Active flow gas zero pressure difference radon exhalation rate measurement device and method

Abstract

An active flow-type zero-pressure differential radon release rate measurement device and method relates to the field of nuclear radiation measurement technology. The device includes a radon collection hood, a radon detector, and a gas pump. The radon detector and the outlet of the radon collection hood are connected. The radon collection hood is connected to a differential pressure gauge. Both the inlet and outlet of the radon collection hood are connected to the outside environment and are each connected to a gas pump. The gas pump can regulate the flow rate at the inlet and outlet of the radon collection hood and maintain pressure balance inside and outside the radon collection hood. The open-loop measurement device of this invention can simultaneously eliminate the influence of back diffusion and negative pressure on the radon release rate and improve measurement accuracy.

Description

Technical Field

[0001] This invention relates to the field of nuclear radiation measurement technology, and in particular to an active flow gas zero-pressure differential radon precipitation rate measurement device and method. Background Technology

[0002] Radon migration within porous media primarily involves diffusion and seepage. Diffusion is driven by a concentration gradient, causing radon to migrate from areas of high concentration to areas of low concentration. Seepage, on the other hand, is driven by pressure, using air or other fluids as carriers for migration. Common methods for measuring radon release rates include closed-loop and open-loop methods. Closed-loop measurement suffers from back diffusion due to excessively high accumulated radon concentration within the radon collection chamber. Open-loop radon release rate measurement avoids this problem by connecting the radon collection chamber's inlet to the external environment; however, the pressure generated during flow rate control can affect radon seepage and release on the surface of the ejected medium. For example, Chinese patent document CN110456405A discloses a method, device and system for measuring radon release rate by electrostatic collection without a flow meter. This method is a typical open-loop radon release rate measurement method. It uses an air pump to draw outside air into the radon collection hood and then sends it into the radon detector. During the process of starting the air pump to promote the exchange of outside gas and gas inside the hood, a relatively negative pressure environment is formed inside the hood, which causes the radon release rate of the ejected gas medium to be greater than the value under natural conditions. Summary of the Invention

[0003] One of the objectives of this invention is to provide an open-loop radon emission rate measuring device that can simultaneously eliminate the effects of back diffusion and negative pressure on the radon emission rate, thereby achieving higher measurement accuracy.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: an active flow-type zero-pressure differential radon emission rate measuring device, comprising a radon collection hood, a radon meter, and an air pump. The radon meter is connected to the outlet of the radon collection hood, the radon collection hood is connected to a differential pressure gauge, and both the inlet and outlet of the radon collection hood are connected to the outside and each is connected to an air pump. The air pump can adjust the flow rate at the inlet and outlet of the radon collection hood and keep the internal and external pressures of the radon collection hood balanced.

[0005] The number of air pumps can be two, with one air pump connected to the air inlet and one air outlet of the radon collection hood.

[0006] Furthermore, if the measurement location is in a high-concentration environment, an adsorption and purification device can be added to the air inlet of the radon collection hood. The adsorption and purification device can adsorb and purify the gas entering from the external environment, thereby reducing the radon concentration of the gas entering the radon collection hood and preventing excessively high external radon concentration from affecting the accumulation of radon inside the collection hood.

[0007] Furthermore, a radon concentration monitoring device is added to the air inlet of the radon collection hood to monitor whether the adsorption and purification device is malfunctioning.

[0008] The differential pressure gauge is used to monitor the pressure difference inside and outside the radon collection hood. By adjusting the flow rate at the inlet and outlet of the radon collection hood using an air pump, the reading of the differential pressure gauge, which displays positive or negative pressure, can be driven to zero (i.e., the pressure difference inside and outside the radon collection hood is zero). Of course, the air pumps at the inlet and outlet of the radon collection hood can also be configured to automatically increase or decrease the flow rate based on the reading of the differential pressure gauge, thereby balancing the air pressure inside and outside the radon collection hood and making the reading of the differential pressure gauge zero.

[0009] Another object of the present invention is to provide an active gas flow zero-pressure difference radon emission rate measurement method, which uses the above-mentioned active gas flow zero-pressure difference radon emission rate measurement device for measurement;

[0010] This method mainly includes the following steps:

[0011] 1. Before the measurement begins, seal the radon collection hood and calibrate it to zero pressure difference. Roughly adjust the air pumps at the inlet and outlet to make the pressure difference between the inside and outside of the sealed radon collection hood zero and keep it stable.

