Volatile organic compound detection device with cleaning function and sampling method thereof

Abstract

The invention discloses a volatile organic compound detection device with a cleaning function. The volatile organic compound detection device comprises an upper cylinder and a lower cylinder which are clamped into a whole, a first isolation plate, a second isolation plate and a third isolation plate are installed in the upper cylinder, an air outlet is formed in the portion, between the first isolation plate and the second isolation plate, of the side wall of the upper cylinder, and a first detection pipe or a second detection pipe is installed in each through groove in the first isolation plate. The bottom end of the first detection pipe downwards penetrates through the second isolation plate and extends to the lower part of the second isolation plate; an air exhaust assembly and a driving assembly are arranged between the second isolation plate and the third isolation plate; an air inlet filtering assembly is arranged on the lower surface of the third isolation plate, and a collecting pipe and a cleaning pipe are further arranged on the third isolation plate in a penetrating mode; and a cleaning frame is fixedly mounted among all the clamping frames. The invention further discloses a sampling method for volatile organic compound detection. According to the device and the method disclosed by the invention, gas sampling is realized, and long-time effective use of the gas inlet filtering assembly is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of atmospheric environment detection, and relates to a volatile organic compound detection device with a self-cleaning function. The invention also relates to a sampling method for volatile organic compound detection. Background Art

[0002] Volatile organic compounds are important precursors to the formation of secondary pollutants such as fine particulate matter and ozone, which in turn cause atmospheric environmental problems such as haze and photochemical smog. The detection of volatile organic compounds in the air is an important indicator of environmental monitoring. Portable detection instruments are often used for direct measurement outdoors. Since impurities suspended in the air can easily clog the detection port of the instrument, it is necessary to initially filter out atmospheric impurities, but not the objects to be detected. This can be achieved by selecting a sparser large-pore filter. However, the current detection device cannot clean the filter in a timely manner, resulting in serious clogging of the filter after the device has been running for a period of time, and the detection accuracy will decrease.

[0003] In the prior art, the application number is 202110285955.6, and the name of the invention is "An automatic sampling and detection device for volatile organic compounds in the air". It sets a cleaning mechanism and uses a motor to drive the cams on both sides to rotate. The cams and the slide plate can make the push rod move up and down repeatedly. The rack set on the push rod and the transmission gear set on the rotating rod act to make the cleaning block swing back and forth around the rotating rod. The brush set on the cleaning block completes the cleaning of the filter frame during the swinging process, so that the device can run for a longer time. However, the setting of this cleaning block can only clean the surface of the filter frame, and it is impossible to effectively clean the impurities accumulated between the meshes of the filter frame, which is prone to mesh clogging. In addition, the detection of volatile organic compounds is often a simple on-site detection, which has great limitations, lacks space for gas storage, and lacks sampling retention.

[0004] Therefore, there is an urgent need to develop a volatile organic compound detection device with a self-cleaning function to significantly solve the technical problem of mesh clogging. Summary of the invention

[0005] The purpose of the present invention is to provide a volatile organic compound detection device with a self-cleaning function, which solves the problem that mesh clogging is easy to occur and the limitations are large during conventional volatile organic compound detection in the prior art.

[0006] Another object of the present invention is to provide a sampling method for detecting volatile organic compounds.

[0007] The technical solution adopted by the present invention is a volatile organic compound detection device with a self-cleaning function, comprising an upper cylinder and a lower cylinder that are snap-connected as one; a first isolation plate, a second isolation plate and a third isolation plate are fixedly installed in the upper cylinder from top to bottom in sequence, and an air outlet is arranged on the side wall of the upper cylinder between the first isolation plate and the second isolation plate, and a plurality of through grooves are opened on the first isolation plate, and a first detection tube or a second detection tube is slidably installed in each through groove, and the bottom ends of all first detection tubes pass downward through the second isolation plate and extend to the bottom of the second isolation plate; an exhaust assembly and a drive assembly are arranged between the second isolation plate and the third isolation plate; an air intake filter assembly is arranged on the lower surface of the third isolation plate, and a collection pipe and a cleaning pipe are also penetrated on the third isolation plate; a cleaning rack is fixedly installed between all the racks.

