Pressing type VOC sampling cover and sampling method

Abstract

The invention relates to the technical field of VOC detection, and discloses a press-fit type VOC sampling cover and a sampling method.The press-fit type VOC sampling cover comprises a pressing rod and an adsorption pipe, the pressing rod is provided with a sampling cover, a suction cup is further fixed to the portion, on the peripheral side of the sampling cover, of the pressing rod, the suction cup is used for being adsorbed to a to-be-detected object, and a pressing plate tightly presses the sampling cover to the to-be-detected object through the suction cup; the adsorption tube is filled with an adsorbent and is used for adsorbing VOC (Volatile Organic Compounds), and the adsorption tube is covered on an object to be detected by a sampling cover; the adsorption tube is placed in the sampling cover for direct adsorption, structures such as an air inlet and an air outlet do not need to be arranged on the sampling cover, the whole structure is simple, and after sampling, the adsorption tube is easy to carry and has no safety risk; according to the sampling mode, a nitrogen cylinder does not need to be carried, door-to-door sampling is facilitated, and the overall sampling cost is low.

Description

Technical Field

[0001] This invention relates to the field of VOC detection technology, and in particular to a press-fit VOC sampling hood and sampling method. Background Technology

[0002] With increasing health awareness, the release of volatile organic compounds (VOCs) from building materials, furniture, and interior decorations has garnered growing attention. VOCs are organic chemical substances that readily volatilize under normal temperature and pressure, such as formaldehyde, benzene compounds, esters, and ketones. Long-term exposure may cause headaches, allergies, respiratory diseases, and even induce cancer. Therefore, accurately measuring the VOC release concentration from material surfaces has become a crucial step in evaluating the environmental performance of products.

[0003] The general method for testing formaldehyde and volatile organic compounds in building materials and furniture is to send the samples to a laboratory and use the climate chamber method for testing. The climate chamber can better simulate the actual use environment of the samples. The release of formaldehyde and VOCs in the samples in the climate chamber is close to the normal emission rate and pattern of the samples. The test results are more consistent with the actual release status of the samples. However, the climate chamber method is costly and time-consuming, so it cannot be widely used.

[0004] Currently, the industry commonly uses a press-fit sampling hood combined with nitrogen purging for VOC collection. Specifically, during sampling, a sealed hood is pressed against the surface of the material to be tested, and high-purity nitrogen is introduced to create an inert environment to displace and collect the VOCs volatilized from the material.

[0005] However, the above-mentioned solution has a complex overall structure. The sampling hood needs to be equipped with inlet and outlet ports, as well as nitrogen cylinders, pressure reducing valves, flow meters, and other devices. The system is bulky and heavy, making transportation and on-site deployment difficult. For customized furniture customers (such as cabinets and wardrobes already installed in residences and offices), manufacturers need to conduct on-site sampling, but the transportation restrictions of nitrogen cylinders make this solution difficult to implement. Moreover, users usually refuse such high-risk operations. Nitrogen cylinders are also high-pressure containers, posing risks of leakage, collision, and explosion during handling, elevator transport, and operation in users' homes, especially in high-rise buildings or confined spaces where the danger is exacerbated. The transportation and labor costs of nitrogen cylinders are high, with the cost of a single sampling accounting for more than 30% of the total testing cost. Furthermore, it requires two people to work together, resulting in low efficiency. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a compression-type VOC sampling hood and sampling method. By placing the adsorption tube in the sampling hood for direct adsorption, there is no need to set up inlet and outlet ports or other structures on the sampling hood. The overall structure is simple, the adsorption tube is easy to carry after sampling, and there is no safety risk. This sampling mode eliminates the need to carry nitrogen cylinders, making it convenient for on-site sampling, and the overall sampling cost is low.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, a pressure-fit VOC sampling cover includes a pressure rod and an adsorption tube. The pressure rod is provided with a sampling cover, and a suction cup is fixed on the pressure rod around the sampling cover. The suction cup is used to adsorb onto the object to be tested, and the pressure plate presses the sampling cover onto the object to be tested through the suction cup. The adsorption tube is filled with an adsorbent for adsorbing VOCs, and the adsorption tube is covered onto the object to be tested by the sampling cover.

[0008] As a further implementation, the sampling cover has an opening at the bottom, and the edge of the opening is provided with a sealing strip.

