Ball valve air tightness detection device and detection method

Abstract

The present invention discloses a ball valve air tightness detection device and a detection method, the detection device comprises a first air inlet valve, a second air inlet valve, an exhaust valve, a connecting valve, a standard bin, a differential pressure gauge, a pressure gauge and a ball valve to be tested, etc. When the test gas enters the first air inlet valve and the second air inlet valve respectively, the first air inlet valve is connected to the differential pressure gauge via a first air pipe, and the second air inlet valve is connected to the differential pressure gauge via a second air pipe at the same time, the connecting valve is connected between the first air pipe and the second air pipe, the ball valve to be tested is connected to the first air pipe, a servo motor is arranged on the first air pipe, the pressure gauge is connected to the first air pipe, the exhaust valve is connected to the second air pipe, the standard bin is connected to the second air pipe, and the first air pipe and the ball valve to be tested constitute an air path A, and the second air pipe and the standard bin constitute an air path B; obviously, the structural design of the above-mentioned ball valve air tightness detection device is more reliable, and combined with the detection method with rigorous steps, that is, the processes of inflation, voltage stabilization, data recording, calculation and judgment are performed in sequence, higher detection accuracy can be achieved, and the detection efficiency is also improved.

Description

Technical Field

[0001] The present invention relates to a detection device and a detection method for air tightness detection using a test gas as a medium, and in particular to a ball valve air tightness detection device and a detection method. Background Art

[0002] With the increasing popularity of automated production equipment in manufacturing enterprises, automated pressure testing equipment, as an important part of automated production equipment, has also received increasing attention. For example, a liquid pressure tester is a device used to test the air tightness of a ball valve. It is widely used in the automatic test of the air tightness of a ball valve. Its principle is to inject high-pressure liquid into the ball valve, and the pressure difference sensor detects the pressure change inside the ball valve to determine whether the air tightness of the ball valve is good. However, there are still some problems in the use of existing pressure testers: 1. At present, all water is used as the liquid medium for testing air tightness. The test process has only one process of keeping air in the ball, and the process is relatively simple; 2. After the water pressure test, in order to ensure that the surface of the ball valve will not rust due to residual water stains, the ball valve needs to be dried. Obviously, if the test gas is used as the medium for air tightness detection, the above-mentioned test defects of using liquid medium for detection can be solved; however, conventional gas detection mainly adopts the differential pressure test method, specifically: after inflation and pressure stabilization, the pressure gauge reading P1 is recorded, and the pressure gauge reading P2 is recorded again after 10s of testing, and the difference between P1 and P2 is calculated and compared with the standard value P0. This method has a disadvantage, that is, the detection device is too crude, the detection method is too simple, and the test medium pressure required by the test standard cannot be lower than 0.6Mpa. Therefore, the range of the selected pressure gauge must exceed 0.6Mpa, but the leakage of qualified ball valve products is generally around tens of Pa to hundreds of Pa. Obviously, it is unreasonable to use a pressure gauge with a range exceeding 0.6Mpa to record data of hundreds of Pa, or the reading of the pressure gauge will not change, resulting in insufficient detection accuracy, inability to detect trace leakage, and low detection efficiency. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a ball valve air tightness detection device and detection method with reliable structural design, high detection accuracy and high detection efficiency.

[0004] The technical problem of the present invention is achieved through the following technical solutions:

[0005] A ball valve air tightness detection device mainly uses test gas as a medium to detect the air tightness of the ball valve. The detection device includes a first air inlet valve, a second air inlet valve, an exhaust valve, a connecting valve, a standard chamber, a differential pressure gauge, a pressure gauge and a ball valve to be tested; the test gas enters the first air inlet valve and the second air inlet valve respectively, the first air inlet valve is connected to the differential pressure gauge via a first air pipe, and the second air inlet valve is connected to the differential pressure gauge via a second air pipe at the same time; the connecting valve is connected between the first air pipe and the second air pipe; the ball valve to be tested is connected to the first air pipe via the ball valve air pipe, a servo motor is provided on the ball valve to be tested, and the pressure gauge is connected to the first air pipe via a pressure air pipe; the exhaust valve is connected to the second air pipe via the exhaust pipe, and the standard chamber is connected to the second air pipe via the chamber inlet air pipe; the first air pipe and the ball valve to be tested constitute air path B; the second air pipe and the standard chamber constitute air path A.

