JP6529892B2 - Valve seat leak inspection device - Google Patents

Description

The present invention relates to a valve seat leak inspection device , and more particularly to a valve seat leak inspection device capable of detecting a minute leak flow rate from a valve seat with high accuracy while having a simple configuration.

  The pressure test performed at the time of manufacturing the valve includes a valve box pressure test (shell test) for confirming the strength and leak of the pressure resistant part and a valve seat leak test (seat test) for checking for leak from the valve seat. And is considered the most important of the valve testing and inspection before shipment. In the valve seat leak test, independent standards are set in detail according to the type, application, use environment, etc. of the valve, and it is tested whether the valve products meet the standards defined in the standards. .

An example of such a standard is "JIS B 2003: 2013 Inspection general rules for valves". Water or air as a test fluid is pressurized and filled in a valve closed state at a predetermined pressure to test for valve seat leakage. Then, according to the above standard example, the allowable leak of the valve in the case of the air pressure test of, for example, the rate 2 and the nominal diameter 50A is specified as 15 mm ³ / sec or less. It becomes.

  Therefore, a highly accurate minute leak amount detection capability is also essential for a valve seat leak inspection apparatus that tests whether or not the valve conforms to such a standard.

  Conventionally, for example, Patent Documents 1 and 2 have been proposed as apparatuses for inspecting the above-mentioned minute leak flow rate with high accuracy. In the minute flow rate measuring device shown in the same document 1, in order to accommodate the object to be measured such as a valve and a pipe joint in a sealed container and shorten the measurement time, the fluid in which the sealed container is filled with a predetermined amount of fluid. A configuration in which a filling device is connected is adopted, and when the compressed air supplied to the object to be measured leaks from a seal location or the like, the flow rate of the fluid flowing out of the sealed container is measured.

  The leak test device shown in the same document 2 has a configuration in which a test object such as a container or a tube is accommodated in a closed and openable container, and the sample is filled with a test gas. An exhaust flow path is connected, and a mass flow meter such as a thermal flow meter is provided in the exhaust flow path, and a bypass parallel to an exhaust path via an on-off valve on the upstream side of the mass flow meter is provided There is.

Patent No. 3510688 gazette Japanese Utility Model Application Publication No. 1-151231

  However, in the inspection apparatus of the type shown in Patent Document 1, a sealing mechanism for completely sealing the object to be measured inside is required in order to realize highly accurate minute flow rate measurement excluding the influence of atmospheric fluctuation. However, this sealing mechanism is a complicated and expensive one consisting of a cylinder, a solenoid valve, etc. in addition to a large sealed container. Therefore, this kind of inspection device has a problem that the manufacturing cost becomes extremely bad. In addition, there is a problem that it is necessary to provide a fairly large volume as a closed container in order to cover a certain shape of the handle and the flange.

  Also in the leak test device of Patent Document 2, since a sealed container for containing the specimen is required, the above-described problem is caused by adopting a sealing mechanism. In addition, although the pressure fluctuation in the sealed container at the time of opening and closing of the sealed container is led to the discharge port via the on-off valve of the bypass, the fluctuation of the indication of the mass flow meter is prevented. The secondary side of the mass flow meter is open to the atmosphere through the exhaust port. Generally, it is desirable that the secondary side of the flow sensor be open to the atmosphere side in order to make the flow of the test fluid stable and not stagnate, but the secondary side of the flow meter is open to the atmosphere If this is the case, the atmospheric pressure fluctuation directly affects the mass flow meter, causing the measurement to become unstable.

  On the other hand, in order not to pick up the influence of the atmospheric pressure fluctuation, for example, even if the secondary side of the mass flowmeter is simply closed, only the internal pressure on the secondary side is increased. Flow rate can not be detected. Heretofore, the problem of the flow meter being adversely affected by the release to the atmosphere, particularly when the minute leak flow rate is inspected with high accuracy, has been common to the inspection apparatus of the type shown in the same document 2, but The proposal of the prior art which eliminated the problem effectively has not been made yet.

  Therefore, the present invention has been developed to solve the above problems, and the object of the present invention is to realize significant cost reduction and space saving of the apparatus by a simple configuration not using a sealing mechanism. The valve seat leak inspection device and the leak detection device which made it possible to detect the minute leak flow rate with high accuracy by shielding the adverse effect due to the air movement very effectively while opening the secondary side of the flow meter to the atmosphere It is to provide a valve seat leak inspection method.

  In order to achieve the above object, the invention according to claim 1 is an inspection device for inspecting a valve seat leak of a valve, wherein a flow sensor is connected to the secondary side of the test valve, and the secondary side of the flow sensor It is a valve seat leak inspection device connected with a tank having a nonreturn function that escapes a minute leak from a test valve to the outside air and prevents the entry of fluctuating outside air.

  The invention according to claim 2 is the valve seat leak inspection device, wherein the tank is a soft tube, and a radial notch is formed in the tube so as to exhibit the non-return function.

  The invention according to claim 3 is the valve seat leak inspection device in which the flow sensor is a thermal mass flow sensor.

  The invention according to claim 4 is a valve seat leak inspection device in which a tube is covered with a non-sealed cover.

  In the invention according to claim 5, the first on-off valve is provided on the primary side which is the pressurized supply side of the test valve, and the pressure gauge and the first exhaust valve are disposed between the first on-off valve and the primary side of the test valve. Valve seat leak inspection device provided with

  The invention according to claim 6 is a valve seat leak inspection device in which a second on-off valve and a second exhaust valve are provided between the secondary side of the test valve and the flow sensor.

