Method for rapid detection of main components of dry powder extinguishing agent

Abstract

The present application belongs to the field of fire extinguishing agent component detection, and particularly relates to a method for rapidly detecting main components of dry powder fire extinguishing agent. The present application combines XRF fluorescence detection method with ultraviolet spectrophotometry, and creatively determines the relationship between the screening value in the present application and the main components in the fire extinguishing agent, so that the fire extinguishing agent can be rapidly detected to determine whether the quality is qualified, thereby providing a new idea for the detection of dry powder fire extinguishing agent. Moreover, the obviously adulterated sample can be distinguished within 120s of detection time, and the first component of the dry powder fire extinguishing agent can be quantified only by 30 minutes or so of pretreatment and color development time by using the rapid quantitative method. Compared with the traditional national standard method which needs more than 5 hours of detection time, the detection efficiency is greatly improved, the experimental condition requirement is low, the sensitivity is high, the accuracy is good, the selectivity is excellent, the reagent used is environmentally friendly, the detection result is ensured to be rapid and accurate, the on-site sampling and detection can be realized, and the present application is suitable for various scenes.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of detection of fire extinguishing agent components, and particularly relates to a method for rapidly detecting main components of dry powder fire extinguishing agent. BACKGROUND

[0002] Dry powder fire extinguishing agent is a dry and easily flowing fine powder used for fire extinguishing, which is composed of inorganic salts (main components) with fire extinguishing efficiency and a small amount of additives through drying, crushing and mixing into fine solid powder, and is generally divided into two categories of BC dry powder fire extinguishing agent (sodium bicarbonate) and ABC dry powder (ammonium phosphate salt).

[0003] The main reason why dry powder fire extinguishing agent can play a role in fire extinguishing lies in the main components, and the specific principle is as follows: (1) inhibiting chemical reaction: the main components in the dry powder fire extinguishing agent can react with the chemical substances in the flame to inhibit the chemical reaction process of the flame; (2) heat absorption and temperature reduction: the main components in the dry powder fire extinguishing agent have high heat absorption capacity, can quickly absorb the heat around the flame, reduce the temperature of the flame, make the flame lose the condition to continue burning, and cause the flame to be extinguished; (3) preventing the spread of flame: the dry powder fire extinguishing agent forms a dust layer formed by the main components and auxiliary components on the fire source, which can effectively prevent the spread of the flame; (5) reducing the burning rate: the main components in the dry powder fire extinguishing agent can react with the combustible substances in the flame to generate inert substances, thereby reducing the burning rate to slow down the spread of the fire.

[0004] The content of the main components in the dry powder fire extinguishing agent becomes a main factor for measuring whether the dry powder fire extinguishing agent is qualified, and the traditional national standard method often uses quinoline molybdenum citone method for determination. The method is to mix the phosphorus solution to be measured with a certain amount of quinoline molybdenum citone solution, and react under acidic conditions for a certain time. During the reaction process, the phosphate ion reacts with quinoline molybdenum citone to generate a yellow complex. Then, the reaction product is separated by filter paper or other appropriate methods to obtain a solid containing the complex. Finally, by weighing the mass change of the dried complex, the mass of the phosphate ion can be calculated, so as to determine the content of ammonium dihydrogen phosphate. However, this method takes too long detection time, and often needs more than 5 hours of detection time, which is not suitable for rapid detection on site. Therefore, how to rapidly and accurately detect the dry powder fire extinguishing agent on site has become a problem to be solved in the field. SUMMARY

[0005] In order to solve the above technical problems, the application provides a method for rapidly detecting main components of dry powder extinguishing agent, and after determining the screening value, further detection is carried out according to the screening value, so that the content of the main components in the dry powder extinguishing agent can be detected, and the content can be rapidly detected on site to rapidly judge whether the extinguishing agent is qualified, thereby solving the problem that the main components in the dry powder extinguishing agent cannot be rapidly and accurately detected to judge the quality of the extinguishing agent.