[0006] A method for detecting air tightness of a ball valve comprises the following steps:

[0007] Step 1: Determine a test gas pressure value, close the ball valve to be tested, open the first air inlet valve and the second air inlet valve to allow the test gas to be filled in at the same time, open the connecting valve and close the exhaust valve at the same time, and fill the gas for a period of time until the gas pressure reading on the pressure gauge reaches the determined test gas pressure value, so as to ensure that the entire pipeline has been fully filled with gas of sufficient pressure;

[0008] Step 2: close the first air inlet valve and the second air inlet valve, and close the connecting valve at the same time, and allow the gas pressure in the entire pipeline to gradually stabilize after a period of time;

[0009] Step 3: Record the differential pressure gauge reading M1 for the first time and obtain the following formula:

[0010] M1=PA1-PB1

[0011] In the formula,

[0012] M1 – the first recorded differential pressure gauge reading;

[0013] PA1——the first recorded pressure of gas path A;

[0014] PB1——the first recorded pressure of gas path B;

[0015] Step 4: After the test starts and a period of time has passed, record the reading M2 of the differential pressure gauge for the second time and obtain the following formula;

[0016] M2=PA2-PB2

[0017] In the formula,

[0018] M2 – the second recorded differential pressure gauge reading;

[0019] PA2——the second recorded pressure of gas path A;

[0020] PB2——the second recorded pressure of gas path B;

[0021] Step 5: Combine the data from step 3 and step 4 and calculate according to the following formula:

[0022] M2-M1=N1

[0023] In the formula,

[0024] M2 – the second recorded differential pressure gauge reading;

[0025] M1 – the first recorded differential pressure gauge reading;

[0026] N1——The pressure difference between the second recorded and the first recorded differential pressure gauge readings;

[0027] and,

[0028] When N1≤B1, the internal leakage test is judged to be qualified and the subsequent steps of the airtight test are continued;

[0029] When N1>B1, the internal leakage test is judged as unqualified and the airtight test is terminated directly;

[0030] B1 is the reference value for setting the leakage of the ball valve to be tested;

[0031] Step 6: The servo motor opens the ball valve to be tested by 45 degrees, and the reading M3 of the differential pressure gauge is recorded for the third time, and the following formula is obtained;

[0032] M3=PA3-PB3

[0033] In the formula,

[0034] M3 – the third recorded differential pressure gauge reading;

[0035] PA3——the third recorded pressure of gas path A;

[0036] PB3——the third recorded pressure of gas path B;

[0037] Step 7. Combine the data from step 4 and step 6 and calculate according to the following formula:

[0038] M3-M2=N2

[0039] In the formula,

[0040] M3 – the third recorded differential pressure gauge reading;

[0041] M2 – the second recorded differential pressure gauge reading;

[0042] N2——The pressure difference between the third and second recorded differential pressure gauge readings;

[0043] and,

[0044] When N2≤B2, the internal leakage test is judged to be unqualified and the airtightness test is terminated directly;

[0045] When N2>B2, the internal leakage test is judged to be qualified and the subsequent steps of the airtight test are continued;

[0046] B2 is the reference value for setting the leakage of the ball valve to be tested;

[0047] Step 8. Keep the ball valve to be tested open at 45 degrees, open the first air inlet valve and the second air inlet valve according to step 1 to allow the test gas to be filled in at the same time, open the connecting valve and close the exhaust valve at the same time, and inflate for a period of time until the gas pressure reading on the pressure gauge reaches the determined test gas pressure value to ensure that the entire pipeline has been fully filled with gas of sufficient pressure; close the first air inlet valve and the second air inlet valve according to step 2, and close the connecting valve at the same time, and allow the gas pressure in the entire pipeline to gradually stabilize after a period of time; record the reading M4 of the differential pressure gauge for the fourth time, and obtain the following formula;

[0048] M4=PA4-PB4

[0049] In the formula,

[0050] M4 – the fourth recorded differential pressure gauge reading;

[0051] PA4——the fourth recorded pressure of gas path A;

[0052] PB4——the fourth recorded pressure of gas path B;

