Four-way automatic sampling and filtering membrane support device and VOCs (volatile organic compounds) online monitoring equipment

Abstract

The embodiment of the utility model discloses a four-way automatic sampling and filtering membrane support device and VOCs (Volatile Organic Compounds) online monitoring equipment, and relates to the technical field of environment monitoring. The four-way automatic sampling filter membrane support device comprises a box body, and an air inlet joint of a filter membrane support penetrates through the side wall of the box body and enters the box body; a vertical partition plate is arranged on the side, away from the filter membrane support, in the box body, so that the box body is divided into a first containing cavity and a second containing cavity, a five-way connector and a six-way valve are arranged in the first containing cavity, and an air inlet and an air outlet are formed in the upper portion of the first containing cavity; the air inlet is connected with an interface at one end of a five-way joint, the other four interfaces of the five-way joint are respectively connected with an air inlet joint of a filter membrane support, an air outlet joint of the filter membrane support penetrates through the side wall of the box body through a pipeline and then is sequentially connected with S1-S4 positions of a six-way valve, and a common end of the six-way valve is connected with the air outlet; and a control panel is arranged in the second accommodating cavity. According to the utility model, long-time continuous work under unattended operation can be realized.

Description

Technical Field

[0001] This utility model relates to the field of environmental monitoring technology, and in particular to a four-channel automatic sampling filter membrane holder and an online VOCs monitoring device. Background Technology

[0002] VOCs (Volatile Organic Compounds) refer to organic compounds with a saturated vapor pressure greater than 70 Pa at room temperature and a boiling point below 260℃ at normal pressure, or all organic compounds with a vapor pressure greater than or equal to 10 Pa at 20℃ that are volatile. VOCs participate in the formation of ozone and secondary aerosols in the atmosphere, and have a significant impact on regional atmospheric ozone pollution and PM2.5 pollution. VOCs are important precursors to urban haze and photochemical smog, mainly originating from processes such as coal chemical industry, petrochemical industry, fuel and coating manufacturing, and solvent manufacturing and use.

[0003] VOCs have a significant impact on environmental safety and harm human health, therefore, it is necessary to detect and treat VOCs generated in industrial activities and daily life. Existing online VOCs monitoring equipment can collect and analyze gases, outputting VOCs analysis results to provide a reference for the formulation of pollution control strategies.

[0004] VOCs online monitoring equipment typically uses a filter membrane to filter and collect the gas. The better the sealing of the sampling device, the more accurate the sampling results. Currently available VOCs online monitoring equipment uses a standard filter membrane holder installed in the middle of the sampling pipeline. This makes it impossible to operate continuously for extended periods (e.g., a month) without human intervention, and is inconvenient to use. Utility Model Content

[0005] In view of this, the present invention provides a four-channel automatic sampling filter membrane holder device and a VOCs online monitoring device that can achieve unattended operation for a long time.

[0006] On the one hand, this utility model provides a four-way automatic sampling filter membrane holder device, including a box body. Four membrane holder mounting holes are provided on one side outer wall of the box body. Filter membrane holders are inserted and fixed in each of the membrane holder mounting holes. The air inlet connector of the filter membrane holder passes through the side wall of the box body and enters the interior of the box body.

[0007] A vertical partition is provided on the side of the box away from the filter membrane holder, thereby dividing the box into a first receiving cavity close to the filter membrane holder and a second receiving cavity away from the filter membrane holder. The first receiving cavity is provided with a five-way connector and a six-way valve, and an air inlet and an air outlet are provided above the first receiving cavity.

[0008] The air inlet is connected to one end of the five-way connector, and the other four ends of the five-way connector are respectively connected to the air inlet of the filter membrane holder. The air outlet of the filter membrane holder is connected to the S1-S4 positions of the six-way valve in sequence after passing through the side wall of the box via pipelines. The common end of the six-way valve is connected to the air outlet.

[0009] The second accommodating cavity is equipped with a control board for controlling the operation of the six-way valve.

[0010] Furthermore, the front of the housing and the side away from the filter membrane holder are both provided with removable covers;

[0011] And / or, the housing is provided with a power interface and a data interface on the side where the filter membrane holder is installed;

[0012] And / or, the rear side wall of the box is provided with a fixing hook.

