JP5245676B2 - Method for measuring volatile organic compounds - Google Patents

Description

  The present invention relates to a volatile organic compound measurement method capable of easily measuring the volatile organic compounds (hereinafter also referred to as “VOC”) emission rate, and in particular, the volatile organic compound emission rate emitted from a component. The present invention relates to a method for measuring a volatile organic compound suitable for the measurement.

  In recent years, sick house syndrome has become a problem, and the Ministry of Health, Labor and Welfare's indoor concentration guideline values and environmental hygiene standards based on the School Health Law have been established and revised. In response to this, the Japan Electronics and Information Technology Industries Association (JEITA) established the “VOC Guidelines for Personal Computers (First Edition)”, and guideline values and emission rates for regulated substances (toluene, xylene, paradichlorobenzene, ethylbenzene and styrene). A speed measurement method is specified.

  In the above-mentioned VOC guideline (hereinafter simply referred to as “VOC guideline”) regarding a personal computer issued by JEITA, it is prescribed that the VOC emission rate is measured by a so-called chamber method. FIG. 1 shows a configuration example of a VOC measurement system used for measuring the VOC emission rate. FIG. 2 shows the measurement conditions for the VOC emission rate, and FIG. 3 shows the guide values for the emission rate of each controlled substance. Note that Vp in FIG. 2 is the volume of the device under measurement (product to be measured), and Vk is the volume of the chamber.

  As shown in FIG. 1, the VOC measurement system includes an air control unit 11, a mixing bath 12, a thermostatic bath 13, a chamber 14, a gas chromatograph analyzer 15, and a TENAX (registered trademark) tube (a tube filled with a granular adsorbent). 16 and the sampling pump 17. A measurement target product (a personal computer or a display) 10 is disposed in a chamber 14. The chamber 14 is required to have a volume 4 to 100 times that of the measurement target product 10. Moreover, the chamber 14 is arrange | positioned in the thermostat 13, and is hold | maintained at fixed temperature (23 degreeC +/- 2 degreeC).

  Air in the chamber 14 is circulated by the air control unit 11, and the ventilation frequency is set to 0.5 times / h or 1 time / h. A mixing tank 12 is disposed between the air control unit 11 and the chamber 14, and the humidity of the air supplied into the chamber 14 is maintained at 50% ± 5% RH by the mixing tank 12.

  The measurement target product 10 is operated in the chamber 14 for 5 hours. Thereafter, the sampling pump 17 is operated to allow the air in the chamber 14 to flow through the TENAX tube 16, and the TENAX tube 16 is attached to the gas chromatograph analyzer 15 to measure the concentration of each regulated substance. Then, the diffusion rate is calculated by the following equation (1).

ここで、ＳＥＲ_UBは各規制物質の放散速度（μｇ/ｈ）、Ｙ_nは各規制物質の濃度（μｇ/ｍ³）、ｎ_Bは換気回数（回/ｈ）、Ｖ_Kはチャンバー１４の容積（ｍ³）である。

Here, SER _UB is the emission rate of each controlled substance (μg / h), Y _n is the concentration of each controlled substance (μg / m ³ ), n _B is the ventilation frequency (times / h), and V _K is the chamber 14 Volume (m ³ ).

  In addition, there exist some which were described in patent documents 1-6 as a prior art considered to be related to this invention. Patent Document 1 describes that gas released from an object (such as a human body) is collected in a bag and then analyzed by a gas chromatograph analyzer or the like. Patent Document 2 describes that a sample is accommodated in a small container made of polypropylene or glass and the volatile components released from the sample are analyzed.

Patent Document 3 describes that after a gas component is adsorbed on a flat surface of a substrate, the gas component is analyzed by either a time-of-flight secondary ion mass spectrometer or a Fourier transform infrared spectrometer. . Patent Documents 4 and 5 describe examples of VOC measurement devices. These VOC measuring devices described in Patent Documents 4 and 5 each measure the amount of VOC by the chamber method. Patent Document 6 describes an example of a gas chromatograph analyzer.
JP 2007-155385 A JP 2007-101337 A JP 2003-42951 A JP 2007-178288 A JP 2005-257588 A JP 2005-77144 A JP 2005-156299 A Japanese Patent No. 3502622 Fumiyo Takeuchi and Mitsuo Ozaki, “Evaluation Method of VOC Emission Rate from Electrical Components (Transformers)”, Proceedings of the 26th Annual Conference on Air Cleaning and Contamination Control, pages 212-214

  The method for measuring the VOC emission rate defined in the VOC guideline described above requires a large amount of equipment and takes time for measurement. In order to reduce VOC, it is important to know the VOC emission rate for each part used in the product, but according to the VOC guidelines, the VOC is measured by actually operating the product to be measured (PC or display). Therefore, the VOC emission rate from a specific part cannot be measured. Although it is conceivable to arrange only a specific part in the chamber and measure the VOC emission rate, there is a problem that the measurement takes time. In addition, the actual use state cannot be reproduced simply by placing specific parts in the chamber.

  When measuring VOCs emitted from parts used in products, the parts and clean gas (air, etc.) are sealed in a sealed bag and after a certain period of time (or after heating for a certain period of time). It is conceivable to analyze the gas in the bag and measure the type and concentration of the VOC. Such a method is called a bag method.

  However, the bag method is usually a one-time measurement, and the result is the relationship between the types of VOCs generated from the parts and the amount of those generated, and the product is actually operated like the chamber method. The emission rate cannot be measured by reproducing the effects of temperature rise and ventilation. The bag method is used for qualitative analysis such as VOC.

  Therefore, a measurement method that can measure the VOC emission rate in a relatively short time using an apparatus having a relatively simple configuration with respect to the volatile organic compound measurement method, and can also be applied to the measurement of the VOC emission rate from a specific part. The purpose is to provide.

According to one aspect, there is provided a method for measuring the emission rate of a volatile organic compound released from a sample in an evaluation target environment, the step of enclosing the sample in a bag, and a bag in which the sample is enclosed A step of injecting a gas with time, a step of measuring the concentration of the volatile organic compound contained in the gas in the bag a plurality of times over time, and the emission rate of the volatile organic compound from the measurement result of the concentration The emission rate value is corrected according to the difference between the temperature in the step of calculating the concentration of the volatile organic compound and the temperature of the evaluation target environment and the ventilation frequency in the evaluation target environment. It possesses a step, wherein in the step of measuring the concentration of volatile organic compounds, the amount of gas taken from the bag, volatile organic compounds measured are small amount relative to the total amount of the gas in the bag The law is provided.

  In the above aspect, after the sample and the gas are sealed in the bag, the concentration of VOC (volatile organic compound) contained in the gas is measured at least twice with a time interval. Then, the VOC emission rate is calculated from the change in concentration.