[0053] Step 9. After the test starts and a period of time has passed, record the reading M5 of the differential pressure gauge for the fifth time and obtain the following formula;

[0054] M5=PA5-PB5

[0055] In the formula,

[0056] M5 – the fifth recorded differential pressure gauge reading;

[0057] PA5——the fifth recorded pressure of gas path A;

[0058] PB5——the fifth recorded pressure of gas path B;

[0059] Step 10: Combine the data from Step 8 and Step 9 and calculate according to the following formula:

[0060] M4-M5=N3

[0061] In the formula,

[0062] M4 – the fourth recorded differential pressure gauge reading;

[0063] M5 – the fifth recorded differential pressure gauge reading;

[0064] N3——The pressure difference between the fourth and fifth recorded differential pressure gauge readings;

[0065] and,

[0066] When N3≤B3, the leakage detection is judged to be qualified;

[0067] When N3>B3, the leakage detection is judged as unqualified;

[0068] B3 is the reference value for setting the leakage of the ball valve to be tested;

[0069] Step 11: The air tightness test of the ball valve to be tested is completed.

[0070] The step five is used to detect the qualified status of the product when there is a slight leakage in the two sealing pairs formed by the valve seat in the ball valve to be tested, and the corresponding B1 is a reference value for setting the slight leakage in the two sealing pairs.

[0071] The step seven is used to detect the product qualification status when there is a large amount of leakage or failure of the two sealing pairs formed by the valve seats in the ball valve to be tested. The corresponding B2 is a reference value for setting the situation of a large amount of leakage or failure of the two sealing pairs.

[0072] The step ten is used to detect the qualified status of the product when there is leakage at the connection between the valve body and the valve cover, and the O-ring connection on the valve stem in the ball valve to be tested. The corresponding B3 is the reference value for setting the leakage at these two connections.

[0073] Compared with the prior art, the present invention mainly designs a ball valve air tightness detection device with an updated structure, which is composed of a first air inlet valve, a second air inlet valve, an exhaust valve, a connecting valve, a standard bin, a differential pressure gauge, a pressure gauge and a ball valve to be tested. When the test gas enters the first air inlet valve and the second air inlet valve respectively, the first air inlet valve is connected to the differential pressure gauge via the first air pipe, and the second air inlet valve is connected to the differential pressure gauge via the second air pipe at the same time; and the connecting valve is connected between the first air pipe and the second air pipe; the ball valve to be tested is connected to the first air pipe via the ball valve air pipe, a servo motor is provided on the ball valve to be tested, and the pressure gauge is connected to the first air pipe via the pressure air pipe; the exhaust valve is connected to the second air pipe via the exhaust pipe, and the standard bin is connected to the second air pipe via the bin intake air pipe; and the first air pipe and the ball valve to be tested constitute an air path B, and the second air pipe and the standard bin constitute an air path A; obviously, the structural design of the above-mentioned ball valve air tightness detection device is more reliable, and it is combined with a detection method with rigorous steps to carry out the processes of inflation, voltage stabilization, data recording, calculation and judgment in sequence, which can achieve higher detection accuracy and improve detection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0075] The embodiments of the present invention will be described in detail below with reference to the above-mentioned drawings.

[0076] like Figure 1 As shown, 1. the first air inlet valve, 2. the second air inlet valve, 3. the exhaust valve, 4. the connecting valve, 5. the standard bin, 6. the differential pressure gauge, 7. the pressure gauge, 8. the ball valve to be tested, 9. the servo motor, 11. the first air pipe, 12. the second air pipe, 13. the ball valve air pipe, 14. the pressure air pipe, 15. the exhaust pipe, and 16. the inlet air pipe.

[0077] A ball valve air tightness detection device and detection method, mainly using test gas as a medium to perform air tightness detection on the ball valve, and the ball valve 8 to be tested usually has three sealing pairs, namely two sealing pairs formed by a valve seat and a sealing pair formed by an O-ring, and the two sealing pairs formed by the valve seat will divide the ball valve into three chambers. The leakage of the ball valve is mainly caused by leakage at these three sealing pairs, which is usually divided into internal leakage and external leakage. Internal leakage refers to leakage of the medium between the two sealing pairs of the ball valve, and external leakage refers to leakage of the medium at the connection between the valve body and the valve cover of the ball valve, and at the connection between the O-ring on the valve stem, that is, the medium leaks from the inside of the ball valve to the outside of the ball valve.