  The invention according to claim 7 is a valve seat leak inspection device in which an O-ring is attached to a clamp jig for clamping the primary side and the secondary side of the test valve for sealing at the time of clamping.

Another invention measures the flow rate of fluid with a flow sensor while maintaining a non-return function that prevents the inflow of the outside air to the secondary side of the flow sensor while letting the fluid flowing down the secondary side of the flow sensor escape to the outside air Inspection method.

In addition, the primary flow path of the test valve is a sealed space, and compressed air is supplied to the sealed space, while the secondary flow path of the test valve is connected to the flow sensor and disconnected to atmospheric pressure. In the pressure step, after the predetermined pressurizing time, when the pressure value of the compressed air is equal to or more than the inspection pressure, the valve seat leakage inspection is performed using the pressure value as a reference value.

  Specifically, the first exhaust valve and the second on-off valve are closed in an initial state in which the first on-off valve and the second on-off valve are closed and the first exhaust valve and the second exhaust valve are open, And, after the first on-off valve and the second exhaust valve are opened, compressed air which is a pressurized supply source is supplied, and if the value of the pressure gauge is equal to or higher than the inspection pressure, it is stored as the reference pressure. Also, in the case of the large leak inspection step in the valve seat leakage inspection, close the first on-off valve and the first exhaust valve and enclose compressed air, which is the test fluid, on the primary side of the test valve to determine the reference pressure It was determined whether or not to perform a large leak inspection process. On the other hand, in the case of the minute leak inspection step in the valve seat leak inspection, the second exhaust valve is closed and the second on-off valve is opened, and the minute leak inspection step is performed by lowering the value of the pressure gauge or measuring the flow sensor. I did it.

  According to the invention as set forth in claim 1, since the tank having the non-return function is provided on the secondary side of the flow sensor for escaping minute leaks from the test valve to the outside air and preventing entry of fluctuating outside air. At the time of seat leak inspection, the condition of the test fluid in the test space of the flow sensor formed on the secondary side of the test valve is outside air while the rise of the internal pressure is suppressed and the pressure approximately the same as the external pressure is maintained. In the constant flow state, the minute leak flow rate flowing in from the valve seat and the flow rate flowing out to the outside air from the tank are substantially the same without being substantially affected by the fluctuation from the valve flow and the backflow. For this reason, at least the test fluid in the vicinity of the flow sensor is maintained in a unidirectional, substantially rectified state, and the flow sensor is not affected by the outside air, and is small toward the atmosphere due to only a minute leak from the valve seat. It is possible to measure the mass transfer amount, that is, a minute flow rate substantially equal to the valve seat leak flow rate with extremely high accuracy. Therefore, extremely accurate and stable valve seat leak inspection can be performed.

  In addition, since a sealed container for covering the test valve is not necessary, the valve seat leak inspection apparatus can be configured inexpensively, simply and compactly, and the usability and versatility of the apparatus are greatly enhanced.

  According to the second aspect of the present invention, the tank is formed of a soft tube having a cut portion formed in the radial direction to exhibit the non-return function, so the non-return function can be made extremely inexpensively and easily. You can configure the tank you have. In addition, since inexpensive and simple tubes can be easily replaced, the maintainability and usability of the tank having a non-return function, and hence the valve seat leak inspection apparatus, are greatly enhanced.

  According to the third aspect of the present invention, since the flow sensor is a thermal mass flow sensor, a thermal flow sensor suitable for measuring a gas such as compressed air as a test fluid can be used, and a wide flow range can be used. Enables accurate mass flow measurement.

  According to the invention as set forth in claim 4, since the tube is covered with the cover in the non-sealing state, the test fluid in the inspection space of the flow sensor formed on the secondary side of the test valve during the valve seat leakage inspection On the other hand, it is possible to effectively shield the adverse effect such as the fluctuation that the outside air gives to the measurement of the flow sensor. Therefore, the valve seat leak inspection can be further enhanced in accuracy.

  According to the invention of claim 5, the first on-off valve is provided on the primary side of the test valve, and the first exhaust valve is provided between the first on-off valve and the primary side of the test valve. By closing these after filling the fluid, the primary side of the test valve can be filled and sealed with the test fluid. Further, since the pressure gauge is provided between the first on-off valve and the primary side of the test valve, the pressure on the primary side of the test valve can be measured. Furthermore, by combining these and measuring the pressure of the test fluid enclosed on the primary side of the test valve, for example, a very bad test valve with valve seat leakage is detected at the initial stage of valve seat leak inspection.・ Excluded.

  According to the invention as set forth in claim 6, the second on-off valve is provided between the secondary side of the test valve and the flow sensor, so when the test fluid is filled in the valve seat leak inspection, it is closed. The test fluid can be prevented from flowing to the flow sensor side, and the flow sensor before the start of measurement is not adversely affected by the test fluid. In addition, since the second exhaust valve is provided, the secondary side of the test valve can be opened to the atmospheric pressure by opening the second exhaust valve. Furthermore, when the second exhaust valve is opened and the second on-off valve is closed, the secondary side of the test valve is opened to the atmosphere side, which is generated along with the supply of compressed air to the primary side of the test valve. Pressure fluctuation on the secondary side of the test valve can be mitigated.

  According to the invention as set forth in claim 7, the clamp jig is equipped with the O-ring for sealing at the time of clamping, so that the O-ring can be easily sealed between the test valve and the clamp jig. At the same time, the pressure resistance of the clamp portion between the test valve and the clamp jig is extremely improved to prevent elastic deformation due to pressure, thereby enabling high-accuracy flow measurement with the flow sensor.