[0013] Furthermore, the filter membrane holder includes a membrane holder block and a membrane pressing block arranged opposite each other, and a membrane tray for supporting the filter membrane is provided between the membrane holder block and the membrane pressing block, wherein:

[0014] The membrane tray is cylindrical, and the bottom of the membrane tray has a porous structure. The membrane tray contains a membrane pressure ring that forms a closed loop after installation. The inner sidewall of the membrane tray has a limiting protrusion, and the lower surface of the limiting protrusion is an inclined surface that can squeeze and fix the membrane pressure ring to fix the filter membrane.

[0015] A first cavity is formed between the membrane support block and the membrane tray, and a second cavity is formed between the membrane tray and the membrane pressing block. Sealing devices are provided on the contact surfaces of the membrane support block and the membrane tray, as well as on the contact surfaces of the membrane tray and the membrane pressing block. An air inlet connector is provided on the membrane support block, and an air outlet connector is provided on the membrane pressing block.

[0016] The outer sides of the membrane support block and the membrane pressing block are provided with locking devices for squeezing and locking their relative positions.

[0017] Furthermore, the membrane pressure ring is a C-shaped membrane pressure ring with an opening;

[0018] Alternatively, the membrane pressure ring may be two semi-circular membrane pressure rings.

[0019] Furthermore, the membrane pressure ring is provided with radial through holes;

[0020] And / or, the membrane support block and the membrane pressing block are both provided with sealing ring receiving grooves on the contact surface with the membrane tray, and the sealing device is a silicone sealing ring disposed in the sealing ring receiving groove.

[0021] Furthermore, the membrane pressing block has a receiving groove at one end near the membrane support block, the outer diameter of the membrane tray is less than or equal to the inner diameter of the receiving groove, and the membrane support block has an insertion part that mates with the receiving groove at one end near the membrane pressing block.

[0022] Furthermore, the locking device is a membrane support lock nut sleeved on the membrane pressing block. The membrane support lock nut includes an annular body and a blocking part that extends inward from the lower end of the annular body and cooperates with the outer end face of the membrane pressing block. The inner side of the upper end of the annular body is provided with an internal thread, and the membrane support block is provided with an external thread that cooperates with the internal thread on the outer side of the upper part of the insertion part.

[0023] Furthermore, the outer end face of the membrane support block is provided with a threaded hole, and a through hole is provided on the side wall of the box body at a position corresponding to the threaded hole. Screws are inserted into the through hole and the threaded hole to fix the filter membrane support.

[0024] Furthermore, the inner side of the end of the air inlet and air outlet is provided with an inverted flared opening, and a retaining sleeve is provided inside the inverted flared opening. The outer side of the air inlet and air outlet is threaded with a nut that can push the retaining sleeve to move.

[0025] And / or, both the first cavity and the second cavity are frustoconical, with the lower surfaces of the two frustocones facing each other.

[0026] On the other hand, this utility model provides an online VOCs monitoring device, including the above-mentioned four-channel automatic sampling filter membrane holder device.

[0027] This utility model discloses a four-channel automatic sampling filter membrane holder device and a VOCs online monitoring device. The four-channel automatic sampling filter membrane holder device has a vertical partition on the side of the housing away from the filter membrane holder, thus dividing the housing into a first receiving chamber closer to the filter membrane holder and a second receiving chamber further away from the filter membrane holder. This isolation design improves the safety of the two receiving chambers. The air inlet connector of the filter membrane holder passes through the side wall of the housing and enters the housing. The filter membrane holder is installed on the outside of the housing, facilitating direct replacement of the filter membrane without opening the housing, making it convenient to use. The air inlet connects to one end of a five-way connector, and the other four ports of the five-way connector are respectively connected to the air inlet connectors of the filter membrane holder. The air outlet connectors of the filter membrane holder pass through the side wall of the housing via pipelines and are sequentially connected to positions S1-S4 of a six-way valve. The common end of the six-way valve is connected to the air outlet. With the help of the six-way valve and the five-way connector, the filter membrane holders can be automatically switched and used sequentially according to user settings, enabling unattended continuous operation for extended periods and extending the maintenance cycle. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the overall structure of the four-channel automatic sampling filter membrane holder device of this utility model;