[0078] The detection device is as follows Figure 1 As shown, it is composed of a first air inlet valve 1, a second air inlet valve 2, an exhaust valve 3, a connecting valve 4, a standard chamber 5, a differential pressure gauge 6, a pressure gauge 7 and a ball valve to be tested 8.

[0079] Among them, the test gas enters the first air intake valve 1 and the second air intake valve 2 respectively, and the first air intake valve is connected to the differential pressure gauge 6 through the first air pipe 11, and the second air intake valve 2 is connected to the differential pressure gauge 6 through the second air pipe 12; the connecting valve 4 is connected between the first air pipe 11 and the second air pipe 12; the ball valve 8 to be tested is connected to the first air pipe 11 through the ball valve air pipe 13, and the ball valve 8 to be tested is provided with a servo motor 9, and the pressure gauge 7 is connected to the first air pipe 11 through the pressure air pipe 14; the exhaust valve 3 is connected to the second air pipe 12 through the exhaust pipe 15, and the standard warehouse 5 is connected to the second air pipe 12 through the warehouse inlet air pipe 16; then, the first air pipe 11 and the ball valve 8 to be tested constitute an air path B, and the second air pipe 12 and the standard warehouse 5 constitute an air path A.

[0080] The ball valve air tightness detection method mainly comprises the following steps:

[0081] Step 1, determine a test gas pressure value, for example, 0.7Mpa, close the ball valve 8 to be tested, open the first air inlet valve 1 and the second air inlet valve 2 to allow the test gas to be filled in at the same time, open the connecting valve 4 and close the exhaust valve 3 at the same time, and inflate for a period of time. After about 5 seconds, the reading on the pressure gauge 7 is 0.7Mpa, that is, the gas pressure reading on the pressure gauge is the determined test gas pressure value. At this time, it can be ensured that the entire pipeline has been fully filled with gas of sufficient pressure. This step is the inflation process of the entire pipeline;

[0082] Step 2: close the first air inlet valve 1 and the second air inlet valve 2, and close the connecting valve 4 at the same time. After a period of time, about 8 seconds, the gas pressure in the entire pipeline gradually stabilizes. This step is the pressure stabilization process of the entire pipeline.

[0083] Step 3: Record the reading M1 of the differential pressure gauge 6 for the first time and obtain the following formula:

[0084] M1=PA1-PB1

[0085] In the formula,

[0086] M1 – the first recorded differential pressure gauge 6 reading;

[0087] PA1——the first recorded pressure of gas path A;

[0088] PB1——the first recorded pressure of gas path B;

[0089] Step 4: The test starts, and after a period of time, about 10 seconds, the reading M2 of the differential pressure gauge 6 is recorded for the second time, and the following formula is obtained;

[0090] M2=PA2-PB2

[0091] In the formula,

[0092] M2 – the second recorded reading of differential pressure gauge 6;

[0093] PA2——the second recorded pressure of gas path A;

[0094] PB2——the second recorded pressure of gas path B;

[0095] Step 5: Combine the data from step 3 and step 4 and calculate by computer according to the following formula:

[0096] M2-M1=N1

[0097] In the formula,

[0098] M2 – the second recorded reading of differential pressure gauge 6;

[0099] M1 – the first recorded differential pressure gauge 6 reading;

[0100] N1——The pressure difference between the second recorded and the first recorded differential pressure gauge 6 readings;

[0101] and,

[0102] When N1≤B1, the internal leakage test is considered qualified and the subsequent airtight test can be continued;

[0103] When N1>B1, the internal leakage detection is judged as unqualified and the airtightness test is terminated directly.

[0104] B1 is the reference value for setting the leakage of the ball valve 8 to be tested;

[0105] The basis for judging whether the step 5 is qualified or unqualified is as follows: since the gas circuit A is a standard chamber, it can be regarded as a completely sealed pipeline, so PA1=PA2; and as long as one of the two sealing pairs of the ball valve 8 to be tested leaks, it will cause the pressure of the gas circuit B to drop, so PB2<PB1.