  The VOC guidelines stipulate that the product is in operation and ventilated to measure the VOC emission rate. Therefore, in the present invention, when a change in the VOC emission amount due to the temperature rise of the component becomes a problem, the VOC emission rate is corrected according to the temperature of the sample during operation. Further, since the diffusion rate changes due to ventilation, the VOC emission rate is corrected according to the number of ventilations.

  In the case of a sample with a large amount of VOC emission, the VOC concentration in the bag rapidly increases immediately after sealing in the bag, and then the rate of increase in the VOC concentration decreases with time. Therefore, when the VOC concentration is measured immediately after sealing in the bag and after a short time has elapsed, and the VOC emission rate is calculated from the measurement results, it is a larger value than when the VOC emission rate is measured according to the VOC guidelines. It becomes.

  In other words, if the VOC emission rate is measured based on the above viewpoint and the emission rate is smaller than the guide value of the VOC guideline, it will be smaller than the guide value even if the release rate is measured according to the VOC guideline. Can do. On the other hand, when the VOC emission rate is measured based on the above viewpoint and the emission rate is larger than the guide value of the VOC guideline, when the emission rate is measured according to the VOC guideline, Sometimes it grows. In such a case, the dissipation rate may be measured according to VOC guidelines as necessary. Alternatively, the VOC reduction processing such as heating may be performed on the component, and it may be mounted on the product after confirming that it is below the guideline value of the VOC guideline.

  Hereinafter, embodiments will be described with reference to the accompanying drawings.

(First embodiment)
FIG. 4 is a schematic diagram showing a VOC measurement method according to the first embodiment. In the first embodiment, a sample (product or a part used for the product) 22 and a clean gas are enclosed in a sealed sampling bag 21. Then, the gas is sampled from the sampling bag 21 at least twice with time, the VOC concentration in the gas is measured by the measuring device 23, and the dissipation rate is calculated from the change in the VOC concentration. And correction calculation is performed with respect to this diffusion rate so as to correspond to the diffusion rate when measured by the chamber method.

  The gas sealed in the sampling bag 21 is preferably the same as the atmosphere when the product is used, and air can be used. However, in that case, it is necessary to sufficiently remove foreign substances contained in the air by a method such as passing through a filter. From the viewpoint of removing the influence of foreign substances contained in the gas, nitrogen or other gas purified in advance may be used. Nitrogen is an element that occupies about 80% of the air, and is also suitable from the viewpoint of reproducing the atmosphere when the product is used.

  The amount of gas sealed in the sampling bag 21 is preferably sufficiently larger than the amount of gas sampled for measurement. Thereby, the gas reduction by sampling can be prevented from affecting the next measurement.

  The measuring device 23 only needs to be capable of quantitatively measuring VOC with an accuracy of about 5%. Various types of measuring instruments having a sampling amount of 5 to 100 mL (milliliter) are commercially available (for example, VOC monitor JHV-1000 manufactured by JMS). If the sampling amount required for one measurement is 100 mL and the gas filling amount in the sampling bag 21 is 20 L (liter), the amount of gas reduction in the sampling bag 21 in one measurement is 0.5%. . As described above, since the accuracy of the VOC quantitative measurement of the measuring device 23 used in the present embodiment is about 5%, it may be considered that the influence of the amount of gas decrease due to sampling can be ignored in about 10 measurements.

  FIG. 5 (a) shows the VOC (xylene) concentration in the bag in which two samples (sample A and sample B) are enclosed, with the elapsed time on the horizontal axis and the VOC (xylene) concentration on the vertical axis. It is a figure which shows the result of having measured the change. FIG. 5B shows the xylene concentration on the vertical axis in FIG. 5A converted into the xylene emission amount. However, in sample A with a small VOC (xylene) emission amount, 20 L of gas is enclosed in the sampling bag 21, and in sample B with a large VOC (xylene) emission amount, 30 L of gas is enclosed in the sampling bag 21. Yes.

  As can be seen from FIGS. 5 (a) and 5 (b), in the sample B with a large amount of VOC (xylene) emission, the VOC concentration in the bag suddenly increases immediately after sealing in the bag, and the concentration increases with time. The rate is small. On the other hand, in the sample A with a small amount of VOC emission, the VOC concentration in the bag increases gently and almost linearly with respect to the elapsed time.

After measuring the time change of the VCO concentration by the above method, the diffusion rate _Sb is calculated by the following equation (2).

ここで、Ｚ₀はＶＯＣ濃度の初期値、Ｚ₁はΔｔ時間経過後のＶＯＣ濃度、Ｖ_Nはサンプリングバッグ２１に封入した気体の量である。なお、本実施形態では、ＶＯＣ濃度の初期値Ｚ₀として、サンプリングバッグ２１内に規定量の気体を封入した直後にバッグ２１内の気体をサンプリングして測定したＶＯＣ濃度を採用する。後述するように、本実施形態では、バッグ２１内への規定量の気体の注入に要する時間を１０分としている。この時間は１０分に限定するものではないが、ＶＯＣ濃度の初期値に関係するので、全ての試料に対し同じ時間とすることが重要である。

Here, Z ₀ is the initial value of the VOC concentration, Z ₁ is the VOC concentration after the lapse of Δt time, and V _N is the amount of gas sealed in the sampling bag 21. In the present embodiment, the VOC concentration measured by sampling the gas in the bag 21 immediately after enclosing a predetermined amount of gas in the sampling bag 21 is used as the initial value Z ₀ of the VOC concentration. As will be described later, in this embodiment, the time required for injecting a prescribed amount of gas into the bag 21 is 10 minutes. This time is not limited to 10 minutes, but is related to the initial value of the VOC concentration, so it is important to set the same time for all samples.

Emission rate S _b represents the slope of the left side portion of the curve shown in Figure 5 (b). When Δt is 1 hour, in the example shown in FIGS. 5A and 5B, the diffusion rate S _{b of} sample A is about 2.5 μg / h, and the diffusion rate S _{b of} sample B is about 40.3 μg / h. It becomes.

By the way, the VOC guideline stipulates that the product is actually operated when the VOC emission rate is measured. Operating the product raises the temperature of the part and increases the amount of VOC emission. Therefore, in order to correspond to the VOC emission rate measured along the (2) VOC guidelines dissipation rate S _b determined by the formula, increases for when operating the product coefficients (hereinafter, referred to as "increase factor according to operating" ) It is necessary to perform correction in consideration of Kon. In the present embodiment, the increase coefficient Kon due to operation is determined as follows.

That is, a sample and a clean gas (air or nitrogen) are enclosed in a sampling bag, and the temperature is raised to a component temperature during operation of the apparatus that has been measured in advance. Thereafter, the VOC concentration in the sampling bag is measured to calculate the VOC emission rate S _b1 . On the other hand, the VOC diffusion rate S _b2 at normal temperature is measured in the same manner as described above except that the component temperature is normal temperature (23 ° C. ± 2 ° C.). Then, the ratio (S _b1 / S _b2 ) of these emission rates is taken as an increase coefficient Kon. Instead of using the actual measured temperature of the component during operation, the component temperature during design may be used as the component temperature during operation of the apparatus.