[0008] Another technical solution adopted by the present invention is a sampling method for volatile organic compound detection, which is implemented by using the above-mentioned volatile organic compound detection device with self-cleaning function according to the following steps:

[0009] Step 1: Position the upper cylinder and the lower cylinder and install the detection instrument;

[0010] Step 2: continuously feeding the sampling gas and testing the sampling gas;

[0011] Step 3, remove dust from the outer surface of the filter cover;

[0012] Step 4: Remove dust from the mesh of the filter cover.

[0013] The beneficial effects of the present invention include the following aspects:

[0014] 1) The present invention ensures effective gas transportation through the coordination of the driving component, the exhaust component and the air intake filter component, provides convenient conditions for the detection of volatile organic compounds in the gas, realizes gas sampling, achieves the purpose of sampling and retention, and can also ensure the long-term effective use of the air intake filter component, and has a wide range of applications.

[0015] 2) The present invention utilizes the cooperation of the plug plate, the slot, the pin, the spring, the limit plate and the positioning hole to ensure the effective adjustment of the distance between the lower cylinder and the upper cylinder, which is convenient to use and can provide more detection environments for the detection of volatile organic compounds.

[0016] 3) The present invention utilizes the coordinated arrangement of a motor, a crankshaft and a driving gear, which can not only drive the vacuum assembly to transport gas, but also drive the filter cover to rotate, and in conjunction with the arrangement of a cleaning frame, effectively ensures the cleanliness of the filter cover surface.

[0017] 4) The present invention utilizes the forward and backward movement of the piston plate to realize the circulation and transportation of gas between the second isolation plate and the third isolation plate, thereby achieving the purpose of on-site sampling, and in the process of ventilation, the replaced gas is sprayed out from the cleaning nozzle to blow off the impurities in the mesh of the rotating filter cover. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the external structure after the upper cylinder and the lower cylinder in the device of the present invention are connected;

[0019] Figure 2 It is a cross-sectional view of the internal structure after the upper cylinder and the lower cylinder in the device of the present invention are butted together;

[0020] Figure 3 is a bottom view schematic diagram of a cross section where a third isolation plate in the device of the present invention is located;

[0021] Figure 4 It is a schematic diagram of the connection between the driving gear, the teeth and the limit ring in the device of the present invention;

[0022] Figure 5 It is a top view of the connection between the card frame and the cleaning frame in the device of the present invention.

[0023] In the figure, 1. detection box; 2. upper cylinder; 3. lower cylinder; 4. clamping assembly; 5. first isolation plate; 6. second isolation plate; 7. third isolation plate; 8. suction assembly; 9. first detection tube; 10. second detection tube; 11. plug; 12. air intake filter assembly; 13. drive assembly; 14. plug plate; 15. pin; 16. slot; 17. limit plate; 18. spring; 19. positioning hole; 20. .Vacuum pump; 21.Piston plate; 22.Drive rod; 23.Tee pipe; 24.Air supply pipe; 25.Inlet pipe; 26.Air outlet; 27.Motor; 28.Crankshaft; 29.Ring; 30.Drive gear; 31.Lifting ring; 32.Filter cover; 33.Annular groove; 34.Card holder; 35.Cleaning rack; 36.Collection pipe; 37.Cleaning pipe; 38.Cleaning nozzle; 39.Cap; 40.Hook. DETAILED DESCRIPTION

[0024] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] Reference Figure 1 , Figure 2 The volatile organic compound detection device of the present invention comprises an upper cylinder 2 and a lower cylinder 3, which are fixedly connected by a clamping assembly 4 to form a detection box 1; the cross section of the detection box 1 can be cylindrical, square or rectangular. Figure 3 That is, a square cylinder;

[0026] The first isolation plate 5, the second isolation plate 6 and the third isolation plate 7 are fixedly installed in the upper cylinder 2 from top to bottom in sequence. The side wall of the upper cylinder 2 between the first isolation plate 5 and the second isolation plate 6 is provided with an air outlet 26. The first isolation plate 5 is provided with a plurality of through grooves, and a first detection tube 9 or a second detection tube 10 is slidably installed in each through groove. All the first detection tubes 9 and the second detection tubes 10 are provided with plugs 11. The bottom ends of all the first detection tubes 9 pass through the second isolation plate 6 downward and extend to the bottom of the second isolation plate 6.