[0106] At the same time, step five is mainly used to detect the product qualification status when there is a trace leakage in the two sealing pairs formed by the valve seat in the ball valve 8 to be tested, and the corresponding B1 is a reference value for setting the trace leakage of the two sealing pairs; therefore, if the test is qualified, continue to the subsequent steps; if the test is unqualified, the test ends.

[0107] Step 6: The servo motor 9 opens the ball valve 8 to be tested by 45 degrees, and the reading M3 of the differential pressure gauge 6 is recorded for the third time, and the following formula is obtained;

[0108] M3=PA3-PB3

[0109] In the formula,

[0110] M3 – the third recorded reading of differential pressure gauge 6;

[0111] PA3——the third recorded pressure of gas path A;

[0112] PB3——the third recorded pressure of gas path B;

[0113] Step 7: Combine the data from Step 4 and Step 6 and calculate using a computer according to the following formula:

[0114] M3-M2=N2

[0115] In the formula,

[0116] M3 – the third recorded reading of differential pressure gauge 6;

[0117] M2 – the second recorded reading of differential pressure gauge 6;

[0118] N2——The pressure difference between the third and second recorded differential pressure gauge 6 readings;

[0119] and,

[0120] When N2≤B2, the internal leakage test is judged to be unqualified and the airtightness test is terminated directly;

[0121] When N2>B2, the internal leakage test is judged to be qualified and the subsequent steps of the airtight test are continued;

[0122] B2 is the reference value for setting the leakage of the ball valve 8 to be tested;

[0123] The basis for judging whether the test is qualified or not in step seven is as follows: since the standard chamber is a completely sealed pipeline, PA1=PA2=PA3; the ball valve to be tested is in a closed state before inflation. If the two sealing pairs of the ball valve 8 to be tested are completely sealed, the pressure in the inner cavity of the ball valve should be 0. At this time, when the ball valve to be tested is opened, the detection chamber becomes larger, and the pressure in the air path B will decrease. Therefore, PB3 is much smaller than PB2 and PB1, indicating that the sealing performance of the ball valve to be tested is qualified; if one or two of the two sealing pairs of the ball valve to be tested are leaking, the pressures in the three chambers of the ball valve to be tested should be the same after inflation and pressure stabilization. At this time, when the ball valve to be tested is opened, the pressure in the air path B should not change significantly, which also indicates that the sealing performance of the ball valve 8 to be tested is unqualified.

[0124] Meanwhile, step seven is mainly used to detect the qualified status of the product when there is a large amount of leakage or failure of the two sealing pairs formed by the valve seats in the ball valve 8 to be tested, and the corresponding B2 is the reference value for setting the situation when there is a large amount of leakage or failure of the two sealing pairs.

[0125] Moreover, steps 1 to 7 are for the internal leakage detection of the ball valve. If the internal leakage detection is qualified, the subsequent steps will be continued.

[0126] Step 8, keep the ball valve 8 to be tested open at 45 degrees, open the first air inlet valve 1 and the second air inlet valve 2 according to step 1 to allow the test gas to be filled in at the same time, open the connecting valve 4 and close the exhaust valve 3 at the same time, and inflate for a period of time until the gas pressure reading on the pressure gauge 7 reaches the determined test gas pressure value to ensure that the entire pipeline has been fully filled with gas of sufficient pressure; close the first air inlet valve 1 and the second air inlet valve 2 according to step 2, and close the connecting valve 4 at the same time, and allow the gas pressure in the entire pipeline to gradually stabilize after a period of time; record the reading M4 of the differential pressure gauge 6 for the fourth time, and obtain the following formula;

[0127] M4=PA4-PB4

[0128] In the formula,

[0129] M4 – the fourth recorded reading of differential pressure gauge 6;

[0130] PA4——the fourth recorded pressure of gas path A;

[0131] PB4——the fourth recorded pressure of gas path B;

[0132] Step 9: After the test starts and a period of time has passed, record the reading M5 of the differential pressure gauge 6 for the fifth time, and obtain the following formula:

[0133] M5=PA5-PB5

[0134] In the formula,

[0135] M5 – the fifth recorded reading of differential pressure gauge 6;

