Liquid sampling valve maintenance management method and maintenance management device

Abstract

To provide a maintenance management method and a maintenance management device that can appropriately manage seal materials of a liquid sampling valve.SOLUTION: A maintenance management method for a liquid sampling valve 10 includes: a drive frequency acquisition step of acquiring the frequency of the drive of a piston 17 after seal materials 141 and 142 are newly attached; and a replacement determination step of determining that the seal materials 141 and 142 need to be replaced when the frequency of the drive of the piston 17 reaches a first replacement threshold or more, regardless of the time elapsed after the seal materials 141 and 142 are newly attached.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present disclosure relates to a maintenance management method and a maintenance management device for a liquid sampling valve. [Background technology]

[0002] BACKGROUND ART Conventionally, a liquid sampling valve is known that moves a sample gas obtained by vaporizing a sample liquid together with a carrier gas to a detection section (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 7-34368 Summary of the Invention [Problem to be solved by the invention]

[0004] In the liquid sampling valve described in Patent Document 1, sample leakage may occur due to wear of the sealing material. It is necessary to properly manage the maintenance of the sealing material.

[0005] The present disclosure has been made in consideration of the above points, and aims to provide a maintenance management method and a maintenance management device that can appropriately manage the maintenance of a sealing material of a liquid sampling valve. [Means for solving the problem]

[0006] (1) According to some embodiments, a maintenance management method manages the maintenance of a liquid sampling valve. The liquid sampling valve includes a housing having a sampling chamber for flowing a liquid sample and a vaporization chamber for vaporizing the liquid sample, a sealant separating the sampling chamber from the vaporization chamber, a stem configured to penetrate a hole in the sealant and be able to enter and exit the vaporization chamber, and a piston for driving the stem. The maintenance management method includes a drive count acquisition step of acquiring the number of times the piston has been driven since the sealant was newly installed, and a replacement determination step of determining that the sealant needs to be replaced if the number of times the piston has been driven is equal to or greater than a first replacement threshold, regardless of the time elapsed since the sealant was newly installed.

[0007] By determining whether or not the seal needs to be replaced based on the number of times the piston is driven, the likelihood that the seal will be replaced when it is worn increases. In other words, the likelihood that the seal will be replaced when it is not worn decreases. By reducing the need to replace seals when they are not worn, costs for parts or replacement work, as well as opportunity losses due to the gas chromatograph being down during the replacement work, can be reduced.

[0008] (2) The maintenance management method described in (1) above may further include a drive data acquisition step of acquiring at least one of the piston movement speed and the seal strain. In the replacement determination step, it may be determined that the seal needs to be replaced in at least one of the cases where the piston movement speed is equal to or greater than a second replacement threshold value or where the seal strain is equal to or less than a third replacement threshold value.

[0009] By determining the need to replace the seal material based on drive data other than the number of times the piston is driven, deterioration of the seal material that cannot be determined by the number of times the piston is driven alone can be identified, and as a result, the maintenance of the seal material can be appropriately managed.

[0010] (3) The maintenance management method described in (2) above may further include a replacement time prediction step of generating extrapolation data that predicts the relationship between the number of times the piston is driven and the movement speed of the piston or the distortion of the sealing material, and calculating at least one of the number of times the piston is driven when the movement speed of the piston in the extrapolation data becomes equal to or greater than the second replacement threshold, or the number of times the piston is driven when the distortion of the sealing material in the extrapolation data becomes equal to or less than a third replacement threshold, as the predicted maintenance time when the sealing material needs to be replaced.

[0011] By predicting the maintenance period based on the predicted drive data, the user can know when to replace the seal material and can plan the replacement accordingly. As a result, the user can create a plan that incorporates the seal material replacement work into the analysis work using a gas chromatograph and then carry out the work.

[0012] (4) The maintenance management method described in any one of (1) to (3) above may further include, before the replacement determination step, a retightening determination step of determining that it is necessary to retighten the nut that applies load to the sealing material when the number of times the piston is driven becomes equal to or greater than a first retightening threshold, regardless of the time that has elapsed since the sealing material was newly installed.

[0013] By retightening the nut before replacing the seal, the frequency of seal replacement is reduced, which reduces the cost of the parts or replacement work, as well as the opportunity loss caused by the gas chromatograph being down during the replacement work.

[0014] (5) In the replacement determination step of the maintenance management method described in (4) above, a determination as to whether to replace the sealing material may be made when the nut has been retightened a predetermined number of times or more.

[0015] If the seal wears or deteriorates, retightening the nut will no longer ensure sufficient adhesion between the seal and the stem. By limiting the number of times the nut is retightened, maintenance work with little effect is reduced. As a result, the maintenance of the seal in the liquid sampling valve is properly managed.

[0016] (6) A maintenance management device according to some embodiments includes a processor that executes the maintenance management method according to any one of (1) to (5) above. [Effects of the Invention]

[0017] According to the liquid sampling valve maintenance determination method and maintenance determination device of the present disclosure, the maintenance of the sealing material of the liquid sampling valve is appropriately managed. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of a gas chromatograph. [Figure 2] FIG. 10 is a cross-sectional view showing an example of the configuration of a liquid sampling valve according to one embodiment, in a state in which a sampling groove is positioned in a sampling chamber. [Figure 3] 3 is an enlarged view of a portion A enclosed by a dashed dotted line in FIG. 2. [Figure 4] 1 is a cross-sectional view showing an example of the configuration of a liquid sampling valve according to an embodiment, in which a sampling groove is positioned in a sample supply passage. FIG. [Figure 5] 5 is an enlarged view of a portion B enclosed by a dashed dotted line in FIG. 4. [Figure 6] FIG. 10 is a cross-sectional view showing an example of the configuration of a liquid sampling valve to which an acceleration sensor and a strain sensor are attached. [Figure 7] 10 is a flowchart showing an example of the procedure of a determination operation in a liquid sampling valve according to an embodiment. [Figure 8] 8 is a flowchart showing an example of a procedure for determining retightening in FIG. 7. [Figure 9]8 is a flowchart showing an example of a procedure for determining replacement in FIG. 7. [Figure 10] 10 is a graph showing an example of a predicted value of piston velocity calculated based on a measured value of piston velocity. [Figure 11] FIG. 10 is a diagram showing a configuration example of a cylinder to which an acceleration sensor is attached externally. [Figure 12] FIG. 10 is a diagram illustrating a configuration example of a cylinder equipped with a proximity sensor. DETAILED DESCRIPTION OF THE INVENTION

[0019] This disclosure relates to a liquid sampling valve for use in a gas chromatograph. A gas chromatograph transports a fixed amount of a multi-component measurement sample to a column using a carrier gas, measures the concentration of each component separated by the column, and outputs the results as a chromatogram. When the measurement sample is a liquid sample, the liquid sampling valve vaporizes the liquid sample and transports it to the column together with the carrier gas, enabling the concentration of the liquid sample to be measured by the gas chromatograph.