[0009] As a further implementation, the pressure rod includes a pressure rod body and a telescopic rod nested with the pressure rod, one end of which can slide inside the pressure rod and the other end of which is located outside the pressure rod.

[0010] As a further implementation, the pressure rod and the telescopic rod are provided with through holes at their opposite ends.

[0011] As a further implementation, the suction cup is connected by a connecting rod, which passes through a through hole and engages with a fixing member.

[0012] As a further implementation, the fixing element is an adjusting nut, and the top end of the connecting rod is threaded.

[0013] As a further implementation, a connecting block is provided at the center of the top of the sampling cover, which is connected to the pressure rod body.

[0014] As a further implementation, the pressure rod body is provided with an axial slide rail for the telescopic rod to slide inside, and one end of the pressure rod body is open.

[0015] As a further implementation, the bottom surface of the pressure rod body is provided with multiple connecting grooves along the length direction, and the connecting rod is engaged with the connecting block or threadedly connected through the connecting grooves.

[0016] Secondly, a sampling method for a press-fit VOC sampling hood, using any of the press-fit VOC sampling hoods described above, includes the following steps: Select a sampling hood of appropriate size according to the object to be tested. Based on the size of the sampling hood, pull the telescopic rod outward relative to the pressure rod body to a suitable position. Select the connecting slot near the middle of the pressure rod and connect it to the connecting block to fix the sampling hood. Place the adsorption tube on the position of the object to be tested, cover the adsorption tube with the sampling hood, and the suction cup will adhere to the object to be tested. Tighten the adjusting nut so that the pressure rod presses the sampling hood tightly, and the adsorption tube adsorbs the VOCs emitted from the sampling hood to achieve sampling.

[0017] The beneficial effects of the present invention are as follows: 1. This invention directly adsorbs by placing the adsorption tube in the sampling hood, eliminating the need for inlet and outlet ports or other structures on the sampling hood. The overall structure is simple, the adsorption tube is easy to carry after sampling, and there is no safety risk. This sampling mode eliminates the need to carry nitrogen cylinders, making it convenient for on-site sampling and reducing overall sampling costs.

[0018] 2. The press-fit VOC sampling cover of the present invention has a simple overall structure, is easy to carry, and has an adjustable rod length to match sampling covers of different sizes; it can achieve multi-point rapid sampling, and the sampling work can be completed quickly by a single person. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0020] Figure 1 This is a schematic diagram of the overall structure of the press-fit VOC sampling cover in an embodiment of the present invention.

[0021] The diagram exaggerates the spacing or dimensions between parts to show their positions; the diagram is for illustrative purposes only.

[0022] The components are: 1. Pressure bar body, 2. Sampling cover, 3. Connecting rod, 4. Suction cup, 5. Sealing strip, 6. Adjusting nut, 7. Connecting block, 8. Adsorption tube, and 11. Telescopic rod. Detailed Implementation

[0023] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] Example 1 In a typical embodiment of the present invention, reference is made to Figure 1 As shown, a pressure-type VOC sampling cover includes a pressure rod and an adsorption tube. The pressure rod is equipped with a sampling cover 2, and a suction cup 4 is fixed on the pressure rod around the sampling cover 2. The suction cup 4 is used to adsorb onto the object to be tested. The pressure plate presses the sampling cover 2 onto the object to be tested through the suction cup. The adsorption tube 8 is filled with an adsorbent for adsorbing VOCs. The adsorption tube is placed on the object to be tested by the sampling cover 2.

[0025] The sampling cover 2 is cylindrical with an opening at the bottom. A sealing strip 5 is installed at the edge of the opening. The sealing end is made of a ring-shaped soft material. After the sampling cover 2 is pressed onto the object to be tested, the sealing strip 5 is pressed tightly. The sealing strip 5 effectively isolates the internal cavity of the sampling cover 2 from the outside, thus achieving a seal.

[0026] Sampling cover 2 is made of polytetrafluoroethylene (PTFE) with a height of 70 mm and an inner diameter of 120 mm. The bottom opening edge is fitted with a 3 mm thick silicone sealing strip to ensure a close fit with the curved surface of the board.

[0027] The pressure rod includes a pressure rod body 1 and a telescopic rod 11 nested with the pressure rod. One end of the telescopic rod can slide inside the pressure rod, and the other end is located outside the pressure rod.