The VOC guideline stipulates that the chamber be ventilated. Therefore, in order to correspond to the emission rate measured along the VOC guidelines dissipation rate S _b obtained by the above equation (2) may be corrected in consideration of changes due to ventilation factor. In the present embodiment, a change coefficient K _vent due to ventilation is obtained by the following equation (3).

但し、（３）式において、ｎは換気回数を示し、１時間で１回換気する場合にはｎ＝１となる。また、ｎ・Δｔ/（１＋ｎ・Δｔ）は時間Δｔにおける容積変化率を示し、Ｚ₁/（Ｚ₁−Ｚ₀）は時間Δｔにおける濃度変化率を示している。

However, in the formula (3), n represents the number of ventilations, and n = 1 when ventilation is performed once in one hour. Further, n · Δt / (1 + n · Δt) represents the volume change rate at time Δt, and Z ₁ / (Z ₁ −Z ₀ ) represents the concentration change rate at time Δt.

In the present embodiment, the dissipation rate S _b obtained by the equation (2) is multiplied by the above-described increase coefficient Kon due to operation, or the increase coefficient Kon and the change coefficient K _vent due to ventilation (that is, the dissipation rate S _b is calculated by Corrected value is the predicted value of the peak of the emission rate when the VOC emission rate is measured by the chamber method, and based on this predicted value (hereinafter referred to as “evaluation value”), whether or not the part is suitable for use in a product To evaluate.

  The VOC emission rate when measured by the chamber method usually shows a change as shown in FIG. That is, a sample with a large amount of VOC emission has a high emission rate peak and reaches the peak in a relatively short time (usually within about 2 hours). And after passing the peak, the dissipation rate gradually decreases. On the other hand, a sample with a small amount of VOC emission has a low peak emission rate and is gentle. Also, the rate of decrease in the dissipation rate after passing the peak is small. From these facts, it can be seen that if the initial behavior of the emission rate can be grasped, the subsequent change in the emission rate can be predicted to some extent.

  As described above, the VOC guidelines stipulate that the emission rate is measured after 5 hours have elapsed since the product was put into operation. As can be seen from FIG. 6, the emission rate when measured by the chamber method after the lapse of 5 hours is usually around the peak. In this embodiment, the peak value of the VOC emission rate when measured by the chamber method is predicted from the VOC concentration in the bag, but the peak value of the VOC emission rate when measured by the chamber method was measured according to the guidelines. It becomes larger than the value of the VOC emission rate (the VOC emission rate after the elapse of 5 hours from the operation state). Therefore, the VOC emission rate (evaluation value) obtained by the present embodiment is usually a value larger than the VOC emission rate measured along the VOC guidelines. That is, when the VOC emission rate (evaluation value) obtained by the present embodiment is lower than the guide value of the VOC guideline, it can be said that even if the VOC release rate is measured according to the VOC guideline, it becomes lower than the guide value.

  According to the present embodiment, the VOC emission rate can be easily measured at the component stage without using a large-scale apparatus. Further, the VCO emission rate in the product operating state when measured according to the VOC guidelines can be estimated from the VOC emission rate obtained at the part stage. As a result, a screening test can be performed on a single component, and whether or not the component is suitable for use in a product can be efficiently evaluated.

Hereinafter, a measurement example of the diffusion rate of the VOC diffused from the liquid crystal display will be described.
The inventors of the present application conducted a decomposition investigation on a liquid crystal display in which xylene was frequently generated by the chamber method. As a result, it has been found that in this liquid crystal display, the VOC generation source is mainly a power transformer. Here, the dissipation rates of two power transformers (sample A and sample B) were measured.

(Measurement Example 1)
First, a Tedlar (registered trademark) bag was prepared as a sampling bag. Then, after cutting a part of the Tedlar bag and inserting the sample A (transformer), the cut portion was sealed by thermocompression bonding. In the same manner, sample B (trans) was also enclosed in a Tedlar bag.

  Next, the cock at the inlet provided in the Tedlar bag was opened and the vacuum was drawn to discharge the gas in the bag. Thereafter, 20 L of clean nitrogen gas was introduced into the Tedlar bag into which the sample A was inserted at a flow rate of 2 L / min for 10 minutes, and then the cock was closed. And immediately after closing a cock, the gas in a bag was sampled and the VOC density | concentration was measured with the VOC measuring device (VOC monitor JHV-1000 by JMS Co., Ltd.). Thereafter, the gas in the bag was sampled every hour, and the VOC concentration was measured with a VOC measuring device.

  Similarly, 30 L of clean nitrogen gas was introduced at a flow rate of 3 L / min into the Tedlar bag into which the sample B was inserted for 10 minutes, and then the cock was closed. And immediately after closing a cock, the gas in a bag was sampled and the VOC density | concentration was measured with the VOC measuring device. Thereafter, the gas in the bag was sampled every hour, and the VOC concentration was measured with a VOC measuring device. FIG. 5A described above shows the measurement results of the VOC concentrations of the two samples (sample A and sample B) measured in this way.

Samples A, since the initial value of VOC (xylene) concentration VOC concentration after 26 micrograms / m ^3, 1 hour is at 149μg / m ^3, when determining the emission rate S _b by the expression (2), the following ( 4) As shown in the formula, it becomes about 2.5 μg / h.

試料Ｂについて、ＶＯＣ（キシレン）濃度の初期値が１７４μｇ/ｍ³、１時間経過後のＶＯＣ濃度が１５１７μｇ/ｍ³であるので、前記（２）式により放散速度Ｓ_bを求めると、下記（５）式に示すように約４０．３μｇ/ｈとなる。

Samples B, since the initial value of VOC (xylene) concentration VOC concentration after 174μg / m ^3, 1 hour is at 1517μg / m ^3, when determining the emission rate S _b by the expression (2), the following ( 5) As shown in the formula, it is about 40.3 μg / h.

なお、図５（ａ）の例では、１時間毎にＶＯＣ（キシレン）濃度を測定している。これは、ＶＯＣ濃度の測定間隔を長くすると、特にＶＯＣ放散量が多い試料ではＶＯＣ放散速度を過少評価してしまうおそれがあるためである。従って、ＶＯＣ濃度は、短い間隔で測定することが好ましい。また、ここでは放散速度Ｓ_bを算出する時間間隔Δｔを１時間としているが、ΔｔはＶＯＣガイドラインで定める１換気に要する時間、すなわち１時間〜２時間の範囲内で定めるのがよい。この時間間隔Δｔを長くすると、やはりＶＯＣ放散速度を過少評価してしまうおそれがある。

In the example of FIG. 5A, the VOC (xylene) concentration is measured every hour. This is because if the measurement interval of the VOC concentration is increased, the VOC emission rate may be underestimated particularly in a sample having a large amount of VOC emission. Therefore, it is preferable to measure the VOC concentration at short intervals. Although here to be 1 hour time interval Delta] t to calculate the emission rate S _b, Delta] t is the time required for one ventilation prescribed in VOC guidelines, namely better to define in the range of 1 to 2 hours. If this time interval Δt is increased, the VOC emission rate may be underestimated.