[0020] The liquid sampling valve includes a liquid sample supply section, a liquid sample vaporization section, and a seal separating the supply section and the vaporization section. The liquid sampling valve uses a stem with a sampling groove to transport a constant amount of liquid sample from the supply section to the vaporization section. The liquid sampling valve can supply a constant amount of liquid sample accumulated in the sampling groove to the vaporization section by moving the stem so that the sampling groove moves from the supply section through the seal to the vaporization section. The liquid sampling valve must be managed to prevent any gaps from forming between the seal and the stem to prevent leakage of the liquid sample from the supply section. Specifically, in the liquid sampling valve, the seal is tightened with a nut, so that a sufficient load is applied from the seal to the stem.

[0021] Wear of the sealant can cause sample leakage between the sealant and the stem, which can change the shape of the chromatogram and lead to problems such as a decrease in the reproducibility of measured values ​​or an instability of the chromatogram baseline.

[0022] In the liquid sampling valve according to the comparative example, when a problem occurs, the nut is tightened. However, this method of responding when a problem occurs does not prevent the problem. Furthermore, to avoid problems caused by wear of the seal material, the seal material is replaced during regular maintenance regardless of its wear state. While replacing the seal material can prevent problems, it may be replaced while the seal material is still fully usable, which can increase the cost of replacing the seal material.

[0023] Therefore, the present disclosure describes a liquid sampling valve that allows the seal material to be replaced at an appropriate time, and a gas chromatograph that uses the liquid sampling valve.

[0024] (Configuration example of gas chromatograph 1) As shown in Figure 1, gas chromatograph 1 comprises a liquid sampling valve 10, a column 20, a detector 30, and a control unit 40. Column 20 is also called a separation tube. Gas chromatograph 1 is an analyzer that collects a fixed amount of a multi-component mixed sample using liquid sampling valve 10, transports it to column 20 using a carrier gas, separates the sample into its individual components using column 20, detects the concentrations of each component using detector 30, and outputs the detection results as a gas chromatogram using control unit 40.

[0025] The liquid sampling valve 10 has a fitting marked "IN" for introducing the liquid sample so that the liquid sample flows inside, and a fitting marked "OUT" for discharging the liquid sample. The liquid sampling valve 10 also has a fitting for introducing a carrier gas used to transport the vaporized liquid sample to the column 20. The liquid sampling valve 10 transports the sample gas, which is a mixture of the vaporized liquid sample and the carrier gas, to the column 20.

[0026] The column 20 separates each component contained in the sample gas. The detector 30 detects the concentration of each component separated by the column 20. The detector 30 is equipped with a fitting for venting the sample gas after the component concentration has been detected.

[0027] The control unit 40 acquires the detection results of the concentration of each component by the detector 30 and outputs them as a chromatogram. The control unit 40 also controls the liquid sampling valve 10 to synchronize the collection of the liquid sample with the detection results by the detector 30.

[0028] The control unit 40 may be configured to include a processor such as a CPU (Central Processing Unit) or a dedicated circuit such as an FPGA (Field Programmable Gate Array). The control unit 40 may be configured to execute programs that realize various functions of the gas chromatograph 1. The control unit 40 may include a memory unit. The memory unit may store various information used in the operation of the control unit 40, or programs for realizing the functions of the control unit 40. The memory unit may function as a work memory for the control unit 40. The memory unit may be configured, for example, as a semiconductor memory. The memory unit may be configured separately from the control unit 40.

[0029] The gas chromatograph 1 may further include an interface. The interface may include, for example, a communication interface for communicating with an external device via a wired or wireless connection. The interface may include a display device. The display device may include various displays such as a liquid crystal display. The interface may include an audio output device such as a speaker. The interface may include an input device for receiving input from a user. The input device may include, for example, a keyboard or physical keys, or a pointing device such as a touch panel or touch sensor or a mouse.

[0030] (Configuration example of liquid sampling valve 10) 2 to 5, an example configuration of the liquid sampling valve 10 will be described. The liquid sampling valve 10 includes a block 11, a nut 12, a liquid sample block 133, seals 141 and 142, a stem 15, a piston 17, and a cylinder 18. The block 11, the nut 12, the liquid sample block 133, the stem 15, the piston 17, or the cylinder 18 may be made of a metal material such as SUS, or may be made of various other materials. The seals 141 and 142 may be made of a resin material such as rubber, or may be made of various other materials.

[0031] The block 11, nut 12, and liquid sample block 133 are also collectively referred to as the housing of the liquid sampling valve 10. As will be described later, the housing of the liquid sampling valve 10 has a sampling chamber 152 (see FIG. 3) and a vaporization chamber 161 inside.

[0032] The liquid sampling valve 10 further includes a pipe 131 through which the liquid sample flows into a sampling chamber 152 (see FIG. 3) defined between the liquid sample block 133 and the seals 141 and 142, and a pipe 132 through which the liquid sample flows out from the sampling chamber 152. The sampling chamber 152 forms part of the flow path for the liquid sample. The seal 141 has a hole defined by an inner wall 141a. The seal 142 also has a hole defined by an inner wall 142a. The holes in the seals 141 and 142 are configured to fit the outer shape of the stem 15 (described below), and are sealed when the stem 15 passes through the hole. The seals 141 and 142 are elastic. By tightening the nut 12 and applying a load to the seals 141 and 142, the inner wall 141a of the seal 141 and the inner wall 142a of the seal 142 come into close contact with the outer surface of the stem 15. The inner walls 141a and 142a are in close contact with the outer surface of the stem 15, thereby improving the sealing performance of the holes of the seal materials 141 and 142.

[0033] The sealing material 142 separates the sampling chamber 152 from the vaporization chamber 161 .

[0034] The liquid sampling valve 10 further includes a pipe 16. The pipe 16 may be configured as, for example, a glass tube, or may be configured to include various other materials. The internal space of the pipe 16 is also referred to as a vaporization chamber 161.

[0035] The block 11 of the liquid sampling valve 10 has an internal inner wall 114 that defines a carrier gas passage 113 that supplies carrier gas to the vaporization chamber 161. The block 11 of the liquid sampling valve 10 has an internal inner wall 115 (see FIG. 5) that defines a space that accommodates the piping 16. The space defined by the internal wall 115 connects the carrier gas passage 113 to one end of the piping 16. As shown in FIG. 5, the carrier gas is supplied from the carrier gas passage 113 through the space between the piping 16 and the internal wall 115 to the vaporization chamber 161 from one end of the piping 16.

[0036] The block 11 of the liquid sampling valve 10 is provided with a heater 111 and a temperature sensor 112 for controlling the temperature of the block 11 including the vaporization chamber 161 to a temperature at which the liquid sample is vaporized.

[0037] The stem 15 is a rod-shaped member. As shown in FIG. 3 or 5, the stem 15 has a sampling groove 151. The sampling groove 151 is configured to have a smaller diameter than other portions, and is also referred to as a small diameter portion. The stem 15 is configured to be able to pass through holes in the sealing materials 141 and 142 and move in and out of the vaporization chamber 161.

[0038] The stem 15 moves into and out of the vaporization chamber 161 in accordance with the movement of the piston 17. In other words, the piston 17 drives the stem 15. The stem 15 is configured so that the sampling groove 151 is located in the sampling chamber 152 when the piston 17 moves to the position farthest from the sampling chamber 152 in the cylinder 18 as shown in FIG. 2. The stem 15 is also configured so that the sampling groove 151 is located in the vaporization chamber 161 when the piston 17 moves to the position closest to the sampling chamber 152 in the cylinder 18 as shown in FIG. 4.