[0006] The technical scheme of the application is as follows:

[0007] The application provides a method for rapidly detecting main components of dry powder extinguishing agent, comprising the following steps:

[0008] S1, using XRF fluorescence detection method to detect the extinguishing agent sample, and if the content is lower than the screening value, it is determined as an unqualified sample;

[0009] The screening value is denoted as V, and the calculation method is as follows:

[0010] V=M-KxR / Sx100%;

[0011] R=M+(0.75+2.5xM)%;

[0012] Wherein, M takes the minimum value of the published value of the first main component content in GB 4066-2017, and M is 75%;

[0013] S is the content of all main components, and S is 90%;

[0014] R is the content of any main component;

[0015] K is a correction coefficient, and K=0.116;

[0016] S2, using ultraviolet spectrophotometry to detect the sample greater than or equal to the screening value, if the detection value is lower than 75%, it is determined as an unqualified sample; if the detection value is greater than or equal to 75%, it is determined as a qualified sample.

[0017] The detection method process is as shown in Figure 1 .

[0018] Preferably, in S1, the extinguishing agent sample is subjected to mixing treatment, and the specific treatment method is as follows:

[0019] S11, preparation: safety inspection is carried out on the dry powder extinguishing agent, and a clean container is prepared for collecting the ejected dry powder extinguishing agent, then the safety pin is pulled out, and the nozzle of the extinguisher is pointed to a safe area;

[0020] S12, ejecting dry powder extinguishing agent: pressing the handle of the extinguisher, the dry powder extinguishing agent is ejected into the prepared container;

[0021] S13, collecting sample: quickly move the container to a safe area, seal the container, stand, then mix the sample thoroughly to obtain a mixed sample.

[0022] The standing time is 15 minutes.

[0023] Preferably, in S1, the detection step of the XRF fluorescence detection method is as follows:

[0024] (1) Establishing a standard curve: 2 g, 4 g, 6 g, 8 g, 10 g, 12 g, and 15 g of ammonium dihydrogen phosphate were respectively weighed and mixed with 18 g, 16 g, 14 g, 12 g, 10 g, 8 g, and 5 g of silicon dioxide, and ground with a quartz mortar to form 20 g of a uniform standard sample, and the content of ammonium dihydrogen phosphate in the standard sample was 10%, 20%, 30%, 40%, 50%, 60%, and 75%, respectively.

[0025] The instrument was preheated to stabilize, the tube pressure, tube flow, and working parameters of the instrument were set according to the recommended parameters of the XRF spectrometer, the prepared standard sample was placed on the measurement window position, and the fluorescence intensity of phosphorus element of each standard sample was measured under the specified operating conditions, and the working curve was drawn with the phosphorus content of the standard sample as the vertical coordinate and the measured phosphorus element X-ray fluorescence intensity (Icps) of the standard sample as the horizontal coordinate.

[0026] (2) Sample preparation: the mixed sample was placed in a sample cup and compacted with a quartz rod for standby;

[0027] (3) Sample measurement: the sample was measured for X-ray fluorescence intensity of phosphorus element under the same analysis conditions as the calibration curve.

[0028] The sample measurement result is expressed as follows:

[0029] The X-ray fluorescence intensity (Icps) of phosphorus element in the sample was measured by experiment, the corresponding phosphorus content was obtained through the standard curve, and the content of ammonium dihydrogen phosphate in the sample was obtained through the conversion coefficient, and the content of ammonium dihydrogen phosphate was calculated according to formula (1):

[0030]

[0031] In the formula,

[0032] w1 is the mass fraction of ammonium dihydrogen phosphate, %;

[0033] w is the phosphorus content of the sample, %;

[0034] 30.97 is the molar mass of phosphorus element, g / mol;

[0035] 115.028 - molar mass of ammonium dihydrogen phosphate, g / mol.

[0036] Preferably, in S2, the step of detecting by ultraviolet spectrophotometry is as follows:

[0037] A, establishment of standard curve: 0.0 mL, 0.25 mL, 0.5 mL, 1.0 mL, 1.5 mL, 2.0 mL, and 2.5 mL of the phosphorus standard solution were respectively taken into 7 100 mL volumetric flasks, and all were diluted to 100 mL with water. The concentrations of phosphorus in the 7 standard curve solutions were 0.0 mg / L, 0.05 mg / L, 0.10 mg / L, 0.20 mg / L, 0.30 mg / L, 0.40 mg / L, and 0.50 mg / L, respectively;

[0038] B, colorimetric determination: 2 mL of the molybdate solution and 1 mL of the ascorbic acid solution were respectively added to the standard curve solutions. After color development at room temperature (20-25 °C) for 15 min, the absorbance value was determined at 720 nm using a 30 mm optical path cuvette with water as the reference. The determination was completed within 30 min. The absorbance value of the blank test was subtracted as the ordinate, and the phosphorus concentration (mg / L) was the abscissa. The standard curve was plotted.