[0012] 2. After calibration, open one end of the radon collection hood, place the radon collection hood on the surface of the medium to be tested, ensure its airtightness, and then fine-tune the air pumps at the inlet and outlet to make the pressure difference zero. Record the inlet and outlet flow rates q. in With q out Then, measurements are taken; the radon concentration is recorded at each measurement cycle ΔT, and the radon concentrations C1, C2, C3...C are recorded sequentially. n ...C n+i Where n is the equilibrium time of radon concentration inside the radon collection hood, and i≥6;

[0013] 3. The radon release rate J on the surface of the medium under test is calculated by combining the differential equation of radon concentration change inside the radon collection hood;

[0014] The differential equation for the change in radon concentration inside the radon collection hood is as follows:

[0015]

[0016] In the formula, V is the internal volume of the radon collection hood, in m³. 3 C represents the radon concentration inside the radon collection hood, in Bq / m³. 3 C0 represents the ambient radon concentration at the radon collection hood inlet, in Bq / m³. 3 t represents the cumulative radon time in seconds; J represents the radon exudation rate on the surface of the test medium in Bq / m³. 2 s; S is the area of ​​the radon collection hood covering the medium to be measured, in m². 2 ;λ e λ is the equivalent decay coefficient of radon.e =λ b +λ l +λ,λ b Let λ be the leakage coefficient. l λ is the anti-diffusion coefficient, and λ is the decay constant, with units of s. -1 ;q in With q out These are the flow rates at the inlet and outlet, respectively, in L / min;

[0017] Solving the differential equation (1) for the radon concentration change above, we get:

[0018]

[0019] Furthermore, during the fine-tuning of the air pump in step two, the following operations are performed based on the observed differential pressure gauge readings:

[0020] a. If the differential pressure gauge reading is zero, the radon detector will begin measurement;

[0021] b. If the differential pressure gauge reading is not zero, fine-tune the air pump: for positive pressure, increase the air pump flow rate at the outlet or decrease the air pump flow rate at the inlet; for negative pressure, decrease the air pump flow rate at the outlet or increase the air pump flow rate at the inlet, until the differential pressure gauge reading is zero, and then start the measurement.

[0022] The measurement time of the radon detector shall not be less than the time during which the radon concentration inside the radon collection hood stabilizes.

[0023] Furthermore, when measured in a low-concentration environment, the environmental concentration is low and can be ignored, i.e., C0 = 0;

[0024] Alternatively, when measuring in a high-concentration environment, an adsorption and purification device located at the air inlet of the radon collection hood can be used to adsorb and purify the gas entering from the external environment, reducing the radon concentration entering the radon collection hood so that the radon concentration C0 entering the radon collection hood approaches 0 Bq / m³. 3 (i.e., C0≈0Bq / m) 3 Repeat the calibration of zero differential pressure step in step one above, then fine-tune the air pump to make the differential pressure zero, and continue the above measurement steps.

[0025] Simplifying equation (2) above, we get:

[0026]

[0027] Furthermore, the above method may also include the following steps:

[0028] IV. Using the above measured values ​​C1, C2, C3...C n ...C n+i Perform a fitting operation and combine the equilibrium concentration obtained from the fitted curve;

[0029] when and The radon concentration inside the radon collection hood (4) tends to stabilize. At this point, the radon release rate J can be calculated using the following formula:

[0030]

[0031] When q out >>λ e V, then λ can be e Ignoring this, formula (4) simplifies to:

[0032]

[0033] The radon detector's measurement time shall not exceed the effective time of the adsorption and purification device; that is, the radon detector's measurement work should be carried out before the adsorption and purification device fails.

[0034] Furthermore,

[0035] make

[0036] Then formula (3) simplifies to:

[0037] C(t)=A(1-e -Bt (6).

[0038] Furthermore,

[0039] The equilibrium concentration is approximately equal to the value A. The radon release rate J on the surface of the gas-ejecting medium to be tested is calculated by combining the value A with formula (4).

[0040] Or, when q out >>λ e V, combined with B value and formula (5), calculate the radon release rate J on the surface of the gas medium to be tested.