[0039] The piston 17 moves when driving air is supplied to the cylinder 18. The piston 17 moves in a direction away from the sampling chamber 152 when driving air is supplied to the driving air supply unit 181 located on the side of the cylinder 18 closer to the sampling chamber 152, and moves in a direction approaching the sampling chamber 152 when driving air is supplied to the driving air supply unit 182 located on the side of the cylinder 18 farther from the sampling chamber 152. As described above, the sampling groove 151 moves between the sampling chamber 152 and the vaporization chamber 161 when the piston 17 moves toward or away from the sampling chamber 152.

[0040] The sampling groove 151 of the stem 15 is filled with a liquid sample when it is positioned in the sampling chamber 152. When the stem 15 moves from the sampling chamber 152 toward the vaporization chamber 161, the sampling groove 151 filled with the liquid sample moves from the sampling chamber 152 to the vaporization chamber 161 through a hole partitioned by the inner wall 142a of the sealing material 142. When the sampling groove 151 passes through the hole in the sealing material 142 and moves to the vaporization chamber 161, only the liquid sample filling the sampling groove 151 is collected in the vaporization chamber 161. The liquid sample accumulated in the sampling groove 151 is also referred to as the collected sample 153. The collected sample 153 is vaporized in the vaporization chamber 161 and converted into sample gas. The sample gas is transported from the vaporization chamber 161 to the column 20 by the carrier gas.

[0041] (Example of gas chromatograph 1 operation) The control unit 40 of the gas chromatograph 1 controls the movement of the stem 15 of the liquid sampling valve 10 to collect the collected sample 153 in the vaporization chamber 161. The amount of the collected sample 153 is determined based on the volume of the sampling groove 151 and is therefore constant. Therefore, the gas chromatograph 1 can collect a constant amount of liquid sample in the vaporization chamber 161. The constant amount of liquid sample is vaporized in the vaporization chamber 161 to become sample gas, which is then transported to the column 20 by the carrier gas. The control unit 40 synchronizes the timing of moving the sampling groove 151 of the stem 15 to the vaporization chamber 161 to collect the liquid sample in the vaporization chamber 161 with the operation of separating each component of the collected sample gas using the column 20. The components of the sample gas separated in the column 20 are sequentially transported to the detector 30 and detected by the detector 30. The control unit 40 generates a chromatogram based on the detection results of each component of the sample gas separated by the column 20.

[0042] In the gas chromatograph 1, each time a liquid sample is collected to detect the concentration of a component contained in the liquid sample, the piston 17 drives the stem 15 to reciprocate once in the axial direction. The number of times the piston 17 drives is also referred to as the number of drives, and corresponds to the number of analyses performed by the gas chromatograph 1.

[0043] (Maintenance of liquid sampling valve 10) As described above, in the gas chromatograph 1, the stem 15 reciprocates once in the axial direction each time a liquid sample is collected and analyzed. The axial movement of the stem 15 causes wear on the inner wall 141a of the seal member 141 or the inner wall 142a of the seal member 142, which is in contact with the stem 15. Wear on the inner wall 141a or 142a easily creates a gap between the outer surface of the stem 15 and the inner wall 141a or 142a. The gap between the outer surface of the stem 15 and the inner wall 141a or 142a reduces the sealing ability of the seal member 141 or 142 in the sampling chamber 152. This reduced sealing ability of the sampling chamber 152 makes the liquid sample more likely to leak into the vaporization chamber 161. When the liquid sample leaks into the vaporization chamber 161, the liquid sample is vaporized and transported to the column 20, even when the sampling groove 151 of the stem 15 has not yet moved to the vaporization chamber 161. As a result, the amount of sample gas transported to the column 20 becomes unstable. In the liquid sampling valve 10, maintenance of the liquid sampling valve 10 is performed to maintain the sealing of the sampling chamber 152.

[0044] <Replacing the seal materials 141 and 142> Worn sealants 141 and 142 may be replaced as maintenance to maintain the sealing performance of the sampling chamber 152. The control unit 40 of the gas chromatograph 1 according to this embodiment determines the need to replace the sealants 141 and 142 based on the drive data of the liquid sampling valve 10.

[0045] <<Replacement based on number of times driven>> The control unit 40 of the gas chromatograph 1 counts the number of times the piston 17 of the liquid sampling valve 10 has been driven after the sealants 141 and 142 have been newly attached to the liquid sampling valve 10, and determines the need to replace the sealants 141 and 142 based on the number of times the piston 17 has been driven. If the control unit 40 determines that the sealants 141 and 142 need to be replaced, it outputs an alarm urging the user to replace the sealants 141 and 142. The control unit 40 may acquire the number of times the piston 17 has been driven by accumulating it itself, or may acquire the number of times the piston 17 has been driven accumulated by another device. The operation of acquiring the number of times the piston 17 has been driven is also referred to as a drive count acquisition step. The operation of determining the need to replace the sealants 141 and 142 is also referred to as a replacement determination step.

[0046] For example, when the number of times the piston 17 is driven reaches or exceeds a predetermined threshold, the control unit 40 may determine that the seals 141 and 142 need to be replaced and output an alarm to prompt the user to replace the seals 141 and 142. The predetermined threshold that is compared with the number of times the piston 17 is driven to determine the need to replace the seals 141 and 142 is also referred to as a first replacement threshold. The first replacement threshold may be determined based on the results of a wear test of the seals 141 and 142, or the number of times the piston 17 is driven when a problem related to the seals 141 and 142 occurs during operation of the gas chromatograph 1. The control unit 40 determines the need to replace the seals 141 and 142 based on the number of times the piston 17 is driven, regardless of the length of time that has elapsed since the seals 141 and 142 were newly installed.

[0047] If the seals 141 and 142 are replaced during regular inspection of the gas chromatograph 1 or the liquid sampling valve 10, the seals 141 and 142 are replaced based on the amount of time that has passed since they were newly attached to the liquid sampling valve 10. In other words, the seals 141 and 142 are replaced simply because they have been attached to the liquid sampling valve 10 for a long time, regardless of the number of times the piston 17 has been driven. Therefore, the seals 141 and 142 may be replaced when they are not very worn.

[0048] On the other hand, in the liquid sampling valve 10 according to this embodiment, regardless of the time that has passed since the seals 141 and 142 were newly installed, the seals 141 and 142 are replaced when the number of times the piston 17 is driven reaches or exceeds the first replacement threshold, which increases the likelihood that the seals 141 and 142 will be worn when they are replaced. Therefore, replacement of the seals 141 and 142 is managed appropriately.

[0049] If the seals 141 and 142 are replaced after waiting for a problem to occur in the gas chromatograph 1, the user will not know when to replace the seals 141 and 142, and will not be able to plan ahead to replace the seals 141 and 142. This will have an adverse effect on the performance of analytical work using the gas chromatograph 1.