[0027] An air extraction component 8 and a driving component 13 are provided between the second isolation plate 6 and the third isolation plate 7. The driving component 13 is used to drive the air extraction component 8 to extract air. The air extraction component 8 transports the outside air from below the third isolation plate 7 to between the first isolation plate 5 and the second isolation plate 6.

[0028] The structure of the vacuum assembly 8 is that it includes a vacuum cylinder 20, a piston plate 21 is slidably mounted inside the vacuum cylinder 20, and the outer end surface ( Figure 2 The left side of the display) is connected to the inner end of the drive rod 22 through a coupling, and the inner end of the piston plate 21 ( Figure 2 The air chamber (shown on the right side) is connected to the three-way pipe 23, and the other two ports of the three-way pipe 23 are respectively connected to the air supply pipe 24 and the air intake pipe 25, the air supply pipe 24 extends upwardly out of the second isolation plate 6, and the air intake pipe 25 passes through the third isolation plate 7 downwardly and extends to the inside of the air intake filter assembly 12, a first one-way valve is provided in the pipeline of the air intake pipe 25, and a second one-way valve is provided in the pipeline of the air supply pipe 24, to ensure the directional flow of air from bottom to top, and to ensure the continuous supply of the detection gas;

[0029] The structure of the driving assembly 13 is that it includes a motor 27, which is a servo motor, electrically connected to an external power supply, and controlled by a control switch. The motor 27 is fixedly mounted on the lower surface of the first isolation plate 5, and the output shaft of the motor 27 is transmission-connected to the crankshaft 28. The curved end of the crankshaft 28 is sleeved with a collar 29, and the collar 29 is fixedly connected to the outer end of the driving rod 22. When the motor 27 works, the crankshaft 28 rotates, and the collar 29 drives the driving rod 22 to move back and forth, thereby realizing the reciprocating motion of the piston plate 21.

[0030] Reference Figure 3 , Figure 4, an air intake filter assembly 12 is provided on the lower surface of the third isolation plate 7, and the structure of the air intake filter assembly 12 is that it includes a plurality of brackets 34 and a limiting ring 31, all brackets 34 are fixedly connected to the lower surface of the third isolation plate 7 upward, and the inner surfaces of all brackets 34 are adapted to the outer surface of the limiting ring 31, and all brackets 34 embrace and support the limiting ring 31; a filter cover 32 is fixedly connected downwardly to the lower part of the inner wall of the limiting ring 31, and the upper part of the inner wall of the limiting ring 31 is a step-shaped annular groove 33, and a circle of teeth is evenly arranged on the inner wall of the annular groove 33, and the bottom end of the crankshaft 28 passes through the third isolation plate 7 downward and is fixedly connected to a driving gear 30, and the driving gear 30 is meshed with a circle of teeth in the annular groove 33, and the driving gear 30 drives the limiting ring 31 and the filter cover 32 to rotate through the teeth;

[0031] The third isolation plate 7 is also provided with a collecting pipe 36 and a cleaning pipe 37, both of which are provided inside the filter cover 32 and are used to transport outside air to the top of the third isolation plate 7. A third one-way valve is provided in the pipe of the collecting pipe 36, and a fourth one-way valve is provided in the pipe of the cleaning pipe 37. The cleaning pipe 37 is connected to a plurality of cleaning nozzles 38 on one side close to the filter cover 32, and the cleaning nozzles 38 can blow away the dust on the filter cover 32, so as to achieve deep cleaning of the filter cover 32 from the inside to the outside.

[0032] Reference Figure 5 A cleaning frame 35 is fixedly installed between all the brackets 34. The cleaning frame 35 is adapted to the shape of the filter cover 32. The filter cover 32 rotates and is scraped by the cleaning frame 35 so as to clean the outer surface of the filter cover 32.