[0039] C, sample solution preparation: about 0.1 g (accurate to 0.01 g) of the dry powder fire extinguant sample was weighed into a quartz mortar and 2 mL of acetone was added. The sample was continuously stirred to remove the silicon film on the surface of the fire extinguant powder. After the acetone was evaporated, 5-10 mL of water (60-70 °C) was added to dissolve and filter the sample. The insoluble matter on the filter paper was washed with 25 mL of water for 3-5 times. The filtrate and washing liquid were collected in a 50 mL volumetric flask and then diluted to the mark with water. 0.1 mL of the above liquid was taken into a colorimetric tube and diluted to the mark with water, which was the sample solution to be determined.

[0040] D, sample solution determination: 2 mL of the ammonium molybdate solution and 1 mL of the ascorbic acid solution were added to the sample solution to be determined. After color development at room temperature for 15 min, the absorbance value was determined at 720 nm using a 30 mm optical path cuvette with water as the reference. The determination was completed within 30 min.

[0041] The determination results of the sample solution are expressed as follows:

[0042] The content of ammonium dihydrogen phosphate was calculated according to formula (2):

[0043]

[0044] In the formula:

[0045] w1 - mass fraction of ammonium dihydrogen phosphate, %;

[0046] A - absorbance value of the sample solution;

[0047] A0-absorbance of the blank sample;

[0048] a-intercept of the standard curve;

[0049] b-slope of the standard curve;

[0050] m-mass of the dry powder extinguishing agent sample, g;

[0051] 50-volume of the sample solution, mL;

[0052] 1000-dilution factor of taking 0.1 mL of the sample solution into a 100 mL colorimetric tube and diluting to the volume;

[0053] 10 -6 conversion factor;

[0054] 30.97-molar mass of phosphorus, g / mol;

[0055] 115.028-molar mass of ammonium dihydrogen phosphate, g / mol.

[0056] The present application obtains a formula for calculating the screening value according to a large number of experiments and data thereof, and determines a correction coefficient through a large number of trial and error and calculation, and the formula can be used to accurately determine the extinguishing agent.

[0057] The present application has the beneficial effects that:

[0058] (1) The present application combines XRF fluorescence detection method with ultraviolet spectrophotometry, and creatively determines the relationship between the screening value in the present application and the main components in the extinguishing agent, so that the extinguishing agent can be quickly detected to determine whether the quality is qualified, and a new idea is provided for the detection of dry powder extinguishing agent;

[0059] (2) The present application can distinguish the obviously adulterated sample within 120 s of detection time, and the rapid quantitative method only needs about 30 minutes of pretreatment and coloration time to quantitatively determine the first component of the dry powder extinguishing agent; compared with the traditional national standard method which needs more than 5 hours of detection time, the detection efficiency is greatly improved, the experimental condition requirement is low, the sensitivity is high, the accuracy is good, the selectivity is excellent, the reagent used is environmentally friendly, the detection result is fast and accurate, and the on-site sampling and detection are realized. BRIEF DESCRIPTION OF DRAWINGS

[0060] Figure 1 The present application is a detection method flowchart. DETAILED DESCRIPTION

[0061] In order to enable those skilled in the art to better understand the present application, the present application will be further described in conjunction with specific embodiments.

[0062] Example 1

[0063] Experimental instruments:

[0064] A method for rapid detection of main components of dry powder extinguishing agent, comprising the following steps:

[0065] S1, using XRF fluorescence detection method to detect the extinguishing agent sample, lower than the screening value, then determine as unqualified sample;

[0066] The screening value is denoted as V, and the calculation method is as follows:

[0067] V=M-K×R / S×100%;

[0068] R=M+(0.75+2.5×M)%;

[0069] Wherein, wherein, M takes the minimum value of the first main component content published value in GB 4066-2017, M is 75%;

[0070] S is the content of all main components, S is 90%;

[0071] R is the content of any main component;

[0072] K is the correction coefficient, K=0.116;

[0073] Wherein the extinguishing agent sample is mixed and treated, and the specific treatment method is as follows:

[0074] Safety inspection: first ensure that the fire extinguisher is in a safe state, no signs of damage or leakage; check if the pressure indicator is normal, and if the safety pin is intact.