[0050] On the other hand, in the liquid sampling valve 10 according to this embodiment, the seals 141 and 142 are replaced when the number of times the piston 17 is driven reaches or exceeds the first replacement threshold, allowing the user to know when to replace the seals 141 and 142 and to systematically replace the seals 141 and 142. As a result, the user can create a plan that incorporates the replacement of the gas chromatograph 1 into the analysis work using the gas chromatograph 1 and then carry out the work.

[0051] By properly managing the replacement timing of the sealants 141 and 142 or by carrying out the work in a planned manner, the cost of materials and work required to replace the sealants 141 and 142, or the losses caused by a decrease in the operating rate of analytical work using the gas chromatograph 1, can be reduced.

[0052] <<Replacement based on piston 17 speed>> 6, the liquid sampling valve 10 may include an acceleration sensor 171 attached to the piston 17. The acceleration sensor 171 can measure the acceleration of the piston 17 when it moves in the axial direction of the stem 15. The control unit 40 of the gas chromatograph 1 may be communicatively connected to the acceleration sensor 171 via a cable 172. The control unit 40 may also be communicatively connected to the acceleration sensor 171 wirelessly.

[0053] The control unit 40 acquires the acceleration of the piston 17 from the acceleration sensor 171 and calculates the movement speed of the piston 17 when the piston 17 is driven. The control unit 40 may acquire the movement speed of the piston 17 by calculating it itself, or may acquire the movement speed of the piston 17 from another device. The movement speed of the piston 17 corresponds to the axial movement speed of the stem 15. If the adhesion between at least one of the seals 141 or 142 and the stem 15 is reduced due to wear of the seals 141 or 142, the frictional force that the stem 15 receives from the seals 141 or 142 when moving axially decreases. Assuming that the pressure of the driving air that drives the piston 17 is constant, the axial movement speed of the stem 15, i.e., the movement speed of the piston 17, increases as the frictional force that the stem 15 receives decreases. The control unit 40 can evaluate the adhesion between at least one of the seal materials 141 and 142 and the stem 15 based on the calculation result of the moving speed of the piston 17, and determine whether the seal materials 141 and 142 need to be replaced.

[0054] Specifically, when the movement speed of the piston 17 is equal to or greater than a predetermined threshold, the control unit 40 may output an alarm to prompt the user to replace the seals 141 and 142. The predetermined threshold that is compared with the movement speed of the piston 17 to determine whether the seals 141 and 142 should be replaced is also referred to as a second replacement threshold. The second replacement threshold may be determined based on, for example, an actual value of the movement speed of the piston 17 when a problem related to the seals 141 and 142 occurs during operation of the gas chromatograph 1.

[0055] In this embodiment, even when the control unit 40 determines that the seals 141 and 142 do not need to be replaced based on the number of times the piston 17 is driven, the control unit 40 may further determine the need to replace the seals 141 and 142 based on the movement speed of the piston 17. By performing a determination based on the movement speed of the piston 17 in addition to a determination based on the number of times the piston 17 is driven, deterioration of the seals 141 or 142 that cannot be determined based on the number of times the piston 17 is driven alone can be determined. As a result, replacement of the seals 141 and 142 can be appropriately managed.

[0056] The control unit 40 may confirm that the piston 17 has completed its movement within the cylinder 18 by acquiring the measurement results of the acceleration sensor 171. Meanwhile, in the liquid sampling valve 10, by supplying driving air from the driving air supply unit 182 for a sufficiently long time, it is ensured that the piston 17 has completed its movement in the direction from the sampling chamber 152 toward the vaporization chamber 161. Even if the acceleration sensor 171 does not need to be used to confirm that the piston 17 has completed its movement, it is used to manage the seals 141 and 142.

[0057] <<Replacement due to distortion of seal material 141 or 142>> 6, the liquid sampling valve 10 may include a strain sensor 143 attached to the sealant 142. The strain sensor 143 may be configured to measure compressive strain caused by the sealant 142 being pressed outward from its inner wall 142a. The strain sensor 143 may be configured to measure shear strain caused in the sealant 142 by a frictional force acting on the inner wall 142a of the sealant 142 from the stem 15, which moves in the axial direction. The control unit 40 of the gas chromatograph 1 may be communicatively connected to the strain sensor 143 via a cable 144. The control unit 40 may also be communicatively connected to the strain sensor 143 wirelessly.

[0058] The control unit 40 acquires the strain of the sealing material 142 from the strain sensor 143. If the inner diameter of the hole defined by the inner wall 142a of the sealing material 142 increases due to wear of the sealing material 142, the compressive force acting from the stem 15 on the inner wall 142a of the sealing material 142 decreases. Furthermore, if the wear of the sealing material 142 reduces the adhesion between the sealing material 142 and the stem 15, the frictional force that the sealing material 142 receives from the stem 15 decreases, assuming that the pressure of the driving air that drives the piston 17 is constant. The lower the frictional force that the sealing material 142 receives, the smaller the shear strain of the sealing material 142. Therefore, whether the strain sensor 143 measures compressive strain or shear strain, the control unit 40 can evaluate the wear of the sealing material 142 based on the strain of the sealing material 142 measured by the strain sensor 143 and determine whether the sealing material 142 needs to be replaced.

[0059] The strain sensor 143 may also be attached to the sealing material 141. When the strain sensor 143 is attached to the sealing material 141, the control unit 40 can evaluate the wear of the sealing material 141 based on the strain of the sealing material 141 measured by the strain sensor 143 and determine the need to replace the sealing material 141.

[0060] When measuring the compressive force acting on the sealing material 141 or 142 from the stem 15, the strain sensor 143 may be replaced with a pressure sensor or a load sensor such as a load cell.

[0061] Specifically, when the strain of the sealing material 141 or 142 is equal to or smaller than a predetermined threshold, the control unit 40 may output an alarm urging the user to replace the sealing materials 141 and 142. The predetermined threshold that is compared with the strain of the sealing material 141 or 142 to determine whether or not to replace the sealing materials 141 and 142 is also referred to as a third replacement threshold. The third replacement threshold may be determined based on, for example, an actual value of the strain of the sealing material 141 or 142 when a problem related to the sealing materials 141 and 142 occurs during operation of the gas chromatograph 1.

[0062] In this embodiment, even when the control unit 40 determines that replacement of the seals 141 and 142 is not necessary based on the number of times the piston 17 is driven, the control unit 40 may further determine the necessity of replacement of the seals 141 and 142 based on the distortion of the seals 141 or 142. By performing a determination based on the distortion of the seals 141 or 142 in addition to a determination based on the number of times the piston 17 is driven, deterioration of the seals 141 or 142 that cannot be determined solely based on the number of times the piston 17 is driven can be determined. As a result, replacement of the seals 141 or 142 can be appropriately managed.

[0063] The movement speed of the piston 17 and the strain of the sealing material 141 or 142 are also collectively referred to as drive data. That is, the drive data includes at least one of the movement speed of the piston 17 or the strain of the sealing material 141 or 142. The drive data may also include the number of times the piston 17 is driven. The control unit 40 may determine the need to replace the sealing materials 141 and 142 based on the drive data. The operation of acquiring the drive data is also referred to as a drive data acquisition step.