[0041] Compared to existing technologies, this invention addresses the issues of back diffusion and negative pressure within the radon collection hood. It incorporates air pumps at both the inlet and outlet of the radon collection hood, using a dual-pump flow control mechanism to manage the pressure difference between the inside and outside of the hood. This approach considers both the impact of back diffusion and the internal pressure difference on radon emission measurement, as well as the influence of seepage within the loose porous medium. The open-loop measuring device of this invention is simple in structure and easy to use. It avoids the back diffusion effect caused by excessive accumulated radon concentration and the negative pressure resulting from excessive circulation flow, which could lead to high-concentration radon emission. Furthermore, it can accurately measure the radon emission rate on the surface of loose porous media in complex environments within a relatively short time. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the radon exudation rate measuring device in the embodiment;

[0043] Figure 2 This is a schematic diagram of the cumulative radon concentration fitting curve at a low flow rate (0.5 L / min) in the example.

[0044] Figure 3 This is a schematic diagram of the cumulative radon concentration fitting curve at a high flow rate (1.48 L / min) in the example.

[0045] In the picture:

[0046] 1 - Air pump; 2 - Adsorption purification device; 3 - Flow meter

[0047] 4—Radon collection hood; 5—Differential pressure gauge; 6—Drying tube

[0048] 7 — Radon detector. Detailed Implementation

[0049] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and accompanying drawings. The content mentioned in the embodiments is not intended to limit the present invention.

[0050] To address the shortcomings of existing open-loop measurement methods, this embodiment considers the issues of back diffusion and negative pressure inside the radon collection hood. It proposes a device structure for controlling the pressure difference inside and outside the radon collection hood using a dual-pump flow coordinated method, along with a corresponding active flow gas-based radon release rate measurement method. This method can simultaneously eliminate the influence of back diffusion and negative pressure on the radon release rate, thereby improving the accuracy of the measurement.

[0051] The open-loop measuring device of this embodiment is an active-flow zero-pressure differential method for measuring radon exhalation rate. It avoids the back-diffusion effect caused by excessively high accumulated radon concentration, and also avoids the negative pressure caused by excessive circulation flow, which leads to high-concentration radon exhalation. Furthermore, it can accurately determine the radon exhalation rate on the surface of the ejected medium in a short time. Simultaneously, the measurement method of this embodiment is an active-flow zero-pressure differential method for continuous measurement of radon exhalation rate. This method uses an active-flow zero-pressure differential method radon exhalation rate measuring device for radon exhalation rate measurement, as detailed below.

[0052] Figure 1The overall structure of the measuring device is shown, which mainly includes a radon detector 7, a high-precision differential pressure gauge 5 (preferably with a resolution of 0.01 Pa), a radon collection hood 4 (the radon collection hood 4 has three vents, corresponding to the inlet, outlet, and vent for connecting the differential pressure gauge 5, respectively; one end of the radon collection hood 4 is completely open, but can be sealed for calibration of zero differential pressure), a precisely adjustable air pump 1, a high-precision flow meter 3 (preferably with a resolution of 0.1 L / min), and a drying tube 6. The air pump 1 and the gas flow meter 3 are installed at both the inlet and outlet of the radon collection hood 4, and are connected to the external environment. The radon detector 7 is located at the end of the outlet. A flow meter 3 is installed on the air pipe between the precisely adjustable air pump 1 and the radon collection hood 4. The radon collection hood 4 is also connected to the high-precision differential pressure gauge 5 (hereinafter referred to as "differential pressure gauge 5"). All the above components can be connected in series using air pipes.

[0053] The measurement method includes the following steps:

[0054] (1) Before the measurement begins, the radon collection hood 4 is sealed and calibrated to zero pressure difference. The air pump 1 at the air inlet and outlet is roughly adjusted, and the reading of the differential pressure gauge 5 is observed to make the internal pressure difference of the sealed radon collection hood 4 zero and stable.