[0136] PA5——the fifth recorded pressure of gas path A;

[0137] PB5——the fifth recorded pressure of gas path B;

[0138] Step 10: Combine the data from Step 8 and Step 9 and calculate according to the following formula:

[0139] M4-M5=N3

[0140] In the formula,

[0141] M4 – the fourth recorded reading of differential pressure gauge 6;

[0142] M5 – the fifth recorded reading of differential pressure gauge 6;

[0143] N3——The pressure difference between the fourth and fifth recorded differential pressure gauge 6 readings;

[0144] and,

[0145] When N3≤B3, the leakage detection is judged to be qualified;

[0146] When N3>B3, the leakage detection is judged as unqualified;

[0147] B3 is the reference value for setting the leakage of the ball valve to be tested;

[0148] This step ten is used to detect the qualified status of the product when there is leakage at the connection between the valve body and the valve cover, and the connection between the O-ring on the valve stem in the ball valve 8 to be tested. The corresponding B3 is the reference value for setting the leakage at these two connections.

[0149] Step 11: The air tightness test of the ball valve 8 to be tested is completed.

[0150] Obviously, the structural design of the above-mentioned ball valve air tightness detection device is more reliable. Combined with a rigorous detection method, that is, inflation, pressure stabilization, data recording, calculation and judgment processes are carried out in sequence, it can achieve higher detection accuracy and improve detection efficiency.

[0151] The above description is only a specific embodiment of the present invention. Those skilled in the art should understand that any structural design similar to this embodiment should be included in the protection scope of the present invention.