[0064] <Tighten nut 12> As a maintenance task for maintaining the sealing performance of the sampling chamber 152, the nut 12 may be retightened so that a sufficient load is applied to the sealants 141 and 142 to ensure close contact between the sealants 141 and 142 and the stem 15. By retightening the nut 12 as a maintenance task before replacing the sealants 141 and 142, the cost of the parts or replacement work, as well as opportunity loss due to the gas chromatograph 1 being shut down during the time spent on the replacement work, etc., are reduced. The control unit 40 of the gas chromatograph 1 according to this embodiment determines the need for retightening the nut based on the drive data of the liquid sampling valve 10.

[0065] The control unit 40 may accumulate the number of times the piston 17 of the liquid sampling valve 10 is driven, and determine the need for retightening of the nut 12 based on the number of times the piston 17 is driven. If the control unit 40 determines that the nut 12 needs to be retightened, it may output an alarm to prompt the user to retighten the nut 12. The operation of determining the need for retightening of the nut 12 is also referred to as a retightening determination step.

[0066] For example, when the number of times the piston 17 is driven reaches or exceeds a predetermined threshold, the control unit 40 may determine that the nut 12 needs to be retightened and output an alarm to prompt the user to retighten the nut 12. The predetermined threshold that is compared with the number of times the piston 17 is driven to determine whether the nut 12 needs to be retightened is also referred to as a first retightening threshold. The first retightening threshold may be determined based on the results of a wear test of the seals 141 and 142, or the number of times the piston 17 is driven when a problem related to the seals 141 and 142 occurs during operation of the gas chromatograph 1. The control unit 40 determines whether the nut 12 needs to be retightened based on the number of times the piston 17 is driven, regardless of the length of time that has elapsed since the seals 141 and 142 were newly installed.

[0067] The control unit 40 may output an alarm to prompt the user to retighten the nut 12 when the movement speed of the piston 17 of the liquid sampling valve 10 is equal to or greater than a predetermined threshold. The predetermined threshold that is compared with the movement speed of the piston 17 to determine whether the nut 12 needs to be retightened is also referred to as a second retightening threshold. The second retightening threshold may be determined based on, for example, an actual value of the movement speed of the piston 17 when a problem with the sealing materials 141 and 142 occurs during operation of the gas chromatograph 1.

[0068] When the strain of the sealing material 141 or 142 of the liquid sampling valve 10 is equal to or smaller than a predetermined threshold, the control unit 40 may output an alarm urging the user to retighten the nut 12. The predetermined threshold that is compared with the strain of the sealing material 141 or 142 to determine whether the nut 12 needs to be retightened is also referred to as a third retightening threshold. The third retightening threshold may be determined based on, for example, the actual value of the strain of the sealing material 141 or 142 when a problem with the sealing material 141 or 142 occurs during operation of the gas chromatograph 1.

[0069] In the present embodiment, even when the control unit 40 determines that retightening of the nut 12 is not necessary based on the number of times the piston 17 is driven, the control unit 40 may further determine the necessity of retightening of the nut 12 based on the movement speed of the piston 17 or on the distortion of the sealing material 141 or 142. By performing a determination based on the movement speed of the piston 17 or on the distortion of the sealing material 141 or 142 in addition to the determination based on the number of times the piston 17 is driven, deterioration of the sealing material 141 or 142 that cannot be determined only by the number of times the piston 17 is driven can be determined. As a result, retightening of the nut 12 can be appropriately managed.

[0070] If wear or deterioration of the sealant 141 or 142 progresses, sufficient adhesion between the sealant 141 or 142 and the stem 15 cannot be ensured even if the nut 12 is retightened. The control unit 40 of the gas chromatograph 1 may manage the liquid sampling valve 10 so that the number of times the nut 12 is retightened is less than a predetermined number. The predetermined number may be determined based on a correlation between the number of times the nut 12 has been retightened and the actual frequency of occurrence of problems related to the sealants 141 and 142. The control unit 40 may set the predetermined number to one, two or more. If the control unit 40 sets the predetermined number to zero, the control unit 40 does not determine the need for retightening the nut 12, but instead determines the need for replacement of the sealants 141 and 142 from the beginning.

[0071] If sufficient adhesion between the sealing material 141 or 142 and the stem 15 cannot be ensured even if the nut 12 is retightened, the maintenance effect obtained by retightening the nut 12 is small. By limiting the number of times the nut 12 is retightened, maintenance work that provides little effect can be reduced. As a result, the maintenance of the liquid sampling valve can be properly managed.

[0072] The control unit 40 of the gas chromatograph 1 according to this embodiment determines the need to replace the seals 141 and 142 after retightening the nut 12 a predetermined number of times. In other words, the control unit 40 of the gas chromatograph 1 according to this embodiment does not determine the need to replace the seals 141 and 142 until retightening the nut 12 a predetermined number of times. The determination of the need to retighten the nut 12 and the determination of the need to replace the seals 141 and 142 are not limited to the above-described combination, and may be performed in an appropriately modified combination.

[0073] <Example of maintenance management procedure for the liquid sampling valve 10> The control unit 40 of the gas chromatograph 1 may execute a maintenance management method for the liquid sampling valve 10, including example procedures of the flowcharts illustrated in Figures 7, 8, and 9. The maintenance management method for the liquid sampling valve 10 may be realized as a maintenance management program executed by a processor constituting the control unit 40 of the gas chromatograph 1. The maintenance management program may be stored on a non-transitory computer-readable medium.

[0074] The control unit 40 acquires driving data of the gas chromatograph 1 (step S1). The driving data includes the number of times the piston 17 is driven. The driving data may include measurement results of the acceleration or speed of the piston 17 when the piston 17 is driven. The driving data may include measurement results of the compressive strain of the sealing material 141 or 142, or the compressive force acting from the stem 15 on the sealing material 141 or 142. The driving data may include measurement results of the shear strain generated in the sealing material 141 or 142 when the piston 17 is driven.

[0075] The control unit 40 determines whether the number of times the nut 12 has been retightened after the sealing materials 141 and 142 have been replaced with new ones is equal to or greater than a predetermined number of times (step S2). If the number of times the nut 12 has been retightened is not equal to or greater than the predetermined number of times (step S2: NO), that is, if the number of times the nut 12 has been retightened is less than the predetermined number of times, the control unit 40 proceeds to a procedure for determining whether the nut 12 has been retightened in step S3, and executes the procedure of the flowchart illustrated in FIG. 8. If the number of times the nut 12 has been retightened is equal to or greater than the predetermined number of times (step S2: YES), the control unit 40 proceeds to a procedure for determining whether the sealing materials 141 and 142 should be replaced in step S4, and executes the procedure of the flowchart illustrated in FIG. 9. After executing the procedure of the flowchart illustrated in FIG. 8 or 9 as the procedure of step S3 or S4, the control unit 40 ends the execution of the procedure of the flowchart illustrated in FIG. 7.