[0033] A cover 39 is buckled on the top of the upper cylinder 2, and a hook 40 is fixedly mounted on the upper end surface of the cover 39 to facilitate the lifting and transportation of the entire device.

[0034] Reference Figure 1 , Figure 2 , Figure 3The structure of the clamping assembly 4 is that, taking a square cylinder as an example, it includes four plug plates 14, four slots 16 and two pins 15; the four slots 16 are respectively arranged at the lower part of the four sides of the upper cylinder 2, and the four plug plates 14 are respectively arranged at the top of the four sides of the lower cylinder 3. A pin 15 is respectively arranged near the bottom of the two opposite slots 16, and a plurality of positioning holes 19 are opened on the two plug plates 14 corresponding to the two slots 16 below. The positioning holes 19 are opened in sequence from top to bottom and are adapted to the pins 15, and at least upper, middle and lower positions are arranged on each plug plate 14. There are three positioning holes 19 at three height positions; a spring 18 is sleeved on the outer periphery of each pin 15, and a limit plate 17 is fixedly installed on the outer end of each pin 15, and the two ends of each spring 18 are respectively fixedly connected to the limit plate 17 on the same side and the adjacent side of the upper cylinder 2; when the upper cylinder 2 is docked with the lower cylinder 3, the four plug plates 14 are correspondingly inserted into the four slots 16, and the two pins 15 are correspondingly inserted into the positioning holes 19 at the same height on the two plug plates 14, so as to adjust and fix the upper and lower positions between the upper cylinder 2 and the lower cylinder 3;

[0035] If a circular cylinder is used as an example, the plug plate 14, the slot 16 and the pin 15 in the clamping assembly 4 are evenly arranged along the outer surface of the cylinder, and the number is 3-4 at the same time, and all correspond to each other from top to bottom. The structure and working principle of each component are consistent with those of a square cylinder.

[0036] The motor 27 is externally connected to a controller and a power source to provide power for air pressurization and cleaning and dust removal.

[0037] The first detection tube 9 or the second detection tube 10 has a difference in length, that is, the first detection tube 9 can detect the gas in the two spaces between the first isolation plate 5 and the second isolation plate 6, and the second isolation plate 6 and the third isolation plate 7; the second detection tube 10 can only detect the gas in the space between the first isolation plate 5 and the second isolation plate 6.

[0038] When there are four brackets 34 , the four scraper arms of the cleaning frame 35 are arranged in a cross shape; when there are three brackets 34 , the cleaning frame 35 has three scraper arms that are equally divided along the circumference.

[0039] The sampling method for volatile organic compound detection of the present invention is implemented by using the above-mentioned volatile organic compound detection device according to the following steps:

[0040] Step 1: Position the upper cylinder 2 and the lower cylinder 3, and install the detection instrument.

[0041] Place the test box 1 on a horizontal ground, and pull each limit plate 17 outward at the same time. Each limit plate 17 overcomes the tension of its own spring 18, and all limit plates 17 drive all pins 15 to separate from the plug plate 14, and the upper cylinder 2 and the lower cylinder 3 are released from the limit.

[0042] Then, the hook 40 is lifted upward, and the hook 40 drives the cover 39 and the upper cylinder 2 to rise. When the upper cylinder 2 is a certain distance away from the lower cylinder 3, the limit plate 17 is released, and the spring 18 pulls the limit plate 17 to insert the pin 15 into the positioning hole 19 on the plug plate 14;

[0043] Then unscrew the cover 39, unscrew the plug 11 on the second detection tube 10, place the detection head of the detection instrument in the second detection tube 10, and cover the cover 39;

[0044] The sampling and detection can be carried out continuously and in real time, or the gas detection in the closed space can be carried out by covering the cover 39, and the gas sample can be stored after covering the cover 39.

[0045] Step 2: Continue to feed the sampling gas and test the sampling gas.