[0055] (2) After calibration, open one end of the radon collection hood 4 and place the radon collection hood 4 on the surface of the medium to be measured. After ensuring its airtightness, observe the reading of the differential pressure gauge 5: if it is zero, start the measurement; if it is not zero, fine-tune the air pump 1: for positive pressure, increase the flow rate of the air pump 1 at the outlet or decrease the flow rate of the air pump 1 at the inlet; for negative pressure, decrease the flow rate of the air pump 1 at the outlet or increase the flow rate of the air pump 1 at the inlet, until the reading of the differential pressure gauge 5 is zero. Then record the inlet and outlet flow rates q. in With q out The measurement officially began. After each measurement cycle ΔT, the radon concentrations C1, C2, C3…C were recorded sequentially. n ...C n+i (n is the moment when the radon concentration inside the radon collection hood 4 reaches equilibrium; i≥6).

[0056] (3) The radon precipitation rate J on the surface of the medium can be calculated by combining the differential equation of radon concentration change inside the radon collection hood; the differential equation of radon concentration change inside the radon collection hood is as follows:

[0057]

[0058] Where V is the internal volume of the radon collection hood 4, in cubic meters (m³). 3 C represents the radon concentration inside radon collection hood 4, in Bq / m³. 3 C0 represents the ambient radon concentration at the four air inlets of the radon collection hood, in Bq / m³. 3 t represents the cumulative radon time in seconds; J represents the radon release rate from the surface of the gas ejection medium (the medium under test) in Bq / m³. 2s; S is the area of ​​the radon collection hood 4 covering the ejected gas medium, in m². 2 ;λ e The equivalent decay coefficient of radon (including the leakage coefficient λ) b anti-diffusion coefficient λ l and decay constant λ; λ e =λ b +λ l +λ), in units of s -1， ;q in With q out These are the inlet and outlet flow rates, respectively, in L / min.

[0059] Solving the above differential equation for radon concentration change yields:

[0060]

[0061] The above applies when the ambient radon concentration (C0) is relatively stable and low.

[0062] Since the ambient concentration is generally low, usually not exceeding 40 Bq / m3, the flow rate is from 1 L / min = 1.67e-5m 3 After / s, the product of the two is relatively low, so the ambient radon concentration C0 can be ignored, i.e., C0 = 0.

[0063] Simplifying the above equation (2) yields:

[0064]

[0065] If the ambient radon concentration is too high or the radon concentration changes significantly over time, an adsorption and purification device 2 can be added at the inlet (air inlet of radon collection hood 4). Figure 1 (As shown), it is used to exclude the influence of high concentrations of radon in the environment on the measurement.

[0066] from Figure 1 As can be seen, the left air inlet of the radon collection hood 4 is connected from left to right to the air pump 1, the adsorption purification device 2 (the adsorption purification device 2 is a preferred addition in high-concentration environments; if the actual measurement is not in a high-concentration environment, then the adsorption purification device 2 does not need to be activated), and the flow meter 3; the right air outlet of the radon collection hood 4 is connected from left to right to the flow meter 3, the drying tube 6, the radon meter 7, and the air pump 1; the differential pressure gauge 5 is connected in the middle of the radon collection hood 4. Of course, the connection order of these components can also be adjusted according to actual needs.

[0067] After installing an adsorption purification device 2 (containing adsorption material, such as activated carbon) at the air inlet, the radon concentration entering the radon collection hood 4 is approximately equal to 0 Bq / m³. 3Repeat the above steps to calibrate to zero differential pressure, then fine-tune air pump 1 to make the differential pressure zero, and continue the above measurement steps.

[0068] At this point, C0 = 0, so simplifying the above equation (2) will also yield:

[0069]

[0070] (4) Using the above measured values ​​C1, C2, C3...C n ...C n+i Perform fitting, and combine the equilibrium concentration obtained from the fitting curve, when and Since the concentration can be considered basically stable, the radon release rate J can be calculated using the following formula:

[0071]

[0072] When q out >>λ e V, i.e., q out Much greater than λ e V, then λ e This can be ignored, and equation (4) simplifies to:

[0073]

[0074] For the aforementioned measuring device, considering the lag in radon concentration measurement by the radon meter 7, the measurement time should be no less than the time it takes for the radon concentration inside the radon collection hood 4 to stabilize, in order to ensure the accuracy of the radon release rate measurement results. Additionally, when an adsorption purification device 2 is installed in the measuring device, a radon concentration monitoring device can be added to the air inlet of the radon collection hood 4 to facilitate observation of whether the adsorption purification device 2 has failed. Furthermore, when an adsorption purification device 2 is added to the air inlet, the measurement time should be less than the penetration time of the adsorption purification device 2 (mainly referring to the activated carbon inside it). Moreover, a separate auxiliary radon collection hood for calibrating zero differential pressure can be installed in the device. This auxiliary radon collection hood is the same size as the cumulative radon collection hood 4, the difference being that the cumulative radon collection hood 4 is fully open on the side facing the ground. In actual testing, an appropriate measurement cycle should be selected based on the flow rate and the volume of the radon collection hood 4.