[0076] The control unit 40 executes the procedure of the flowchart for determining whether or not the piston 17 has been driven, as illustrated in Fig. 8, as the procedure of step S3 in Fig. 7. The control unit 40 determines whether or not the number of times the piston 17 has been driven is equal to or greater than a first retightening threshold (step S31). If the number of times the piston 17 has been driven is equal to or greater than the first retightening threshold (step S31: YES), the control unit 40 proceeds to the procedure of step S34.

[0077] If the number of times the piston 17 has been driven is not equal to or greater than the first retightening threshold (step S31: NO), that is, if the number of times the piston 17 has been driven is less than the first retightening threshold, the control unit 40 determines whether the movement speed of the piston 17 is equal to or greater than the second retightening threshold (step S32). If the movement speed of the piston 17 is equal to or greater than the second retightening threshold (step S32: YES), the control unit 40 proceeds to step S34.

[0078] If the movement speed of the piston 17 is not equal to or greater than the second retightening threshold (step S32: NO), that is, if the movement speed of the piston 17 is less than the second retightening threshold, the control unit 40 determines whether the distortion of the sealing material 141 or 142 is equal to or less than the third retightening threshold (step S33). If the distortion of the sealing material 141 or 142 is equal to or less than the third retightening threshold (step S33: YES), the control unit 40 proceeds to step S34. If the distortion of the sealing material 141 or 142 is not equal to or less than the third retightening threshold (step S33: NO), that is, if the distortion of the sealing material 141 or 142 is greater than the third retightening threshold, the control unit 40 determines that retightening of the nut 12 is not necessary and ends the execution of the steps in the flowchart of FIG. 8.

[0079] When the control unit 40 determines that the number of times the piston 17 is driven is equal to or greater than the first retightening threshold (step S31: YES), when the control unit 40 determines that the movement speed of the piston 17 is equal to or greater than the second retightening threshold (step S32: YES), or when the control unit 40 determines that the distortion of the sealing material 141 or 142 is equal to or less than the third retightening threshold (step S33: YES), the control unit 40 determines that retightening of the nut 12 is necessary and outputs a retightening alarm to prompt the user to retighten (step S34). After executing the procedure of step S34, the control unit 40 ends the execution of the procedure of the flowchart in FIG. 8.

[0080] The control unit 40 executes the procedure of the replacement determination flowchart illustrated in Fig. 9 as the procedure of step S4 of Fig. 7. The control unit 40 determines whether the number of times the piston 17 has been driven is equal to or greater than the first replacement threshold (step S41). If the number of times the piston 17 has been driven is equal to or greater than the first replacement threshold (step S41: YES), the control unit 40 proceeds to the procedure of step S44.

[0081] If the number of times that the piston 17 has been driven is not equal to or greater than the first replacement threshold (step S41: NO), that is, if the number of times that the piston 17 has been driven is less than the first replacement threshold, the control unit 40 determines whether the movement speed of the piston 17 is equal to or greater than the second replacement threshold (step S42). If the movement speed of the piston 17 is equal to or greater than the second replacement threshold (step S42: YES), the control unit 40 proceeds to the procedure of step S44.

[0082] If the movement speed of piston 17 is not equal to or greater than the second replacement threshold (step S42: NO), that is, if the movement speed of piston 17 is less than the second replacement threshold, control unit 40 determines whether the strain of sealing material 141 or 142 is equal to or less than the third replacement threshold (step S43). If the strain of sealing material 141 or 142 is equal to or less than the third replacement threshold (step S43: YES), control unit 40 proceeds to step S44. If the strain of sealing material 141 or 142 is not equal to or less than the third replacement threshold (step S43: NO), that is, if the strain of sealing material 141 or 142 is greater than the third replacement threshold, control unit 40 determines that replacement of sealing materials 141 and 142 is not necessary, and ends execution of the procedure of the flowchart in FIG. 8.

[0083] When the control unit 40 determines that the number of times the piston 17 has been driven is equal to or greater than the first replacement threshold (step S41: YES), when the control unit 40 determines that the movement speed of the piston 17 is equal to or greater than the second replacement threshold (step S42: YES), or when the control unit 40 determines that the distortion of the sealing material 141 or 142 is equal to or less than the third replacement threshold (step S43: YES), the control unit 40 determines that replacement of the sealing materials 141 and 142 is necessary and outputs a replacement alarm to prompt the user to perform replacement (step S44). After performing the procedure of step S44, the control unit 40 ends the execution of the procedure of the flowchart in FIG. 8.

[0084] (summary) As described above, according to the maintenance management method for the gas chromatograph 1 of this embodiment, the replacement of the seals 141 and 142 is managed based on the number of times the piston 17 of the liquid sampling valve 10 is driven. By managing the replacement of the seals 141 and 142 based on the number of times the piston 17 is driven, the likelihood that the seals 141 and 142 will be replaced when they are worn increases. In other words, the likelihood that the seals 141 and 142 will be replaced when they are not worn decreases. Reducing the need to replace the seals 141 and 142 when they are not worn reduces the cost of the parts or the replacement work, as well as opportunity loss due to the gas chromatograph 1 being shut down during the time spent on the replacement work.

[0085] Furthermore, as a maintenance task for the liquid sampling valve 10, before replacing the seals 141 and 142, the nut 12 may be retightened based on the number of times the piston 17 is driven. By retightening the nut 12 before replacing the seals 141 and 142, the cost of the parts or replacement work, as well as opportunity loss due to the gas chromatograph 1 being shut down during the time spent on the replacement work, can be reduced.

[0086] As maintenance work for the liquid sampling valve 10, the maintenance of the seals 141 and 142 is appropriately managed by replacing the seals 141 and 142 or tightening the nut 12 based on the number of times the piston 17 is driven.

[0087] Furthermore, by managing the maintenance of the seals 141 and 142 based on the number of times the piston 17 is driven, the user can know when to maintain the seals 141 and 142 and can systematically replace the seals 141 and 142 or retighten the nuts 12. As a result, the user can create a plan that incorporates maintenance work for the gas chromatograph 1 into analysis work using the gas chromatograph 1 and then carry out the work.

[0088] The gas chromatograph 1 and liquid sampling valve 10 according to this embodiment allow for appropriate management of maintenance timing or planned operation of the sealants 141 and 142. As a result, the cost of materials and work required for maintaining the sealants 141 and 142, or losses caused by a decrease in the availability rate of analytical work using the gas chromatograph 1, can be reduced.

[0089] Furthermore, the maintenance of the seals 141 and 142 may be managed based on the moving speed of the piston 17 or the strain of the seals 141 or 142. By managing the maintenance of the seals 141 and 142 based not only on the number of times the piston 17 is driven but also on other drive data of the liquid sampling valve 10, it is possible to determine the deterioration of the seals 141 or 142 that cannot be determined solely by the number of times the piston 17 is driven. As a result, the maintenance of the seals 141 or 142 can be appropriately managed.

[0090] (Other embodiments) Other embodiments of the gas chromatograph 1 and the liquid sampling valve 10 will now be described.

[0091] <Prediction of maintenance timing based on changes in drive data> In the liquid sampling valve 10, the seal material 141 or 142 wears as the number of times the piston 17 is driven increases. The more the seal material 141 or 142 wears, the faster the movement speed of the piston 17 becomes. Furthermore, the more the seal material 141 or 142 wears, the smaller the distortion of the seal material 141 or 142 becomes. In other words, there is a correlation between the number of times the piston 17 is driven and drive data such as the movement speed of the piston 17 or the distortion of the seal material 141 or 142.