[0075] Prepare tools: prepare a clean container for collecting the ejected dry powder extinguishing agent, which should be large enough to contain the required sample amount.

[0076] Pull out the safety pin: according to the use instructions of the fire extinguisher, pull out the safety pin or safety pin.

[0077] Point to a safe area: point the nozzle of the fire extinguisher to a safe, windless or low wind area to avoid blowing the dry powder away.

[0078] Short spray: gently press the pressure handle of the fire extinguisher for 5 short sprays to spray some dry powder extinguishing agent into the prepared container, note that do not completely release all the dry powder in the fire extinguisher to avoid affecting its future use.

[0079] Collect samples: quickly move the container to a safe area and seal the container to prevent the sample from being contaminated, and use the "four division method" to mix the sample evenly after 15 min.

[0080] Disposal of remaining dry powder: clean the spray area and dispose of the remaining dry powder extinguishing agent properly.

[0081] The detection step of the XRF fluorescence detection method is as follows:

[0082] (1) Establishment of standard curve: 2 g, 4 g, 6 g, 8 g, 10 g, 12 g, and 15 g of ammonium dihydrogen phosphate were respectively weighed and mixed with 18 g, 16 g, 14 g, 12 g, 10 g, 8 g, and 5 g of silicon dioxide, and ground with a quartz mortar to form 20 g of uniform standard sample, and the content of ammonium dihydrogen phosphate in the standard sample was 10%, 20%, 30%, 40%, 50%, 60%, and 75% respectively;

[0083] The instrument was preheated to be stable, the tube pressure, tube flow, and working parameters of the instrument were set according to the recommended parameters of the XRF spectrometer, the prepared standard sample was placed on the measurement window position, and the fluorescence intensity of phosphorus element of each standard sample was measured under the specified operating conditions, and the working curve was drawn with the phosphorus content of the standard sample as the vertical coordinate and the measured phosphorus element X-ray fluorescence intensity (Icps) of the standard sample as the horizontal coordinate;

[0084] For the requirement of on-site rapid detection, the standard curve can be established in the laboratory, and the accuracy of the calibration curve should be verified regularly, and the verification frequency is required by the XRF spectrometer instruction manual or 3 months, and the verification is performed at a shorter time interval. When verifying, one of the standard substances used to make the calibration curve can be selected, and the deviation analysis is performed on the test result and the standard value or reference value of the standard substance, and when the relative standard deviation is greater than 15%, recalibration is performed until it is qualified.

[0085] (2) Sample preparation: the mixed sample was placed in a sample cup and compacted with a quartz rod for standby;

[0086] (3) Sample measurement: the sample was measured for X-ray fluorescence intensity of phosphorus element under the same analysis conditions as the calibration curve.

[0087] The expression of the sample measurement result is as follows:

[0088] The X-ray fluorescence intensity (Icps) of phosphorus element in the sample was measured by experiment, the corresponding phosphorus content was obtained through the standard curve, and the content of ammonium dihydrogen phosphate in the sample was obtained through the conversion coefficient, and the content of ammonium dihydrogen phosphate was calculated according to formula (1):

[0089]

[0090] In the formula,

[0091] w1 is the mass fraction of ammonium dihydrogen phosphate, %;

[0092] w - phosphorus content of the sample, %;

[0093] 30.97 - molar mass of phosphorus, g / mol;

[0094] 115.028 - molar mass of ammonium dihydrogen phosphate, g / mol.

[0095] The calculation result is rounded to three significant digits.

[0096] Each sample is analyzed in duplicate, and the average value is calculated.

[0097] S2, samples greater than or equal to the screening value are detected by ultraviolet spectrophotometry. If the detection value is less than 75%, the sample is determined to be unqualified; if the detection value is greater than or equal to 75%, the sample is determined to be qualified.