  Furthermore, in the above example, the gas injection amount (Tedlar bag capacity) is changed according to the sample. This is for avoiding that the VOC concentration in the sampled gas becomes extremely high (or extremely low) and the measurement accuracy by the VOC measuring device is lowered.

(Measurement example 2)
First, in order to measure the temperature of the power transformer during operation, the back cover of the display was removed so that the power transformer could be seen from the outside. Moreover, a personal computer was connected to the display, and the personal computer and the display were energized to be in an operating state. In this state, the temperature of the power transformer was measured with a thermocouple. As a result, the temperature of the power transformer was 60 ° C. Note that the power transformer used in the display is different from the sample A and the sample B described above.

Next, in order to measure the VOC emission rate at room temperature from the power transformer, a power transformer of the same type as that used for the display was placed in a Tedlar bag having a capacity of 30 L and evacuated. Thereafter, 30 L of clean nitrogen was sealed in a Tedlar bag at a flow rate of 3 L / min for 10 minutes. The gas was sampled from the Tedlar bag immediately after sealing and after 1 hour, and the VOC (xylene) concentration was measured with a VOC measuring device. As a result, the VOC concentration immediately after encapsulation was 174 μg / m ³ , and the VOC (xylene) concentration after 1 hour was 884 μg / m ³ . From these values, the VOC (xylene) diffusion rate S _b at room temperature is calculated to be about 21.3 μg / h as shown in the following equation (6).

次に、稼働状態における電源トランスからのＶＯＣ放散速度を測定するために、ディスプレイに使用されているのと同種の電源トランスを容量が５０Ｌのテドラーバッグに入れ、真空引きした。その後、テドラーバッグ内に４０Ｌの清浄な窒素を４Ｌ/ｍｉｎの流量で１０分かけて封入した。そして、封入直後にテドラーバッグから気体をサンプリングし、ＶＯＣ測定器でＶＯＣ（キシレン）濃度を測定した。その結果、ＶＯＣ（キシレン）濃度は１６２μｇ/ｍ³であった。なお、ここでは、テドラーバッグの容量及び窒素の注入量を、電源トランスからのＶＯＣ放散量と加熱による熱膨張とを考慮して決めている。

Next, in order to measure the VOC emission rate from the power transformer in the operating state, a power transformer of the same type as that used for the display was put in a Tedlar bag having a capacity of 50 L and evacuated. Thereafter, 40 L of clean nitrogen was sealed in the Tedlar bag at a flow rate of 4 L / min for 10 minutes. And gas was sampled from the Tedlar bag immediately after enclosure, and the VOC (xylene) density | concentration was measured with the VOC measuring device. As a result, the VOC (xylene) concentration was 162 μg / m ³ . Here, the capacity of the Tedlar bag and the amount of nitrogen injected are determined in consideration of the amount of VOC emission from the power transformer and the thermal expansion due to heating.

The Tedlar bag filled with the power transformer and nitrogen described above was placed in a thermostat at 60 ° C., and after 1 hour, 200 mL of gas was sampled from the thermostat and transferred to another bag and cooled to room temperature. Then, normal temperature gas was sampled from the bag and the concentration of VOC (xylene) was measured with a VOC measuring device. As a result, the VOC (xylene) concentration was 1510 μg / m ³ . When the VOC (xylene) emission rate S _b in the operating state is calculated from the value of the VOC concentration immediately after the encapsulation and after 1 hour has elapsed, it is about 52.9 μg / h as shown in the following equation (7).

稼働による増加係数Ｋonは、前述したように常温におけるＶＯＣ放散速度と稼動状態におけるＶＯＣ放散速度との比をとることにより得られる。ここで、稼働による増加係数Ｋonを計算すると、下記（８）式に示すように約２．５となる。

The increase coefficient Kon due to operation is obtained by taking the ratio between the VOC emission rate at normal temperature and the VOC emission rate in the operation state as described above. Here, when the increase coefficient Kon due to operation is calculated, it becomes about 2.5 as shown in the following equation (8).

図７に、測定条件、ＶＯＣ濃度の測定タイミング、ＶＯＣ（キシレン）濃度の測定値、
放散速度の計算値及び稼働による増加係数Ｋonをまとめて示す。

FIG. 7 shows measurement conditions, measurement timing of VOC concentration, measured value of VOC (xylene) concentration,
The calculated value of the emission rate and the increase coefficient Kon due to operation are shown together.

  Note that when a high-temperature gas is directly sampled from the sampling bag, the VOC passes through without being adsorbed by the adsorbent (TENAX-TA or the like). For this reason, in the above example, the gas sampled from the Tedlar bag is transferred to another bag and cooled to room temperature, and then the room temperature gas is sampled from the bag to measure the VOC concentration. Instead of such a method, for example, as shown in FIG. 8, a pipe 33 a that connects between the sampling bag 21 in which the sample 22 is sealed and a pump 32 that extracts the gas in the sampling bag 21 to the outside of the thermostat 31. A cooler 34 is attached to cool the gas to room temperature, and a sampling port 35 is provided in the return pipe 33b from the pump 32 to the sampling bag 21 so that the room temperature gas can be sampled from the sampling port 35. Good.

(Estimation of emission rate)
Based on the measurement result of Measurement Example 2, the peak value of the VOC emission rate when measured by the chamber method was estimated. Then, the estimated peak value (evaluation value) of the VOC emission rate was compared with the peak value of the VOC emission rate actually measured by the chamber method. That is, a power transformer of the same type as that used in the above-mentioned display is housed in a chamber with a capacity of 20 L, and the ventilation frequency is 1 hour / h under normal temperature environment (333 mL / min in terms of flow rate). The flow of clean nitrogen was continued, the discharged gas was sampled every hour, and the VOC concentration was measured by a VOC measuring device. As described in the Measurement Example 2, VOC concentration Z ₀ immediately after encapsulation is 174μg / m ^3, since VOC concentration Z ₁ after a lapse of 1 hour is the 884μg / m ^3, changes due to ventilation coefficient K _vent is As shown in the following formula (9), it is 0.62.