[0092] For example, Figure 10 shows a graph representing the correlation between the number of times the piston 17 is driven and the movement speed of the piston 17. In the graph of Figure 10, the horizontal axis represents the number of times the piston 17 is driven, and the vertical axis represents the movement speed of the piston 17. Measurement data of the movement speed of the piston 17 obtained in an actual liquid sampling valve 10 is shown by solid circles. A tendency can be seen in which the movement speed of the piston 17 increases according to the number of times the piston 17 is driven.

[0093] The relationship between the number of times the piston 17 is driven and the movement speed of the piston 17 can be formulated, for example, by linear approximation. In the graph of FIG. 10, extrapolated data obtained by extrapolating the measurement data of the movement speed of the piston 17 using linear approximation is shown by a dashed line. The extrapolated data of the movement speed of the piston 17 extends the relationship between the number of times the piston 17 is driven and the movement speed of the piston 17 to a range of times the piston 17 has not actually been driven yet, and is used as data for predicting the movement speed of the piston 17 when it is assumed that the number of times the piston 17 is driven has increased. By generating the extrapolated data based on the measurement data of the movement speed of the piston 17, the control unit 40 of the gas chromatograph 1 can predict the movement speed of the piston 17 when it is assumed that the number of times the piston 17 has been driven has reached a number that has not actually been driven yet.

[0094] The control unit 40 can predict the number of times the piston 17 is driven when the predicted value of the movement speed of the piston 17 becomes equal to or greater than the second retightening threshold or the second replacement threshold in the extrapolated data of the movement speed of the piston 17 as the maintenance time when maintenance such as retightening of the nut 12 or replacement of the seals 141 and 142 will be required. In the graph of FIG. 10, the threshold value of the movement speed of the piston 17 is represented by a dashed line extending horizontally. The maintenance time is represented by a dashed line extending vertically. When the piston 17 is driven at a constant cycle, the control unit 40 can calculate the date and time when the maintenance time will arrive by calculating the product of the number of times until the number of drives corresponding to the maintenance time is reached and the drive cycle of the piston 17.

[0095] The number of times the piston 17 is driven also correlates with the strain of the sealing material 141 or 142. The control unit 40 may generate extrapolated data by approximating the measurement data of the strain of the sealing material 141 or 142 relative to the number of times the piston 17 is driven. The extrapolated data of the strain of the sealing material 141 or 142 extends the relationship between the number of times the piston 17 is driven and the strain of the sealing material 141 or 142 to a range of times the piston 17 has not actually been driven yet, and is used as data for predicting the strain of the sealing material 141 or 142 when it is assumed that the number of times the piston 17 is driven has increased. By generating the extrapolated data based on the measurement data of the strain of the sealing material 141 or 142, the control unit 40 can predict the strain of the sealing material 141 or 142 when it is assumed that the number of times the piston 17 has been driven has reached a number that has not actually been driven yet.

[0096] The control unit 40 can predict the number of times the piston 17 is driven when the predicted value of the strain of the sealing material 141 or 142 in the extrapolated data of the strain of the sealing material 141 or 142 becomes equal to or less than the third retightening threshold or the third replacement threshold, as the time for maintenance such as retightening the nut 12 or replacing the sealing materials 141 and 142.

[0097] The control unit 40 is not limited to linear approximation, and may perform various other approximations such as polynomial approximation to generate extrapolated data of the drive data.

[0098] As described above, the control unit 40 can predict the maintenance timing based on the predicted drive data. The predicted maintenance timing is also referred to as the predicted maintenance timing. The user can determine when to replace the seals 141 and 142 based on the predicted maintenance timing, and can replace the seals 141 and 142 in a planned manner. The user can also plan the retightening of the nut 12 based on the predicted maintenance timing. As a result, the user can create a plan that incorporates maintenance work for the liquid sampling valve 10 into analysis work using the gas chromatograph 1 and perform the work. The operation of predicting the maintenance timing is also referred to as a maintenance timing prediction step. The operation of predicting the replacement timing of the seals 141 and 142 is also referred to as a replacement timing prediction step. The operation of predicting when to retighten the nut 12 is also referred to as a retightening timing prediction step.

[0099] <Another Way of Calculating the Moving Speed ​​of the Piston 17> In the embodiment described above, the moving speed of piston 17 is calculated based on the acceleration measurement result by acceleration sensor 171 attached to piston 17. Hereinafter, other modes for calculating the moving speed of piston 17 will be described.

[0100] 11, the acceleration sensor 171 may be attached to the cylinder 18 instead of the piston 17. The control unit 40 of the gas chromatograph 1 may be communicatively connected to the acceleration sensor 171 via a cable 172. The control unit 40 may also be communicatively connected to the acceleration sensor 171 wirelessly.

[0101] When the piston 17 moves in a direction pushing the stem 15 from the sampling chamber 152 toward the vaporization chamber 161, the piston 17 moves until it hits the wall of the cylinder 18 on the side closer to the sampling chamber 152. Conversely, when the piston 17 moves in a direction pulling the stem 15 from the vaporization chamber 161 toward the sampling chamber 152, the piston 17 moves until it hits the wall of the cylinder 18 on the side farther from the sampling chamber 152. An acceleration sensor 171 attached to the cylinder 18 detects the acceleration occurring in the cylinder 18 when the piston 17 hits the wall of the cylinder 18.

[0102] The control unit 40 of the gas chromatograph 1 acquires the time at which the acceleration sensor 171 detects acceleration as the time at which the piston 17 hits the wall of the cylinder 18. The control unit 40 calculates the time from when driving air is supplied to the driving air supply unit 181 or 182 to start driving the piston 17 to when the piston 17 hits the wall of the cylinder 18 as the movement time of the piston 17. The control unit 40 acquires the distance that the piston 17 moves within the cylinder 18 as known information, and can calculate the movement speed of the piston 17 by dividing the movement distance of the piston 17 by the movement time.

[0103] Since the moving speed of the piston 17 can be calculated simply by attaching the acceleration sensor 171 to the cylinder 18, the configuration required to calculate the moving speed of the piston 17 can be easily added to an existing liquid sampling valve 10.

[0104] 12 , a proximity sensor 173 or 175 may be attached to the cylinder 18. The proximity sensor 175 is attached to a wall of the cylinder 18 closer to the sampling chamber 152. The proximity sensor 173 is attached to a wall of the cylinder 18 farther from the sampling chamber 152. The control unit 40 of the gas chromatograph 1 may be communicatively connected to the proximity sensor 173 via a cable 174. The control unit 40 may be communicatively connected to the proximity sensor 175 via a cable 176. The control unit 40 may be communicatively connected to the proximity sensor 173 or 175 wirelessly.