[0098] The step of ultraviolet spectrophotometry detection is as follows:

[0099] A, establishment of standard curve: 0.0 mL, 0.25 mL, 0.5 mL, 1.0 mL, 1.5 mL, 2.0 mL, and 2.5 mL of phosphorus standard solution are respectively taken into 7 100 mL volumetric flasks, and all are diluted to 100 mL with water. The concentrations of phosphorus in the 7 standard curve solutions are 0.0 mg / L, 0.05 mg / L, 0.10 mg / L, 0.20 mg / L, 0.30 mg / L, 0.40 mg / L, and 0.50 mg / L, respectively;

[0100] B, colorimetric determination: 2 mL of molybdate solution and 1 mL of ascorbic acid solution are added to each of the standard curve solutions. After color development at room temperature (20-25°C) for 15 min, the absorbance value is measured at a wavelength of 720 nm using a 30 mm optical path cuvette with water as the reference. The measurement is completed within 30 min. The absorbance value of the blank test is subtracted as the ordinate, and the phosphorus concentration (mg / L) is the abscissa. The standard curve is drawn;

[0101] For the convenience of on-site rapid detection, the standard curve can be established in the laboratory. To ensure measurement quality, each batch of samples should have an intermediate calibration point. The relative error between the determination value of the intermediate calibration point and the concentration of the corresponding point on the standard curve should not exceed 10%;

[0102] C. Sample solution preparation: about 0.1 g (accurate to 0.01 g) of dry powder fire extinguishing agent sample was weighed into a quartz mortar and 2 mL of acetone was added, and stirred constantly to remove the silicon film on the surface of the fire extinguishing agent powder; after the acetone was evaporated, 5-10 mL of water (60-70 °C) was added to dissolve and filter, and the insoluble matter on the filter paper was washed with about 25 mL of water for 3-5 times, and the filtrate and washing liquid was collected in a 50 mL volumetric flask, and then diluted to the mark with water; 0.1 mL of the above liquid was taken into a colorimetric tube and diluted to the mark with water, and the sample solution was obtained;

[0103] D. Sample solution determination: 2 mL of ammonium molybdate solution and 1 mL of ascorbic acid solution were added to the sample solution, and the absorbance value was measured at 720 nm wavelength using a 30 mm optical path cuvette after color development for 15 min at room temperature, and the measurement was completed within 30 min.

[0104] The sample solution determination results are expressed as follows:

[0105] The content of ammonium dihydrogen phosphate is calculated according to formula (2):

[0106]

[0107] In the formula:

[0108] w1 - mass fraction of ammonium dihydrogen phosphate, %;

[0109] A - absorbance of sample solution;

[0110] A0 - absorbance of blank sample;

[0111] a - intercept of standard curve;

[0112] b - slope of standard curve;

[0113] m - mass of dry powder fire extinguishing agent sample, g;

[0114] 50 - sample solution dilution volume, mL;

[0115] 1000 - dilution factor of 0.1 mL sample solution to 100 mL colorimetric tube and dilution;

[0116] 10 -6 - unit conversion factor;

[0117] 30.97 - molar mass of phosphorus element, g / mol;

[0118] 115.028 - molar mass of ammonium dihydrogen phosphate, g / mol.

[0119] The calculation results are rounded to 3 significant figures.

[0120] Each sample was analyzed in parallel twice, and the average value was calculated.

[0121] Six kinds of commercially available dry powder extinguishing agent products were selected, and the same amount of sample was taken for each product, two samples respectively. The traditional national standard method and the above method were used for determination, and the results were shown in Table 1:

[0122] Table 1 Comparison of detection content between the embodiment and the national standard method

[0123]

[0124] The detection time and other parameters were shown in Table 2:

[0125] Table 2 Comparison between the embodiment and the national standard method

[0126]

[0127] As shown in Table 1, the difference between the content determined by the method of the embodiment and the national standard method was not large, but as shown in Table 2, the accuracy of the detection method of the embodiment was high and the detection speed was fast, which could be used for the detection of the main component of the dry powder extinguishing agent, and could be used as a detection method of on-site immediate detection.

Claims

1. A method for rapid detection of the main component of dry powder extinguishing agent, characterized in that, Comprising the following steps: S1, using XRF fluorescence detection method for detecting fire extinguishing agent sample, below the screening value, then determine as unqualified sample; The screening value is denoted as V, and the calculation method is as follows: V = M-K×R / S×100%; R= M+(0.75+2.5×M)%; Wherein, M takes the minimum value of the first main component content published value in GB 4066-2017, M is 75%; S is all the main component content, S takes 90%; R is any main component content; K is the correction coefficient, K=0.116; S2, using ultraviolet spectrophotometry to detect the sample greater than or equal to the screening value, if the detection value is less than 75%, then determine as unqualified sample; if the detection value is greater than or equal to 75%, then determine as qualified sample.