[0030] Figure 2 for Figure 1 Side view;

[0031] Figure 3 for Figure 2 Sectional view along axis AA;

[0032] Figure 4 This is a schematic diagram of the air path of the four-channel automatic sampling filter membrane holder device of this utility model;

[0033] Figure 5 for Figure 1 A schematic diagram of the overall structure of the filter membrane holder;

[0034] Figure 6 for Figure 5 A schematic diagram of the cross-sectional structure;

[0035] Figure 7 for Figure 5 A schematic diagram of the structure of the middle membrane block, wherein (a) is a cross-sectional view and (b) is a bottom view;

[0036] Figure 8 for Figure 5 A schematic diagram of the structure of the medium-film tray, wherein (a) is a cross-sectional view and (b) is a top view;

[0037] Figure 9 for Figure 5 A schematic diagram of the structure of the middle membrane support block, wherein (a) is a cross-sectional view and (b) is a top view;

[0038] Figure 10 for Figure 5 A schematic diagram of the structure of the middle membrane pressure ring, wherein (a) is a cross-sectional view and (b) is a top view;

[0039] Figure 11 for Figure 5 A schematic diagram of the structure of the middle membrane locking nut, wherein (a) is a cross-sectional view and (b) is a bottom view;

[0040] Figure 12 for Figure 5A schematic diagram of the structure of the nut, wherein (a) is a front view and (b) is a cross-sectional view along the AA direction;

[0041] Figure 13 This is a schematic diagram of the software function interface of the four-channel automatic sampling filter membrane holder device of this utility model. Detailed Implementation

[0042] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0043] It should be understood that the described embodiments are merely some embodiments of this utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model.

[0044] On the one hand, this utility model embodiment provides a four-channel automatic sampling filter membrane holder device, such as... Figures 1-4 As shown, the device includes a housing 101. Four membrane support mounting holes (not shown) are provided on one side outer wall of the housing 101. A filter membrane support 102 is inserted and fixed in each of the membrane support mounting holes. The air inlet connector 32 of the filter membrane support 102 passes through the side wall of the housing 101 and enters the interior of the housing 101.

[0045] A vertical partition 1011 is provided on the side of the housing 101 away from the filter membrane holder 102, thereby dividing the housing 101 into a first receiving cavity 1012 close to the filter membrane holder 102 and a second receiving cavity 1013 away from the filter membrane holder 102. The first receiving cavity 1012 is provided with a five-way (pipe) connector 103 and a six-way valve 104. An air inlet 105 and an air outlet 106 are provided above the first receiving cavity 1012.

[0046] Air inlet 105 is connected to one end of five-way connector 103. The other four ports of five-way connector 103 are connected to air inlet connector 32 of filter membrane holder 102. Air outlet connector 12 of filter membrane holder 102 is connected to the S1-S4 positions of six-way valve 104 in sequence after passing through the side wall of housing 101 via pipeline 107. The common end of six-way valve 104 is connected to air outlet 106.

[0047] The second receiving cavity 1013 is equipped with a control board 108 for controlling the operation of the six-way valve 104.

[0048] This utility model discloses a four-channel automatic sampling filter membrane holder device. A vertical partition is installed on the side of the housing away from the filter membrane holder, dividing the housing into a first receiving cavity near the filter membrane holder and a second receiving cavity away from the filter membrane holder. This isolation design improves the safety of the two receiving cavities. The air inlet connector of the filter membrane holder passes through the side wall of the housing and enters the housing. The filter membrane holder is installed on the outside of the housing, facilitating direct replacement of the filter membrane without opening the housing, making it convenient to use. The air inlet connects to one end of a five-way connector, and the other four ports of the five-way connector are respectively connected to the air inlet connectors of the filter membrane holder. The air outlet connectors of the filter membrane holder pass through the side wall of the housing via pipelines and are sequentially connected to positions S1-S4 of a six-way valve. The common end of the six-way valve is connected to the air outlet. With the help of the six-way valve and the five-way connector, the filter membrane holders can be automatically switched and used sequentially according to user settings, enabling unattended continuous operation for extended periods and extending the maintenance cycle.

