pressed tightly, and the position where the high-pressure chamber and the low-pressure chamber contact the reference iron sample is provided with a sealing ring. The sealing ring is used to ensure the sealing between the edge of the sample and the high-pressure chamber and low-pressure chamber to prevent gas Leakage from the periphery of the sample affects the experimental results.

The invention relates to a plastic airtightness testing device. The high pressure chamber and the low pressure chamber of the test chamber and the reference chamber can adopt other quick-press fastening connection methods.

The invention relates to a plastic air tightness testing device. The high pressure measuring element may be a pressure gauge or a pressure sensor, and the differential pressure measuring element may be a differential pressure gauge or a differential pressure sensor.

The present invention is a plastic air tightness testing device. A metal porous plate with an outer diameter smaller than the inner diameter of the sealing ring is provided on the side of the plastic sample and the reference iron sample that is in contact with the low-pressure chamber, or the porous plate is located in a sink that is smaller than the inner diameter of the sealing ring. In the hole, a single-layer or multi-layer filter can be placed between the porous plate and the plastic sample and the reference iron sample. The combination of the porous plate and the filter is used to hold the plastic sample and the reference iron sample to prevent The deformation or creep of the plastic sample and the reference iron sheet sample under the action of gas in the high-pressure chamber will cause errors in the measurement. When calculating the air permeability, only the sum of the areas of the holes in the perforated plate is calculated as the effective area of the plastic sample. . Since the reference iron sample is not easily deformed, the porous plate and the filter screen may not be installed, but the porous plate and the filter screen are installed at the same time in order to ensure that the mechanisms of the two low-pressure chambers are identical.

A testing method of a plastic airtightness testing device of the present invention is characterized in that: the testing steps are as follows:

(1) Place the tested plastic sample and the reference iron sample between the high-pressure chamber and the low-pressure chamber of the test room, and fasten them through threaded connections to ensure that there is no leakage at the sealing ring;

(2) Initial state inspection: confirm that the air pump outlet switch is closed, the intake on-off valve is closed, and the three-way ferrule ball valve is opened (in the state of connecting the two low-pressure chambers and the atmosphere);

(3) Turn on the air pump outlet switch, then slowly turn the air intake on-off valve to open it until the pressure of the high-pressure load cell reaches the set value, then close the air intake on-off valve and the air pump outlet switch in sequence;

(4) Close the three-way ferrule ball valve (in the state of separating the two low-pressure chambers and not communicating with the atmosphere);

(5) After the ventilation process of the plastic sample is stable (after about 1 hour), record the readings of the high-voltage pressure measuring element, the reading of the differential pressure measuring element and the ambient temperature, and start the test.

(6) After the test time is up, record the indication of the differential pressure measuring element, open the three-way ferrule ball valve, return the indication of the differential pressure measuring element to the original position, and end the test;

(7) Use the recorded data to calculate the gas transmission rate or air permeability coefficient of the material.

A testing method of a plastic air tightness testing device of the present invention is characterized in that: the recording of data, the calculation of gas permeation rate or air permeability coefficient can also be realized through a data acquisition system and a microcomputer processing system.

As can be seen from the above technical solutions, the present invention has the following advantages compared with the prior art: (1) in the technical solution, a reference room is provided, and the size of the reference room is exactly the same as that of the test room, and the two are mutually compared to reduce system errors; ( 2) The initial test pressure of the low-pressure chamber is atmospheric pressure, which reduces gas leakage, does not require vacuuming, reduces equipment investment, and saves energy.

Description of drawings

Fig. 1 is the schematic diagram of a kind of plastic airtightness testing device of the present invention

In the figure: 1-air pump, 2-air filter, 3-intake on-off valve, 4-high pressure measuring element, 5, 11-high pressure chamber, 6-plastic sample, 7,9-low pressure chamber, 8- Differential pressure measuring element, 10-reference iron sample, 12-test chamber, 13-reference chamber, 14-trachea, 15-three-way ferrule ball valve, 16-sealing ring, 17-relief valve