[0105] When the piston 17 moves in a direction that pushes the stem 15 from the sampling chamber 152 toward the vaporization chamber 161, the piston 17 moves until it hits the wall of the cylinder 18 that is closer to the sampling chamber 152. The proximity sensor 175 detects that the piston 17 has hit the wall of the cylinder 18 that is closer to the sampling chamber 152. Conversely, when the piston 17 moves in a direction that pulls the stem 15 from the vaporization chamber 161 toward the sampling chamber 152, the piston 17 moves until it hits the wall of the cylinder 18 that is farther from the sampling chamber 152. The proximity sensor 175 detects that the piston 17 has hit the wall of the cylinder 18 that is farther from the sampling chamber 152.

[0106] The control unit 40 of the gas chromatograph 1 acquires the time when the proximity sensor 173 or 175 detects that the piston 17 has struck the wall of the cylinder 18 as the time when the piston 17 strikes the wall of the cylinder 18. The control unit 40 calculates the time from when driving air is supplied to the driving air supply unit 181 or 182 to start driving the piston 17 to when the piston 17 strikes the wall of the cylinder 18 as the movement time of the piston 17. The control unit 40 acquires the distance that the piston 17 moves within the cylinder 18 as known information, and can calculate the movement speed of the piston 17 by dividing the movement distance of the piston 17 by the movement time.

[0107] The movement speed of the piston 17 can be calculated using the proximity sensor 173 or 175, so that the movement speed of the piston 17 can be calculated with a simple or inexpensive configuration.

[0108] <Determination taking into account driving air pressure fluctuations> The control unit 40 of the gas chromatograph 1 can determine the need for replacement of the seal material 141 or 142 by comparing the movement speed of the piston 17 with the second replacement threshold, assuming that the pressure of the driving air supplied from the driving air supply unit 181 or 182 into the cylinder 18 to drive the piston 17 is constant. If the pressure of the driving air fluctuates, the control unit 40 may change the second replacement threshold in accordance with the pressure of the driving air. For example, the movement speed of the piston 17 increases as the driving air pressure increases. Therefore, the second replacement threshold may be increased as the driving air pressure increases. Furthermore, the third replacement threshold, which is compared with the distortion of the seal material 141 or 142, may be increased as the driving air pressure increases.

[0109] The control unit 40 may change the second retightening threshold value used to determine the need for retightening of the nut 12 in accordance with the pressure of the driving air. For example, the higher the pressure of the driving air, the larger the second retightening threshold value may be. Also, the higher the pressure of the driving air, the larger the third retightening threshold value may be.

[0110] The control unit 40 may correct the drive data according to the pressure of the driving air. For example, when the pressure of the driving air is higher than the reference pressure, the control unit 40 may calculate a corrected value for the movement speed of the piston 17 when the pressure of the driving air is the reference pressure based on the measured value of the movement speed of the piston 17 and the pressure of the driving air, and compare the corrected value with the second replacement threshold or the second retightening threshold. Furthermore, when the pressure of the driving air is higher than the reference pressure, the control unit 40 may calculate a corrected value for the distortion of the seal material 141 or 142 when the pressure of the driving air is the reference pressure based on the measured value of the distortion of the seal material 141 or 142 and the pressure of the driving air, and compare the corrected value with the third replacement threshold or the third retightening threshold.

[0111] As described above, the control unit 40 can change the determination criteria depending on the pressure of the driving air. By taking the pressure of the driving air into consideration, the accuracy of determining the need for maintenance is improved.

[0112] <Other aspects regarding the entity that manages conservation> As described above, the maintenance management method for determining whether to output an alarm regarding maintenance of the liquid sampling valve 10 has been described as being executed by the control unit 40 of the gas chromatograph 1. The liquid sampling valve 10 may also be equipped with a processor that executes the maintenance management method for the liquid sampling valve 10. In other words, the maintenance management method or maintenance management program described above may be executed not only by the control unit 40 of the gas chromatograph 1, but also by the processor of the liquid sampling valve 10.

[0113] The gas chromatograph 1 may include a maintenance management device that executes the maintenance management method for the liquid sampling valve 10, and that has a configuration separate from the control unit 40 and the processor of the liquid sampling valve 10. When the control unit 40 of the gas chromatograph 1 or the processor of the liquid sampling valve 10 has the function of executing the maintenance management method, it is also referred to as a maintenance management device.

[0114] The above describes an embodiment of the present disclosure with reference to the drawings, but the specific configuration is not limited to this embodiment, and various modifications are also included within the scope that does not deviate from the spirit of the present disclosure. [Explanation of symbols]

[0115] 1 Gas chromatograph (20: column, 30: detector, 40: controller) 10 Liquid sampling valve 11 Block (111: heater, 112: temperature sensor, 113: carrier gas passage, 114, 115: inner wall) 12 nuts 131, 132 Piping 133 Liquid Sample Block 141, 142 sealing material (141a, 142a: inner wall) 143 Strain Sensor 144 Cable 15 Stem (151: sampling groove, 153: liquid sample) 152 Sampling Room 16 Piping 161 Vaporization chamber 17 Piston 171 Acceleration Sensor 173, 175 Proximity sensors 172, 174, 176 Cables 18 Cylinder (181, 182: drive air supply section)

Claims

1. a housing having a sampling chamber for flowing a liquid sample and a vaporization chamber for vaporizing the liquid sample; a sealant that separates the sampling chamber from the vaporization chamber; a stem configured to be able to penetrate a hole in the sealing material and be inserted into and removed from the vaporization chamber; a piston that drives the stem; A maintenance management method for a liquid sampling valve, comprising: a driving count acquisition step of acquiring the number of times the piston is driven after the sealing material is newly attached; a replacement determination step of determining that the sealing material needs to be replaced when the number of times the piston is driven becomes equal to or greater than a first replacement threshold value, regardless of the time elapsed since the sealing material was newly attached; A conservation management method, including:

2. further comprising a drive data acquisition step of acquiring at least one of a moving speed of the piston or a strain of the sealing material; 2. The maintenance management method described in claim 1, wherein in the replacement determination step, it is determined that there is a need to replace the sealing material in at least one of the following cases: when the piston movement speed becomes equal to or greater than a second replacement threshold, or when the distortion of the sealing material becomes equal to or less than a third replacement threshold.

3. 3. The maintenance management method of claim 2, further comprising a replacement timing prediction step of generating extrapolation data that predicts the relationship between the number of times the piston is driven and the movement speed of the piston or the distortion of the sealing material, and calculating at least one of the number of times the piston is driven when the movement speed of the piston in the extrapolation data becomes equal to or greater than the second replacement threshold, or the number of times the piston is driven when the distortion of the sealing material in the extrapolation data becomes equal to or less than a third replacement threshold, as the predicted maintenance time when the sealing material needs to be replaced.

4. A maintenance management method as described in any one of claims 1 to 3, further comprising a retightening determination step, before the replacement determination step, of determining that it is necessary to retighten a nut that applies load to the sealing material when the number of times the piston is driven becomes equal to or greater than a first retightening threshold, regardless of the time that has elapsed since the sealing material was newly installed.

5. 5. The maintenance management method according to claim 4, wherein in the replacement determination step, a determination is made as to whether or not the sealing material needs to be replaced if the nut has been retightened a predetermined number of times or more.

6. A maintenance management device comprising a processor that executes the maintenance management method according to any one of claims 1 to 3.

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