According to another invention, since the flow rate is measured while preventing the outside air from entering while the secondary side of the flow sensor is released to the outside air, even if the flow rate is extremely small, the measurement is exposed to the flow sensor The flow of the target fluid becomes a flow according to the minute flow rate with high accuracy, the influence by the fluctuation due to the outside air or the reverse flow is extremely reduced, and the minute flow rate measurement with high accuracy becomes possible.

In addition, an appropriate control operation of each valve and compressed air enables an inspection process to compare and determine the internal pressure of the test fluid in the flow passage space on the primary side of the test valve and the inspection pressure. By properly detecting and eliminating rejected products before flow measurement, valve seat leak inspection can be rationalized, and an appropriate pressure higher than the inspection pressure corresponding to each individual test valve can be extracted as the reference pressure. can do.

It is a block diagram showing composition of a valve seat leak inspection device of the present invention. It is a sectional view showing an example of a sample valve clamped to a valve seat leak inspection device of the present invention. It is sectional drawing which showed the case where another seal member was used between a clamp jig | tool and a test valve in FIG. It is the partial expanded sectional view which showed the structure of the tank and cover of the valve seat leak inspection apparatus of this invention. It is the flowchart figure which showed the valve seat leak inspection method of this invention. (A) is Table 1, (b) is Table 2 and (c) is a graph of Table 3.

  Hereinafter, an embodiment of a valve seat leak inspection apparatus of the present invention and a valve seat leak inspection method using the same will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of the valve seat leak inspection apparatus of the present invention in the present embodiment, 1 is a first on-off valve, 2 is a first exhaust valve, 3 is a second exhaust valve, 4 is a second 2. 2 on-off valve, 5 is a test valve, 6 is a clamp jig, 7 is a flow sensor, 8 is a tank, 9 is a pressure gauge, 10 and 11 are secondary side flow paths, 12 is a primary side flow path ing.

  As shown in FIG. 1, the valve seat leak inspection apparatus according to the present embodiment is an inspection apparatus for inspecting a valve seat leak of a valve, and on the secondary side of the test valve 5, secondary side flow paths 10 and 11. The flow sensor 7 is connected to the secondary side of the flow sensor 7. The small leak from the test valve 5 is released to the outside air, and the tank 8 having a non-return function to prevent the entry of fluctuating outside air is provided on the secondary side. Connected Further, the first on-off valve 1 is provided on the primary side which is the pressurized supply side of the test valve 5 via the primary side flow passage 12, and the first on-off valve 1 and the primary side of the test valve 5 Between the pressure gauge 9 and the first exhaust valve 2 via the exhaust passage, and between the secondary side of the test valve 5 and the flow sensor 7 via the second on-off valve 4 and the exhaust passage 2 Exhaust valve 3 is provided.

  Although the pressurized supply source of the test fluid is not shown, in the present embodiment, the test fluid is connected to the left side (primary side) of the first on-off valve 1 and the test fluid is primary via the first on-off valve 1. It can be supplied into the side flow passage 12. In addition, although a test fluid can also be selected suitably, compressed air is used in this embodiment. When the first exhaust valve 2 is opened, the inside of the primary flow passage 12 is opened to the atmosphere, and the internal pressure of the primary flow passage 12 can be measured by the pressure gauge 9. Similarly, when the second exhaust valve is opened, the inside of the secondary flow passage 10 is opened to the atmosphere, and the opening and closing of the second on-off valve 4 opens and closes between the secondary flow passages 10 and 11. The flow rate of the test fluid in the secondary side flow paths 10 to 11 can be measured by the flow sensor 7.

  The flow sensor 7 is not particularly limited as long as it is a flow meter capable of measuring a minute flow rate of a predetermined level, but a thermal mass flow sensor is preferable. In this embodiment, as the thermal mass flow sensor, a predetermined thermal microflow sensor having a mass flow measurement capability of at least about 0.15 ml / min of a semiconductor type using MEMS (Micro Electro Mechanical Systems) technology or the like is used. I use it. In recent years, microflow sensors of this type can use various types of flow sensors with high sensitivity, wide range (flow rate), high-speed response, low power consumption, and space saving by microfabrication using MEMS technology etc. .

  As an example of the basic structure of the above-mentioned sensor, silicon nitride is formed on a cavity with a depth of about 200 μm formed in the center of the base with a silicon chip of about 1.7 mm on a side and a thickness of about 0.5 mm as a base. A diaphragm with a size of about 1 μm is provided, and a heater is provided at the center of this diaphragm, and upstream and downstream temperature sensors (temperature measuring resistors made of platinum thin film etc.) are provided on both sides of the heater. It is constituted, and this becomes a sensor element. When the fluid has a flow, the temperature distribution on the upstream side and the downstream side with respect to the heater causes an asymmetric gradient, thereby causing a difference in resistance value between the upstream and downstream temperature sensors. This resistance value difference is taken out as a voltage difference by an output circuit consisting of a predetermined resistance bridge while controlling the heater to a constant temperature higher than the fluid temperature by a predetermined control circuit, and the taken out output value is a sensor with a predetermined function It is converted to the mass flow rate of the fluid flowing on the top surface. The mass flow velocity gradient in the vicinity of the sensor is determined by the various characteristics of the flow channel (channel diameter, flow straightening mechanism such as throttling, average flow velocity, etc.), the type of fluid, or the installation state of the flow sensor. The flow rate value can be obtained from the measurement data with extremely high repeatability by installing in the flow channel of the appropriate diameter and performing precise flow rate calibration (acquisition of the relationship between the sensor output and the flow rate) in advance.