前述したように、この電源トランスの常温における１時間後のＶＯＣ（キシレン）放散速度は約２１．３μｇ/ｈである。これらのことから、この電源トランスをチャンバー法で測定した場合のＶＯＣ放散速度のピーク値は、下記（１０）式に示すように１３．２μｇ/ｈと推定される。従って、ここでは、電源トランスのＶＯＣ放散速度の評価値を１３．２μｇ/ｈとした。

As described above, the VOC (xylene) emission rate after 1 hour at room temperature of this power transformer is about 21.3 μg / h. From these facts, the peak value of the VOC emission rate when this power transformer is measured by the chamber method is estimated to be 13.2 μg / h as shown in the following equation (10). Therefore, here, the evaluation value of the VOC dissipation rate of the power transformer is 13.2 μg / h.

この電源トランスについて、実際に上記の条件でチャンバー法により１時間毎の放散速度を測定した。その結果を図９に示す。この図９からわかるように、放散速度のピーク値は１３．８μｇ/ｈであり、本実施形態の方法により求めた評価値（１３．２μｇ/ｈ）に近いことがわかる。

With respect to this power transformer, the diffusion rate per hour was actually measured by the chamber method under the above conditions. The result is shown in FIG. As can be seen from FIG. 9, the peak value of the emission rate is 13.8 μg / h, which is close to the evaluation value (13.2 μg / h) obtained by the method of the present embodiment.

(Evaluation of suitability of power transformer)
Regarding Sample A and Sample B, whose diffusion rates at room temperature were measured in Measurement Example 1, the suitability for use in products was examined. Here, the ventilation frequency n is set to 1 / h in accordance with the VOC guidelines.

When the coefficient of change K _vent due to ventilation is calculated for sample A, the initial value Z _{0 of the} VOC concentration is 2
Since 6 μg / m ³ and VOC concentration Z ₁ after 1 hour is 149 μg / m ³ , the following (11)
As shown in the equation, 0.61 is obtained.

また、温度による増加係数Ｋonは前述の測定例２に示すように２．５であり、放散速度Ｓ_bは測定例１に示すように２．５μｇ/ｈであるので、ＶＯＣガイドラインに沿って測定した場合のＶＯＣ放散速度のピーク値の推定値（評価値）ＳＥＲは、下記（１２）式に示すように３．８μｇ/ｈとなる。

Further, since the increase factor Kon with temperature is 2.5 as shown in Measurement Example 2 above, are emission rates S _b as is shown in Measurement Example 1 2.5 [mu] g / h, measured along the VOC guidelines In this case, the estimated value (evaluation value) SER of the peak value of the VOC emission rate is 3.8 μg / h as shown in the following equation (12).

これと同様に、試料Ｂについて換気による変化係数Ｋ_ventを計算すると、ＶＯＣ濃度の
初期値Ｚ₀が１７４μｇ/ｍ³、１時間経過後のＶＯＣ濃度Ｚ₁が１５１７μｇ/ｍ³であるので、下記（１３）式に示すように０．５６となる。

Similarly, when the change coefficient K _vent due to ventilation is calculated for sample B, the initial value Z ₀ of the VOC concentration is 174 μg / m ³ , and the VOC concentration Z ₁ after one hour has elapsed is 1517 μg / m ^3. As shown in the equation (13), it is 0.56.

また、温度による増加係数Ｋonは前述の測定例２に示すように２．５であり、放散速度Ｓ_bは測定例１に示すように４０．３μｇ/ｈであるので、ＶＯＣガイドラインに沿って測定した場合のＶＯＣ放散速度のピーク値の推定値（評価値）ＳＥＲは、下記（１４）式に示すように５６．４μｇ/ｈとなる。

Further, the increase coefficient Kon due to temperature is 2.5 as shown in the above-described measurement example 2, and the diffusion rate S _b is 40.3 μg / h as shown in the measurement example 1, so that the measurement is performed according to the VOC guidelines. In this case, the estimated value (evaluation value) SER of the peak value of the VOC emission rate is 56.4 μg / h as shown in the following equation (14).

ＶＯＣガイドラインに規定するディスプレイのキシレン放散速度の指針値は、４３５μｇ/ｈ・unitである（図３参照）。従って、本実施形態により求めた試料Ａ及び試料Ｂのトランスのキシレン放散速度（評価値）はいずれもＶＯＣガイドラインに規定するキシレン放散速度の指針値よりも小さく、ディスプレイへの使用に適していると判定することができる。

The guide value for the xylene emission rate of the display specified in the VOC guidelines is 435 μg / h · unit (see FIG. 3). Therefore, the xylene emission rates (evaluation values) of the transformers of sample A and sample B obtained by this embodiment are both smaller than the guide value of the xylene emission rate specified in the VOC guidelines, and are suitable for use in displays. Can be determined.

  As a result of mounting these sample A and sample B transformers on a display that is actually a product and measuring them by the chamber method according to the VOC guidelines, the xylene emission rate (emission rate after 5 hours) of sample A is 5 μg / h. The xylene emission rate (emission rate after 5 hours) of Sample B was 41 μg / h, and showed a good correlation with the VOC emission rate (evaluation value) obtained by this embodiment. From this, it was confirmed that there is no problem even if the VOC emission rate is measured by the VOC measurement method according to the present embodiment and the suitability for use in a product is determined based on the result.

  Note that, as described above, in the case of a sample (sample A) having a low emission rate, the VOC emission rate (evaluation value) obtained in this embodiment may be smaller than the VOC emission rate actually measured by the chamber method. . This is because, in the case of a sample with a low emission rate, the peak time is delayed compared to a sample with a high emission rate. However, since there is no possibility that the VOC emission rate exceeds the guide value in a sample with a low VOC emission rate, the VOC emission rate (evaluation value) obtained by the method of this embodiment is actually the chamber method in the case of a sample with a low emission rate. Even if it becomes smaller than the VOC emission rate measured in (1), there is no problem. On the other hand, for a sample with a high emission rate, the VOC emission rate (evaluation value) obtained by the method of this embodiment is a value larger than the VOC emission rate measured according to the VOC guidelines. In other words, it is possible to determine the suitability of using a product with a sufficient margin for a part having a high diffusion rate.

  The display used in the above measurement example used only one power transformer. For example, a desktop personal computer or the like has a plurality of transformers as VOC generation sources, or the generation source is called a transformer and an adhesive. There may be multiple types. In these cases, the VOC emission rate may be measured for each part (or member), and those values may be added to estimate the VOC emission rate of the entire product. Moreover, this embodiment can also be applied to the measurement of the VOC emission rate of the housing | casing used for a personal computer etc.

(Second Embodiment)
As described above, in the first embodiment, a certain amount of gas is sampled from the sampling bag 21, and the VOC contained therein is separated for each component by the measuring device 23 (VOC monitor or the like) to perform quantitative analysis. However, since the above-described VOC monitor uses a chromatographic method to separate VOC into each component, measurement takes time. Further, when the number of times of gas sampling is increased, the amount of gas in the bag 21 is reduced and the measurement accuracy of the concentration is lowered. Therefore, the number of samplings is limited.