[0049] To facilitate component installation, the front of the housing 101 and the side away from the filter membrane holder 102 may both be equipped with removable covers 1014. A power interface 109 and a data interface 1010 may be provided on the side of the housing 101 where the filter membrane holder 102 is installed. Thus, the power interface 109 provides power, and the data interface 1010 facilitates data communication. A fixing hook 1015 may be provided on the rear side wall of the housing 101 for easy securing of the entire device.

[0050] In existing technologies, conventional membrane holders also exhibit poor sealing performance, with occasional minor air leakage. This is primarily due to the lack of a sealing ring, or the sealing ring being in direct contact with the filter membrane. Furthermore, since the filter membrane itself is permeable, a complete seal cannot be achieved. To address this issue, such as... Figures 5-12 As shown, preferably, the filter membrane holder includes a membrane holder block 3 and a membrane pressing block 1 arranged opposite to each other, and a membrane tray 2 for supporting the filter membrane 9 is provided between the membrane holder block 3 and the membrane pressing block 1, wherein:

[0051] The membrane tray 2 is cylindrical, and the bottom of the membrane tray 2 has a porous structure. The membrane tray 2 is provided with a membrane pressure ring 7 that forms a closed ring after installation. The inner side wall of the membrane tray 2 is provided with a limiting protrusion 21. The lower surface of the limiting protrusion 21 is an inclined surface 211 that can squeeze and fix the membrane pressure ring 7 to fix the filter membrane 9.

[0052] A first cavity 31 is formed between the membrane support block 3 and the membrane tray 2, and a second cavity 11 is formed between the membrane tray 2 and the membrane pressing block 1. Sealing devices are provided on the contact surfaces of the membrane support block 3 and the membrane tray 2, as well as on the contact surfaces of the membrane tray 2 and the membrane pressing block 1. An air inlet connector 32 is provided on the membrane support block 3, and an air outlet connector 12 is provided on the membrane pressing block 1.

[0053] The outer sides of the membrane support block 3 and the membrane pressure block 1 are provided with locking devices for squeezing and locking their relative positions.

[0054] In use, first install the filter membrane 9 in the membrane tray 2 and fix the filter membrane 9 with the membrane pressure ring 7. At this time, the membrane pressure ring 7 is pressed and fixed by the inclined surface 211 of the limiting protrusion 21 on the inner side wall of the membrane tray 2. Then, place the membrane tray 2 between the membrane support block 3 and the membrane pressure block 1 that are arranged opposite to each other. Then, use the sealing device to seal the contact surface between the membrane support block 3 and the membrane tray 2 and the contact surface between the membrane tray 2 and the membrane pressure block 1. Use the locking device to press and lock the membrane support block 3 and the membrane pressure block 1 on the outside. Finally, install the filter membrane support (sealed sampling membrane support) into the sampling device of the VOCs online monitoring equipment for use.

[0055] Thus, the filter membrane holder includes a membrane holder block and a membrane pressing block arranged opposite each other. Between the membrane holder block and the membrane pressing block is a membrane tray for supporting the filter membrane. The membrane tray is cylindrical, and inside the membrane tray is a membrane pressing ring that forms a closed loop after installation. The inner side wall of the membrane tray has a limiting protrusion. The lower surface of the limiting protrusion is an inclined surface that can compress and fix the membrane pressing ring to fix the filter membrane. The inclined surface can lock and press the membrane pressing ring, which in turn can press the filter membrane firmly. The bottom of the membrane tray has a porous structure, so that when the sampling gas flows through the membrane tray, the sampling gas can pass smoothly through the middle, resulting in good sampling effect. Sealing devices are provided on the contact surfaces between the membrane holder block and the membrane tray, as well as on the contact surfaces between the membrane tray and the membrane pressing block. The filter membrane placement position is isolated by a separate component, and then the isolated component is sealed. In this way, even when used in low-flow VOCs monitoring equipment, it can still have strong sealing performance and accurate sampling values.