  Further, at the stage of measuring the minute leak flow rate from the valve seat by the flow sensor 7, the inside of the flow path on the secondary side of the test valve 5 in a state where the second exhaust valve 3 is closed and the second on-off valve 4 is opened. A space, that is, the internal space of the valve seat of the test valve 5 in the closed state in FIG. 1, the second exhaust valve 3, and the secondary side flow passages 10 and 11 closed by the tank 8 It becomes space.

  The first on-off valve 1, the first exhaust valve 2, the second exhaust valve 3, and the second on-off valve 4 are not limited as long as they can be opened and closed, respectively, but in this example, predetermined solenoid valves (solenoid valves) You are using The pressure gauge 9 uses a predetermined pressure gauge having a pressure measurement capability of, for example, about 1 KPa (about 0.01 atmosphere). Furthermore, although not shown, the valve seat leak inspection apparatus of the present invention is provided with a control unit (microcomputer) connected to various valves and sensors. The control unit includes, for example, a storage unit (memory) such as a reference pressure, a valve drive unit, an arithmetic processing unit, a data input / output unit, etc., and an interface unit, a display unit, etc. It is configured to be able to control various processes and processes such as the process.

  FIG. 2 is a cross-sectional view showing a state where the test valve 5 is clamped by the clamp jigs 6 and 6 'in the valve seat leak inspection device of the present invention. The test valve 5 is not particularly limited and may be appropriately selected according to the practice of the present invention. However, as shown in the figure, in the present embodiment, flange-connected cast iron of nominal diameter 80A as the test valve 5 A glove valve is used. As the test valve 5, other than this, for example, a screw connection type gate valve or globe valve with a nominal diameter of 1/4 to 1/2 inch, a flange connection type gate valve or glove valve with a nominal diameter of 40 to 80 A (mm), etc. However, it can be applied to other various valves.

  The test valve 5 shown in FIG. 2 is provided with a handle 13 at the top of a stem 14, and the stem 14 is pivotally attached to a shaft mounting portion via a screw portion, a packing, etc. The reference numeral 14 can move up and down while pivoting the shaft mounting portion. Further, the valve body 15 is fixed by caulking to the lower part of the stem 14, and the valve body 15 is seated on and separated from the valve seat 50 by moving up and down in the valve chamber while rotating with the stem 14, The test valve 5 is opened and closed.

  As shown in FIG. 2, in the test valve 5, the end face of the primary side area 16 and the end face of the secondary side area 19 are clamped by clamping jigs 6 and 6 ′ in a disk shape from the left and right respectively It is done. In this state, the end face of the primary side area 16 is in pressure contact with the O-ring 17 of the clamp jig 6 on the left side in FIG. There is. Similarly, the end face of the secondary side area 19 is pressure-sealed by the O-ring 17 'of the clamp jig 6' on the right side of the figure, and the secondary side area 19 is connected in communication with the flow path hole 18 '. The O-rings 17 and 17 'have a shape capable of sealing the end face of the primary side area 16 or the secondary side area 19 of the test valve 5, and in the present embodiment, concentric with the flow path holes 18 and 18'. In the mounting groove of the end face of the clamp jig 6. The flow passage holes 18 communicate with the primary flow passage 12 in FIG. 1, and the flow passage holes 18 ′ communicate with the secondary flow passage 10 in FIG. 1.

  FIG. 3 shows a state in which a rubber thick disc-like seal member 20, 20 'is attached to the clamp jig 6 in FIG. 2 in place of the O-rings 17, 17' for sealing at the time of clamping. There is. The sealing member 20 is a holding jig made entirely of rubber, and is suitable for sharing the clamping jig 6 with the clamps of valves of different shapes and sizes. However, when sealed by this sealing member 20, it has elasticity. Since the area of the seal portion is too large, when the primary side 16 is pressurized and filled with compressed air, the pressure of the test fluid causes elastic deformation of the seal members 20 and 20 'to easily cause fluctuation, and this fluctuation is a valve body The internal pressure of the secondary side area 19 fluctuates by affecting 15, and the flow rate measurement by the flow sensor 7 is likely to be adversely affected. Therefore, as with the O-ring 17 shown in FIG. 2, a seal using a seal member that fits the shape and size of the valve and minimizes the area of the elastic seal area and does not shake due to elastic deformation due to internal pressure is preferable. .

  FIG. 4 shows the structure of the tank and the cover of the valve seat leak inspection apparatus according to the present embodiment, and is a partially enlarged sectional view enlarging the main part of the tank 8 schematically shown in FIG. As described above, the tank 8 of the present invention has a non-return function that allows the minute leak from the test valve 5 to escape to the outside air and prevents the inflow of fluctuating outside air. The tank 8 shown in FIG. 1 corresponds to the soft tube 30 shown in FIG. 4, and the cylindrical tube 30 is formed with a radial cut 32 to exert the non-return function. And the tube 30 is covered with a non-sealed cover 23.

  As shown in FIG. 4, the cover 23 is a transparent acrylic cylindrical member, and both ends of the cover 23 are not sealed in the circular recesses 24 and 24 ′ respectively formed on the side surfaces of the metal bases 22 and 22 ′. It is detachably mounted in the state. This non-sealed state is due to the loose fit between the circular recesses 24 and 24 'and the both ends of the cover 23 so as to leave a slight gap. In the base 22 shown on the right side of the figure, a flow passage hole 25 connected in communication with the secondary flow passage 11 shown in FIG. 1 is formed, and an open end of the flow passage hole 25 is an external thread 27 of the joint 26. A female screw portion 28 capable of screwing is formed.