Detailed ways

As shown in Figure 1, a plastic airtightness test device includes an air pump 1, a pressure reducing valve 17, an air filter 2, an air intake on-off valve 3, a high pressure measuring element 4, a differential pressure measuring element 8, and a gas pipe 14. The test chamber 12, the reference chamber 13 and the three-way ferrule ball valve 15 are composed. The test chamber 12 is composed of the high pressure chamber 5, the low pressure chamber 7, the sealing ring 16, and the plastic sample 6. The reference chamber 13 is composed of the high pressure chamber 11, the low pressure chamber Chamber 9, sealing ring 16 and reference iron sample 10, test chamber 12 and reference chamber 13 have the same structural size, and the two are compared with each other to reduce system errors; the air outlet of air pump 1 is sequentially connected with pressure reducing valve 17, air filter 2 , air intake on-off valve 3, high-pressure load cell 4 are connected by air pipe 14, and pressure reducing valve 17 can reduce the gas pressure charged in the device, so that the air intake is stable. The dust and impurities in the air are filtered before, and the moisture in the air is separated to avoid interference to the test results. The intake on-off valve 3 is used to block the gas and prevent the gas in the high-pressure chamber 5 and 11 from entering the experiment. Leakage occurs during the process, the test chamber 12 is connected in parallel with the reference chamber 13, its high-pressure chamber 5 and high-pressure chamber 11 are connected with the high-pressure pressure measuring element 4 through the air pipe 14, and its low-pressure chamber 7 and low-pressure chamber 9 are connected in parallel with a differential pressure measuring element 8 and The three-way ferrule ball valve 15 is connected to the low-pressure chamber 7 and the low-pressure chamber 9 by the air pipe 14. The three-way ferrule ball valve 15 is used to make the low-pressure chamber 7 of the test chamber 12 and the low-pressure chamber 9 of the reference chamber 13 before the experiment begins. It is communicated with the atmosphere to ensure that its initial pressure is atmospheric pressure. During the experiment, the pressure difference between the low pressure chamber 7 of the test chamber 12 and the low pressure chamber 9 of the reference chamber 13 can be directly read through the pressure difference metering element 8; the high pressure of the test chamber 12 The chamber 5 and the low-pressure chamber 7 are connected by threads, and the plastic sample 6 arranged therein is pressed tightly. The positions where the high-pressure chamber 5 and the low-pressure chamber 7 are in contact with the plastic sample 6 are provided with sealing rings 16; refer to the high-pressure chamber 13. The chamber 11 and the low-pressure chamber 9 are also threadedly connected, and the reference iron sample 10 arranged therein is compressed, and the positions where the high-pressure chamber 11 and the low-pressure chamber 9 are in contact with the reference iron sample 10 are all provided with sealing rings 16, The sealing ring 16 is used to ensure the sealing between the plastic sample 6, the edge of the reference iron sample 10 and the high-pressure chamber 5, the high-pressure chamber 11 and the low-pressure chamber 7, and the low-pressure chamber 9, so as to prevent gas from leaking from the periphery of the sample. affect the experimental results;

The present invention is a plastic airtightness testing device, which is characterized in that the high-pressure chamber 5, high-pressure chamber 11, low-pressure chamber 7, and low-pressure chamber 9 of the test chamber 12 and the reference chamber 13 can adopt other quick-press fastening connection methods.

The present invention is a plastic air tightness testing device, which is characterized in that: the high pressure measuring element 4 can be a pressure gauge or a pressure sensor, and the differential pressure measuring element 8 can be a differential pressure gauge or a differential pressure sensor.

A testing method of a plastic airtightness testing device of the present invention is characterized in that: the testing steps are as follows:

(1) Place the tested plastic sample 6 between the high pressure chamber 5 and the low pressure chamber 7 of the test chamber, and fasten it by threaded connection;

(2) Initial state inspection: confirm that the air outlet switch of the air pump 1 is closed, the intake on-off valve 3 is closed, and the three-way ferrule ball valve 15 is opened (in the state of connecting the two low-pressure chambers and the atmosphere);

(3) Turn on the air outlet switch of the air pump 1, then slowly turn the intake on-off valve 3 to open it until the pressure of the high-pressure load cell 4 reaches the set value, then close the intake on-off valve 3 and the air pump in sequence 1 gas outlet switch;

(4) Close the three-way ferrule ball valve 15 (in the state that the two low-pressure chambers 7, 9 are cut off and not communicated with the atmosphere);

(5) After the ventilation process of the plastic sample 6 is stable (about 1 hour later), record the readings of the high-voltage pressure measuring element 4, the reading of the differential pressure measuring element 8, and the ambient temperature, and the test begins.