[0046] The motor 27 is started, the motor 27 drives the crankshaft 28 to rotate, the crankshaft 28 drives the collar 29 to rotate, the collar 29 drives the drive rod 22 to reciprocate, and the drive rod 22 drives the piston plate 21 to reciprocate in the pump 20; the piston plate 21 moves outward ( Figure 2 During the pulling process (left), negative pressure appears in the air chamber of the vacuum cylinder 20, and the outside air flows through the filter cover 32 into the air inlet pipe 25, and is sucked into the vacuum cylinder 20 (the air chamber on the right) through the three-way pipe 23; the piston plate 21 moves inward ( Figure 2 During the pushing process (right side of the display), the air in the air chamber of the vacuum cylinder 20 is squeezed and called pressurized air. The pressurized air passes through the three-way pipe 23 and the air supply pipe 24 and enters between the first isolation plate 5 and the second isolation plate 6, and is detected by the detection head of the detection instrument, and finally discharged from the air outlet 26;

[0047] After starting the motor 27, set the detection time, use the air in the second isolation plate 6 and the third isolation plate 7 as the sampling gas, open the plug 11 on the first detection tube 9, and place the detection head of the detection instrument in the first detection tube 9, so as to detect the volatile organic compounds in the sampling gas between the second isolation plate 6 and the third isolation plate 7.

[0048] Step 3: remove dust from the outer surface of the filter cover 32.

[0049] In step 2, while the crankshaft 28 drives the piston plate 21, the crankshaft 28 also drives the driving gear 30 to rotate. The driving gear 30 meshes with the teeth on the annular groove 33, so that the limit ring 31 drives the filter cover 32 to rotate. When the turbid air from the outside enters the filter cover 32, large impurities are intercepted. As the filter cover 32 rotates, the large impurities on the filter cover 32 are swept by the cleaning frame 35 and fall into the lower cylinder 3.

[0050] Step 4: Remove dust from the mesh of the filter cover 32.

[0051] During the process of the crankshaft 28 driving the piston plate 21 inward in step 2, the air pressure between the second isolation plate 6 and the third isolation plate 7 decreases, and the turbid air from the outside is filtered by the filter cover 32 and enters between the second isolation plate 6 and the third isolation plate 7 from the collecting pipe 36; during the process of the piston plate 21 being pulled outward in step 2, the filtered air between the second isolation plate 6 and the third isolation plate 7 is squeezed and the air pressure increases rapidly, and the squeezed air enters the cleaning pipe 37 and is then quickly ejected from the cleaning nozzle 38 to blow off the impurities in the mesh of the filter cover 32.

[0052] Example 1

[0053] At a joint testing station in Yan'an City, Changqing Oilfield, the device of the present invention was used to conduct continuous VOCs gas testing, and the recorded data are as follows:

[0054]

[0055] By comparing this value with the detection data and usage time of the prior art equipment, it is determined that the detection result of the device of the present invention is accurate and the usage time is longer.

[0056] Example 2

[0057] At a joint testing station in Qingyang City, Changqing Oilfield, the device of the present invention was used to conduct continuous VOCs gas testing, and the recorded data are as follows:

[0058]

[0059] By comparing this value with the detection data and usage time of the prior art equipment, it is determined that the detection result of the device of the present invention is accurate and the usage time is longer.

[0060] Example 3

[0061] At a joint testing station in Qingyang City, Changqing Oilfield, the device of the present invention was used to conduct continuous VOCs gas testing, and the recorded data are as follows:

[0062]

[0063] By comparing this value with the detection data and usage time of the prior art equipment, it is determined that the detection result of the device of the present invention is accurate and the usage time is longer.

[0064] Example 4

[0065] At a sewage pool detection point in Qingyang City, Changqing Oilfield, the device of the present invention was used to perform continuous VOCs gas detection, and the recorded data are as follows:

[0066]

[0067]

[0068] In the above four embodiments, the values ​​of days 4 to 14 and days 16 to 29 are omitted and not shown.

[0069] By comparing this value with the detection data and usage time of the prior art equipment, it is determined that the detection result of the device of the present invention is accurate and the usage time is longer.