 Therefore, in the second embodiment, a VOC measurement method that does not require sampling for measuring the VOC concentration and can perform more rapid measurement will be described. FIG. 10 is a schematic diagram showing a VOC measurement method according to the second embodiment. In FIG. 10, the sampling bag 21 and the measuring instrument 23 are the same as those in the first embodiment, and detailed description thereof is omitted. In the following description, the measuring device 23 is referred to as a VOC measuring device 23 for convenience of description.

 As shown in FIG. 10, the sampling bag 21 contains a sample 22, a clean gas, and a TVOC (Total Volatile Organic Compounds) measuring device 24 (or a sensor portion of the TVOC measuring device 24). The Here, the TVOC measuring instrument is a measuring instrument that can detect at least toluene, xylene, ethylbenzene, styrene, and paradichlorobenzene. In the present embodiment, a TVOC monitor FTVR-01 manufactured by Figaro Giken is used as the TVOC measuring device 24.

 The TVOC measuring device 24 is a passive measuring device including a semiconductor gas sensor, and can measure the TVOC concentration without sampling the gas in the sampling bag 21. The TVOC measuring device 24 outputs the concentration of all VOC components as a toluene equivalent concentration.

 The TVOC measuring device 24 cannot measure a plurality of types of VOCs by separating them into concentrations for each component. Therefore, in the second embodiment, a conversion coefficient (concentration of VOC component / TVOC concentration) is calculated based on the correlation between the concentration of each VOC component measured by the VOC measuring device 23 and the TVOC concentration measured by the TVOC measuring device 24. To do. By multiplying the TVOC concentration by this conversion coefficient, the concentration of the VOC component of interest is obtained.

 The conversion database 26 stores the above-described conversion coefficient. Further, when evaluating the VOC emission rate of the sample, the information processing device 27 reads a conversion coefficient corresponding to the type of the sample from the conversion database 26 and converts the TVOC concentration into a predetermined VOC component concentration.

 The conversion factor is obtained by the following procedure. First, the sample 22, the TVOC measuring device 24 (or its sensor unit), and gas are sealed in the sampling bag 21. Next, the gas in the sampling bag 21 is sampled after elapse of a certain time from the enclosure, and the VOC concentration is measured by the VOC measuring device 23. Simultaneously with the sampling, the TVOC measuring device 24 measures the TVOC concentration.

 Next, a conversion coefficient for each VOC component is obtained based on the correlation between the TVOC concentration measured by the TVOC measuring device 24 and the concentration of each VOC measured by the VOC measuring device 23. This conversion coefficient is calculated for each VOC component as the ratio of the VOC concentration to the TVOC concentration (VOC concentration / TVOC concentration). The conversion coefficient is obtained as described above.

 If the parts have the same model number, the VOC components to be dissipated are the same, so that the VOC concentration can be obtained using the same conversion factor even if the individual or the production lot changes. On the other hand, when the type numbers are different even between parts of the same type, the VOC components to be diffused or their ratios are different, so that it is generally impossible to obtain an accurate VOC concentration even if the same conversion factor is used. Therefore, it is preferable to obtain the conversion coefficient by measuring the correlation between the TVOC and the concentration of each VOC component for each sample type (part type number).

 By the way, it is necessary to evaluate the VOC concentration for components having a large emission amount (emission rate) among the regulated substances. Therefore, paying attention to a component with a large amount of emission or a component with a high emission rate and a high ratio to the guideline value (emission rate from the sample / dissipation rate of the guideline value), the conversion coefficient and VOC concentration are calculated only for that component. Also good. As a result, it is possible to efficiently determine whether or not a component is suitable for use in a product.

 In the present embodiment, the VOC emission rate of the sample using the TVOC measuring device 24 is evaluated according to the following procedure. First, the sample 22, the TVOC measuring device 24, and the gas (air or nitrogen) are sealed in the sampling bag 21, and the TVOC measuring device 24 measures the time change of the TVOC concentration in the gas.

 Next, the time change of the concentration of the VOC component of interest is obtained by multiplying the measurement result of the TVOC concentration by a conversion coefficient corresponding to the VOC component of interest. Then, from the temporal change in the concentration of the VOC component of interest, the dissipation rate of the VOC component of interest is obtained from equation (2) of the first embodiment.

Next, in the same procedure as in the first embodiment, at least one of the increase coefficient K _ON due to operation and the change coefficient K _VENT due to ventilation is multiplied to obtain an evaluation value of the dissipation rate when measured by the chamber method. Based on the evaluation value, the suitability when used for a part product is evaluated.

 As described above, in this embodiment, the VOC emission rate of the sample 22 is evaluated using the TVOC measuring instrument 24 without sampling the gas by obtaining the conversion coefficient. In addition, since the TVOC measuring device 24 using the semiconductor gas sensor completes the measurement in a shorter time than the VOC monitor using the chromatograph, the time required for the VOC measurement can be shortened.

  Hereinafter, the VOC measurement method according to the second embodiment will be described in more detail with reference to measurement examples.

(Measurement Example 3)
In Measurement Example 3, a conversion coefficient was obtained for the power supply transformer (sample X) for display. First, a Tedlar bag having a capacity of 20 L was prepared as a sampling bag. Then, after cutting a part of the Tedlar bag and inserting the sample X and the sensor part of the TVOC measuring device (figaro Giken personal TVOC monitor FTVR-01), the cut part was sealed by thermocompression bonding. Next, the cock at the inlet provided in the Tedlar bag was opened and the vacuum was drawn to discharge the gas in the bag. Thereafter, 20 L of clean nitrogen gas was introduced into the Tedlar bag into which the sample X was inserted over a period of 10 minutes at a flow rate of 2 L / min, and then the cock was closed.

 And 1 hour after closing the cock, the gas in the bag was sampled, and the concentration of each VOC component was measured with a VOC measuring device (VOC monitor JHV-1000 manufactured by JMS). Simultaneously with sampling, the TVOC concentration in the bag was measured with a TVOC measuring device.

(Calculation of conversion factor)
FIG. 11 is a diagram showing measurement results and conversion factors for each VOC component concentration and TVOC concentration in Measurement Example 3. Based on the measurement results shown in FIG. 11, a value obtained by dividing each VOC component concentration by the measured value of TVOC was calculated as the conversion coefficient of sample X. For example, the conversion factor of xylene is 1895/6586 = 0.288.

 From the results of FIG. 11, it can be seen that Sample X has a high concentration of xylene and ethylbenzene and a conversion factor. According to the guideline value established by JEITA, the emission rate allowed for ethylbenzene is larger than the emission rate allowed for xylene. Therefore, the ratio of the emission rate of each component to the guide value (emission rate from the sample / guide value of the emission rate) is greater for xylene than for ethylbenzene. Therefore, it is understood that it is necessary to pay attention to the emission rate of xylene in the screening for the same type of sample (trans) as the sample X.