  The cover of the valve seat leak inspection device according to the present invention is intended to protect the tank from disturbances or vibrations of the atmosphere around the outer periphery of the tank, and to stably exhibit the nonreturn function of the small amount of exhaust that the tank has. On the other hand, if the tank is completely sealed, the air exhausted from the tank fills the cover and the air can not be exhausted from the tank, and the internal pressure of the tank rises, so the tank is non-sealing structure. It covers the Therefore, the cover is not limited to the one shown in the above embodiment as long as it is a cover that exhibits such a function, and is not limited to the cylindrical shape like the shape of the cover 23, for example. Furthermore, there is no limitation on the structure for covering the tank in a non-sealing state. Therefore, for example, the cover 23 may be provided with an appropriate slit or the like to ensure the non-sealing state of the tank 8.

  The tube 30 is a soft tubular member made of resin or the like, and in this example, a silicone soft hose (polyurethane tube) is used, and as shown in the figure, one end is closed by the lid member 31. And the other end is connected to the joint 26. The joint 26 is also a substantially cylindrical member made of metal, and a male screw portion 27 is formed at one end, and the other end is connected to the tube 30. Therefore, the inside of the tube 30 and the inside of the joint 26 are in communication. Further, a pressure resistant cylindrical member 29 is provided on the inner diameter side of the tube 30 and the inner diameter side of the joint 26 so that the pressure-resistant cylindrical member 29 is inserted, and the connection between the tube 30 and the joint 26 is strengthened.

  In FIG. 4, one cut portion 32 of appropriate depth and width is formed at a suitable middle upper half position of the tube 30 so as to face the radial direction. The notched portion 32 has a non-return function that functions as a valve slit that can be closed when the internal pressure is not applied to the tube 30 to shut off the outside air. On the other hand, in the case of a mere slit in which the incision 32 is always open regardless of the internal pressure, the internal pressure slightly rising due to valve seat leakage is not maintained in the tube 30, and thereby the incision 32 This is not preferable because outside air easily enters the inside of the tube 30. The non-returning action of the incision 32 will be described later.

  As shown in FIG. 4, by screwing the male screw portion 27 of the joint 26 to the female screw portion 28 of the base 22, the tube 30 can be attached to and detached from the base 22 in a one-touch manner. In this case, the tube 30 is connected to the base 22 via the joint 26 and the cover 23 is attached to the base 22, 22 ′ so as to cover the tube 30. Further, after the connection to the base 22 is completed, the inside of the tube 30, the inside of the joint 26, and the inside of the flow path hole 25 form a space in sealed communication with the outside, and the fluid in this space is In the same figure, it becomes possible to communicate with the outside only by opening and closing the incision 32.

  In the present embodiment, the tube 30 has an outer diameter 6 6 mm, an inner diameter 4 4 mm, and a length 30 mm, the tubular member (pressure resistant hose) 29 has an outer diameter 4 4 mm and an inner diameter 2 2 mm. It is formed in 2 mm. The total length from one end of the tube 30 on the lid 31 side to one end of the joint 26 on the male screw 27 side is 50 mm.

  The tank of the valve seat leak inspection apparatus according to the present invention does not disturb the flow of a minute flow of air leaked from the valve seat of the test valve in the valve closed state to the secondary side in the valve seat leak inspection process. It is provided on the secondary side of the flow sensor for the purpose of preventing the atmospheric fluctuation from reaching the flow sensor while venting to the air, and specifically, air that leaked out to the secondary side of the flow sensor It is provided to form a space-saving area for maintaining the pressure of. In order to maintain the sensitivity of the flow leaking from a large volume container such as a valve, the sensitivity can not be maintained in the atmospheric pressure release condition, and therefore, it is necessary to control the flow with an extremely low resistance.

  Therefore, the function required for the tank of the present invention is at least an adverse effect due to the fluctuation of the outside air received by the flow sensor of the flow sensor due to the simplification and space saving function of the valve seat leak inspection device and the air release on the secondary side. And a stable relief function for minute flow according to the rise of minute tank internal pressure due to valve seat leakage.

  The tank 5 is not limited to the tank 5 (tube 30) shown in the above embodiment as long as it exhibits such a function, and its shape, material, size, hardness, mounting aspect, etc. The structure (the structure of the cut portion 32) which exhibits the non-return function can be appropriately selected depending on the type of the test valve to be inspected, the use condition, and the like. For example, the function of the above-mentioned tank of the present invention is intended to be realized by a check valve which is opened by a minute flow, a check valve which opens with a minute pressure, a metal tank having a small hole on the secondary side, etc. Also, the structure of the notches 32 is not limited to the structure shown in the above embodiment, but the number, direction, position, width and depth of the notches, or the shape of the notches Punching into an arbitrary shape such as a cross shape, a * shape, or a star shape can be appropriately selected depending on the implementation.

  On the other hand, for example, the flow path provided with the flow sensor (the secondary side flow path 11 in FIG. 1) is used as a long pipe to separate the air release point from the flow sensor to suppress the influence from the air. Alternatively, even if the secondary side of the flow sensor is sealed with a sealed container as in the prior art, there remains a problem that simplification of the device or space saving can not be realized, so it can not be a solution to the problem of the present invention.