[0070] It can be seen from the above four embodiments that in accordance with the "Technical Requirements and Detection Methods for Portable Monitors of Total Hydrocarbons, Methane and Non-methane Total Hydrocarbons in Ambient Air and Exhaust Gas" (HJ 1012-2018), a gas collecting bag is used to collect high-concentration VOCs samples at the oil measuring port of the storage tank, and a commonly used portable gas detector (FID) and a volatile organic compound detection device with a self-cleaning function of the present invention are used to detect the same VOCs sample. The results show that the initial non-methane total hydrocarbon detection result error of the two instruments is 1%-2%. After 30 days of continuous detection, the non-methane total hydrocarbon detection result error of the two instruments is 5%-10%. Among them, the volatile organic compound detection device with a self-cleaning function of the present invention is relatively stable and has a higher accuracy.

Claims

1. A volatile organic compound detection device with a self-cleaning function, characterized in that: The invention comprises an upper cylinder (2) and a lower cylinder (3) which are snap-fitted together as a whole; a first isolation plate (5), a second isolation plate (6) and a third isolation plate (7) are fixedly installed in the upper cylinder (2) from top to bottom in sequence; an air outlet (26) is arranged on the side wall of the upper cylinder (2) between the first isolation plate (5) and the second isolation plate (6); a plurality of through grooves are opened on the first isolation plate (5); a first detection tube (9) or a second detection tube (10) is slidably installed in each through groove; the bottom ends of all the first detection tubes (9) pass through the second isolation plate (6) downward and extend to the bottom of the second isolation plate (6); an exhaust assembly (8) and a drive assembly (13) are arranged between the second isolation plate (6) and the third isolation plate (7); an air intake filter assembly (12) is arranged on the lower surface of the third isolation plate (7); a collecting tube (36) and a cleaning tube (37) are also passed through the third isolation plate (7); a cleaning frame (35) is fixedly installed between all the brackets (34).

2. The volatile organic compound detection device with self-cleaning function according to claim 1, characterized in that: The structure of the vacuum assembly (8) is as follows: it comprises a vacuum cylinder (20), a piston plate (21) is slidably mounted inside the vacuum cylinder (20), the outer end surface of the piston plate (21) is drivingly connected to the inner end of the driving rod (22), the air chamber at the inner end of the piston plate (21) is connected to the three-way pipe (23), the other two ports of the three-way pipe (23) are respectively connected to the air supply pipe (24) and the air intake pipe (25), the air supply pipe (24) extends upwardly out of the second isolation plate (6), the air intake pipe (25) passes through the third isolation plate (7) downwardly and extends to the interior of the air intake filter assembly (12), a first one-way valve is arranged in the pipeline of the air intake pipe (25), and a second one-way valve is arranged in the pipeline of the air supply pipe (24).

3. The volatile organic compound detection device with self-cleaning function according to claim 1, characterized in that: The structure of the driving assembly (13) is that it includes a motor (27), the motor (27) is fixedly mounted on the lower surface of the first isolation plate (5), the output shaft of the motor (27) is transmission-connected to the crankshaft (28), the bent end of the crankshaft (28) is provided with a collar (29), and the collar (29) is fixedly connected to the outer end of the driving rod (22).

4. The volatile organic compound detection device with self-cleaning function according to claim 1, characterized in that: The structure of the air intake filter assembly (12) is that it includes a plurality of brackets (34) and a limiting ring (31), all of the brackets (34) are fixedly connected to the lower surface of the third isolation plate (7) upward, the inner surfaces of all the brackets (34) are matched with the outer surface of the limiting ring (31), and all the brackets (34) embrace and support the limiting ring (31); the lower part of the inner wall of the limiting ring (31) is fixedly connected to a filter cover (32) downward, the upper part of the inner wall of the limiting ring (31) is in a step shape called an annular groove (33), and the inner wall of the annular groove (33) is evenly provided with a circle of teeth, the bottom end of the crankshaft (28) passes through the third isolation plate (7) downward and is fixedly connected to a driving gear (30), the driving gear (30) is meshed with a circle of teeth of the annular groove (33), and the driving gear (30) drives the limiting ring (31) and the filter cover (32) to rotate through the teeth.

5. The volatile organic compound detection device with self-cleaning function according to claim 1, characterized in that: The collecting pipe (36) and the cleaning pipe (37) are both arranged inside the filter cover (32); a side of the cleaning pipe (37) close to the filter cover (32) is connected to a plurality of cleaning nozzles (38); a third one-way valve is arranged in the pipeline of the collecting pipe (36); and a fourth one-way valve is arranged in the pipeline of the cleaning pipe (37).