[0028] The pressure rod body 1 is internally provided with a slide rail for the telescopic rod 11 to slide on, and one end of the pressure rod body 1 is open, such as... Figure 1 As shown, the right end of the pressure rod body 1 is open, and the right end of the telescopic rod 1 extends out of the opening. Pulling the telescopic rod 1 to the right can adjust the length of the pressure rod.

[0029] The pressure rod and the telescopic rod are provided with through holes at opposite ends. Figure 1 In the middle, the left end of the pressure plate body 1 and the right end of the telescopic rod 11 are provided with through holes, the suction cup 4 is connected to the connecting rod 3, and the connecting rod 3 passes through the through holes and cooperates with the fixing part.

[0030] The fixing component is an adjusting nut. The top of the connecting rod is threaded and passes through a through hole. The adjusting nut 6 is threaded with the connecting rod 3 above the pressure rod body and the telescopic rod 11. By adjusting the nut 6, the pressure rod presses down on the sampling cover, ensuring that the sampling cover is pressed tightly on the object to be tested.

[0031] like Figure 1 As shown, a connecting block 7 is provided at the center of the top of the sampling cover 2, and it is connected to the pressure rod body through the connecting block 7.

[0032] The bottom surface of the pressure rod body 1 is provided with multiple connecting grooves (not shown in the figure) along the length direction, which are connected to the connecting block by snapping or threading through the connecting grooves.

[0033] The shape of the connecting groove is adapted to the shape of the connecting block 7. The connecting groove is not connected to the internal sliding space of the pressure rod body 1. The connecting groove is threaded. The connecting block 7 is cylindrical with threads on its circumference. The sampling cover is fixed to the pressure rod body 1 by the threaded engagement between the connecting block 7 and the connecting groove. Alternatively, neither the connecting block 7 nor the connecting groove is threaded, and the two are directly snapped together.

[0034] When installing sampling covers of different sizes, determine the length of the extension rod 11 according to the diameter of the sampling cover, select the appropriate connecting groove and connecting block 7 for installation, so that the sampling cover is installed in the middle of the overall length of the pressure rod. The left and right suction cups, together with the adjustment nut, can achieve better compression of the sampling cover.

[0035] Understandably, the inner wall of sampling hood 2 is coated with a non-adhesive, gas-free coating to prevent it from affecting the sampling results.

[0036] During sampling, the adsorption tube 8 is located inside the sampling hood 2, placed on the object to be tested, and covered by the sampling hood 2. The VOC content in the air inside the sampling hood 2 is limited and has little impact on the sampling structure, which can be ignored.

[0037] Adsorption tube: Tenax-TA stainless steel tube (outer diameter 6 mm, length 89 mm), filled with 200 mg adsorbent, and sealed at both ends with PTFE plugs.

[0038] In this embodiment, the pressure rod has a body length of 300mm and a telescopic rod 11 that can be pulled outward to 500mm. The pressure rod body 1 is provided with an M4 threaded connection groove every 20mm along the axial direction, with a total of 10 adjustable positions.

[0039] Example 2 A sampling method for a press-fit VOC sampling hood, using the press-fit VOC sampling hood described in Example 1, includes the following steps: Select a sampling cover of appropriate size according to the object to be tested. Based on the size of the sampling cover, pull the telescopic rod outward relative to the pressure rod body to a suitable position. Select the connecting slot near the middle of the pressure rod and connect it to the connecting block. Specifically, pull the telescopic rod 1 out to 400 mm so that the span of the suction cups at both ends matches the width of the wardrobe shelf. Select the 5th setting connecting slot and tighten the sampling cover threaded to the center of the pressure rod. Remove the PTFE plugs at both ends of the adsorption tube and place the tube horizontally in the center of the shelf. Snap the cover onto the adsorption tube, gently press the suction cups to expel air, and tighten the adjusting nut until the sealing tape is compressed by 1 mm. After a set time for static sampling, the adsorption tube adsorbs the VOCs emitted from the sampling hood, thus achieving sampling; the adsorption tube is then removed, both ends are resealed, and the sample is sent to the laboratory for thermal desorption-GC / MS analysis.

[0040] Application scenario: During the project acceptance site, VOC screening needs to be carried out at 5 random points on a 50m² floor. Rapid deployment and simultaneous sampling are required.