 In Measurement Example 3, the TVOC concentration of one sample X was measured only once to obtain a conversion coefficient. However, in order to increase the accuracy, the TVOC concentration of one sample X was measured several times over time. The conversion factor may be obtained by measurement. Alternatively, the conversion coefficient may be obtained statistically by measuring the TVOC concentration of a plurality of samples of the same type as the sample X a plurality of times.

(Measurement Example 4)
Next, the VOC emission rate was evaluated for the sample Y (transformer) of the same type as the sample X. First, a part of the Tedlar bag was cut, the sample Y and the sensor part of the TVOC measuring instrument were inserted, and then the cut part was sealed by thermocompression bonding. Next, the cock at the inlet was opened, and after evacuating and discharging the internal gas, 20 L of clean nitrogen was introduced at 2 L / min over 10 minutes, and the cock was closed. Then, TVOC was measured with a TVOC meter every two minutes immediately after the cock was closed. In addition, the sample OC was measured for TVOC under the same conditions.

  As a result of the measurement, the result shown in FIG. 12 was obtained. FIG. 12 is a diagram illustrating the TVOC measurement result of Measurement Example 4. FIG. 13 is a graph showing xylene concentration (converted value) obtained by multiplying the measurement result shown in FIG. 12 by the xylene conversion coefficient of 0.288 obtained in Measurement Example 3.

  Next, the xylene emission rate of the sample Y is calculated based on the result of FIG.

Than 13, xylene concentration in the sampling bag encapsulating sample Y is 15 minutes after after encapsulation is 225μg / m ^3, 45 minutes after encapsulation was 930μg / m ^3. Thereby, the diffusion rate from 15 minutes to 45 minutes after encapsulation becomes 28.2 μg / h as shown in the following formula (15).

図１４は、図１３に示す曲線を微分し、清浄気体の封入量を乗じた結果を示す図である。図１４に示すように図１３のキシレン濃度の変化からキシレンの放散速度を求めることができる。

FIG. 14 is a diagram showing a result of differentiating the curve shown in FIG. 13 and multiplying by the amount of clean gas enclosed. As shown in FIG. 14, the emission rate of xylene can be obtained from the change in the xylene concentration in FIG.

In addition, as a simpler screening test of the sample X, it may be checked whether or not the xylene concentration (converted value) after a certain time has elapsed after gas filling is equal to or less than a predetermined reference value. Here, for example, for a display transformer, the reference value of the xylene emission amount 30 minutes after the start of measurement is set to 100 μg or less (corresponding to the peak value of the emission rate of 200 μg / h) in consideration of the margin for the guideline value. The reference value of the emission amount corresponds to a xylene concentration of 5000 μg / m ³ (= 100 μg ÷ (20 L / 1000 L / m ³ )) or less when 20 L of gas is used as in Measurement Example 4. Therefore, 30 minutes after gas filling, the TVOC concentration is measured and converted to the xylene concentration. If the converted xylene concentration is (5000 μg / m ³ ) or less, the sample X can be determined as a usable part. According to the result of the measurement example 4 (FIG. 13), it can be seen that both the sample X and the sample Y satisfy this criterion because the xylene concentration (converted value) after 30 minutes is 5000 μg / m ³ or less.

(Measurement Example 5)
In measurement example 5, the result of obtaining the VOC emission rate for the sample A (transformer) of measurement example 1 (first embodiment) by the method shown in the second embodiment will be described.

 First, the sample A (transformer) and the sensor portion of the TVOC measuring device were inserted into the Tedlar bag, and then the opening of the Tedlar bag was sealed by thermocompression bonding. Next, the cock at the inlet provided in the Tedlar bag was opened and the vacuum was drawn to discharge the gas in the bag.

 Next, 20 L of clean nitrogen gas is introduced into the Tedlar bag into which the sample A is inserted at a flow rate of 2 L / min for 10 minutes, and then the cock is closed, and the TVOC measuring device starts measuring the TVOC concentration in the bag. did.

The TVOC concentration 15 minutes after the start of gas introduction was 90 μg / m ³ . The TVOC concentration after 1 hour and 15 minutes from the start of gas introduction was 520 μg / m ³ . By multiplying these values by the conversion factor 0.288 to the xylene concentration measured in advance, the xylene concentration after 15 minutes (converted value) 25.9 μg / m ³ and the xylene concentration after 1 hour 15 minutes (converted value) 149.8 μg / m ³ is obtained. From this concentration and equation (2), the release rate was about 2.5 μg / h.

  After that, the correction coefficient is calculated based on the formula (3), and the emission rate when measured by the chamber method is estimated by multiplying the emission rate, and even if it is incorporated in the product, it does not exceed the guideline value of the VOC guidelines. I was able to confirm.

  Regarding the above embodiment, the following additional notes are disclosed.

(Appendix 1) Enclosing a sample and gas in a bag;
Measuring the concentration of the volatile organic compound contained in the gas a plurality of times over time;
Calculating the emission rate of the volatile organic compound from the measurement result of the concentration;
And a step of correcting the value of the emission rate according to the temperature of the sample.

 (Supplementary note 2) The method for measuring a volatile organic compound according to supplementary note 1, further comprising correcting the value of the emission rate according to the number of ventilations when the sample is used in an environment in which ventilation is possible.

(Supplementary Note 3) The correction of the diffusion rate according to the ventilation rate is made by changing the ventilation rate per unit time to n, the concentration of the volatile organic compound immediately after injecting the gas into the bag to Z ₀ , and volatilization after Δt time. Supplementary note 2 characterized by being performed by multiplying (n · Δt / (1 + n · Δt)) × (Z ₁ / (Z ₁ −Z ₀ )) when the concentration of the organic compound is Z ₁ The volatile organic compound measuring method as described in 2.

(Supplementary Note 4) The volatile organic compound emission rate is determined such that the concentration of the volatile organic compound immediately after injecting the gas into the bag is Z ₀ , the concentration of the volatile organic compound after Δt time is Z ₁ , and the bag The method for measuring a volatile organic compound according to appendix 1 or 2, wherein the calculation is performed by (Z ₁ −Z ₀ ) × V _N / Δt, where V _N is an amount of the gas enclosed.

 (Supplementary Note 5) The correction of the diffusion rate according to the temperature of the sample is performed by multiplying the ratio of the diffusion rate at normal temperature and the diffusion rate at the temperature of the sample during operation. The method for measuring a volatile organic compound according to appendix 1 or 2.

(Appendix 6) Enclosing a sample and gas in a bag;
Measuring the concentration of the volatile organic compound contained in the gas a plurality of times over time;
Calculating the emission rate of the volatile organic compound from the measurement result of the concentration;
And a step of correcting the value of the emission rate in accordance with the number of ventilations when the sample is used in a ventilable environment.