[0056] like Figure 10 As shown, the membrane pressure ring 7 can be any structural form readily conceived by those skilled in the art. To facilitate insertion and removal of the membrane pressure ring 7 from the membrane tray 2, the membrane pressure ring 7 can be a C-shaped membrane pressure ring with an opening. The C-shaped structure can generate large elastic deformation when squeezed by the inclined surface 211 of the restricted position protrusion 21, tightly adhering to the filter membrane, achieving a reliable seal, reducing the risk of leakage, and thus making the sampling values ​​more accurate.

[0057] Alternatively, the membrane pressure ring 7 can be two semi-circular membrane pressure rings. Two semi-circular membrane pressure rings are more flexible in installation and removal, and they apply more uniform pressure to the membrane. This uniform pressure can ensure the stability of the filter membrane during use, thereby making the sampling values ​​more accurate.

[0058] To facilitate the disassembly of the membrane pressure ring 7, a radial through hole 71 may be provided on the membrane pressure ring 7, so that the membrane pressure ring 7 can be disassembled (hooked out) with a tool (such as an iron hook).

[0059] like Figure 6 , Figure 7 and Figure 9As shown, both the membrane support block 3 and the membrane pressure block 1 have sealing ring receiving grooves 60 on their contact surfaces with the membrane tray 2, and the sealing device is a silicone sealing ring 6 installed in the sealing ring receiving groove 60. In this way, the two silicone sealing rings 6 seal the contact surfaces of the membrane tray 2 with the membrane support block 3 and the membrane pressure block 1, avoiding the influence of gap leakage, further enhancing the sealing performance, and improving the accuracy of the sampling values.

[0060] like Figures 7-9 As shown, the membrane pressing block 1 may have a receiving groove 13 at one end near the membrane support block 3. The outer diameter of the membrane tray 2 is less than or equal to the inner diameter of the receiving groove 13. The membrane support block 3 has an insertion part 33 that mates with the receiving groove 13 at one end near the membrane pressing block 1. In use, the membrane tray 2 is placed into the receiving groove 13, and then the insertion part 33 is inserted into the receiving groove 13. This not only makes the assembly of the membrane pressing block 1, membrane tray 2 and membrane support block 3 more convenient, but also enhances the sealing effect on the membrane tray 2.

[0061] like Figure 6 and Figure 11 As shown, the locking device can be a membrane holder locking nut 8 sleeved on the membrane pressing block 1. The membrane holder locking nut 8 includes an annular body 81 and a blocking part 82 extending inward from the lower end of the annular body 81 and cooperating with the outer end face of the membrane pressing block 1. The inner side of the upper end of the annular body 81 is provided with an internal thread, and the membrane holder 3 is provided with an external thread on the outer side of the upper part of the insertion part 33 that cooperates with the internal thread. In this way, the membrane holder locking nut 8 can pass through the membrane pressing block 1 and engage with the membrane holder 3 through the thread, that is, it can squeeze and lock the membrane pressing block 1 and the membrane holder 3; and after removing the membrane holder locking nut 8, the filter membrane 9 can be directly replaced, which is more convenient to replace the filter membrane 9 in the filter membrane holder 102 without opening the box, making it convenient to use.

[0062] like Figure 9 As shown, in order to firmly fix the filter membrane holder 102, the outer end face of the membrane holder block 3 may be provided with a threaded hole 34, and a through hole (not shown) is provided on the side wall of the housing 101 at a position corresponding to the threaded hole 34. Screws (not shown) are inserted into the through hole and the threaded hole 34 to fix the filter membrane holder 102.

[0063] like Figure 6 and Figure 12 As shown, the inner sides of the ends of the air inlet connector 32 and the air outlet connector 12 can be provided with a flared opening 321. A retaining sleeve 5 (specifically, a 1 / 4 PTFE retaining sleeve) is provided inside the flared opening 321. A nut 4 (specifically an M12 nut) is threadedly connected to the outer sides of the air inlet connector 32 and the air outlet connector 12, capable of moving the retaining sleeve 5. In this way, the retaining sleeve 5 and the nut 4 cooperate to reduce gas leakage at the air inlet connector 32 and the air outlet connector 12, thereby improving the accuracy of the sampling results.