2. The method of claim 1, wherein, In S1, the fire extinguishing agent sample is mixed and treated, and the specific treatment method is as follows: S11, preparation: safety inspection is carried out on the dry powder fire extinguishing agent, and a clean container is prepared for collecting the ejected dry powder fire extinguishing agent, then the safety pin is pulled out, and the nozzle of the fire extinguisher is pointed to the safety area; S12, eject dry powder fire extinguishing agent: press the handle of the fire extinguisher, and eject the dry powder fire extinguishing agent into the prepared container; S13, collect the sample: quickly move the container to the safety area, seal the container, and stand still, then mix the sample thoroughly, and obtain the mixed and treated sample.

3. The method of claim 2, wherein, In S13, the standing time is 15 min.

4. The method of claim 1, wherein, In S1, the detection steps of the XRF fluorescence detection method are as follows: (1) Establishment of standard curve: 2g, 4g, 6g, 8g, 10g, 12g, 15g of ammonium dihydrogen phosphate and 18g, 16g, 14g, 12g, 10g, 8g, 5g of silicon dioxide are mixed, and are ground with a quartz mortar to form 20g of uniform standard sample; Preheat the instrument to stabilize it, set the tube pressure, tube flow and working parameters of the instrument according to the recommended parameters of the XRF spectrometer, place the prepared standard sample on the measurement window position, and measure the fluorescence intensity of phosphorus element of each standard sample under the specified operating conditions, and draw the working curve with the phosphorus content of the standard sample as the vertical coordinate and the measured phosphorus element X-ray fluorescence intensity (Icps) of the standard sample as the horizontal coordinate; (2) Sample preparation: the mixed sample is placed in a sample cup, and is compacted with a quartz rod for standby; (3) Sample determination: the sample is determined for X-ray fluorescence intensity of phosphorus element under the same analysis conditions as the calibration curve.

5. The method of claim 4, wherein, In (1), the content of ammonium dihydrogen phosphate in the standard sample is 10%, 20%, 30%, 40%, 50%, 60% and 75% respectively.

6. The method of claim 1, wherein, In S2, the steps of ultraviolet spectrophotometry detection are as follows: A, establishment of standard curve: 0.0 mL, 0.25 mL, 0.5 mL, 1.0 mL, 1.5 mL, 2.0 mL, 2.5 mL of phosphorus standard solution are respectively taken into 7 100 mL volumetric flasks, and all are diluted to 100 mL with water; B, colorimetric determination: in the standard curve solution, each add 2 mL molybdate solution and 1 mL ascorbic acid solution, colorimetric 15 min at room temperature, using water as reference, using optical path 30 mm cuvette at 720 nm wavelength to determine its absorbance value, 30 min within measurement; deduct the absorbance value of blank test as ordinate, phosphorus concentration mg / L as abscissa, draw standard curve; C, sample solution preparation: take 0.1 g dry powder fire extinguant sample, put in quartz mortar and add 2 mL acetone, continuously stir to remove the silicon film on the surface of fire extinguant powder; After the acetone volatilizes, add 5-10 mL water to dissolve and filter, wash the insoluble on filter paper with 25 mL water for 3-5 times, collect the filtrate and washing liquid with 50 mL volumetric flask, then use water to constant volume; take 0.1 mL from the above liquid to colorimetric tube, dilute to constant volume with water to the scale line, which is the sample solution to be measured; D, sample solution determination: in the sample solution to be measured, add 2 mL ammonium molybdate solution and 1 mL ascorbic acid solution, colorimetric 15 min at room temperature, using water as reference, using optical path 30 mm cuvette at 720 nm wavelength to determine its absorbance value, 30 min within measurement.

7. The method of claim 6, wherein, In A, the concentration of phosphorus in 7 standard curve solutions is respectively 0.0 mg / L, 0.05 mg / L, 0.10 mg / L, 0.20 mg / L, 0.30 mg / L, 0.40 mg / L, 0.50 mg / L.

8. The method of claim 6, wherein, In B, the room temperature is 20-25℃.

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