  Next, an example of the inspection method of the present invention will be described. The present embodiment is a valve seat leak inspection method using the above-described valve seat leak inspection apparatus of the present invention. FIG. 5 is a flow chart for explaining the valve seat leak inspection method of the present invention. According to the inspection method of the present invention, while the fluid flowing down the secondary side of the flow sensor 7 is released to the outside air, the flow rate of the fluid is maintained while maintaining the non-return function to prevent the outside air from entering the secondary side of the flow sensor 7 It is measured by the flow sensor 7.

  When carrying out the valve seat leak inspection method of the test valve 5, the valve body 15 of the test valve 5 is seated on the valve seat 50 with a predetermined sealing force, as described with reference to FIGS. A valve in which the test fluid leaks from the valve seat 50 to the secondary side area 19 in a state where the secondary side is clamped by the clamp jigs 6, 6 'and the primary side area 16 is pressurized and filled with the compressed air which is the test fluid. It is to check the seat leak flow rate. The valve seat leak flow rate of the test fluid can take various values depending on the sealing state of the closed valve body 15 and the valve seat 50 or the like.

  In FIG. 5, step S0 shows the initial state in the valve seat leak inspection method of the present invention. In the initial state, the first on-off valve 1 and the second on-off valve 4 are closed, and the first exhaust valve 2 and the second exhaust valve 3 are open. By closing the first on-off valve 1, compressed air is not supplied to the sample valve 5 from a pressurized supply source (not shown), and by closing the second on-off valve 4, the sample valve 5 and the flow sensor The space between 7 and 8 is airtightly shut off. Further, by opening the first exhaust valve 2 and the second exhaust valve 3, the inside of the primary side flow path 12 and the inside of the secondary side flow path 10 of the test valve 5 are opened to the atmospheric pressure. .

  In FIG. 5, steps S1, S2 and S3 show the pressurizing step of the valve seat leak inspection method of the present invention. In this pressurization step, the primary side flow passage 12 of the test valve 5 is used as a sealed space, and compressed air is supplied to the sealed space, while the secondary flow passage 10 of the test valve 5 is connected to the flow sensor 7 Release to atmospheric pressure while cutting Then, after the predetermined pressurizing time, when the pressure value of the compressed air is equal to or more than the inspection pressure, the valve seat leakage inspection is performed using this pressure value as a reference value.

  In step S1, the first exhaust valve 2 and the second on-off valve 4 are closed, and the first on-off valve 1 and the second exhaust valve 3 are opened. In this state, compressed air is supplied from the pressurized supply source. Pressure is supplied into the primary side flow passage 12. The supply pressure of compressed air, that is, the inspection pressure is set to a predetermined pressure such as, for example, 0.6 MPa. By closing the first exhaust valve 2, the inside of the primary side flow passage 12 becomes a sealed space, and compressed air can be pressurized and filled. At this time, by opening the second exhaust valve 3 and opening the inside of the secondary flow passage 10 to the atmospheric pressure, the test valve 5 generated along with the supply of the compressed air to the primary side of the test valve 5 To reduce pressure fluctuations on the secondary side of the Further, closing the second on-off valve 4 prevents the pressure fluctuation on the secondary side of the test valve 5 from affecting the flow sensor 7 before the start of measurement. The pressurizing time of the compressed air based on the test pressure to the primary side of the test valve 5 is set to a predetermined time such as 5 to 10 seconds, for example. The above process will be described with reference to FIGS. 2 and 3. With respect to the test valve 5 in a predetermined valve closed state, compressed air is pressurized and charged on the primary side 16 thereof, and the valve seat 50 causes valve seat leakage. In the state, the pressurized and filled compressed air leaks to the secondary side 19 as the valve seat leak flow rate of the test valve 5.

  In step S2, after the predetermined pressurization time in step S1, it is determined whether the pressure measured by the pressure gauge 9 is equal to or higher than the inspection pressure (0.6 MPa). If the measured pressure is less than the inspection pressure, it can be judged that a large amount of valve seat leakage has occurred (No judgment), and the inspection proceeds to step S3. If the measured pressure is equal to or higher than the inspection pressure It judges that it passes (Yes determination), and advances inspection to Step S4. In step S3, the first on-off valve 1 is closed, the first exhaust valve 2 is opened, the compressed air in the primary side flow passage 12 is opened to the atmosphere, and the inspection is returned to the initial state.

  By providing the pressurization step, it is possible to detect and remove a test valve that causes a large amount of valve seat leakage at an early stage of the inspection step, and the valve seat leakage inspection method can be rationalized.

  In step S4, when the measured pressure in the pressure gauge 9 in step S2 is the inspection pressure or more, the measured pressure is stored as the reference pressure in the storage means of the valve seat leak inspection apparatus. This reference pressure is used as a predetermined reference value in a later step.

  In FIG. 5, steps S5, S6 and S7 show the large leak inspection process of the valve seat leak inspection method of the present invention. In the large leak inspection step, the first on-off valve 1 and the first exhaust valve 2 are closed, and compressed air which is a test fluid is enclosed on the primary side of the test valve 5 to determine whether it is a reference pressure.

  In step S5, the first on-off valve 1 and the first exhaust valve 2 are closed, the pressurized supply source and the test valve 5 are shut off, and the compressed air is in the primary side flow passage 12 of the test valve 5. To be enclosed in At this time, the second exhaust valve 3 is open and the second on-off valve 4 is closed.