[0075] This embodiment uses dual-pump flow rate coordination to control the pressure difference inside and outside the radon collection hood 4. It takes into account both the influence of back diffusion inside the radon collection hood 4 and the pressure difference inside and outside on the radon precipitation measurement, as well as the influence of seepage inside the loose porous medium. At the same time, it can accurately measure the radon precipitation rate on the surface of the loose porous medium in a complex environment in a relatively short time.

[0076] In addition, the measuring device and method were also tested in practice in this embodiment, as detailed below.

[0077] The internal volume of the radon collection hood 4 was pre-measured to be approximately 3.14 L, and the coverage area was approximately 0.0314 m². 2 .according to Figure 1 After connecting the devices as shown, begin the zero differential pressure calibration operation. Then, place the radon collection hood 4 on the surface of the medium to be measured, turn on the radon meter 7, and measure and record the radon concentration C1, C2, C3...C inside the radon collection hood 4 in sequence, with each measurement cycle lasting 5 minutes. n ...C n+i .

[0078] The estimated time for the concentration to reach stability is given. In the 3.14L radon collection hood 4, 0.5L / min and 1.5L / min correspond to 8h and 1h35min, respectively.

[0079] To ensure the universality of the zero pressure difference control between the inside and outside of the radon collection hood 4 by the coordinated flow control of the dual pumps, this embodiment adopts the control of the zero pressure difference between the inside and outside of the radon collection hood 4 under two flow rates (0.5L / min and 1.5L / min).

[0080] For ease of calculation, we let

[0081] Then, simplifying, we get: C(t) = A(1-e -Bt (6).

[0082] The results of fitting the experimental data can be found in [reference]. Figure 2 The diagram shows the fitted curve of cumulative radon concentration at a low flow rate (0.5 L / min). Figure 3 The diagram shows the fitted curve of cumulative radon concentration at a high flow rate (1.48 L / min).

[0083] The fitting results are shown in the table below:

[0084] Table 1 Fitting Results

[0085] 0.5±0.01 1862.06±90.36 0.00266±5.28E-4 0.91 1.48±0.01 632.91±26.79 0.00786±0.0018 0.82

[0086] Considering the mathematical characteristics of the fitted curve, the equilibrium concentration is approximately equal to the value of A. Using Formula 4, the radon exhalation rate J on the surface of the gas-ejecting medium can be preliminarily calculated. Furthermore, combining this with the value of B, we find that q... out >>λ e Therefore, formula 5 also applies.

[0087] Table 2. Calculation results of radon exhalation rate at different flow rates

[0088] 0.5±0.01 0.494±0.05 1.48±0.01 0.497±0.04

[0089] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any content that does not depart from the technical solution of the present invention shall still fall within the patent scope of the technical solution of the present invention.

Claims

1. A method for measuring the emanation rate of radon with active flow and zero pressure difference, characterized in that, The active flow type zero pressure difference radon emission rate measurement device is used for measurement; the active flow type zero pressure difference radon emission rate measurement device includes a radon collection hood (4), a radon meter (7) and an air pump (1). The radon meter (7) is connected to the outlet of the radon collection hood (4). The radon collection hood (4) is connected to a differential pressure gauge (5). The inlet and outlet of the radon collection hood (4) are both connected to the outside and each is connected to an air pump (1). The air pump (1) can adjust the flow rate of the inlet and outlet of the radon collection hood (4) and keep the internal and external pressures of the radon collection hood (4) balanced. The method includes the following steps:

1. Before the measurement begins, seal the radon collection hood (4) and calibrate it to zero pressure difference. Roughly adjust the air pump (1) connected to the air inlet and outlet to make the pressure difference inside and outside the sealed radon collection hood (4) zero and keep it stable.