(6) After the test time is up, record the reading of the differential pressure measuring element 8, open the three-way ferrule ball valve 15, return the reading of the differential pressure measuring element 8, and the test ends;

(7) Use the recorded data to calculate the gas transmission rate or air permeability coefficient of the material.

A testing method of a plastic air tightness testing device of the present invention is characterized in that: the recording of data, the calculation of gas permeation rate or air permeability coefficient can also be realized through a data acquisition system and a microcomputer processing system.

Claims (3)

1. a plastic cement test device for air tightness, include air pump, reduction valve, air filter, air inlet on-off valve, high pressure load cell, pressure differential metering element, tracheae, test cabinet, with reference to chamber and threeway cutting ferrule ball valve, test cabinet is comprised of hyperbaric chamber, low-pressure chamber, O-ring seal and plastic cement sample, with reference to chamber, by hyperbaric chamber, low-pressure chamber, O-ring seal with form with reference to iron plate sample, test cabinet is with measure-alike with reference to cell structure, air pump gas outlet is connected by tracheae with reduction valve, air filter, air inlet on-off valve, high pressure load cell successively, test cabinet is with in parallel with reference to chamber, test cabinet is connected with high pressure load cell by tracheae with the hyperbaric chamber with reference to chamber, between test cabinet and the low-pressure chamber with reference to chamber, be arranged in parallel pressure differential metering element and threeway cutting ferrule ball valve, and by tracheae, two low-pressure chambers connected, hyperbaric chamber and the low-pressure chamber of test cabinet are threaded connection, and the plastic cement sample being arranged at is wherein compressed, and hyperbaric chamber is provided with O-ring seal with low-pressure chamber with the position that plastic cement sample contacts, hyperbaric chamber and low-pressure chamber with reference to chamber are also threaded connection, and compressing with reference to iron plate sample wherein will be arranged at, hyperbaric chamber is provided with O-ring seal with low-pressure chamber with the position contacting with reference to iron plate sample, it is characterized in that: plastic cement sample and the one side contacting with low-pressure chamber with reference to iron plate sample respectively arrange the metallic porous sheet that an external diameter is less than internal diameter of the seal ring, or porous plate is arranged in the counterbore that is less than internal diameter of the seal ring, porous plate and plastic cement sample and with reference to placing single or multiple lift screen pack between iron plate sample, porous plate and screen pack are combined and are held plastic cement sample and with reference to iron plate sample.

2. adopt the method for testing of a kind of plastic cement test device for air tightness according to claim 1, it is characterized in that, testing procedure is as follows:

The first step, by tested plastic cement sample and be positioned over respectively with reference to iron plate sample between the hyperbaric chamber and low-pressure chamber of test cabinet, and it is fastening to be threaded connection mode;

Second step, init state check: confirmation air pump gas outlet switch cuts out, and air inlet on-off valve is closed, and threeway cutting ferrule ball valve is opened;

The 3rd step, open air pump gas outlet switch, then slowly turn air inlet on-off valve is opened it, until the pressure of high pressure pressure tester while reaching setting value, is closed air inlet on-off valve and air pump gas outlet switch in order;

The 4th step, close threeway cutting ferrule ball valve;

The 5th step, until the ventilative process of sample steadily after, record high pressure pressure tester registration, pressure differential metering device registration and environment temperature, test starts;

After the 6th step, test duration reach, record pressure differential metering device registration, open threeway cutting ferrule ball valve, the playback of pressure differential metering device registration, test finishes;

Gas permeation amount or the air transmission coefficient of the data Calculating material of the 7th step, employing record.

3. the method for testing of a kind of plastic cement test device for air tightness according to claim 2, is characterized in that: the calculating of the record of data, gas permeation amount or air transmission coefficient realizes by data acquisition system (DAS) and microprocessor system.

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