  In step S6, the pressure of the compressed air enclosed in primary side flow passage 12 in step S5 is measured with pressure gauge 9 after maintaining the enclosed state for a predetermined time (eg, 3 seconds), and the measured pressure It is determined whether or not the pressure is equal to or higher than a predetermined first prescribed pressure. If the measured pressure is less than the first specified pressure, the valve seat leak is judged to be a large leak, so it is judged as a rejection (No judgment), and the inspection proceeds to step S7, and the measured pressure is higher than the first specified pressure. If there is, it is judged as pass (Yes judgment), and the inspection is advanced to step S8. The first prescribed pressure is set to a predetermined pressure such as 98% of the reference pressure, for example. In step S7, the first on-off valve 1 is closed, the first exhaust valve 2 is opened, the compressed air in the primary side flow passage 12 is opened to the atmosphere, and the inspection is returned to the initial state.

  By providing the above-mentioned large leak inspection process, it becomes possible to detect and remove a test valve causing a large amount of large leakage before proceeding to the minute leak inspection process by the flow sensor, and the valve seat leakage inspection method can be rationalized. . The minute leak inspection with the flow sensor has a relatively large inspection process and inspection time, and there is also a load and wear of the flow sensor itself, such as the calibration value becoming incorrect due to the large flow rate measurement. It is preferable to sort out the test valves that are worthy to be tested with sufficient accuracy.

  In FIG. 5, steps S8, S9, S10, S11 and S12 show the micro leak inspection process of the valve seat leak inspection method of the present invention. In the minute leak inspection process, the second exhaust valve 3 is closed, and the second on-off valve 4 is opened, so that the inspection process is performed by decreasing the value of the pressure gauge 9 or measuring the flow sensor 9.

  In step S8, the second exhaust valve 3 is closed and the second on-off valve 4 is opened. Further, the first on-off valve 1 and the first exhaust valve 2 are both kept closed. In this state, the test fluid on the primary side of the test valve 5 is kept sealed in the primary flow passage 12, and the test fluid leaking from the valve seat is discharged from the secondary flow passages 10 and 11. It will be in the state which can be detected by flow sensor 7 via. Therefore, the minute valve seat leak flow rate can be measured with high accuracy by the pressure drop by the pressure gauge 9 and the flow rate measurement by the flow sensor 7.

  In step S9, the pressure of the compressed air enclosed in the primary side flow passage 12 in step S8 is measured by the pressure gauge 9 while maintaining the enclosed state for a predetermined inspection time (eg, 20 seconds). Then, it is determined whether the measured pressure is equal to or higher than a predetermined second predetermined pressure. If the measured pressure is less than the second specified pressure, the valve seat leak can be determined to be large, so it is determined to be a rejection (No judgment), and the inspection proceeds to step S10. (Yes determination), and advances the inspection to step S11. The second prescribed pressure is set to a predetermined pressure such as 96% of the reference pressure, for example. In step S10, the first on-off valve 1 is closed, the first exhaust valve 2 is opened, the compressed air in the primary side flow passage 12 is opened to the atmosphere, and the inspection is returned to the initial state.

  In step S11, the flow rate is measured by the flow sensor 7 within a predetermined inspection period, and it is determined whether the measured flow rate is equal to or less than a predetermined flow rate. If the measured flow rate is equal to or higher than the specified flow rate, it is judged as a rejection because it corresponds to a valve seat leak (No judgment), the inspection proceeds to step S12, and if the measured flow rate is equal to or less than the specified flow rate Then, the examination is advanced to step S13. The inspection period of this step is set to, for example, a predetermined period such as the second half period or the last predetermined period (last half 10 seconds of 20 seconds) of the inspection time (20 seconds) of step S9. As described above, the inspection period is set after a predetermined time has elapsed from the start of the inspection time in step S9, and the second on-off valve 4 is opened to alleviate pressure fluctuation in the secondary flow passage 11 accompanying release of compressed air. By waiting, the flow rate measurement by the flow sensor 7 can be stabilized. In steps S12 and S13, the second on-off valve 4 is closed, the second exhaust valve 3 is opened, the compressed air in the secondary flow passage 10 is opened to the atmosphere, and the inspection is returned to the initial state.

  By providing the above-mentioned minute leak inspection step in which the drop of the value of the pressure gauge 9 and the measurement of the flow sensor 7 are appropriately combined, it becomes possible to appropriately extract an object to be subjected to high accuracy minute leak inspection by the flow sensor 7 , Valve seat leak inspection can be rationalized appropriately.

  Here, the non-returning action of the tank 8 (tube 30) in the micro leak inspection process will be described. First, the minute leak amount (specifically, about 0.15 ml / min) of the compressed air from the valve seat flows into the inspection space, and the internal pressure in the tube 30 gradually increases. On the other hand, as described above, when there is no differential pressure between the inside and the outside, the cut portion 32 of the tube 30 is in a closed state by the shape restoring force by the elasticity of the tube 30. Then, when the cut portion 32 changes its shape and gradually opens due to the expansion of the tube 30 caused by the increase of the internal pressure due to the inflow of the minute leak amount, when the internal pressure exceeds the atmospheric pressure (about 0.1 MPa) by a predetermined value, The incised portion 32 is opened, and the inside and outside of the tube 30 are in a slightly communicated state (ventable state). As a result, the compressed air inside the tube 30 is in a state of being relieved to the outside.

  In this relief state, as described above, a minute flow (or an increase in internal pressure accompanying the flow of compressed air) into the inspection space due to a valve seat leak and a small flow (or Is in a state where air flows in and out continuously because the differential pressure required to open the cut part 32 balances with high accuracy, and only the amount of air flow leaked from A state of being continuously pushed out is realized. On the other hand, if the internal pressure of the tube 30 becomes equal to or less than the predetermined value, the cut portion 32 closes so as to quickly respond to the pressure change (negative pressure), and the outside air exhibits the cut portion 32 by exerting the backstop function. And prevent the air flow in the inspection space from being affected by the backflow of ambient air such as fluctuation. In this state, the flow of compressed air in the inspection space becomes a unidirectional flow according to the inflow amount due to valve seat leakage without being affected by the outside air, and highly accurate minute flow rate measurement by the flow sensor 7 is possible. It becomes.