2. After calibration, open one end of the radon collection hood (4), place the radon collection hood (4) on the surface of the medium to be tested, ensure its airtightness, and then fine-tune the air pump (1) connected to the air inlet and outlet to make the pressure difference zero, and record the inlet and outlet flow rates q. in With q out Then, measurements are taken; the radon concentration is recorded at each measurement cycle ΔT, and the radon concentrations C1, C2, C3...C are recorded sequentially. n ...C n+i Where n is the equilibrium time of radon concentration inside the radon collection hood (4), and i≥6; III. Calculate the radon exhalation rate of the surface of the medium to be measured in combination with the differential equation of the radon concentration change in the radon collection hood ; The differential equation for the change in radon concentration inside the radon collection hood is as follows: （1）； In the formula, V is the internal volume of the radon collection hood (4), in m³. 3 C represents the radon concentration inside the radon collection hood (4), in units of Bq / m³. 3 C0 represents the ambient radon concentration at the air inlet of the radon collection hood (4), in Bq / m³. 3 t represents the cumulative radon time in seconds; J represents the radon exudation rate on the surface of the test medium in Bq / m³. 2 s; S is the area of ​​the radon collection hood (4) covering the medium to be measured, in m². 2 ; The equivalent decay coefficient of radon. , Leakage coefficient, The anti-diffusion coefficient is... The decay constant is expressed in seconds. -1 ;q in With q out These are the flow rates at the inlet and outlet, respectively, in L / min; 1 L / min = 1.67e-5m 3 / s; Solving the differential equation (1) for the radon concentration change above, we get: （2）； When measuring in a low-concentration environment, let C0=0; Alternatively, when measuring in a high-concentration environment, the adsorption and purification device (2) located at the air inlet of the radon collection hood (4) is used to adsorb and purify the gas entering from the external environment, reducing the radon concentration entering the radon collection hood (4) so ​​that the radon concentration C0 entering the radon collection hood (4) approaches 0 Bq / m³. 3 Repeat the above calibration zero pressure difference steps, then fine-tune the air pump (1) to make the pressure difference zero, and continue the above measurement steps; Simplifying equation (2) above, we get: （3）； Using the above measured values ​​C1, C2, C3...C n ...C n+i Perform a fitting operation and combine the equilibrium concentration obtained from the fitted curve; When , and , the radon concentration in the set radon cover (4) tends to be stable, and at this time, the radon exhalation rate J is calculated using the following formula: （4）； When then Neglecting, equation (4) is simplified as: （5）。 2. The method of claim 1, wherein, In step two, when fine-tuning the air pump (1), perform the following operations based on the observed reading of the differential pressure gauge (5): a. If the reading of the differential pressure gauge (5) is zero, the radon meter (7) will start measuring; b. If the reading of the differential pressure gauge (5) is not zero, fine-tune the air pump (1): for positive pressure, increase the flow rate of the air pump (1) connected to the outlet or decrease the flow rate of the air pump (1) connected to the inlet; for negative pressure, decrease the flow rate of the air pump (1) connected to the outlet or increase the flow rate of the air pump (1) connected to the inlet until the reading of the differential pressure gauge (5) is zero, and then start the measurement.

3. The active flow gas zero-pressure differential radon exudation rate measurement method according to claim 1, characterized in that: Let ; ; Then formula (3) simplifies to: （6）。 4. The active flow gas zero-pressure differential radon precipitation rate measurement method according to claim 3, characterized in that: The equilibrium concentration is approximately equal to the value of A. Combine the value of A with formula (4) to calculate the radon release rate J on the surface of the gas-ejecting medium to be tested. Or, when The radon exhalation rate J of the surface of the measured emanation medium is calculated in combination with the value of B and equation (5).

5. The method of claim 1, wherein: The measurement time of the radon meter (7) shall not exceed the effective time of the adsorption purification device (2).

6. The method of claim 1, wherein: The air inlet of the radon collection hood (4) is also connected to an adsorption purification device (2), which can adsorb and purify the gas entering from the external environment, thereby reducing the radon concentration in the gas entering the radon collection hood (4).

7. The method of claim 6, wherein: The radon collection hood (4) is equipped with a radon concentration monitoring device at its air inlet to monitor whether the adsorption and purification device (2) is malfunctioning.

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