[0064] like Figure 6As shown, both the first cavity 31 and the second cavity 11 can be frustoconical, with the lower surfaces of the two frustocones facing each other. This ensures a smooth and stable airflow, reduces the possibility of leakage, and improves sampling accuracy.

[0065] In summary, the four-channel automatic sampling filter membrane holder device of this utility model is used for air sampling filtration in the automatic sampling filtration device of VOCs online monitoring equipment. The device includes four particulate filter membrane holders (i.e., filter membrane holders), which can automatically switch and be used sequentially according to user settings, thereby extending the operation and maintenance cycle. Each filter membrane holder can guarantee a working cycle of 7 to 14 days. The VOCs sampling intelligent monitoring system using this device can achieve at least one continuous sampling / working cycle under unattended conditions.

[0066] The specific working principle is as follows: Figure 4 As shown, when using the device, connect the air inlet to the sampling manifold and the air outlet to the instrument. Connect the power supply and the data cable to the industrial control computer and software. Leak testing is required after the entire device is installed and before membrane replacement to ensure there are no leaks. Device maintenance should be performed when the instrument is not running. Open the filter membrane holder, replace the filter membrane, reinstall it, and after the leak test is normal, reset the software and run it.

[0067] In this utility model's four-channel automatic sampling filter membrane holder device, the control board 8 can be customized with software functions according to user needs, such as... Figure 13 As shown, the specific software functions in this embodiment can be as follows:

[0068] When using it for the first time, set all parameters according to the instrument's current status and conditions, then click Save and then Start to run it.

[0069] After maintenance, only the current channel parameters need to be changed. Click "Save" and then "Start" to run the software. Other parameters will adjust automatically without manual modification.

[0070] The automated operation and maintenance software features include current channel, replacement hour / minute, valid days, cycle days, remaining quantity, automatic replacement time, and next operation and maintenance time;

[0071] Current Channel: The membrane replacement software is currently using the current channel.

[0072] Change hour / minute: Set the channel switching time;

[0073] Valid Days: Displays the remaining usage time of the current channel;

[0074] Cycle Days: Displays the switching cycle of each channel;

[0075] Remaining quantity: Displays the number of unused channels;

[0076] Automatic switching time: time of the next channel switch;

[0077] Next maintenance time: Maintenance time required after all channels are in use.

[0078] On the other hand, this utility model provides an online VOCs monitoring device, including the aforementioned four-channel automatic sampling filter membrane holder. The structure of the four-channel automatic sampling filter membrane holder is the same as described above, and will not be repeated here.

[0079] This utility model discloses an online VOCs monitoring device, comprising a four-channel automatic sampling filter membrane holder. A vertical partition is located on the side of the housing away from the filter membrane holder, dividing the housing into a first receiving chamber near the filter membrane holder and a second receiving chamber away from the filter membrane holder. This isolation design improves the safety of the two receiving chambers. The air inlet connector of the filter membrane holder passes through the side wall of the housing and enters the interior of the housing. The filter membrane holder is installed on the outside of the housing, facilitating direct replacement of the filter membrane without opening the housing, making it convenient to use. The air inlet connects to one end of a five-way connector, and the other four ports of the five-way connector are respectively connected to the air inlet connectors of the filter membrane holders. The air outlet connectors of the filter membrane holders pass through the side wall of the housing via pipelines and are sequentially connected to positions S1-S4 of a six-way valve. The common end of the six-way valve is connected to the air outlet. With the help of the six-way valve and the five-way connector, the filter membrane holders can be automatically switched and used sequentially according to user settings, enabling unattended continuous operation for extended periods and extending the maintenance cycle.

[0080] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A four-channel automatic sampling filter membrane holder device, characterized in that, The device includes a housing, on one side of which four membrane support mounting holes are provided. A filter membrane support is inserted and fixed in each of the membrane support mounting holes. The air inlet connector of the filter membrane support passes through the side wall of the housing and enters the interior of the housing. A vertical partition is provided on the side of the box away from the filter membrane holder, thereby dividing the box into a first receiving cavity close to the filter membrane holder and a second receiving cavity away from the filter membrane holder. The first receiving cavity is provided with a five-way connector and a six-way valve, and an air inlet and an air outlet are provided above the first receiving cavity. The air inlet is connected to one end of the five-way connector, and the other four ends of the five-way connector are respectively connected to the air inlet of the filter membrane holder. The air outlet of the filter membrane holder is connected to the S1-S4 positions of the six-way valve in sequence after passing through the side wall of the box via pipelines. The common end of the six-way valve is connected to the air outlet. The second accommodating cavity is equipped with a control board for controlling the operation of the six-way valve.