[0041] The sampling cover can be replaced with transparent PC material, and the height can be reduced to 20 mm to facilitate observation of the adsorption tube position; The pressure rod body 1 and the telescopic rod 11 can be made of carbon fiber, reducing the weight to 0.4 kg; the suction cup is equipped with a rotating paddle, which can quickly release pressure and remove the device with one hand.

[0042] Operation steps for multi-point sampling: Five sampling hoods were arranged in a quincunx pattern on the floor; the distance between the suction cups at both ends of each pressure rod was adjusted to 600 mm (maximum travel of the telescopic rod) to ensure that it spanned multiple floor seams; sampling was started at five points simultaneously, and the adsorption tubes were collected after a set time to complete the initial screening on site.

[0043] The sealing strip has been changed to a segmented airbag structure: a ring-shaped EPDM airbag is embedded in the edge of the cover opening, and the airbag is connected to an external hand-operated inflation ball through a miniature one-way valve; this can be used for adaptive improvements to curved furniture (cylindrical table legs). Before sampling, the airbag is inflated by an inflation balloon to adaptively fill the gap between the cover and the cylinder, thus achieving airtightness.

[0044] In some examples, a support structure can be provided inside the sampling hood so that the adsorption tube is placed on the support and located at the center of the sampling hood.

[0045] The adsorption tube is a passive adsorption tube, which relies on the natural diffusion of VOC molecules to the surface of the adsorbent, and adsorption is achieved without external force.

[0046] By placing the adsorption tube directly in the sampling hood, there is no need to set up structures such as inlet and outlet ports on the sampling hood. The overall structure is simple, the adsorption tube is easy to carry after sampling, and there is no safety risk. This sampling mode eliminates the need to carry nitrogen cylinders, making it convenient for on-site sampling and reducing the overall sampling cost.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A press-fit VOC sampling cover, characterized in that, The device includes a pressure bar and an adsorption tube. The pressure bar is equipped with a sampling cover, and a suction cup is fixed on the pressure bar around the sampling cover. The suction cup is used to adsorb onto the object to be tested. The pressure plate presses the sampling cover onto the object to be tested through the suction cup. The adsorption tube is filled with an adsorbent for adsorbing VOCs. The adsorption tube is covered onto the object to be tested by the sampling cover.

2. The compression-type VOC sampling cover according to claim 1, characterized in that, The sampling cover has an opening at the bottom, and the edge of the opening is provided with a sealing strip.

3. The compression-type VOC sampling cover according to claim 1, characterized in that, The pressure rod includes a pressure rod body and a telescopic rod nested with the pressure rod. One end of the telescopic rod can slide inside the pressure rod, and the other end is located outside the pressure rod.

4. A press-fit VOC sampling cover according to claim 3, characterized in that, The pressure rod and the telescopic rod are provided with through holes at their opposite ends.

5. A press-fit VOC sampling cover according to claim 4, characterized in that, The suction cup is connected to a connecting rod, which passes through a through hole and engages with a fixing component.

6. A press-fit VOC sampling cover according to claim 5, characterized in that, The fixing component is an adjusting nut, and the top of the connecting rod is threaded.

7. A press-fit VOC sampling cover according to claim 3 or 6, characterized in that, A connecting block is provided at the center of the top of the sampling cover, which is connected to the pressure rod body.

8. A press-fit VOC sampling cover according to claim 7, characterized in that, The pressure rod body is provided with an axial slide rail for the telescopic rod to slide inside, and one end of the pressure rod body is open.

9. A press-fit VOC sampling cover according to claim 7, characterized in that, The bottom surface of the pressure rod body is provided with multiple connecting grooves along the length direction, and the rod is connected to the connecting block by snapping or threading through the connecting grooves.

10. A sampling method for a pressure-fit VOC sampling hood, characterized in that, The method of using the compression-type VOC sampling cover as described in any one of claims 9 includes the following steps: Select a sampling hood of appropriate size according to the object to be tested. Based on the size of the sampling hood, pull the telescopic rod outward relative to the pressure rod body to a suitable position. Select the connecting slot near the middle of the pressure rod and connect it to the connecting block to fix the sampling hood. Place the adsorption tube on the position of the object to be tested, cover the adsorption tube with the sampling hood, and the suction cup will adhere to the object to be tested. Tighten the adjusting nut so that the pressure rod presses the sampling hood tightly, and the adsorption tube adsorbs the VOCs emitted from the sampling hood to achieve sampling.

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