6. A sampling method for volatile organic compound detection, using any one of the volatile organic compound detection devices with self-cleaning function described in claims 1-7, characterized in that: Follow these steps to implement: Step 1: Position the upper cylinder (2) and the lower cylinder (3) and install the detection instrument; Step 2: continuously feeding the sampling gas and testing the sampling gas; Step 3, removing dust from the outer surface of the filter cover (32); Step 4: remove dust from the mesh of the filter cover (32).

7. The sampling method for volatile organic compound detection according to claim 6, characterized in that: In step 1, the specific process is: The detection box (1) is placed on a horizontal ground, and each limit plate (17) is pulled outward at the same time, so that each limit plate (17) overcomes the tension of its own spring (18), and all the limit plates (17) drive all the pins (15) to separate from the plug plate 14, and the upper cylinder (2) and the lower cylinder (3) are released from the limit; The hook (40) is then lifted upward, and the hook (40) drives the sealing cover (39) and the upper cylinder (2) to rise. When the upper cylinder (2) is a certain distance away from the lower cylinder (3), the limit plate (17) is released, and the spring (18) pulls the limit plate (17) to insert the pin (15) into the positioning hole (19) on the plug plate (14); Then, unscrew the sealing cap (39), unscrew the plug (11) on the second detection tube (10), place the detection head of the detection instrument in the second detection tube (10), and cover the sealing cap (39).

8. The sampling method for volatile organic compound detection according to claim 6, characterized in that: In step 2, the specific process is: The motor (27) is started, the motor (27) drives the crankshaft (28) and the collar (29) to rotate, the collar (29) drives the driving rod (22) to reciprocate, and the driving rod (22) drives the piston plate (21) to reciprocate in the air pump (20); when the piston plate (21) is pulled outward, negative pressure appears in the air chamber of the air pump (20), and the outside air flows into the air inlet pipe (25) through the filter cover (32), and is sucked into the air pump (20) through the three-way pipe (23); When the piston plate (21) is pushed inward, the air in the air chamber of the air pump (20) is squeezed and called pressurized air. The pressurized air passes through the three-way pipe (23) and the air supply pipe (24) and enters between the first isolation plate (5) and the second isolation plate (6) to be detected by the detection head of the detection instrument, and finally discharged from the air outlet (26); After the motor (27) is started, the detection time is set, the air between the second isolation plate (6) and the third isolation plate (7) is used as the sampling gas, the plug (11) on the first detection tube (9) is opened, and the detection head of the detection instrument is placed in the first detection tube (9), so that the volatile organic matter in the sampled gas between the second isolation plate (6) and the third isolation plate (7) can be detected.

9. The sampling method for detecting volatile organic compounds according to claim 6, characterized in that: In step 3, the specific process is: When the crankshaft (28) drives the piston plate (21), the crankshaft (28) also drives the driving gear (30) to rotate. The driving gear (30) meshes with the teeth on the annular groove (33) to drive the limit ring (31) to drive the filter cover (32) to rotate. When the turbid air from the outside enters the filter cover (32), large impurities are intercepted. As the filter cover (32) rotates, the large impurities on the filter cover (32) are swept by the cleaning frame (35) and fall into the lower cylinder (3).

10. The sampling method for volatile organic compound detection according to claim 6, characterized in that: In step 4, the specific process is: When the crankshaft (28) drives the piston plate (21) to move inward, the air pressure between the second isolation plate (6) and the third isolation plate (7) decreases, and the turbid air from the outside enters between the second isolation plate (6) and the third isolation plate (7) through the collection pipe (36) after being filtered by the filter screen (32); When the piston plate (21) is pulled outward, the filtered air between the second isolation plate (6) and the third isolation plate (7) is squeezed and the air pressure increases rapidly. The squeezed air enters the cleaning pipe (37) and is then quickly ejected from the cleaning nozzle (38), blowing off impurities in the mesh of the filter cover (32).

Images