2. The four-channel automatic sampling filter membrane holder device according to claim 1, characterized in that, The front of the housing and the side away from the filter membrane holder are both provided with removable covers; And / or, the housing is provided with a power interface and a data interface on the side where the filter membrane holder is installed; And / or, the rear side wall of the box is provided with a fixing hook.

3. The four-channel automatic sampling filter membrane holder device according to claim 1 or 2, characterized in that, The filter membrane holder includes a membrane holder block and a membrane pressing block arranged opposite each other, and a membrane tray for supporting the filter membrane is provided between the membrane holder block and the membrane pressing block, wherein: The membrane tray is cylindrical, and the bottom of the membrane tray has a porous structure. The membrane tray contains a membrane pressure ring that forms a closed loop after installation. The inner sidewall of the membrane tray has a limiting protrusion, and the lower surface of the limiting protrusion is an inclined surface that can squeeze and fix the membrane pressure ring to fix the filter membrane. A first cavity is formed between the membrane support block and the membrane tray, and a second cavity is formed between the membrane tray and the membrane pressing block. Sealing devices are provided on the contact surfaces of the membrane support block and the membrane tray, as well as on the contact surfaces of the membrane tray and the membrane pressing block. An air inlet connector is provided on the membrane support block, and an air outlet connector is provided on the membrane pressing block. The outer sides of the membrane support block and the membrane pressing block are provided with locking devices for squeezing and locking their relative positions.

4. The four-channel automatic sampling filter membrane holder device according to claim 3, characterized in that, The membrane pressure ring is a C-shaped membrane pressure ring with an opening; Alternatively, the membrane pressure ring may be two semi-circular membrane pressure rings.

5. The four-channel automatic sampling filter membrane holder device according to claim 4, characterized in that, The membrane pressure ring is provided with radial through holes; And / or, the membrane support block and the membrane pressing block are both provided with sealing ring receiving grooves on the contact surface with the membrane tray, and the sealing device is a silicone sealing ring disposed in the sealing ring receiving groove.

6. The four-channel automatic sampling filter membrane holder device according to claim 3, characterized in that, The membrane pressing block has a receiving groove at one end near the membrane support block, the outer diameter of the membrane tray is less than or equal to the inner diameter of the receiving groove, and the membrane support block has an insertion part that mates with the receiving groove at one end near the membrane pressing block.

7. The four-channel automatic sampling filter membrane holder device according to claim 6, characterized in that, The locking device is a membrane support lock nut sleeved on the membrane pressing block. The membrane support lock nut includes an annular body and a blocking part that extends inward from the lower end of the annular body and cooperates with the outer end face of the membrane pressing block. The inner side of the upper end of the annular body is provided with an internal thread, and the membrane support block is provided with an external thread that cooperates with the internal thread on the outer side of the upper part of the insertion part.

8. The four-channel automatic sampling filter membrane holder device according to claim 3, characterized in that, The outer end face of the membrane support block is provided with a threaded hole, and a through hole is provided on the side wall of the box corresponding to the threaded hole. Screws are inserted into the through hole and the threaded hole to fix the filter membrane support.

9. The four-channel automatic sampling filter membrane holder device according to claim 3, characterized in that, The inner side of the end of the air inlet and air outlet is provided with an inverted flared opening, and a retaining sleeve is provided inside the inverted flared opening. The outer side of the air inlet and air outlet is threaded with a nut that can push the retaining sleeve to move. And / or, both the first cavity and the second cavity are frustoconical, with the lower surfaces of the two frustocones facing each other.

10. A VOCs online monitoring device, characterized in that, Includes the four-channel automatic sampling filter membrane holder device as described in any one of claims 1-9.

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