  Then, the Example which verified the said effect by the tank (tube) of this invention is described. In the present embodiment, as in the state of the flow sensor 7 provided in the inspection space, the flow sensor 7 is provided in the predetermined flow passage space so that the flow rate can be measured, and the valve from one side of the flow passage space to the inside A minute flow rate supposing the amount of seat leakage can be supplied, and the other side of the flow path space is divided into the case where it is opened to the atmosphere and the case where it is blocked by the tank (tube) of the present invention. The said minute flow rate was measured and the stability of the flow measurement by a flow sensor was confirmed from comparison of both flow rate data.

  First, the minute flow rate supplied as the valve seat leakage amount to the flow passage space was set to 0.25 ml / min, and the flow rate was measured by the flow sensor 7 used in the above embodiment. Table 1 below shows the respective measurement times in the case where the tube 30 of the present invention used in the above embodiment is provided at one end side of the flow path space, and in the case where the tube 30 is not provided. It is a flow-rate measured value (ml / min) for every 1 second for every 10 seconds, and tabulates measurement (measurement 1-measurement 3) for 3 times. Further, FIG. 6 (a) is a graph showing the average value (ave) of the measured values for three times shown in Table 1 in a graph, and FIG. 6 (b) similarly shows the average value (ave shown in Table 2) ) Is graphed.

  As shown in Table 1 (FIG. 6 (a)), the flow rate measurement value when having the tank (tube 30) of the present invention is close to the actual minute flow rate of 0.25 ml / min at least within the measurement period. It is stable with the value maintained. On the other hand, as shown in Table 2 (FIG. 6 (b)), the flow rate measurement value in the case where the tank (tube 30) of the present invention is not provided and the air is simply opened is the actual flow rate over time. It keeps falling below the minute flow rate. Therefore, according to this embodiment, the minute flow rate measurement when opened to the atmosphere is unstable, and it is difficult to measure the actual minute flow rate, and the minute flow rate measurement having the tank (tube 30) of the present invention In the above, it was proved that stable value measurement was possible to a value close to the actual minute flow rate.

  Table 3 below shows the measurement time (1 second) when the micro flow is zero and the tube 30 of the present invention is provided at one end of the flow path space, and when the tube 30 is not provided without air. It shows the flow rate measurement value (ml / min) every 10 seconds). Moreover, FIG.6 (c) is the graph which graphed the measured value of Table 3. FIG. Here, the measurement time is 1 to 5 seconds when the tube 30 is provided, and the measurement time is 6 seconds to 10 seconds when the tube 30 is removed and the air is open.

  As shown in Table 3 (Fig. 6 (c)), when the tank (tube 30) of the present invention is used (measurement time 1 to 5 seconds), the value is stable maintaining a value close to the actual value (zero). Therefore, it can be understood that the flow sensor is hardly affected by the flow measurement due to the fluctuation of the atmosphere and the like. On the other hand, when the tank (tube 30) of the present invention is not provided (measurement time 6 to 10 seconds), fluctuation is measured despite the fact that there is no flow rate, and in particular, the atmosphere of the flow path space In this example in which a minute turbulent flow is intentionally generated in the vicinity of the open portion, it can be understood that the measurement of the negative value is large, and thus the influence of the fluctuation from the atmosphere side to the flow path space is greatly affected. Therefore, also according to this embodiment, when the tank (tube 30) of the present invention is provided, an adverse effect such as atmospheric fluctuation to which the flow sensor is subjected in the minute flow rate measurement is extremely effective as compared with the case of open to the atmosphere. It was proved to be shielded.

  Furthermore, the present invention is not limited to the description of the above embodiment, and various modifications can be made without departing from the scope of the invention described in the claims of the present invention.

1 first on-off valve 2 first exhaust valve 3 second exhaust valve 4 second on-off valve 5 test valve 6, 6 'clamp jig 7 flow sensor 8 tank 9 pressure gauge 17, 17' O-ring 23 cover 30 tube 32 Cutting section

Claims (7)

  An inspection apparatus for inspecting a valve seat leak of a valve, wherein a flow sensor is connected to a secondary side of a test valve, and a micro leak from the test valve is released to the outside air on the secondary side of the flow sensor, A valve seat leak inspection apparatus characterized in that a tank having a nonreturn function to prevent the inflow of fluctuating external air is connected.   The valve seat leak inspection apparatus according to claim 1, wherein the tank is a soft tube, and a radial notch is formed in the tube so as to exert the non-return function.   The valve seat leak inspection device according to claim 1, wherein the flow sensor is a thermal mass flow sensor.   The valve seat leak inspection device according to claim 2, wherein the tube is covered with a non-sealed cover.   A first on-off valve is provided on the primary side which is a pressurized supply side of the test valve, and a pressure gauge and a first exhaust valve are provided between the first on-off valve and the primary side of the test valve. The valve seat leak inspection device according to any one of 1 to 4.   The valve seat leak inspection device according to any one of claims 1 to 5, wherein a second on-off valve and a second exhaust valve are provided between the secondary side of the test valve and the flow sensor.   The valve seat leak inspection device according to any one of claims 1 to 6, wherein an O-ring is attached to a clamp jig for clamping the primary side and the secondary side of the test valve for sealing at the time of clamping. .

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