 (Supplementary note 7) The volatile organic compound measuring method according to supplementary note 3 or 4, wherein the Δt time is 2 hours or less.

 (Appendix 8) In the step of measuring the concentration of the volatile organic compound, the gas in the bag is sampled, and the sampled volatile organic compound is quantitatively analyzed for each component. 8. The method for measuring a volatile organic compound according to any one of 7 above.

  (Supplementary Note 9) In the step of measuring the concentration of the volatile organic compound, the total volatile organic compound concentration of the gas in the bag is measured, and the conversion to convert the total volatile organic compound concentration into the volatile organic compound concentration The method for measuring a volatile organic compound according to any one of appendices 1 to 7, wherein a coefficient is multiplied.

(Appendix 10) The conversion factor is
Enclose a sample and gas of the same type as the sample in a bag,
Sampling the gas from the bag, quantitative analysis of volatile organic compounds for each component from the sampled gas,
Measure the total volatile organic compound concentration of the gas simultaneously with the sampling,
The volatile organic compound measuring method according to appendix 9, wherein the concentration of each component of the volatile organic compound is determined by dividing the concentration by the total volatile organic compound concentration.

  (Additional remark 11) The said conversion factor is calculated about the component with a high ratio with respect to the predetermined | prescribed guideline value of a diffusion rate among the components with a high density | concentration among each component of the said volatile organic compound, or each component of the said volatile organic compound. The method for measuring a volatile organic compound according to appendix 9, wherein:

  (Additional remark 12) It is characterized by calculating | requiring a density | concentration about the component with a high ratio with respect to the predetermined guideline value of a diffusion rate among the components with a high density | concentration among each component of the said volatile organic compound, or each component of the said volatile organic compound, It is characterized by the above-mentioned. The volatile organic compound measuring method according to any one of Supplementary notes 1 and 7.

(Supplementary note 13) Enclosing a sample and gas in a bag;
Sampling the gas in the bag;
Measuring the concentration of total volatile organic compounds contained in the gas simultaneously with the sampling;
A step of quantitatively analyzing, for each component, a volatile organic compound contained in the sampled gas;
Conversion factor for converting the concentration of the total volatile organic compound into the concentration of each component of the volatile organic compound based on the measurement result of the concentration of the total volatile organic compound and the measurement result of the concentration of each component of the volatile organic compound The process of seeking
A method for measuring a volatile organic compound, comprising:

(Additional remark 14) The process of enclosing a sample and gas in a bag,
A step of measuring the total volatile organic compound concentration in the gas after elapse of a certain time after enclosing the sample in a bag;
Multiplying the total volatile organic compound concentration by a conversion factor to convert to a volatile organic compound concentration;
Obtaining a diffusion rate of the volatile organic compound from the concentration of the volatile organic compound obtained by the multiplication;
And a step of evaluating the quality of the sample by comparing the emission rate with a preset value.

FIG. 1 is a diagram showing a configuration example of a VOC measurement system based on a chamber method used for measuring a VOC emission rate. FIG. 2 is a diagram showing measurement conditions for the VOC emission rate defined by the VOC guidelines. FIG. 3 is a diagram showing guide values for the emission rate of each regulated substance defined by the VOC guidelines. FIG. 4 is a schematic diagram showing a VOC measurement method according to the first embodiment. FIG. 5 (a) is a graph showing the results of measuring the change in VOC (xylene) concentration in the bag containing two samples (sample A and sample B), and FIG. 5 (b) is a graph of FIG. 5 (a). It is a figure which converts the xylene density | concentration of a vertical axis | shaft into xylene emission amount, and shows it. FIG. 6 is a diagram showing the change over time in the VOC emission rate when measured by the chamber method. FIG. 7 is a diagram collectively showing measurement conditions, measurement timing of VOC concentration, measured value of VOC (xylene) concentration, calculated value of emission rate, and increase coefficient Kon due to operation in Measurement Example 2. FIG. 8 is a diagram illustrating an example of a method for setting the temperature of the sampling gas to room temperature. FIG. 9 is a diagram showing the results of measuring the VOC dissipated from the power transformer by the chamber method. FIG. 10 is a schematic diagram illustrating a VOC measurement method according to the second embodiment. FIG. 11 is a diagram showing measurement results and conversion factors for each VOC component concentration and TVOC concentration in Measurement Example 3. FIG. 12 is a diagram illustrating a TVOC measurement result of Measurement Example 4. FIG. 13 is a diagram showing the xylene concentration (converted value) obtained by multiplying the measurement result shown in FIG. 12 by the xylene conversion coefficient of 0.288 obtained in Measurement Example 3. FIG. 14 is a diagram showing a result of differentiating the curve shown in FIG. 13 and multiplying by the amount of clean gas enclosed.

Explanation of symbols

11 ... Air control unit,
12 ... mixing tank,
13, 31 ... constant temperature bath,
14 ... Chamber 15 ... Gas chromatograph analyzer,
16 ... TENAX tube,
17 ... Sampling pump,
21 ... Sampling bag,
22 ... Sample,
23 ... Measuring instrument,
24 ... TVOC measuring instrument,
26 ... Conversion database,
27. Information processing device,
32 ... pump,
33a, 33b ... piping,
34 ... Cooler,
35 ... Sampling port.

Claims (4)

A method for measuring the emission rate of a volatile organic compound released from a sample in an evaluation target environment,
Enclosing the sample in a bag;
Injecting a gas into the bag in which the sample is sealed for a certain period of time;
Measuring the concentration of the volatile organic compound contained in the gas in the bag multiple times over time; and
Calculating the emission rate of the volatile organic compound from the measurement result of the concentration;
Possess a step of correcting the difference between the temperature and the temperature of the evaluation target environment in the process of measuring the concentration of the volatile organic compound, the value of the emission rate in accordance with the air exchange rate in the evaluation environment,
In the step of measuring the concentration of the volatile organic compound, the amount of gas collected from the bag is smaller than the total amount of gas in the bag . The volatile organic compound according to claim 1 , wherein in the step of measuring the concentration of the volatile organic compound, the gas in the bag is sampled, and the sampled volatile organic compound is quantitatively analyzed for each component. Organic compound measurement method. In the step of measuring the concentration of the volatile organic compound, the conversion factor for measuring the total volatile organic compound concentration of the gas in the bag and converting the total volatile organic compound concentration into a specific volatile organic compound concentration The volatile organic compound measuring method according to claim 1 , wherein the volatile organic compound measuring method is multiplied. Regarding the component having a high concentration among the components of the volatile organic compound contained in the gas or the component having a large ratio to the predetermined guideline value of the emission rate among the components of the volatile organic compound contained in the gas, the conversion 4. The volatile organic compound measuring method according to claim 3 , wherein a coefficient is calculated.

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