Claims

1. A ball valve air tightness detection method, based on a ball valve air tightness detection device, using a test gas as a medium to perform air tightness detection on the ball valve; the detection device comprises a first air inlet valve (1), a second air inlet valve (2), an exhaust valve (3), a connecting valve (4), a standard chamber (5), a differential pressure gauge (6), a pressure gauge (7) and a ball valve to be tested (8); the test gas enters the first air inlet valve (1) and the second air inlet valve (2) respectively, the first air inlet valve (1) is connected to the differential pressure gauge (6) via a first air pipe (11), and the second air inlet valve (2) is connected to the differential pressure gauge (6) via a second air pipe (12); the connecting valve ( 4) is connected between the first air pipe (11) and the second air pipe (12); the ball valve (8) to be tested is connected to the first air pipe (11) via the ball valve air pipe (13), the ball valve (8) to be tested is provided with a servo motor (9), the pressure gauge (7) is connected to the first air pipe (11) via the pressure air pipe (14); the exhaust valve (3) is connected to the second air pipe (12) via the exhaust pipe (15), and the standard bin (5) is connected to the second air pipe (12) via the bin inlet pipe (16); the first air pipe (11) and the ball valve (8) to be tested constitute an air path B; the second air pipe (12) and the standard bin (5) constitute an air path A; Features The detection method comprises the following steps: Step 1: determine a test gas pressure value, close the ball valve (8) to be tested, open the first air inlet valve (1) and the second air inlet valve (2) to allow the test gas to be filled in at the same time, open the connecting valve (4) and close the exhaust valve (3) at the same time, and fill the gas for a period of time until the gas pressure reading on the pressure gauge (7) is the determined test gas pressure value, so as to ensure that the entire pipeline has been completely filled with gas of sufficient pressure; Step 2: close the first air inlet valve (1) and the second air inlet valve (2), and simultaneously close the connecting valve (4), and allow the gas pressure in the entire pipeline to gradually stabilize over a period of time; Step 3: Record the reading M1 of the differential pressure gauge (6) for the first time and obtain the following formula: M1=PA1-PB1 In the formula, M1 – the first recorded differential pressure gauge (6) reading; PA1——the first recorded pressure of gas path A; PB1——the first recorded pressure of gas path B; Step 4: After the test starts and a period of time has passed, record the reading M2 of the differential pressure gauge (6) for the second time and obtain the following formula: M2=PA2-PB2 In the formula, M2 – the second recorded differential pressure gauge (6) reading; PA2——the second recorded pressure of gas path A; PB2——the second recorded pressure of gas path B; Step 5: Combine the data from step 3 and step 4 and calculate according to the following formula: M2-M1=N1 In the formula, M2 – the second recorded differential pressure gauge (6) reading; M1 – the first recorded differential pressure gauge (6) reading; N1 – the pressure difference between the second recorded and the first recorded differential pressure gauge (6) readings; and, When N1≤B1, the internal leakage test is judged to be qualified and the subsequent steps of the airtight test are continued; When N1>B1, the internal leakage test is judged as unqualified and the airtight test is terminated directly; B1 is the reference value for setting the leakage of the ball valve (8) to be tested; Step 6: The servo motor (9) opens the ball valve (8) to be tested by 45 degrees, and the reading M3 of the differential pressure gauge (6) is recorded for the third time, and the following formula is obtained; M3=PA3-PB3 In the formula, M3 – the third recorded differential pressure gauge (6) reading; PA3——the third recorded pressure of gas path A; PB3——the third recorded pressure of gas path B; Step 7. Combine the data from step 4 and step 6 and calculate according to the following formula: M3-M2=N2 In the formula, M3 – the third recorded differential pressure gauge (6) reading; M2 – the second recorded differential pressure gauge (6) reading; N2 – the pressure difference between the third and second recorded differential pressure gauge (6) readings; and, When N2≤B2, the internal leakage test is judged to be unqualified and the airtightness test is terminated directly; When N2>B2, the internal leakage test is judged to be qualified and the subsequent steps of the airtight test are continued; B2 is the reference value for setting the leakage of the ball valve (8) to be tested; Step 8: Keep the ball valve (8) to be tested open at 45 degrees, open the first air inlet valve (1) and the second air inlet valve (2) to allow the test gas to be filled in at the same time, open the connecting valve (4) and close the exhaust valve (3) at the same time, and fill the gas for a period of time until the gas pressure reading on the pressure gauge (7) is the determined test gas pressure value, so as to ensure that the entire pipeline has been completely filled with gas of sufficient pressure; close the first air inlet valve (1) and the second air inlet valve (2), and close the connecting valve (4) at the same time, and allow the gas pressure in the entire pipeline to gradually stabilize after a period of time; record the reading M4 of the differential pressure gauge (6) for the fourth time, and obtain the following formula; M4=PA4-PB4 In the formula, M4 – the fourth recorded differential pressure gauge (6) reading; PA4——the fourth recorded pressure of gas path A; PB4——the fourth recorded pressure of gas path B; Step 9: After the test starts and a period of time has passed, record the reading M5 of the differential pressure gauge (6) for the fifth time and obtain the following formula: M5=PA5-PB5 In the formula, M5 – the fifth recorded differential pressure gauge (6) reading; PA5——the fifth recorded pressure of gas path A; PB5——the fifth recorded pressure of gas path B; Step 10: Combine the data from Step 8 and Step 9 and calculate according to the following formula: M4-M5=N3 In the formula, M4 – the fourth recorded differential pressure gauge (6) reading; M5 – the fifth recorded differential pressure gauge (6) reading; N3 – the pressure difference between the fourth and fifth recorded differential pressure gauge (6) readings; and, When N3≤B3, the leakage detection is judged to be qualified; When N3>B3, the leakage detection is judged as unqualified; B3 is the reference value for setting the leakage of the ball valve (8) to be tested; Step 11: The air tightness test of the ball valve (8) to be tested is completed.

2. A ball valve air tightness detection method according to claim 1, characterized in that The step five is used to detect the product qualification status of the ball valve (8) under test when there is a slight leakage in the two sealing pairs formed by the valve seat, and the corresponding B1 is the reference value for setting the slight leakage in the two sealing pairs.

3. A ball valve air tightness detection method according to claim 1, characterized in that The step 7 is used to detect the product qualification status of the two sealing pairs formed by the valve seat in the ball valve (8) to be tested when there is a large amount of leakage or the sealing pair fails. The corresponding B2 is a reference value for setting the situation that the two sealing pairs have a large amount of leakage or the sealing pair fails.

4. A ball valve air tightness detection method according to claim 1, characterized in that The step 10 is used to detect the product qualification status of the ball valve (8) under test when there is leakage at the connection between the valve body and the valve cover, and at the connection between the O-ring on the valve stem. The corresponding B3 is the reference value for setting the leakage at these two connections.

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